Name: Long-Term Continuous Measurement of Renal Blood Flow in Conscious Rats (Video) | JoVE Journal
Uploaded: 2022-02-08T15:00:00.000+00:00
Duration: 5 min 9 s
Description: Learn long-term continuous measurement of renal blood flow in conscious rats for hypertension research using implanted catheters. This method enables chronic 24-hour monitoring in naturalistic home environments.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This study was supported by grants for scientific research (P01 HL116264, RO1 HL137748). The authors would like to thank Theresa Kurth for her advice and help in maintaining the experimental environment as the lab manager.

The protocol is approved by the Medical College of Wisconsin Institutional Animal Care and Use. Dahl salt-sensitive rats (males and females), ~8 weeks of age, 200-350 g, were used for the experiments.
1. Animal preparation
<ol>
	<li>Install a movement response caging system for the rat, a perivascular flow module, syringe pump, recording device, and software (see Table of Materials) in the animal room.</li>
	<li>Place the rats in the cage to become familiar with the environment, food, and water system at least the week prior to surgery. Fast the rats from the day before the surgery because a high stomach content may interfere with the placement of the flow probe into the left renal artery and can cause tracheal aspiration.</li>
	<li>Connect a 5 cm of polyurethane tubing (inner diameter 0.30 mm and outer diameter 0.64 mm) to the end of the 90 cm of polyurethane tubing (inner diameter 0.64 mm and outer diameter 1.02 mm) with PVC cement to make a femoral arterial catheter (see Table of Materials).
	<ol>
		<li>Sterilize the catheters with an Ethylene oxide sterilizer, the flow probe with 2.5% glutaraldehyde, and the surgical instruments in a steam autoclave. Wipe surgical tables, microscopy, and lights with 1% sodium hypochlorite.</li>
	</ol>
	</li>
</ol>
2. Surgery
<ol>
	<li>Place the RBF probe following the steps below.
	<ol>
		<li>Anesthetize the rats with 2.0%-2.5% Isoflurane to the degree that the rats do not respond to the pain stimulus. Place it on the surgical table set at 37 &#176;C and inject 0.09 mg/kg of buprenorphine SR and 15 mg/kg of cefazolin (see Table of Materials) before surgery.</li>
		<li>Shave the entire abdomen with an electric clipper and a region on the nape of the neck around the 7th cervical vertebrae where the catheter and flow prove wires will exit.</li>
		<li>After shaving, wipe the area with 70% ethanol, 10% povidone-iodine, and again with 70% ethanol.</li>
		<li>Place the rat in the prone position. Make a 1 cm cut using a scalpel on the nape of the neck and the left flank. Then, perform a blunt dissection with hemostatic forceps and clear a subcutaneous space from the flank incision to the back of the neck.</li>
		<li>Pass the flow probe through this subcutaneous tunnel from the neck to the flank incision with hemostatic forceps.</li>
		<li>Place the rat in the supine position. Make a 4-5 cm midline abdominal incision.</li>
		<li>Dissect the area around the renal artery with curved tweezers to expose a space sufficient to place the flow probe (see Table of Materials). Then bluntly pierce the left quadratus lumborum muscle with the hemostatic forceps and pull the head of the flow probe into the abdominal cavity.</li>
		<li>Hook the tip of the flow probe to the left renal artery and connect it to the flow meter (see Table of Materials). Add some gel around the probe tip, and the value of the flow rate will appear on the flow meter. 
		NOTE: Although it depends on the size of the rat, a flow of about 3-5 mL/min will be observed in a 230 g rat.</li>
		<li>Glue the polyester fiber mesh attached to the probe with tissue adhesive to the abdominal wall and hold until dry and bonded (~1-2 min). Once the flow is in place, disconnect the flow probe from the flow meter and cover the abdomen with saline-soaked gauze and move on to the step of inserting the catheter.</li>
	</ol>
	</li>
	<li>Insert the femoral catheter following the steps below. 
	NOTE: The method for inserting a fluid-filled catheter is the same as regular telemetry installations. Although telemetry is preferred, the arterial catheter enables pressure monitoring and period blood sampling from the conscious rat.
	<ol>
		<li>First, fill the catheter with saline and clamp it with vascular forceps before making a 1 cm skin incision using a scalpel on the left thigh to dissect and expose the femoral artery. While blocking the flow at the proximal side of the femoral artery with a thread, insert the catheter.</li>
		<li>Flush with a small amount of saline, plug with appropriate size stainless wire, and tie the catheter with a thread to fix it.</li>
		<li>Once the ligature is tied around the catheter, create a subcutaneous tunnel by using a stainless-steel trocar from the thigh to the back of the neck to bring the catheter to the neck region. Secure it with 3-0 silk sutures placed in the trapezius muscle.</li>
	</ol>
	</li>
	<li>Suture the probe.
	<ol>
		<li>Turn the rat to the prone position and stitch the circular loop of the flow probe subcutaneously at the flank. Suture the incision at the flank and the neck with 4-0 surgical suture (see Table of Materials).</li>
		<li>Attach a skin button to the flow probe and suture it with 3-0 silk at the back of the neck.</li>
		<li>Connect the flow probe to the flow meter again, turn the rat back to the dorsal position to check RBF, and make final adjustments of the flow probe to optimize its position on the renal artery.</li>
		<li>Finally, suture the muscle with 3-0 silk and the skin with 4-0 surgical suture.</li>
	</ol>
	</li>
</ol>
3. Recovery of the animal
<ol>
	<li>After careful observation, until the rats are fully recovered from the anesthesia, return the rats to a movement response caging system, connect the flow probe to the blood flow meter, and allow a recovery period of about a week to stabilize the probe and flow measurement. 
	NOTE: Recording doesn&#39;t have to be done during this period.</li>
	<li>Infuse 3% heparinized saline continuously throughout the study from the arterial catheter at the rate of 100 &#181;L/h to prevent the clotting.</li>
	<li>When the flow stabilizes after 5-6 days, set the flowmeter calibration to measure blood flow at 0-20 mL/min and begin the continuous recording of RBF.</li>
</ol>

