In JoVE (1)

Other Publications (66)

Articles by Kathryn Sandberg in JoVE

 JoVE Biology

Live Cell Imaging and 3D Analysis of Angiotensin Receptor Type 1a Trafficking in Transfected Human Embryonic Kidney Cells Using Confocal Microscopy

1Department of Biochemistry, Georgetown University Medical Center, 2Department of Medicine, Georgetown University Medical Center, 3Department of Physics, Georgetown University Medical Center, 4Department of Oncology, Georgetown University Medical Center


JoVE 55177

Other articles by Kathryn Sandberg on PubMed

Estradiol Attenuates Angiotensin-Induced Aldosterone Secretion in Ovariectomized Rats* *This Work Was Supported by NIH Grants HL-57502 (to K.S.), AG-16902 (to K.S.), and DK-38094 (to J.G.V.)

Endocrinology. Dec, 2000  |  Pubmed ID: 28200758

Vasopressin V2 Receptor Binding Is Down-Regulated During Renal Escape from Vasopressin-Induced Antidiuresis1

Endocrinology. Jan, 2000  |  Pubmed ID: 28204374

HRT and SERMs: the Good, the Bad...and the Lovely?

Trends in Endocrinology and Metabolism: TEM. Oct, 2002  |  Pubmed ID: 12217481

Recent studies have provided strong evidence that the biological activity of selective estrogen-receptor modulators (SERMs) depends on the conformation of the SERM-receptor complex, the estrogen-receptor-signaling mechanism, and the tissue co-regulator composition. In addition to these new observations, other studies convincingly demonstrate that estrogen has cardioprotective properties, favorably regulating genes that are crucial to vascular physiology. These novel findings could thus be key to generating SERMs that solve the risks currently associated with hormone replacement therapy. In addition, further development could result in SERMs that possess not only anti-estrogenic actions in the breast and uterus, but also estrogenic protective actions in bone and the cardiovascular system.

Introduction: Gender and Kidney Disease

Advances in Renal Replacement Therapy. Jan, 2003  |  Pubmed ID: 12616457

Sex and the Renin Angiotensin System: Implications for Gender Differences in the Progression of Kidney Disease

Advances in Renal Replacement Therapy. Jan, 2003  |  Pubmed ID: 12616459

Two recognized risk factors implicated in the pathogenesis of progressive renal disease are overactivation of the renin angiotensin system and male gender. The peptide hormone, angiotensin II, produced by the renin angiotensin system cascade, plays a crucial role in maintaining blood pressure and electrolyte homeostasis. Medications that block the action of angiotensin II by either inhibiting its synthesis or by blocking its ability to bind its receptor are in wide clinical use because of their ability to significantly retard the progression of kidney disease. Analysis of data from national end-stage renal disease registries, clinical trials, and experimental animal models suggest that the progression of chronic kidney disease from several etiologies is more rapid in men than in women. In this review, we examine the data supporting the hypothesis that modulation of the activity of the renin angiotensin system by sex steroids markedly contributes to the gender differences observed in the pathophysiology of progressive kidney disease.

Estrogen Regulates Adrenal Angiotensin Type 1 Receptors by Modulating Adrenal Angiotensin Levels

Endocrinology. Apr, 2003  |  Pubmed ID: 12639918

Estrogen inhibits adrenal angiotensin type 1 receptor (AT(1)R) binding sites and attenuates the adrenal responsivity to angiotensin II (Ang II). Ang II modulates AT(1)R expression. Here, we determined if estrogen-induced down-regulation of adrenal AT(1)Rs involves modulation of adrenal Ang II. Female rats were ovariectomized (OVX) and injected with 17beta-estradiol benzoate (E(2); 40 micro g/kg) or vehicle for 7 d. Adrenal Ang II was separated from other angiotensin peptides by HPLC and measured by RIA. Scatchard analysis of radioligand binding curves showed that E(2) or captopril (Cap; 0.5 g/liter water) significantly reduced adrenal AT(1)R binding (maximum binding capacity) by 22% and 19%, respectively, compared with OVX (276 +/- 2.09 fmol/mg protein). E(2) and Cap lowered adrenal Ang II levels by 39% and 21%, respectively, compared with OVX (4.10 +/- 0.44 pmol/g). E(2) caused no further reductions in adrenal AT(1)R binding or in Ang II levels in Cap-treated OVX rats. High-dose Ang II infusion (1000 ng/kg.min) increased adrenal Ang II levels by 71% and lowered AT(1)R binding by 18%. Under these infusion conditions, E(2) did not reduce adrenal Ang II or AT(1)R binding. No differences in AT(1)R affinity (dissociation constant) were observed among groups. These data suggest that E(2) regulates the number of adrenal AT(1)R binding sites indirectly by modulating adrenal Ang II.

Estrogen Regulates Adrenal Angiotensin AT1 Receptors by Modulating AT1 Receptor Translation

Endocrinology. Jul, 2003  |  Pubmed ID: 12810582

Hypertension and associated cardiovascular disease increase after menopause. Angiotensin AT(1) receptor (AT(1)R) antagonists are effective treatments, in part, by inhibiting angiotensin II (Ang II)-induced aldosterone release from the adrenal zona glomerulosa (ZG). Estrogen decreases the number of AT(1)Rs in the adrenal gland and attenuates acute Ang II-induced aldosterone release. Here, we examined the effects of 17beta-estradiol (E(2)) on AT(1)R gene regulation in the rat adrenal cortex (AC). Female rats were ovariectomized and injected with vehicle or E(2). Immunohistochemistry revealed the presence of both estrogen receptor (ER)alpha and ERbeta in the ZG, and E(2) treatment increased the intensity of their nuclear staining. Under conditions in which AT(1)R maximal binding capacity was decreased by 46%, chronic miniosmotic pump Ang II-induced aldosterone secretion was reduced by 43%. E(2) treatment had no effect on AT(1a)R and AT(1b)R mRNA levels in the AC, whereas the AT(1)R mRNA polysome distribution in sucrose gradients was shifted to lighter fractions, indicating that E(2) treatment reduces AT(1)R translation. RNA binding proteins (RBPs) in AC extracts formed complexes with the 5' leader sequence (5'LS), coding region, and the 3'-untranslated region (3'UTR); however, only the activity of 5'LS RBPs was regulated by E(2) treatment. These data suggest that E(2), acting through its receptors in the ZG, reduces AT(1)R density and Ang II-induced aldosterone release, primarily by inhibiting AT(1)R translation, possibly by blocking ribosomal scanning caused by increased steric hindrance from 5'LS RBPs. Dysregulation of this posttranscriptional mechanism may contribute to the increased incidence of cardiovascular disease associated with menopause.

Growth Hormone Regulation of Glomerular AT1 Angiotensin Receptors in Adult Uninephrectomized Male Rats

American Journal of Physiology. Renal Physiology. Dec, 2003  |  Pubmed ID: 12824079

Sex differences exist in the mechanisms initiating early compensatory renal growth after unilateral nephrectomy (UNX); remnant kidney growth is growth hormone (GH) independent in adult female rats and GH dependent in adult male rats. The present study determined whether sex differences also exist in angiotensin type 1 receptor (AT1R) regulation during early remnant kidney (REM) growth after UNX, and if so, whether GH modulates AT1R expression after UNX in the male rat. Scatchard analysis of radioligand binding in glomeruli demonstrated that 48 h post-UNX, AT1R density (Bmax) was significantly decreased by 20% in female REM compared with control kidneys. In contrast, male REM glomerular Bmax was significantly increased by 28% compared with control kidneys. Furthermore, GH-suppressed male rats displayed attenuated REM growth, which was associated with a 35% decrease in AT1R Bmax. Losartan treatment also decreased REM AT1R Bmax by 55%. The activity of mRNA binding proteins that bind to the 5' leader sequence of the AT1R was regulated by UNX and GH treatment in an inverse manner to AT1R expression. These findings suggest that in rats 1) there are sex differences in the regulation of glomerular AT1R expression after UNX; 2) the increase in AT1R binding sites in the male REM is regulated by GH and mediates early remnant kidney growth; and 3) AT1R 5' leader sequence mRNA binding proteins play a role in UNX and GH regulation of glomerular AT1Rs in both males and females.

In Vivo Investigation of Estrogen Regulation of Adrenal and Renal Angiotensin (AT1) Receptor Expression by PET

Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine. Jan, 2004  |  Pubmed ID: 14734680

The renin angiotensin system (RAS) has been implicated as one mediator of the cardiovascular effects of estrogen. Since changes in angiotensin type 1 (AT(1)) receptor expression are central to modulation of the RAS, we used the noninvasive PET imaging technique to study for the in vivo effects of estrogen on membrane and intracellular AT(1) receptors.

