isolation-intrapulmonary-artery-smooth-muscle-cells-to-investigate

Isolation of Intrapulmonary Artery and Smooth Muscle Cells to Investigate Vascular Responses

The intrapulmonary artery (IPA) and vascular smooth muscle cells (VSMCs) isolated from rat lungs can be used to study the underlying mechanisms of ...

Naresuan University

Cardiovascular effects (e.g., tachycardia, hypo- and/or hypertension) are often clinical outcomes of snake envenoming. Malayan krait () envenoming has been reported to cause cardiovascular effects that may be related to abnormalities in parasympathetic activity. However, the exact mechanism for this effect has yet to be determined. In the present study, we investigated the  and  cardiovascular effects of  venoms from Southern (BC-S) and Northeastern (BC-NE) Thailand. SDS-PAGE analysis of venoms showed some differences in the protein profile of the venoms.  venoms (50 µg/kg-100 µg/kg, i.v.) caused dose-dependent hypotension in anaesthetised rats. The highest dose caused sudden hypotension (phase I) followed by a return of mean arterial pressure to baseline levels and a decrease in heart rate with transient hypertension (phase II) prior to a small decrease in blood pressure (phase III). Prior administration of monovalent antivenom significantly attenuated the hypotension induced by venoms (100 µg/kg, i.v.). The sudden hypotensive effect of BC-NE venom was abolished by prior administration of hexamethonium (10 mg/kg, i.v.) or atropine (5 mg/kg, i.v.). BC-S and BC-NE venoms (0.1 µg/kg-100 µg/ml) induced concentration-dependent relaxation (EC = 8 ± 1 and 13 ± 3 µg/mL, respectively) in endothelium-intact aorta. The concentration-response curves were markedly shifted to the right by pre-incubation with L-NAME (0.2 mM), or removal of the endothelium, suggesting that endothelium-derived nitric oxide (NO) is likely to be responsible for venom-induced aortic relaxation. Our data indicate that the cardiovascular effects caused by  venoms may be due to a combination of vascular mediators (i.e., NO) and autonomic adaptation via nicotinic and muscarinic acetylcholine receptors.

A Pharmacological Examination of the Cardiovascular Effects of Malayan Krait (Bungarus candidus) Venoms.

The leaves of  spp. promote "physiological balance", and are "cardiotonic and provide blood nourishment". In Asia, these leaves are increasingly consumed as tea and claimed to provide benefits to cardiovascular function, albeit without any scientific proof. Therefore, this study sought to evaluate the action of  leaf aqueous extract (AE) on vascular function and vascular smooth muscle cytotoxicity. AE and a main constituent, mangiferin were investigated for their vasorelaxation of rat mesenteric arteries and aortae . Acute cytotoxicity of AE (0.1-1000 μg/ml) and mangiferin (0.1-100 μM) on rat enzymatically isolated vascular smooth muscle cells was assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. AE dilated rat mesenteric arteries (EC∼107 μg/ml, E∼95%) more than aorta (EC∼265 μg/ml, E∼76%,  < 0.05). AE-induced vasodilation in mesenteric artery was reduced by endothelial removal (EC∼202 μg/ml,  < 0.05), incubation with endothelial nitric oxide synthase (eNOS) (100 μM, L-NAME) (EC∼309 μg/ml,  < 0.05), and partly reduced by L-type Ca channel blockade at higher concentrations. Likewise, mangiferin (1-100 μM) dilated the mesenteric artery more potently than the aorta. However, its maximum relaxation was less than with AE (41% in the mesenteric artery and <10% in the aorta). Isolated vascular smooth muscle cells incubated in AE or mangiferin for 1 h showed no cytotoxicity. Thus, AE is a vasorelaxant while being free of acute cytotoxicity towards vascular smooth muscle, thus potentially ameliorating human vascular dysfunction.

Extract of  leaves and mangiferin are vasodilators while showing no cytotoxicity.

Yahom Navakot (YN), is a Thai traditional medicine, consisting of 54 plants, for treating fainting and dizziness. Thus, YN might relieve orthostatic hypotension (OH) symptoms, but its therapeutic action is unclear. Therefore, this study evaluated YN in OH rats, using a head-up tilt test (HUT).

Article	Year
A Pharmacological Examination of the Cardiovascular Effects of Malayan Krait (Bungarus candidus) Venoms. Toxins\| PubMed ID: 28353659	2017
Extract of leaves and mangiferin are vasodilators while showing no cytotoxicity. Journal of traditional and complementary medicine\| PubMed ID: 31453117	2019
Anti-hypotensive effect of "Yahom Navakot" in rats with orthostatic hypotension. Journal of traditional and complementary medicine\| PubMed ID: 35528473	2022

Anjaree Inchan

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