<ol><li>Chonchol, M., Smogorzewski, M., Stubbs, J., Yu, A. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aChonchol%2C+M+%22Brenner+%26+Rector%27s+The+Kidney%22">Brenner & Rector's The Kidney</a>. 11, Elsevier Inc. Philadelphia, PA. (2019).</li>
<li>Chen, J. -K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Phosphatidylinositol+3-kinase+signaling+determines+kidney+size%5BTitle%5D)+AND+%22Journal+of+Clinical+Investigation%22%5BJournal%5D)">Phosphatidylinositol 3-kinase signaling determines kidney size.</a> Journal of Clinical Investigation. 125 (6), 2429-2444 (2015).</li>
<li>Sigmon, D. H., Gonzalez-Feldman, E., Cavasin, M. A., Potter, D. L., Beierwaltes, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+nitric+oxide+in+the+renal+hemodynamic+response+to+unilateral+nephrectomy%5BTitle%5D)+AND+%22Journal+of+the+American+Society+of+Nephrology%22%5BJournal%5D)">Role of nitric oxide in the renal hemodynamic response to unilateral nephrectomy.</a> Journal of the American Society of Nephrology. 15 (6), 1413-1420 (2004).</li>
<li>Romero, C. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Noninvasive+measurement+of+renal+blood+flow+by+magnetic+resonance+imaging+in+rats%5BTitle%5D)+AND+%22American+Journal+of+Physiology-Renal+Physiology%22%5BJournal%5D)">Noninvasive measurement of renal blood flow by magnetic resonance imaging in rats.</a> American Journal of Physiology-Renal Physiology. 314 (1), 99-106 (2018).</li>
<li>Basile, D. P., Anderson, M. D., Sutton, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pathophysiology+of+acute+kidney+injury%5BTitle%5D)+AND+%22Comprehensive+Physiology%22%5BJournal%5D)">Pathophysiology of acute kidney injury.</a> Comprehensive Physiology. 2 (2), 1303-1353 (2012).</li>
<li>Regan, M. C., Young, L. S., Geraghty, J., Fitzpatrick, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Regional+renal+blood+flow+in+normal+and+disease+states%5BTitle%5D)+AND+%22Urological+Research%22%5BJournal%5D)">Regional renal blood flow in normal and disease states.</a> Urological Research. 23 (1), 1-10 (1995).</li>
<li>Ter Wee, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+calcium+antagonists+on+renal+hemodynamics+and+progression+of+nondiabetic+chronic+renal+disease%5BTitle%5D)+AND+%22Archives+of+Internal+Medicine%22%5BJournal%5D)">Effects of calcium antagonists on renal hemodynamics and progression of nondiabetic chronic renal disease.</a> Archives of Internal Medicine. 154 (11), 1185(1994).</li>
<li>Mazze, R. I., Cousins, M. J., Barr, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Renal+effects+and+metabolism+of+isoflurane+in+man%5BTitle%5D)+AND+%22Anesthesiology%22%5BJournal%5D)">Renal effects and metabolism of isoflurane in man.</a> Anesthesiology. 40 (6), 536-542 (1974).</li>
<li>Corrigan, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((PAH+extraction+and+estimation+of+plasma+flow+in+human+postischemic+acute+renal+failure%5BTitle%5D)+AND+%22American+Journal+of+Physiology-Renal+Physiology%22%5BJournal%5D)">PAH extraction and estimation of plasma flow in human postischemic acute renal failure.</a> American Journal of Physiology-Renal Physiology. 277 (2), 312-318 (1999).</li>