Glomerulosclerosis and Tubulointerstitial Fibrosis Are Attenuated with 17beta-estradiol in the Aging Dahl Salt Sensitive Rat

Journal of the American Society of Nephrology : JASN. Jun, 2004  |  Pubmed ID: 15153565

This study examined the effects of estrogen deficiency by ovariectomy (OVX) and 17beta-estradiol (E(2)) replacement (OVX+E(2)) on glomerulosclerosis and tubulointerstitial fibrosis and the mechanisms contributing to these changes, including expression of collagen type IV and laminin, transforming growth factor-beta (TGF-beta), and activity of matrix metalloproteinases (MMP) in the kidneys of young (4 mo [4M]) and aged (12 mo [12M]) Dahl salt-sensitive (DSS) rats maintained on a low-salt (0.1% NaCl) diet. While normal renal morphology was observed in the 4M rats in all treatment groups, moderate to severe glomerulosclerosis (glomerulosclerotic index [GSI]: 4M, 0.22 +/- 0.09 versus 12M, 1.43 +/- 0.17; P < 0.001) and cortical tubulointerstitial fibrosis (CTIFI: 4M, 0 versus 12M, 57.1 +/- 4.9; P < 0.01) was observed in the 12M rats. The severity of glomerulosclerosis and cortical tubulointerstitial fibrosis in the 12M group was augmented with OVX (GSI, 3.27 +/- 0.34; CTIFI, 74.4 +/- 9.2; P < 0.01 versus Intact at 12M) and attenuated with E(2) replacement ([GSI], 1.09 +/- 0.09; CTIFI, 49.2 +/- 6.8). In the 12M animals, OVX was also associated with increased deposition and expression of laminin (Intact, 228.1 +/- 6.7; OVX, 277.4 +/- 9.6 AU; P < 0.01), increased expression of TGF-beta (Intact, 85.0 +/- 23.0; OVX, 178.0 +/- 20.5 AU; P < 0.001), and decreased activity of cortical MMP-9 (Intact, 3.8 +/- 0.8; OVX, 2.4 +/- 0.6 AUC; P < 0.01). E(2) replacement opposed these effects (laminin, 229.9 +/- 6.2 AU; TGF-beta, 101.3 +/- 25.2 AU; MMP-9, 5.2 +/- 0.2 AUC). The severity of the disease in the 12M rats correlated with a modest decrease in creatinine clearance (Intact, 0.26 +/- 0.01; OVX, 0.22 +/- 0.01; OVX+E(2), 0.28 +/- 0.01 mg/min per 100 g) and increase in BUN (Intact, 20.3 +/- 2.1; OVX, 32.6 +/- 5.1; OVX+E(2), 24.3 +/- 2.4 mg/dl). The authors conclude that E(2) is renoprotective in the aging DSS rat by attenuating glomerulosclerosis and tubulointerstitial fibrosis.

A Novel Radioligand for Imaging the AT1 Angiotensin Receptor with PET

Nuclear Medicine and Biology. Jul, 2004  |  Pubmed ID: 15219274

2-Butyl-5-methoxymethyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-3H-imidazo[4,5-b]pyridine (KR31173) was radiolabeled by coupling a tetrazole-protected hydroxy precursor with [(11)C] methyl iodide and removing the protecting group by acid hydrolysis. In mice, the highest uptake of [(11)C] KR31173 was in the adrenal glands, kidneys, and liver. Tissue to blood ratios were generally greater than 10:1. Uptake of the tracer in the adrenal glands, kidneys, lungs, and heart was blocked with a 1 mg/kg dose of KR31173 or MK-996.

Translational Regulation of Angiotensin Type 1a Receptor Expression and Signaling by Upstream AUGs in the 5' Leader Sequence

The Journal of Biological Chemistry. Oct, 2004  |  Pubmed ID: 15319432

Rat angiotensin type 1a receptor (AT(1a)R) is regulated by four upstream AUGs present in the 5' leader sequence (5'-LS). Disruption of all four upstream AUGs (QM) results in 2-3-fold higher levels of angiotensin type 1 receptor (AT(1)R) densities in transiently transfected rat aortic smooth muscle cells (A10 cells) and stably transfected Chinese hamster ovary cells. Cells expressing QM have 5-fold higher levels of angiotensin II-induced inositol phosphate production than wild type (WT). Polysome analysis showed that QM mRNA is present in heavier fractions than the WT transcript, and 5.7-fold more AT(1)R protein is produced by in vitro translation from QM transcripts compared with WT transcripts. The AT(1a)R comprises 3 exons. Exon 3 (E3) encodes the entire open reading frame and 3'-untranslated region. Exons 1 and 2 (E1 and E2) and 52 nucleotides of E3 encode the 5'-LS. The AUGs in both exons contribute to the inhibitory effect on AT(1)R expression but not to the same degree. Disruption of the AUGs in exon 2 (DM2) relieves half of the inhibition, whereas disruption of the AUGs in exon 1 (DM1) is without effect. Disruption of the AUGs in exon 2 results in levels of receptor expression and translation that are indistinguishable from the alternative splice variant E1,3, which we previously showed was more efficiently translated than the E1,2,3 transcript. Individual mutations revealed that only the fourth AUG increased AT(1)R translation. In conclusion, all four AUGs present in the 5'-LS function cumulatively to suppress AT(1a)R expression and signaling by inhibiting translation. These data also show that both AUGs in E2 contribute to the inhibitory cis element present in this alternatively spliced exon.

Ovariectomy Augments Hypertension in Aging Female Dahl Salt-sensitive Rats

Hypertension. Oct, 2004  |  Pubmed ID: 15337736

The ovariectomized (OVX) Dahl salt-sensitive (DS) rat fed a low-salt diet is a model of postmenopausal hypertension. In addition to estrogen loss, aging can also contribute to postmenopausal hypertension. We hypothesized that: (1) female DS rats on a low-salt diet become hypertensive with age; (2) ovariectomy accelerates age-dependent hypertension in the DS rat caused by estrogen depletion; and (3) this hypertension correlates with increased type 1 angiotensin receptor (AT1R) number (Bmax). Blood pressure was monitored by telemetry from 3 to 12 months and AT1R Bmax was determined by Scatchard analysis in glomeruli and adrenal cortex. Three groups of DS rats were studied: intact, OVX, and 17beta-estradiol-replaced OVX (OVX+E). In intact rats, aging to 12 months resulted in hypertension (159+/-6 mm Hg) and an 82% decrease in estrogen. Blood pressure in OVX was significantly higher than OVX+E through 12 months of age (173+/-4 versus 150+/-8 mm Hg). At 4 months, OVX increased AT1R Bmax compared with intact and OVX+E in both glomeruli and adrenal cortex. Aging also increased AT1R Bmax in these tissues in intact rats. In summary, female DS rats fed a low-salt diet have hypertension develop with age, that is accelerated by OVX and attenuated by estrogen replacement. Concurrently, AT1Rs are upregulated by age and OVX, which is prevented by estrogen replacement. This study suggests that an increased activity of the renin angiotensin system contributes to the development of hypertension, and estrogen protects against this process.

Translational Control of the Rat Angiotensin Type 1a Receptor by Alternative Splicing

Gene. Oct, 2004  |  Pubmed ID: 15474292

The rat angiotensin type 1a receptor (AT1aR) is comprised of three exons. Two transcripts are possible due to alternative splicing of exon 2 (E1,3 and E1,2,3). Both transcripts code for identical AT1aR proteins since they differ only in the length of their 5' leader sequence (5'LS). We investigated the functional differences of these two transcripts in stably transfected Chinese hamster ovary (CHO) cells and also determined the splice variant composition in rat tissues. E1,3 expressing cells exhibited 1.8-fold higher AT1R densities and five-fold higher levels of Ang II-stimulated inositol phosphate production compared to E1,2,3 expressing cells. No differences in E1,3 and E1,2,3 mRNA levels or mRNA stability were seen. In vitro translation assays revealed 1.8-fold higher AT1aR protein levels from E1,3 compared to E1,2,3 transcripts, suggesting exon 2 reduces functional AT1R expression by inhibiting translation. Deletion of 10 nucleotides in exon 2 increased translation of the mutated E1,2,3 transcript to levels which were indistinguishable from E1,3, suggesting that this loop region of a predicted hairpin contributes to the inhibitory RNA cis element within exon 2. Comparison of AT1aR exonic composition and AT1R densities in rat tissues suggests alternative splicing is regulated in a tissue-specific manner and contributes to tissue-specific differences in AT1R density.

Sex Differences in Renal Injury and Nitric Oxide Production in Renal Wrap Hypertension

American Journal of Physiology. Heart and Circulatory Physiology. Jan, 2005  |  Pubmed ID: 15319201

To investigate the faster rate of renal disease progression in men compared with women, we addressed the following questions in the renal wrap (RW) model of hypertension: 1) Do sex differences exist in RW-induced renal injury, which are independent of sex differences in blood pressure? 2) Do sex differences in nitric oxide (NO) production exist in RW hypertension? Male (M) and female (F) rats underwent sham-operated (M-Sham, n = 7; F-Sham, n = 10) or RW (M-RW, n = 13; F-RW, n = 14) surgery for 9 wk. Markers of renal injury, including the glomerulosclerosis index (F-RW, 0.70 +/- 0.1 vs. M-RW, 2.2 +/- 0.6; P < 0.05), mean glomerular volume (F-RW, 1.05 +/- 0.050 x 10(6) vs. M-RW, 1.78 +/- 0.15 x 10(6) microm(3); P < 0.001), and proteinuria (F-RW, 68.7 +/- 15 vs. M-RW, 124 +/- 7.7 mg/day; P < 0.001) were greater in RW males compared with RW females. Endothelial NO synthase protein expression was elevated in the renal cortex (3.2-fold) and medulla (2.2-fold) 9 wk after RW in males, whereas no differences were observed in females. Neuronal NO synthase protein expression was unchanged in the renal cortex in males and in both the renal cortex and medulla in females, whereas in the male medulla, neuronal NOS was decreased by 57%. These data suggest the degree of renal injury is greater in male compared with female rats in RW hypertension despite similar degrees of hypertension and renal function and may involve sex differences in renal NO metabolism.

Gonadal Steroid Regulation of Renal Injury in Renal Wrap Hypertension

American Journal of Physiology. Renal Physiology. Mar, 2005  |  Pubmed ID: 15572525

Renal injury is greater in male compared with female rats after renal wrap (RW) hypertension. We investigated the role of gonadal steroids in the sex differences in RW disease severity in male (M) and female (F), castrated (Cast), and ovariectomized (OVX) rats and after dihydrotestosterone (DHT) and 17beta-estradiol (E2) treatment. Male castration attenuated the severity of RW-induced glomerulosclerosis (GS) [GS index (GSI): RW-M, 2.1 +/- 0.2; RW-Cast, 1.3 +/- 0.2; RW-Cast+DHT, 2.4 +/- 0.4], mean glomerular volume (MGV; microm3 x 10(6): RW-M, 1.9 +/- 0.1; RW-Cast, 1.45 +/- 0.15; RW-Cast+DHT, 1.91 +/- 0.15), tubular damage, and proteinuria (mg/day: RW-M, 130 +/- 8; RW-Cast, 105 +/- 5; RW-Cast+DHT, 142 +/- 9), whereas DHT treatment abrogated these effects. Ovariectomy increased the GSI (RW-F, 0.69 +/- 0.05; RW-OVX, 1.2 +/- 0.1; RW-OVX+E2, 0.65 +/- 0.05), tubular damage, and MGV (microm3 x 10(6): RW-F, 1.0 +/- 0.06; RW-OVX, 1.5 +/- 0.05; RW-OVX+E2, 0.96 +/- 0.06), whereas E2 treatment prevented these effects. Furthermore, DHT treatment of RW-OVX animals exacerbated the GSI (1.9 +/- 0.19), MGV (1.7 +/- 0.2 x 10(6) microm3), and proteinuria (171 +/- 21 mg/day) even further. Our data show that the lack of E2 and presence of androgens contribute to progressive renal disease induced by RW hypertension, suggesting that gonadal steroid status is an independent factor in the greater susceptibility men exhibit toward hypertension-associated renal disease compared with women.

Small Interfering RNA-mediated Functional Silencing of Vasopressin V2 Receptors in the Mouse Kidney

Physiological Genomics. May, 2005  |  Pubmed ID: 15784697

The antidiuretic effects of arginine vasopressin (AVP) on the kidney are mediated by V2 subtype AVP receptors (V2R). To investigate the role of regulation of V2R in water and sodium homeostasis, we have developed a method for small interfering RNA (siRNA)-mediated inhibition of V2R expression in vivo. Three 21-nt siRNA sequences were chosen that specifically targeted the mouse V2R but shared no appreciable sequence homology to any other known mouse genes, including the vasopressin V1a and V1b receptors. Additionally, an siRNA sequence that shared no significant matches to any known mammalian gene sequences was chosen for use as a control. Chemically synthesized siRNA was complexed with the liposomal transfection reagent DOTAP. Each mouse (male C57BL/6) received 3.6 nmol (approximately 50 microg) of either the control (nonsilencing) or one of the V2R-targeting siRNAs via intravenous injection. Forty-eight hours after injection membranes were prepared from the inner medulla of the kidneys, and V2R expression was measured by a radioligand binding assay and Western immunoblotting. Treatment with one of the V2R-targeting siRNAs (R2) caused a 39.7 +/- 8.7% reduction in V2R-specific binding compared with the control (n = 11, P < 0.05) and a 37.0 +/- 2.3% reduction in V2R protein expression as measured by Western immunoblotting (n = 4, P < 0.001). Additionally, real-time PCR revealed that R2 siRNA treatment induced a 68.8 +/- 2.2% reduction in V2R mRNA. However, this siRNA treatment did not alter the animals' basal urine concentrating capacity under unstimulated conditions. In subsequent experiments, treatment with R2 siRNA was found to significantly attenuate the antidiuretic effects the V2R-specific AVP agonist 1-desamino-[8-D-arginine]vasopressin (dDAVP). Mice were infused with dDAVP (0.25 ng/h) for 3 days to produce maximal antidiuresis and then were injected with either the R2 siRNA or the nonsilencing control. On day 2 after treatment, urine osmolality was significantly decreased from 3,455 +/- 72 in control animals (n = 12) to 3,155 +/- 129 mosmol/kgH2O in R2 siRNA-treated animals (n = 12) (P < 0.05); similarly, on day 2 24-h urine volume was significantly increased from 0.86 +/- 0.07 ml/day to 1.11 +/- 0.06 ml/day in R2 siRNA-treated animals (P < 0.05). In summary we have demonstrated that RNA interference methodology can be used successfully in vivo to significantly reduce functional expression of the V2R in the mouse kidney.

Estrogen Regulation of Tumor Necrosis Factor-alpha: a Missing Link Between Menopause and Cardiovascular Risk in Women?

Hypertension (Dallas, Tex. : 1979). Jul, 2005  |  Pubmed ID: 15911737

Regulation of ACE2 and ANG-(1-7) in the Aorta: New Insights into the Renin-angiotensin System in the Control of Vascular Function

American Journal of Physiology. Heart and Circulatory Physiology. Sep, 2005  |  Pubmed ID: 16100255

Posttranscriptional Mechanisms Contribute to Osmotic Regulation of ANG Type 1 Receptors in Cultured Rat Renomedullary Interstitial Cells

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Jan, 2006  |  Pubmed ID: 16099820

Previously, we showed that ANG II receptors in cultured rat renomedullary interstitial cells (RMICs) are osmotically regulated (19). The current study examined the mechanisms underlying this osmotic regulation in RMICs cultured in isoosmotic (300 mosmol/kgH2O) and hyperosmotic (600 mosmol/kgH2O) conditions. Radioligand competition analysis coupled with RNase protection assays (RPA) and ligand-mediated receptor internalization studies revealed that RMICs primarily express the type 1a angiotensin receptor (AT(1a)R). When cultured under hyperosmotic conditions, the density (B(max)) of AT1R in RMIC membranes decreased by 31% [B(max) (pmol/mg protein): 300 mosmol/kgH2O, 6.44 +/- 0.46 vs. 600 mosmol/kgH2O, 4.42 +/- 0.37, n = 8, P < 0.01], under conditions in which no detectable changes in AT(1a)R mRNA expression or in the kinetics of ligand-mediated AT1R internalization were observed. RNA electromobility shift assays showed that RNA protein complex (RPC) formation between RMIC cytosolic RNA binding proteins and the 5' leader sequence (5'LS) of the AT(1a)R was increased 1.5-fold under hyperosmotic conditions [5'LS RPC (arbitrary units): 300 mosmol/kgH2O, 0.79 +/- 0.08 vs. 600 mosmol/kgH2O, 1.17 +/- 0.07, n = 4, P < 0.01]. These results suggest that the downregulation of AT(1a)R expression in RMICs cultured under hyperosmotic conditions is regulated at the posttranscriptional level by RNA binding proteins that interact within the 5'LS of the AT(1a)R mRNA. The downregulation of AT(1a)R expression under hyperosmotic conditions may be an important mechanism by which the activity of ANG II is regulated in the hyperosmotic renal medulla.

Translational Regulation of ANG II Type 1 Receptors in Proliferating Vascular Smooth Muscle Cells

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Jan, 2006  |  Pubmed ID: 16123226

The current study examined angiotensin receptor (ATR) regulation in proliferating rat aortic vascular smooth muscle cells (VSMCs) in culture. Radioligand competition analysis coupled with RNase protection assays (RPAs) revealed that angiotensin type 1a receptor (AT(1a)R) densities (B(max)) increased by 30% between 5 and 7 days in culture [B(max) (fmol/mg protein): day 5, 379 +/- 8.4 vs. day 7, 481 +/- 12, n = 3, P < 0.05] under conditions in which no significant changes in AT(1a)R mRNA expression occurred [in RPA arbitrary units (AU): day 5, 0.23 +/- 0.01 vs. day 7, 0.24 +/- 0.04, n = 4] or in mRNA synthesis determined by nuclear run-on assays [AU: day 5, 0.35 +/- 0.14 vs. day 7, 0.33 +/- 0.11, n = 5]. In contrast, polysome distribution analysis indicated that AT(1a)R mRNA was more efficiently translated in day 7 cells compared with day 5 [% of AT(1a)R mRNA in fraction 2 out of total AT1R mRNA recovered from the sucrose gradient: day 5, 20.9 +/- 9.9 vs. day 7, 56.8 +/- 5.6, n = 3, P < 0.001]. Accompanying the polysome shift was 50% less RNA-protein complex (RPC) formation between VSMC cytosolic RNA binding proteins in day 7 cells compared with 5-day cultures and the 5' leader sequence (5'LS) of the AT(1a)R [5'LS RPC (AU): day 5, 0.62 +/- 0.15 vs. day 7, 0.23 +/- 0.03; n = 4, P < 0.05] and also with exon 2 [Exon 2 RPC (AU): day 5, 35.0 +/- 5.7 vs. day 7, 17.2 +/- 3.6; n = 4, P < 0.05]. Taken together, these results suggest that AT(1a)R expression is regulated by translation during VSMC proliferation in part by RNA binding proteins that interact within exon 2 in the 5'LS of the AT(1a)R mRNA.