<li>Laroute, V., Lefebvre, H. P., Costes, G., Toutain, P. -L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Measurement+of+glomerular+filtration+rate+and+effective+renal+plasma+flow+in+the+conscious+beagle+dog+by+single+intravenous+bolus+of+iohexol+and+p-aminohippuric+acid%5BTitle%5D)+AND+%22Journal+of+Pharmacological+and+Toxicological+Methods%22%5BJournal%5D)">Measurement of glomerular filtration rate and effective renal plasma flow in the conscious beagle dog by single intravenous bolus of iohexol and p-aminohippuric acid.</a> Journal of Pharmacological and Toxicological Methods. 41 (1), 17-25 (1999).</li>
<li>Wei, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Quantification+of+renal+blood+flow+with+contrast-enhanced+ultrasound%5BTitle%5D)+AND+%22Journal+of+the+American+College+of+Cardiology%22%5BJournal%5D)">Quantification of renal blood flow with contrast-enhanced ultrasound.</a> Journal of the American College of Cardiology. 37 (4), 1135-1140 (2001).</li>
<li>Cao, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Contrast-enhanced+ultrasound+for+assessing+renal+perfusion+impairment+and+predicting+acute+kidney+injury+to+chronic+kidney+disease+progression%5BTitle%5D)+AND+%22Antioxidants+%26+Redox+Signaling%22%5BJournal%5D)">Contrast-enhanced ultrasound for assessing renal perfusion impairment and predicting acute kidney injury to chronic kidney disease progression.</a> Antioxidants & Redox Signaling. 27 (17), 1397-1411 (2017).</li>
<li>Markl, M., Frydrychowicz, A., Kozerke, S., Hope, M., Wieben, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((4D+flow+MRI%5BTitle%5D)+AND+%22Journal+of+Magnetic+Resonance+Imaging%22%5BJournal%5D)">4D flow MRI.</a> Journal of Magnetic Resonance Imaging. 36 (5), 1015-1036 (2012).</li>
<li>Juillard, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dynamic+renal+blood+flow+measurement+by+positron+emission+tomography+in+patients+with+CRF%5BTitle%5D)+AND+%22American+Journal+of+Kidney+Diseases%22%5BJournal%5D)">Dynamic renal blood flow measurement by positron emission tomography in patients with CRF.</a> American Journal of Kidney Diseases. 40 (5), 947-954 (2002).</li>
<li>Juárez-Orozco, L. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Imaging+of+cardiac+and+renal+perfusion+in+a+rat+model+with+13N-NH3+micro-PET%5BTitle%5D)+AND+%22The+International+Journal+of+Cardiovascular+Imaging%22%5BJournal%5D)">Imaging of cardiac and renal perfusion in a rat model with 13N-NH3 micro-PET.</a> The International Journal of Cardiovascular Imaging. 31 (1), 213-219 (2015).</li>
<li>Mori, T., Cowley, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+pressure+in+angiotensin+II-induced+renal+injury%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Role of pressure in angiotensin II-induced renal injury.</a> Hypertension. 43 (4), 752-759 (2004).</li>
<li>Mori, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((High+perfusion+pressure+accelerates+renal+injury+in+salt-sensitive+hypertension%5BTitle%5D)+AND+%22Journal+of+the+American+Society+of+Nephrology%22%5BJournal%5D)">High perfusion pressure accelerates renal injury in salt-sensitive hypertension.</a> Journal of the American Society of Nephrology. 19 (8), 1472-1482 (2008).</li>
<li>Polichnowski, A. J., Cowley, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pressure-induced+renal+injury+in+angiotensin+II+versus+norepinephrine-induced+hypertensive+rats%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Pressure-induced renal injury in angiotensin II versus norepinephrine-induced hypertensive rats.</a> Hypertension. 54 (6), 1269-1277 (2009).</li>