Splice Variant-specific Silencing of Angiotensin II Type 1a Receptor Messenger RNA by RNA Interference in Vascular Smooth Muscle Cells

Biochemical and Biophysical Research Communications. Jan, 2006  |  Pubmed ID: 16307726

In the rat, two distinct angiotensin II type 1a (rAT(1a)) receptor mRNAs are synthesized from a single rAT(1a) receptor gene by alternative splicing. These two transcripts are comprised of exons 1, 2, and 3 (E1,2,3) or exons 1 and 3 (E1,3). Since exon 3 contains the entire coding region, both transcripts encode identical rAT(1a) receptors. Real-time PCR revealed that in rat aortic smooth muscle cells (RASMC), E1,2,3 mRNA accounted for 69.5+/-0.9% of total rAT(1a) receptor mRNA. The aim of this study was to use RNA interference (RNAi) to selectively silence the rAT(1a) receptor splice variants. Forty-eight hour treatment of RASMC with E1,3-targeting siRNA (10nM; S1(E1,3)) resulted in a 91.2+/-0.5% (n=3, P<0.001) reduction in E1,3 mRNA and a 19.0+/-3.0% (n=4, P<0.05) reduction in AT(1) receptor specific binding compared with cells treated with a non-silencing control siRNA; under these conditions, no effect was observed on levels of E1,2,3 mRNA. Conversely, treatment with E1,2,3-targeting siRNA (S2(E2)) had no effect on E1,3 mRNA while reducing E1,2,3 mRNA by 73.9+/-4.2% (n=3, P<0.001), and AT(1) receptor binding by 39.4+/-5.4% (n=4, P<0.001) compared with control. These data show that the majority of functional AT(1) receptor expression in RASMC derives from the E1,2,3 splice variant. These data also demonstrate that rAT(1a) receptor mRNA can be silenced in a splice-variant specific manner using siRNA in RASMC, thus providing an excellent model system for investigating the role of alternative splicing in the regulation of rAT(1a) receptor expression.

PET Imaging of the AT1 Receptor with [11C]KR31173

Nuclear Medicine and Biology. Jan, 2006  |  Pubmed ID: 16459253

The goal of this study was to investigate the binding characteristics of [(11)C]KR31173 and its applicability for PET studies of the AT(1) receptor (AT(1)R).

Does 2-methoxyestradiol Represent the New and Improved Hormone Replacement Therapy for Atherosclerosis?

Circulation Research. Aug, 2006  |  Pubmed ID: 16888248

Role of Extracellular Superoxide Dismutase in the Mouse Angiotensin Slow Pressor Response

Hypertension (Dallas, Tex. : 1979). Nov, 2006  |  Pubmed ID: 17015770

Low rates of angiotensin II (Ang II) infusion raise blood pressure, renal vascular resistance (RVR), NADPH oxidase activity, and superoxide. We tested the hypothesis that these effects are ameliorated by extracellular superoxide dismutase (EC-SOD). EC-SOD knockout (-/-) and wild type (+/+) mice were equipped with blood pressure telemeters and infused subcutaneously with Ang II (400 ng/kg per minute) or vehicle for 2 weeks. During vehicle infusion, EC-SOD -/- mice had significantly (P<0.05) higher MAP (+/+: 107+/-3 mm Hg versus -/-: 114+/-2 mm Hg; n=11 to 14), RVR, lipid peroxidation, renal cortical p22(phox) expression, and NADPH oxidase activity. Ang II infusion in EC-SOD +/+ mice significantly (P<0.05) increased MAP, RVR, p22(phox), NADPH oxidase activity, and lipid peroxidation. Ang II reduced SOD activity in plasma, aorta, and kidney accompanied by reduced renal EC-SOD expression. During Ang II infusion, both groups had similar values for MAP (+/+ Ang II: 125+/-3 versus -/- Ang II: 124+/-3 mmHg; P value not significant), RVR, NADPH oxidase activity, and lipid peroxidation. SOD activity in the kidneys of Ang II-infused mice was paradoxically higher in EC-SOD -/- mice (+/+: 8.8+/-1.2 U/mg protein(-1) versus -/-: 13.7+/-1.6 U/mg protein(-1); P<0.05) accompanied by a significant upregulation of mRNA and protein for Cu/Zn-SOD. In conclusion, EC-SOD protects normal mice against oxidative stress by attenuating renal p22(phox) expression, NADPH oxidase activation, and the accompanying renal vasoconstriction and hypertension. However, during an Ang II slow pressor response, renal EC-SOD expression is reduced and, in its absence, renal Cu/Zn-SOD is upregulated and may prevent excessive Ang II-induced renal oxidative stress, renal vasoconstriction, and hypertension.

Effect of Sex Hormones on Renal Estrogen and Angiotensin Type 1 Receptors in Female and Male Rats

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Feb, 2007  |  Pubmed ID: 16990489

Although the mechanisms are not understood, evidence suggests that 17beta-estradiol (E2) confers protection from cardiovascular and renal complications in many diseases. We have reported that E2 decreases angiotensin type 1 receptors (AT1Rs) in different tissues and hypothesize that E2 exerts tonic inhibition on AT1Rs, reducing effects of ANG II. This study determined the effects of E2 and dihydrotestosterone (DHT) on cortical estrogen receptors (ERs) and glomerular AT1R binding in rats. Animals underwent sham operation, ovariectomy (Ovx) or orchidectomy (Cas) and were treated (Ovx +/- E2; Cas +/- DHT) for 3 wk. Cortical ERalpha protein was 2.5 times greater, and ERbeta was 80% less in females vs. males (P < 0.01). Glomerular AT1R binding was lower in females than males [4,657 +/- 838 vs. 7,457 +/- 467 counts per minute (cpm), P < 0.01]. Ovx reduced ERalpha protein by 50%, whereas E2 increased ERalpha expression after Ovx. The decrease in cortical ERalpha in Ovx rats was associated with a significant increase in AT1R binding (6,908 +/- 609 cpm), and E2 prevented this increase. There was no change in ERalpha or AT1R binding following Cas +/- DHT (25 mg) treatment, although Cas did elevate cortical ERbeta (P < 0.01). Interestingly, the high dose DHT (200 mg) elevated ERalpha 150% above intact levels and profoundly decreased AT1R binding (1,824 +/- 705 cpm, P < 0.001 vs. intact male). This indicates that under normal conditions, glomerular AT1R binding is significantly greater in male than female animals, which may be important in development of cardiovascular and renal disease in males. Furthermore, E2 regulates ERalpha and is inversely associated with glomerular AT1R binding, supporting our hypothesis that E2 tonically suppresses AT1Rs and suggesting a potential mechanism for the protective effects of estrogen.

17beta-estradiol Deficiency Reduces Potassium Excretion in an Angiotensin Type 1 Receptor-dependent Manner

American Journal of Physiology. Heart and Circulatory Physiology. Jul, 2007  |  Pubmed ID: 17449550

This study examined the effects of ovariectomy (OVX) and 17beta-estradiol (E(2)) replacement (OVX + E(2)) on renal function in Sprague-Dawley rats. OVX caused a 40% decrease in the fractional excretion of potassium (FE(K(+))) that was prevented by E(2) replacement [Sham, 24.2 +/- 2.9%; OVX, 14.5 +/- 2.1% (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 26.2 +/- 2.7%; n = 7-11] and that corresponded to significant increases in plasma potassium [(in mmol/l): Sham, 3.15 +/- 0.087; OVX, 3.42 +/- 0.048 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 3.19 +/- 0.11; n = 7-11]. No effects of OVX were detected on plasma levels of sodium and aldosterone. Angiotensin II type 1 receptor (AT(1)R) densities in ovariectomized rats were 1.4-fold and 1.3-fold higher in glomerular [maximum binding capacity (B(max); in fmol/mg protein): Sham, 482 +/- 21; OVX, 666 +/- 20 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 504 +/- 26; n = 7-11] and proximal tubular [B(max) (in fmol/mg protein): Sham, 721 +/- 16; OVX, 741 +/- 24 (P < 0.05 vs. OVX + E(2)); and OVX + E(2), 569 +/- 23; n = 7-11] membranes compared with E(2) replete animals, respectively. Both the angiotensin-converting enzyme inhibitor captopril and the AT(1)R antagonist losartan prevented the OVX-induced decrease in the FE(K(+)) and the increase in renal AT(1)R densities, suggesting that E(2) deficiency reduces potassium excretion in an ANG II/AT(1)R-dependent manner. These findings may have implications for renal function in postmenopausal women as well as contribute to the reasons underlying the age-induced increase in susceptibility to hypertension-associated disease in women.

Female Protection in Progressive Renal Disease is Associated with Estradiol Attenuation of Superoxide Production

Gender Medicine. Mar, 2007  |  Pubmed ID: 17584628

Several types of renal disease progress at a faster rate in men compared with women, but the reasons for this sex difference are not well understood. Chronic renal disease is associated with elevated levels of toxic reactive oxygen species (ROS). Superoxide, the major ROS in the kidney, is generated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase.

Chronic ACE Inhibitor Treatment Increases Angiotensin Type 1 Receptor Binding in Vivo in the Dog Kidney

European Journal of Nuclear Medicine and Molecular Imaging. Jun, 2008  |  Pubmed ID: 18180920

PET imaging has been recently introduced for investigating the type 1 angiotensin II receptor (AT(1)R) in vivo. The goal of the present study was to investigate the effects of acute and chronic exposure to angiotensin converting enzyme inhibitors (ACEI) on the AT(1)R in the dog kidney.

Effect of Dietary Sodium on Estrogen Regulation of Blood Pressure in Dahl Salt-sensitive Rats

American Journal of Physiology. Heart and Circulatory Physiology. Apr, 2008  |  Pubmed ID: 18245561

The effects of high-sodium (HS) and normal-sodium (NS) diets on ovarian hormone modulation of mean arterial pressure (MAP) were examined in Dahl salt-resistant (DR) and salt-sensitive (DS) rats. Ovariectomy increased MAP (OVX-Sham) to a greater extent in DS rats maintained for 2 wk on a HS (22 mmHg) compared with a NS (6 mmHg) diet. Ovariectomy had no effect on MAP in DR rats on NS but did increase MAP in rats on HS (10 mmHg) diets. On HS diets, glomerular filtration rate (GFR) was 36% less in the DS-Sham than DR-Sham animals; ovariectomy increased GFR in both strains by 1.4-1.5-fold; glomerular angiotensin II type 1 receptor (AT(1)R) densities were 1.6-fold higher in the DS-Sham than in the DR-Sham group; ovariectomy increased glomerular AT(1)R densities by 1.3-fold in DR rats but had no effect in DS rats; 17beta-estradiol (E(2)) downregulated adrenal AT(1)R densities in both strains on either diet; ovariectomy reduced estrogen receptor-alpha (ER-alpha) protein expression in the renal cortex by 40-50% although renal ER-alpha expression was 34% lower in DS than in DR rats. These observed effects of gonadectomy were prevented by E(2) treatment, suggesting that E(2) deficiency mediates the effects of ovariectomy on MAP, GFR, AT(1)R densities, and renal ER-alpha protein expression. In conclusion, ovariectomy-induced increases in MAP are augmented by HS diet in both strains, and this effect is not mediated by a reduction in GFR. Aberrant renal AT(1)R regulation and reduced renal ER-alpha expression are potential contributors to the hypertensive effects of E(2) deficiency in DS rats. These findings have implications for women with salt-sensitive hypertension and women who are E(2) deficient, such as postmenopausal women.

Role of Angiotensin-converting Enzyme 2 and Angiotensin(1-7) in 17beta-oestradiol Regulation of Renal Pathology in Renal Wrap Hypertension in Rats

Experimental Physiology. May, 2008  |  Pubmed ID: 18296494

17beta-Oestradiol (E2)-mediated inhibition of angiotensin-converting enzyme (ACE) protects the E2-replete kidney from the progression of hypertensive renal disease. Angiotensin-converting enzyme 2 (ACE2), a homologue of ACE, counters the actions of ACE by catalysing the conversion of angiotensin II (Ang II) to angiotensin(1-7) [Ang(1-7)]. We investigated E2 regulation of ACE2 in the renal wrap (RW) model of hypertension in rats. After 6 weeks on a high-sodium diet (4% NaCl), the activity of ACE2 was reduced in the renal cortex by 31%, which was mirrored by similar decreases in ACE2 protein (30%) and mRNA expression (36%) in the ovariectomized RW rat (RW-OVX); E2 replacement prevented these effects. The RW-OVX rats exhibited greater renal injury, including 1.7-fold more tubulointerstitial fibrosis and 1.6-fold more glomerulosclerosis than E2-replete females (RW-Intact and RW-OVX+E2). Angiotensin(1-7) infusion prevented these exacerbating effects of ovariectomy on renal pathology; no differences in indicators of renal injury were observed between RW-OVX-Ang(1-7) and RW-Intact rats. These renal protective effects of Ang(1-7) infusion were not attributable to increased ACE2 activity or to changes in heart rate or body weight, since these parameters were unchanged by Ang(1-7) infusion. Furthermore, Ang(1-7) infusion did not attenuate renal injury by reducing mean arterial pressure (MAP), since infusion of the peptide did not lower MAP but rather caused a slight increase during a 6 week chronic treatment for Ang(1-7). These results suggest that E2-mediated upregulation of renal ACE2 and the consequent increased Ang(1-7) production contribute to E2-mediated protection from hypertensive renal disease. These findings have implications for E2-deficient women with hypertensive renal disease and suggest that therapeutics targeted towards increasing ACE2 activity and Ang(1-7) levels will be renal protective.

Hypertension and Cardiovascular Disease in Women

Hypertension (Dallas, Tex. : 1979). Apr, 2008  |  Pubmed ID: 18356141

Mechanisms Underlying Sex Differences in Progressive Renal Disease

Gender Medicine. Mar, 2008  |  Pubmed ID: 18420162

Men with nondiabetic renal disease exhibit a faster rate of decline in renal function compared with women. To investigate this sex difference in renal disease progression, our research group has been studying the renal wrap (RW) model of hypertension in rats. Compared with RW female rats, the glomerulosclerosis index, mean glomerular volume, and proteinuria were greater (3.1-, 1.7-, and 1.8-fold, respectively) in RW males under conditions in which no differences in the degree of hypertension were detected, suggesting that sex differences may exist in the mechanisms underlying renal injury, independent of blood pressure. Gonadal steroids contribute to these sex differences, because orchidectomy attenuated and ovariectomy exacerbated the severity of renal injury, whereas dihydrotestosterone and 17beta-estradiol (E(2)) replacement prevented these respective effects. Chronic renal disease is associated with impairment in nitric oxide (NO) signaling and elevated levels of superoxide. Sex differences were observed in RW-induced changes in renal nitric oxide synthesis (NOS) protein abundance. Whereas RW had no effect on NOS in the female kidney, endothelial NOS was elevated and neuronal NOS was decreased in the male kidney, suggesting that renal injury may cause dysfunction in NO metabolism in the male. Sex differences in superoxide signaling were also observed. Renal cortical nicotinamide adenine dinucleotide phosphate oxidase activity was 1.3-fold higher in RW males than in RW females, and ovariectomy increased enzyme activity 1.4-fold, whereas E(2) replacement prevented this effect. These changes in enzyme activity were mirrored by changes in protein abundance of the p22(phox) regulatory subunit. Our findings suggest that E(2) may protect the female kidney from hypertension-associated renal disease by attenuating injury-induced superoxide production.

Age-related Renal Disease in Female Dahl Salt-sensitive Rats is Attenuated with 17 Beta-estradiol Supplementation by Modulating Nitric Oxide Synthase Expression

Gender Medicine. Jun, 2008  |  Pubmed ID: 18573482

The incidence of chronic renal disease in women increases with aging, especially after menopause, suggesting that loss of sex hormones may contribute to the development and progression of renal disease. However, the mechanisms by which sex hormones, particularly estrogens, contribute to the disease process are unclear.

Why Can't a Woman Be More Like a Man?: Is the Angiotensin Type 2 Receptor to Blame or to Thank?

Hypertension (Dallas, Tex. : 1979). Oct, 2008  |  Pubmed ID: 18711007

The Metabolic Syndrome: Racist, Sexist, or Both?

Gender Medicine. Dec, 2008  |  Pubmed ID: 19108809

Response to Can the Study of Female Rats Help Our Understanding of Women?

Hypertension (Dallas, Tex. : 1979). Dec, 2008  |  Pubmed ID: 25278642

Sex Chromosome Effects Unmasked in Angiotensin II-induced Hypertension

Hypertension (Dallas, Tex. : 1979). May, 2010  |  Pubmed ID: 20231528

Sex differences in mean arterial pressure (MAP) are reported in many experimental models of hypertension and are ascribed to gonadal sex based on studies showing that gonadectomy and gonadal hormone replacement affect MAP. The interpretation of these studies, however, has been confounded by differences in the sex chromosome complement (XX versus XY). To investigate the sex chromosome complement independent of gonadal sex, we used the 4 core genotype mouse model in which gonadal sex is separated from the sex chromosome complement enabling comparisons among XX and XY females and XX and XY males. We found that, in the gonadectomized (GDX) 4 core genotype, MAP after 2 weeks of angiotensin II infusion (200 ng/kg per minute) was greater in XX than XY (MAP [in millimeters of mercury]: GDX-XX-female, 148+/-4.5; GDX-XY-female, 133+/-4.4; GDX-XX-male, 149+/-9.4; GDX-XY-male, 138+/-5.5; P<0.03, XX versus XY; n=8 to 9 per group). In contrast, no sex chromosome effects were found on heart rate, body weight, or plasma angiotensin II 2 weeks after angiotensin II infusion. This study suggests that, in addition to effects of gonadal hormones on blood pressure, X- or Y-linked genes, parental imprinting, or X mosaicism contributes to sex differences in hypertension. Furthermore, the finding that MAP was greater in XX mice compared with XY mice in the GDX state suggests that adverse sex chromosome effects encoded within the XX sex chromosome complement could contribute to hypertension in women with ovarian hormone deficiency, such as postmenopausal women and women with premature ovarian failure.