<li>Polichnowski, A. J., Jin, C., Yang, C., Cowley, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+renal+perfusion+pressure+versus+angiotensin+II+renal+oxidative+stress+in+angiotensin+II-induced+hypertensive+rats%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Role of renal perfusion pressure versus angiotensin II renal oxidative stress in angiotensin II-induced hypertensive rats.</a> Hypertension. 55 (6), 1425-1430 (2010).</li>
<li>Evans, L. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Increased+perfusion+pressure+drives+renal+T-cell+infiltration+in+the+dahl+salt-sensitive+rat%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Increased perfusion pressure drives renal T-cell infiltration in the dahl salt-sensitive rat.</a> Hypertension. 70 (3), 543-551 (2017).</li>
<li>Shimada, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Renal+perfusion+pressure+determines+infiltration+of+leukocytes+in+the+kidney+of+rats+with+angiotensin+II-induced+hypertension%5BTitle%5D)+AND+%22Hypertension%22%5BJournal%5D)">Renal perfusion pressure determines infiltration of leukocytes in the kidney of rats with angiotensin II-induced hypertension.</a> Hypertension. 76 (3), 849-858 (2020).</li>
<li>Cousins, M. J., Mazze, R. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Anaesthesia%2C+surgery+and+renal+function%3A+Immediate+and+delayed+effects%5BTitle%5D)+AND+%22Anaesthesia+and+Intensive+Care%22%5BJournal%5D)">Anaesthesia, surgery and renal function: Immediate and delayed effects.</a> Anaesthesia and Intensive Care. 1 (5), 355-373 (1973).</li>
<li>Cousins, M. J., Skowronski, G., Plummer, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Anaesthesia+and+the+kidney%5BTitle%5D)+AND+%22Anaesthesia+and+Intensive+Care%22%5BJournal%5D)">Anaesthesia and the kidney.</a> Anaesthesia and Intensive Care. 11 (4), 292-320 (1983).</li>
<li>Schiffer, T. A., Christensen, M., Gustafsson, H., Palm, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+effect+of+inactin+on+kidney+mitochondrial+function+and+production+of+reactive+oxygen+species%5BTitle%5D)+AND+%22PLOS+ONE%22%5BJournal%5D)">The effect of inactin on kidney mitochondrial function and production of reactive oxygen species.</a> PLOS ONE. 13 (11), 0207728(2018).</li>
<li>Evans, R. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chronic+renal+blood+flow+measurement+in+dogs+by+transit-time+ultrasound+flowmetry%5BTitle%5D)+AND+%22Journal+of+Pharmacological+and+Toxicological+Methods%22%5BJournal%5D)">Chronic renal blood flow measurement in dogs by transit-time ultrasound flowmetry.</a> Journal of Pharmacological and Toxicological Methods. 38 (1), 33-39 (1997).</li>
<li>Bell, T. D., DiBona, G. F., Biemiller, R., Brands, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Continuously+measured+renal+blood+flow+does+not+increase+in+diabetes+if+nitric+oxide+synthesis+is+blocked%5BTitle%5D)+AND+%22American+Journal+of+Physiology-Renal+Physiology%22%5BJournal%5D)">Continuously measured renal blood flow does not increase in diabetes if nitric oxide synthesis is blocked.</a> American Journal of Physiology-Renal Physiology. 295 (5), 1449-1456 (2008).</li>
</ol>

The authors have nothing to disclose.

The present protocol describes a technique that utilizes commercially available instrumentation to record RBF and arterial pressure continuously over many weeks. In addition, urine can be collected using the device described in step 1.1. It can also be used to evaluate metabolites in the urine and, when an arterial catheter is implanted, blood sampling for analysis.
Traditionally, RBF measurements have been obtained acutely in surgically prepared anesthetized animals or estimated by PAH cleara...

The kidneys are only 0.5% of the bodyweight but rich in blood flow, receiving 20%-25% of the total cardiac output1. The regulation of renal blood flow (RBF) is central to kidney function, body fluid, and electrolyte homeostasis. The importance of blood flow regulation to the kidney is nicely illustrated by the substantial increase of RBF in the remaining kidney after unilateral nephrectomy2,3,4 and by the reductions of RBF that occur in kidney failure5,6,7. Whether such changes in RBF occur in response to alterations in kidney function or a decrease in function due to reduction of RBF has been challenging to ascertain in anesthetized surgically prepared animals or human subjects. Temporal studies are required in which the events can be determined before and following a defined change and observed in the same animal during the progression of events. In the animal and human studies, RBF has been estimated indirectly by the clearance of para-amino hippuric acid (PAH)8,9,10 and in more recent time by imaging techniques such as ultrasound9,11,12, MRI4,13, and PET-CT14,15 which give helpful snapshot images of each kidney and which can follow the progression of the disease. It is challenging to evaluate RBF in small animals by ultrasound or MRI scans without anesthesia. It has been impossible to continuously measure RBF under conscious conditions in the same rat over prolonged periods.
The present protocol, therefore, developed techniques that enable simultaneous continuous 24 h/day measurements of RBF, which has been combined with continuous blood pressure measurement methods for freely moving rats as described previously16,17,18,19,20,21. This technology allows for the temporal evaluation of RBF in various models of rats to study cause-effect relationships in various renal disorders in the future.

<table><tbody><tr><td>1RB probe</td><td>Transonic</td><td>1RB</td><td>ultrasonic flow probe</td></tr><tr><td>Betadine</td><td>Avrio Health</td><td></td><td>povidone-iodine</td></tr><tr><td>Buprenorphine SR-LAB</td><td>ZooPharm</td><td></td><td>Buprenorphine</td></tr><tr><td>Cefazolin</td><td>APOTEX</td><td>NDC 60505</td><td>Cefazolin</td></tr><tr><td>Crile Hemostats</td><td>Fine Surgical Instruments</td><td>13004-14</td><td>Hemostats for blunt dissection</td></tr><tr><td>Isoflurane</td><td>Piramal</td><td>NDC 66794</td><td>Isoflurane</td></tr><tr><td>Medium Clear PVC cement</td><td>Oatey</td><td></td><td>PVC cement</td></tr><tr><td>Mersilene polyester fiber mesh</td><td>Ethicon</td><td></td><td>polyester fiber mesh</td></tr><tr><td>MetriCide28</td><td>Metrex</td><td>SKU 10-2805</td><td>2.5% glutaraldehyde</td></tr><tr><td>Micro-Renathane 0.025 x 0.012</td><td>Braintree Scientific</td><td>MRE 025</td><td>use for catheter</td></tr><tr><td>MINI HYPE-WIPE</td><td>Current Technologies</td><td>#9803</td><td>1% sodium hypochlorite</td></tr><tr><td>Oatey Medium Clear PVC Cement</td><td>Oatey</td><td>#31018</td><td>PVC cement</td></tr><tr><td>PHD2000 syringe pump</td><td>Harvard apparatus</td><td>71-2000</td><td>syringe pump</td></tr><tr><td>Ponemah software</td><td>DSI</td><td></td><td>recording software</td></tr><tr><td>Precision 3630 Tower</td><td>Dell</td><td></td><td>Computer for recording</td></tr><tr><td>Raturn Stand-Alone System</td><td>BASi</td><td>MD-1407</td><td>a movement response caging system</td></tr><tr><td>RenaPulse High Fidelity Pressure Tubing 0.040 x 0.025</td><td>Braintree Scientific</td><td>RPT 040</td><td>use for catheter</td></tr><tr><td>Silicone cuff</td><td>Transonic</td><td>AAPC102</td><td>skin button</td></tr><tr><td>Surgical lubricant sterile bacteriostatic</td><td>Fougera</td><td>0168-0205-36</td><td>gell for flow probe</td></tr><tr><td>Tergazyme</td><td>Alconox</td><td></td><td>protease contained anionic detergent</td></tr><tr><td>TS420 Perivascular Flow Module</td><td>Transonic</td><td>TS420</td><td>perivascular flow module</td></tr><tr><td>Vetbond</td><td>3M</td><td>1469SB</td><td>tissue adhesive</td></tr><tr><td>WinDaq software</td><td>DATAQ</td><td></td><td>recording software</td></tr></tbody></table>