Equine Estrogens Impair Nitric Oxide Production and Endothelial Nitric Oxide Synthase Transcription in Human Endothelial Cells Compared with the Natural 17{beta}-estradiol

Hypertension (Dallas, Tex. : 1979). Sep, 2010  |  Pubmed ID: 20606108

Conjugated equine estrogen therapy is the most common hormone replacement strategy used to treat postmenopausal women. However, the ability of an individual conjugated equine estrogen to modulate NO production and, therefore, to induce cardiovascular protection is largely unknown. The effects of equine and naturally occurring estrogens on NO generation were evaluated in human aortic endothelial cells by measuring in vivo NO production, as well as NO synthase (eNOS) activity and expression. The transcriptional activity on the eNOS gene was determined by the ability of estrogen receptors (alpha and beta) to activate the eNOS promoter and induce transcription. Docking and molecular dynamics simulations were used to study structural features of the interaction between estrogenic compounds and estrogen receptor-alpha. After 24 hours of incubation, we found that estrone upregulated NO production almost as effectively as estradiol by increasing eNOS activity and expression. However, the effect of equine estrogens (equilin, equilenin, and their metabolites) were marked decreased. eNOS promoter activity by equine estrogens was 30% to 50% lower than the naturally occurring estrogens. Computational analysis of estrogen molecules revealed that position 17 and the saturation of estrogenic compounds in ring B are important determinants for estrogen receptor-alpha transcriptional activity. Equine estrogens increase NO production less effectively than naturally occurring estrogens, partially because of their lesser ability to activate the eNOS promoter and induce transcription. Differences in NO production by different estrogens may account for the differences in cardiovascular benefits achieved by the distinct estrogen replacement therapies.

Sex Differences in Renal Angiotensin Converting Enzyme 2 (ACE2) Activity Are 17β-oestradiol-dependent and Sex Chromosome-independent

Biology of Sex Differences. Nov, 2010  |  Pubmed ID: 21208466

Angotensin converting enzyme 2 (ACE2) is a newly discovered monocarboxypeptidase that counteracts the vasoconstrictor effects of angiotensin II (Ang II) by converting Ang II to Ang-(1-7) in the kidney and other tissues.

Sex Differences in Vasopressin V₂ Receptor Expression and Vasopressin-induced Antidiuresis

American Journal of Physiology. Renal Physiology. Feb, 2011  |  Pubmed ID: 21123493

The renal vasopressin V(2) receptor (V(2)R) plays a critical role in physiological and pathophysiological processes associated with arginine vasopressin (AVP)-induced antidiuresis. Because clinical data suggests that females may be more prone to hyponatremia from AVP-mediated antidiuresis, we investigated whether there are sex differences in the expression and function of the renal V(2)R. In normal Sprague-Dawley rat kidneys, V(2)R mRNA and protein expression was 2.6- and 1.7-fold higher, respectively, in females compared with males. To investigate the potential physiological implications of this sex difference, we studied changes in urine osmolality induced by the AVP V(2)R agonist desmopressin. In response to different doses of desmopressin, there was a graded increase in urine osmolality and decrease in urine volume during a 24-h infusion. Females showed greater mean increases in urine osmolality and greater mean decreases in urine volume at 0.5 and 5.0 ng/h infusion rates. We also studied renal escape from antidiuresis produced by water loading in rats infused with desmopressin (5.0 ng/h). After 5 days of water loading, urine osmolality of both female and male rats escaped to the same degree physiologically, but V(2)R mRNA and protein in female kidneys was reduced to a greater degree (-63% and -73%, respectively) than in males (-32% and -48%, respectively). By the end of the 5-day escape period, renal V(2)R mRNA and protein expression were reduced to the same relative levels in males and females, thereby abolishing the sex differences in V(2)R expression seen in the basal state. Our results demonstrate that female rats express significantly more V(2)R mRNA and protein in kidneys than males, and that this results physiologically in a greater sensitivity to V(2)R agonist administration. The potential pathophysiological implications of these results are that females may be more susceptible to the development of dilutional hyponatremia because of a greater sensitivity to endogenously secreted AVP.

Sex Differences in Resting Hemodynamics and Arterial Stiffness Following 4 Weeks of Resistance Versus Aerobic Exercise Training in Individuals with Pre-hypertension to Stage 1 Hypertension

Biology of Sex Differences. 2011  |  Pubmed ID: 21867499

ABSTRACT:

P47(phox) is Required for Afferent Arteriolar Contractile Responses to Angiotensin II and Perfusion Pressure in Mice

Hypertension. Feb, 2012  |  Pubmed ID: 22184329

Myogenic and angiotensin contractions of afferent arterioles generate reactive oxygen species. Resistance vessels express neutrophil oxidase-2 and -4. Angiotensin II activates p47(phox)/neutrophil oxidase-2, whereas it downregulates NOX-4. Therefore, we tested the hypothesis that p47(phox) enhances afferent arteriolar angiotensin contractions. Angiotensin II infusion in p47(phox) +/+ but not -/- mice increased renal cortical NADPH oxidase activity (7±1-12±1 [P<0.01] versus 5±1-7±1 10(3) · RLU · min(-1) · μg protein(-1) [P value not significant]), mean arterial pressure (77±2-91±2 [P<0.005] versus 74±2-77±1 mm Hg [P value not significant]), and renal vascular resistance (7.5±0.4-10.1±0.7 [P<0.01] versus 7.9±0.4-8.3±0.4 mm Hg/mL · min(-1) · gram kidney weight(-1) [P value not significant]). Afferent arterioles from p47(phox) -/- mice had a lesser myogenic response (3.1±0.4 versus 1.4±0.2 dynes · cm(-1) · mm Hg(-1); P<0.02) and a lesser (P<0.05) contraction to 10(-6) M angiotensin II (diameter change +/+: 9.3±0.2-3.4±0.6 μm versus -/-: 9.9±0.6-7.5±0.4 μm). Angiotensin and increased perfusion pressure generated significantly (P<0.05) more reactive oxygen species in p47(phox) +/+ than -/- arterioles. Angiotensin II infusion increased the maximum responsiveness of afferent arterioles from p47(phox) +/+ mice to 10(-6) M angiotensin II yet decreased the response in p47(phox) -/- mice. The angiotensin infusion increased the sensitivity to angiotensin II only in p47(phox) +/+ mice. We conclude that p47(phox) is required to enhance renal NADPH oxidase activity and basal afferent arteriolar myogenic and angiotensin II contractions and to switch afferent arteriolar tachyphylaxis to sensitization to angiotensin during a prolonged angiotensin infusion. These effects likely contribute to hypertension and renal vasoconstriction during infusion of angiotensin II.

Sex Differences in Primary Hypertension

Biology of Sex Differences. Mar, 2012  |  Pubmed ID: 22417477

Men have higher blood pressure than women through much of life regardless of race and ethnicity. This is a robust and highly conserved sex difference that it is also observed across species including dogs, rats, mice and chickens and it is found in induced, genetic and transgenic animal models of hypertension. Not only do the differences between the ovarian and testicular hormonal milieu contribute to this sexual dimorphism in blood pressure, the sex chromosomes also play a role in and of themselves. This review primarily focuses on epidemiological studies of blood pressure in men and women and experimental models of hypertension in both sexes. Gaps in current knowledge regarding what underlie male-female differences in blood pressure control are discussed. Elucidating the mechanisms underlying sex differences in hypertension may lead to the development of anti-hypertensives tailored to one's sex and ultimately to improved therapeutic strategies for treating this disease and preventing its devastating consequences.

Is β the α Dog in Estrogen Receptor-mediated Protection from Hypertension?

Hypertension (Dallas, Tex. : 1979). Jun, 2013  |  Pubmed ID: 23608652

Growth Hormone Exacerbates Diabetic Renal Damage in Male but Not Female Rats

Biology of Sex Differences. 2013  |  Pubmed ID: 23805912

Human and animal studies support the idea that there are sex differences in the development of diabetic renal disease. Our lab and others have determined that in addition to Ang II (through the AT1R), growth hormone (GH) contributes to renal damage in models of renal failure; however, the impact of sex and GH on the mechanisms initiating diabetic renal disease is not known. This study examined the effect of sex and GH on parameters of renal damage in early, uncontrolled streptozotocin (STZ)-induced diabetes.

Decoding Noncoding RNA: Da Vinci Redux?

Circulation Research. Jul, 2013  |  Pubmed ID: 23868825

Sex and the Basic Scientist: is It Time to Embrace Title IX?

Biology of Sex Differences. Jul, 2013  |  Pubmed ID: 23889980

A Home for Body and Soul: Substance Using Women in Recovery

Harm Reduction Journal. Dec, 2013  |  Pubmed ID: 24359089

We report on an in-depth qualitative study of 28 active and former substance addicted women of low or marginal income on the core components of a harm reduction-based addiction recovery program. These women volunteered to be interviewed about their perceptions of their therapeutic needs in their transition from substance addiction to recovery.

Selective Inhibition of Angiotensin Receptor Signaling Through Erk1/2 Pathway by a Novel Peptide

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Apr, 2014  |  Pubmed ID: 24523339

A seven-amino acid peptide (PEP7) is encoded within a short open reading frame within exon 2 (E2) in the 5'-leader sequence (5'LS) upstream of the rat ANG 1a-receptor (rAT1aR) mRNA. A chemically synthesized PEP7 markedly inhibited ANG II-induced Erk1/2 activation in cell culture by 62% compared with a scrambled PEP7 (sPEP7) [pErk1/2/Erk1/2 (AU): ANG II, 1.000 ± 0.0, ANG II+PEP7, 0.3812 ± 0.086, ANG II+sPEP7, 1.069 ± 0.18; n = 3]. Under these same conditions, PEP7 had no effect on ANG II-stimulated inositol-trisphosphate production. PEP7 also had no effect on epidermal growth factor- and phorbol methyl ester-induced Erk1/2 activation, suggesting PEP7 selectively inhibits AT1aR-mediated Erk1/2 signaling. PEP7 intracerebroventricularly inhibited ANG II-induced saline intake but had no effect on water intake in male and female rats, indicating PEP7 also selectively inhibits the ANG II-Erk1/2 pathway in vivo since saline drinking is Erk1/2-mediated, while water drinking is not. PEP7 inhibition of ANG II-induced saline ingestion was rapidly reversed by a subsequent intracerebroventricular injection of an oxytocin antagonist, suggesting when PEP7 blocks ANG II-stimulated Erk1/2 activation, animals no longer ingest saline to balance the continued water intake, due to the release of oxytocin and its subsequent inhibitory effects on saline drinking. PEP7 also attenuated ANG II-induced increases in arterial pressure by 35% compared with sPEP7 at the same dose. Thus, we have identified a novel peptide encoded within the rAT1aR E2 that selectively inhibits Erk1/2 activation, resulting in physiological consequences for sodium ingestion and arterial pressure that may have implications for treating sodium-sensitive diseases like hypertension and chronic kidney disease.

Endothelial Dysfunction and Enhanced Contractility in Microvessels from Ovariectomized Rats: Roles of Oxidative Stress and Perivascular Adipose Tissue

Hypertension (Dallas, Tex. : 1979). May, 2014  |  Pubmed ID: 24591333

Ovarian hormone loss increases reactive oxidative species, endothelial dysfunction, and cardiovascular disease. Because perivascular adipose tissue (PVAT) regulates endothelial function, we hypothesized that reactive oxidative species in PVAT mediate adverse microvascular effects of ovarian hormone deficiency. Rats were ovariectomized or sham operated and given vehicle or tempol for 6 weeks. Mesenteric resistance arterioles from ovariectomized compared with sham-operated rats had dysfunctional responses to acetylcholine (ACh) including decreased ACh-induced endothelium-dependent relaxation (50±6% versus 72±2%) and endothelium-dependent relaxation factor (17±4% versus 37±2%) and increased endothelium-dependent contracting factor (27±5% versus 9±3%). OVX rat mesenteric arterioles had increased contractions to the thromboxane/prostanoid receptor agonist U-46 619 (58±3% versus 40±5%) and increased reactive oxidative species (tempo-9-AC fluorescence) with U-46 619 (0.65±0.17 versus 0.14±0.06 Δ unit) or ACh (0.49±0.09 versus 0.09±0.05 Δ unit) and increased p22(phox) protein expression (0.89±0.05 versus 0.18±0.04 Δ unit), whereas nitric oxide activity (DAF-FM [4-amino-5-methylamino-2',7'-difluorofluorescein diacetate] fluorescence) with ACh was reduced (0.39±0.1 versus 0.70±0.10 Δ unit). No differences were found in endothelium-dependent hyperpolarizing factor or contractile responses to phenylephrine. PVAT enhanced ACh-induced relaxation, endothelium-dependent relaxation factor, and nitric oxide only in sham-operated rats. Tempol prevented ovariectomy-induced endothelial dysfunction and restored the enhancing effects of PVAT on ACh-induced relaxation, endothelium-dependent relaxation factor, and nitric oxide in ovariectomized rat vessels, but both tempol and PVAT were required to normalize the enhanced U-46 619 contractions after ovariectomy. In conclusion, ovariectomy redirects endothelial responses from relaxation to contraction by reducing vascular nitric oxide, augmenting thromboxane/prostanoid receptor signaling, and attenuating the vasodilatory effects of PVAT, all of which were dependent on reactive oxidative species.

Sex Differences in T-lymphocyte Tissue Infiltration and Development of Angiotensin II Hypertension

Hypertension (Dallas, Tex. : 1979). Aug, 2014  |  Pubmed ID: 24890822

There is extensive evidence that activation of the immune system is both necessary and required for the development of angiotensin II (Ang II)-induced hypertension in males. The purpose of this study was to determine whether sex differences exist in the ability of the adaptive immune system to induce Ang II-dependent hypertension and whether central and renal T-cell infiltration during Ang II-induced hypertension is sex dependent. Recombinant activating gene-1 (Rag-1)(-/-) mice, lacking both T and B cells, were used. Male and female Rag-1(-/-) mice received adoptive transfer of male CD3(+) T cells 3 weeks before 14-day Ang II infusion (490 ng/kg per minute). Blood pressure was monitored via tail cuff. In the absence of T cells, systolic blood pressure responses to Ang II were similar between sexes (Δ22.1 mm Hg males versus Δ18 mm : Hg females). After adoptive transfer of male T cells, Ang II significantly increased systolic blood pressure in males (Δ37.7 mm : Hg; P<0.05) when compared with females (Δ13.7 mm : Hg). Flow cytometric analysis of total T cells and CD4(+), CD8(+), and regulatory Foxp3(+)-CD4(+) T-cell subsets identified that renal lymphocyte infiltration was significantly increased in males versus females in both control and Ang II-infused animals (P<0.05). Immunohistochemical staining for CD3(+)-positive T cells in the subfornical organ region of the brain was increased in males when compared with that in females. These results suggest that female Rag-1(-/-) mice are protected from male T-cell-mediated increases in Ang II-induced hypertension when compared with their male counterparts, and this protection may involve sex differences in the magnitude of T-cell infiltration of the kidney and brain.

Sex-specific T-cell Regulation of Angiotensin II-dependent Hypertension

Hypertension. Sep, 2014  |  Pubmed ID: 24935938

Studies suggest T cells modulate arterial pressure. Because robust sex differences exist in the immune system and in hypertension, we investigated sex differences in T-cell modulation of angiotensin II-induced increases in mean arterial pressure in male (M) and female (F) wild-type and recombination-activating-gene-1-deficient (Rag1(-/-)) mice. Sex differences in peak mean arterial pressure in wild-type were lost in Rag1(-/-) mice (mm Hg: wild-type-F, 136±4.9 versus wild-type-M, 153±1.7; P<0.02; Rag1(-/-)-F, 135±2.1 versus Rag1(-/-)-M, 141±3.8). Peak mean arterial pressure was 13 mm Hg higher after adoptive transfer of male (CD3(M)→Rag1(-/-)-M) versus female (CD3(F)→Rag1(-/-)-M) T cells. CD3(M)→Rag1(-/-)-M mice exhibited higher splenic frequencies of proinflammatory interleukin-17A (2.4-fold) and tumor necrosis factor-α (2.2-fold)-producing T cells and lower plasma levels (13-fold) and renal mRNA expression (2.4-fold) of interleukin-10, whereas CD3(F)→Rag1(-/-)-M mice displayed a higher activation state in general and T-helper-1-biased renal inflammation. Greater T-cell infiltration into perivascular adipose tissue and kidney associated with increased pressor responses to angiotensin II if the T cell donor was male but not female and these sex differences in T-cell subset expansion and tissue infiltration were maintained for 7 to 8 weeks within the male host. Thus, the adaptive immune response and role of pro- and anti-inflammatory cytokine signaling in hypertension are distinct between the sexes and need to be understood to improve therapeutics for hypertension-associated disease in both men and women.

Sex and Basic Science. A Title IX Position

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Aug, 2014  |  Pubmed ID: 24944252

NIH Initiative to Balance Sex of Animals in Preclinical Studies: Generative Questions to Guide Policy, Implementation, and Metrics

Biology of Sex Differences. 2014  |  Pubmed ID: 25780556

In May of 2014, the NIH Director together with the Director of the Office of Research on Women's Health announced plans to take a multi-dimensional approach to address the over reliance on male cells and animals in preclinical research. The NIH is engaging the scientific community in the development of policies to improve the sex balance in research. The present, past, and future presidents of the Organization for the Study of Sex Differences, in order to encourage thoughtful discussion among scientists, pose a series of questions to generate ideas in three areas: 1. research strategies, 2. educational strategies, and 3. strategies to monitor effectiveness of policies to improve the sex balance in research. By promoting discussion within the scientific community, a consensus will evolve that will move science forward in a productive and effective manner.

Sex-specific Immune Modulation of Primary Hypertension

Cellular Immunology. Apr, 2015  |  Pubmed ID: 25498375

It is well known that the onset of essential hypertension occurs earlier in men than women. Numerous studies have shown sex differences in the vasculature, kidney and sympathetic nervous system contribute to this sex difference in the development of hypertension. The immune system also contributes to the development of hypertension; however, sex differences in immune system modulation of blood pressure (BP) and the development of hypertension has only recently begun to be explored. Here we review findings on the effect of one's sex on the immune system and specifically how these effects impact BP and the development of primary hypertension. We also propose a hypothesis for why mechanisms underlying inflammation-induced hypertension are sex-specific. These studies underscore the value of and need for studying both sexes in the basic science exploration of the pathophysiology of hypertension as well as other diseases.

Recommendations Concerning the New U.S. National Institutes of Health Initiative to Balance the Sex of Cells and Animals in Preclinical Research

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology. May, 2015  |  Pubmed ID: 25713032

The U.S. National Institutes of Health (NIH) announced last May that steps will be taken to address the over-reliance on male cells and animals in preclinical research. To further address this announcement, in September 2014, scientists with varying perspectives came together at Georgetown University to discuss the following questions. (1) What metrics should the NIH use to assess tangible progress on policy changes designed to address the over-reliance on male cells and animals in preclinical research? (2) How effective can education be in reducing the over-reliance on male cells and animals in preclinical research and what educational initiatives sponsored by the NIH would most likely effect change? (3) What criteria should the NIH use to determine rigorously defined exceptions to the future proposal requirement of a balance of male and female cells and animals in preclinical studies? (4) What additional strategies in addition to proposal requirements should NIH use to reduce the overreliance of male cells and animals in preclinical research? The resulting consensus presented herein includes input from researchers not only from diverse disciplines of basic and translational science including biology, cell and molecular biology, biochemistry, physiology, pharmacology, neuroscience, cardiology, endocrinology, nephrology, psychiatry, and obstetrics and gynecology, but also from recognized experts in publishing, industry, advocacy, science policy, clinical medicine, and population health. We offer our recommendations to aid the NIH as it selects, implements, monitors, and optimizes strategies to correct the over-reliance on male cells and animals in preclinical research.

A 5'-upstream Short Open Reading Frame Encoded Peptide Regulates Angiotensin Type 1a Receptor Production and Signalling Via the β-arrestin Pathway

The Journal of Physiology. Mar, 2016  |  Pubmed ID: 26333095

AUG sequences and short open reading frames are commonly present in the 5'-leader sequence of G protein-coupled receptor mRNAs. The presence of these upstream AUG sequences has been demonstrated to inhibit downstream receptor translation efficiency and, most recently, receptor signal transduction. A seven amino acid peptide encoded by a short open reading frame in exon 2 of the angiotensin type 1a receptor has been shown to inhibit non-G protein-coupled signalling of angiotensin II, without altering the classical G protein-coupled pathway activated by the ligand. This finding may lead to the development of a new class of angiotensin receptor antagonists with activities biased for one, but not all, of the signalling cascades activated by angiotensin II, which could have therapeutic implications for the myriad hormones and neurotransmitters that signal through G protein-coupled receptors.

Is Immune System-related Hypertension Associated with Ovarian Hormone Deficiency?

Experimental Physiology. Mar, 2016  |  Pubmed ID: 26419911

What is the topic of this review? This review summarizes recent data on the role of ovarian hormones and sex in inflammation-related hypertension. What advances does it highlight? The adaptive immune system has recently been implicated in the development of hypertension in males but not in females. The role of the immune system in the development of hypertension in women and its relationship to ovarian hormone production are highlighted. The immune system is known to contribute to the development of high blood pressure in males. However, the role of the immune system in the development of high blood pressure in females and the role of ovarian hormones has only recently begun to be studied. In animal studies, both the sex of the host and the T cell are critical biological determinants of susceptibility and resistance to hypertension induced by angiotensin II. In women, natural menopause is known to result in significant changes in the expression of genes regulating the immune system. Likewise, in animal models, ovariectomy results in hypertension and an upregulation in T-cell tumour necrosis factor-α-related genes. Oestrogen replacement results in decreases in inflammatory genes in the brain regions involved in blood pressure regulation. Together, these studies suggest that the response of the adaptive immune system to ovarian hormone deficiency is a significant contributor to hypertension in women.

Aging-related Impairment of Urine-concentrating Mechanisms Correlates with Dysregulation of Adrenocortical Angiotensin Type 1 Receptors in Male Fischer Rats

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Mar, 2016  |  Pubmed ID: 26702152

To investigate age-associated impairments in fluid homeostasis, 4-mo (young) and 32-mo (old) Fischer 344/BN male rats were studied before and after a dietary sodium load. Transferring young rats from a low-sodium (LS) to a high-sodium (HS) diet increased water intake and urine volume by 1.9- and 3.0-fold, respectively, while urine osmolality and plasma aldosterone decreased by 33 and 98%. Concomitantly, adrenocortical angiotensin type 1 receptor (AT1R) density decreased by 35%, and AT1bR mRNA decreased by 39%; no changes were observed in AT1aR mRNA. In contrast, the increase in water intake (1.4-fold) was lower in the old rats, and there was no effect of the HS diet on urine volume or urine osmolality. AT1R densities were 29% less in the old rats before transferring to the HS diet, and AT1R densities were not reduced as rapidly in response to a HS diet compared with the young animals. After 6 days on the HS diet, plasma potassium was lowered by 26% in the old rats, whereas no change was detected in the young rats. Furthermore, while plasma aldosterone was substantially decreased after 2 days on the HS diet in both young and old rats, plasma aldosterone was significantly lower in the old compared with the young animals after 2 wk on the LS diet. These findings suggest that aging attenuates the responsiveness of the adrenocortical AT1R to a sodium load through impaired regulation of AT1bR mRNA, and that this dysregulation contributes to the defects in water and electrolyte homeostasis observed in aging.

Report of the National Heart, Lung, and Blood Institute Working Group on Sex Differences Research in Cardiovascular Disease: Scientific Questions and Challenges

Hypertension (Dallas, Tex. : 1979). May, 2016  |  Pubmed ID: 26975706

National Heart, Lung, and Blood Institute Working Group Report on Salt in Human Health and Sickness: Building on the Current Scientific Evidence

Hypertension (Dallas, Tex. : 1979). Aug, 2016  |  Pubmed ID: 27324228

How to Study the Impact of Sex and Gender in Medical Research: a Review of Resources

Biology of Sex Differences. 2016  |  Pubmed ID: 27785348

There is a growing appreciation by the biomedical community that studying the impact of sex and gender on health, aging, and disease will lead to improvements in human health. Sex- and gender-based comparisons can inform research on disease mechanisms and the development of new therapeutics as well as enhance scientific rigor and reproducibility. This review will assist basic researchers, clinical investigators, as well as epidemiologists, population, and social scientists by providing an annotated bibliography of currently available resource tools on how to consider sex and gender as independent variables in research design and methodology. These resources will assist investigators applying for funding from the National Institutes of Health since all grant applicants will be required (as of January 25, 2016) to address the role of sex as a biological variable in vertebrate animal and human studies.

Considering Sex As a Biological Variable in Preclinical Research

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology. Jan, 2017  |  Pubmed ID: 27682203

In June 2015, the National Institutes of Health (NIH) released a Guide notice (NOT-OD-15-102) that highlighted the expectation of the NIH that the possible role of sex as a biologic variable be factored into research design, analyses, and reporting of vertebrate animal and human studies. Anticipating these guidelines, the NIH Office of Research on Women's Health, in October 2014, convened key stakeholders to discuss methods and techniques for integrating sex as a biologic variable in preclinical research. The workshop focused on practical methods, experimental design, and approaches to statistical analyses in the use of both male and female animals, cells, and tissues in preclinical research. Workshop participants also considered gender as a modifier of biology. This article builds on the workshop and is meant as a guide to preclinical investigators as they consider methods and techniques for inclusion of both sexes in preclinical research and is not intended to prescribe exhaustive/specific approaches for compliance with the new NIH policy.-Miller, L. R., Marks, C., Becker, J. B., Hurn, P. D., Chen, W.-J., Woodruff, T., McCarthy, M. M., Sohrabji, F., Schiebinger, L., Wetherington, C. L., Makris, S., Arnold, A. P., Einstein, G., Miller, V. M., Sandberg, K., Maier, S., Cornelison, T. L., Clayton, J. A. Considering sex as a biological variable in preclinical research.

How Consumer Physical Activity Monitors Could Transform Human Physiology Research

American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. Mar, 2017  |  Pubmed ID: 28052867

A sedentary lifestyle and lack of physical activity are well-established risk factors for chronic disease and adverse health outcomes. Thus, there is enormous interest in measuring physical activity in biomedical research. Many consumer physical activity monitors, including Basis Health Tracker, BodyMedia Fit, DirectLife, Fitbit Flex, Fitbit One, Fitbit Zip, Garmin Vivofit, Jawbone UP, MisFit Shine, Nike FuelBand, Polar Loop, Withings Pulse O2, and others have accuracies similar to that of research-grade physical activity monitors for measuring steps. This review focuses on the unprecedented opportunities that consumer physical activity monitors offer for human physiology and pathophysiology research because of their ability to measure activity continuously under real-life conditions and because they are already widely used by consumers. We examine current and potential uses of consumer physical activity monitors as a measuring or monitoring device, or as an intervention in strategies to change behavior and predict health outcomes. The accuracy, reliability, reproducibility, and validity of consumer physical activity monitors are reviewed, as are limitations and challenges associated with using these devices in research. Other topics covered include how smartphone apps and platforms, such as the Apple ResearchKit, can be used in conjunction with consumer physical activity monitors for research. Lastly, the future of consumer physical activity monitors and related technology is considered: pattern recognition, integration of sleep monitors, and other biosensors in combination with new forms of information processing.

Sex Hormones and Sex Chromosomes Cause Sex Differences in the Development of Cardiovascular Diseases

Arteriosclerosis, Thrombosis, and Vascular Biology. Mar, 2017  |  Pubmed ID: 28279969

This review summarizes recent evidence concerning hormonal and sex chromosome effects in obesity, atherosclerosis, aneurysms, ischemia/reperfusion injury, and hypertension. Cardiovascular diseases occur and progress differently in the 2 sexes, because biological factors differing between the sexes have sex-specific protective and harmful effects. By comparing the 2 sexes directly, and breaking down sex into its component parts, one can discover sex-biasing protective mechanisms that might be targeted in the clinic. Gonadal hormones, especially estrogens and androgens, have long been found to account for some sex differences in cardiovascular diseases, and molecular mechanisms mediating these effects have recently been elucidated. More recently, the inherent sexual inequalities in effects of sex chromosome genes have also been implicated as contributors in animal models of cardiovascular diseases, especially a deleterious effect of the second X chromosome found in females but not in males. Hormonal and sex chromosome mechanisms interact in the sex-specific control of certain diseases, sometimes by opposing the action of the other.

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