long-term continuous measurement of renal blood flow in conscious rats

Long-Term Continuous Measurement of Renal Blood Flow in Conscious Rats

The kidneys play a crucial role in maintaining the homeostasis of body fluids. The regulation of renal blood flow (RBF) is essential to the vital functions of filtration and metabolism in kidney function. Many acute studies have been carried out in anesthetized animals to measure RBF under various conditions to determine mechanisms responsible for the regulation of kidney perfusion. However, for technical reasons, it has not been possible to measure RBF continuously (24 h/day) in unrestrained unanesthetized rats over prolonged periods. These methods allow the continuous determination of RBF over many weeks while also simultaneously recording blood pressure (BP) with implanted catheters (fluid-filled or by telemetry). RBF monitoring is carried out with rats placed in a circular servo-controlled rat cage that enables the unrestrained movement of the rat throughout the study. At the same time, the tangling of cables from the flow probe and arterial catheters is prevented. Rats are first instrumented with an ultrasonic flow probe placement on the left renal artery and an arterial catheter implanted in the right femoral artery. These are routed subcutaneously to the nape of the neck, and connected to the flowmeter and pressure transducer, respectively, to measure RBF and BP. Following surgical implantation, rats are immediately placed in the cage to recover for at least one week and stabilize the ultrasonic probe recordings. Urine collection is also feasible in this system. The surgical and post-surgical procedures for continuous monitoring are demonstrated in this protocol.

The mean arterial pressure data (Figure 1A) and blood flow data (Figure 1B) from a representative male Dahl salt-sensitive rat are shown. The Dahl salt-sensitive rats are maintained in a colony and bred at the Medical College of Wisconsin. The surgery was done at the age of 8 weeks, and the bodyweight was 249 g at the time of surgery. Rats were fed with a 0.4% NaCl diet, and the diet was changed to a 4% NaCl diet at the age of 10 weeks. Measurements were continu...

The present protocol describes a long-term continuous measurement of renal blood flow in conscious rats and simultaneously recording blood pressure with implanted catheters (fluid-filled or by telemetry).

The kidneys play a crucial role in maintaining the homeostasis of body fluids. The regulation of renal blood flow (RBF) is essential to the vital ...

long-term-continuous-measurement-of-renal-blood-flow-in-conscious-rats

Research

JoVE Journal

Medicine

Chronic catheterization of blood vessels in the rat is often required for administration of substances, obtain blood sample over a period of time or for direct conscious blood pressure measurements.  Femoral arterial catheterization of the rat and corresponding measurements of blood pressure in the conscious animal will be demonstrated.

Femoral Arterial and Venous Catheterization for Blood Sampling, Drug Administration and Conscious Blood Pressure and Heart Rate Measurements

Measurement of glomerular filtration rate (GFR) is the gold standard for kidney function assessment. Here we describe a high-throughput method which allows the determination of GFR in conscious mice by using a single bolus injection, determination of fluorescein isothiocyanate (FITC)-inulin in plasma and calculation of GFR by a two-phase exponential decay model.

A High-throughput Method for Measurement of Glomerular Filtration Rate in Conscious Mice

A method is presented to measure microcirculatory blood flow velocity in pulmonary cancer metastases of the pleural surface in rats in an automated fashion, using closed-chest pulmonary intravital microscopy. This model has potential to be used as a widespread tool to perform physiologic research on pulmonary metastases in rodents.

Automated Measurement of Microcirculatory Blood Flow Velocity in Pulmonary Metastases of Rats

Early stage hemodynamic dysfunction is critical to the development of kidney disease. Yet, detection methodologies are limited. Recent advances in sonography provide a noninvasive, accurate option for early detection of kidney injury. This study outlines a step-by-step, sonographic methodology for detecting kidney dysfunction using a drug-induced nephrotoxicity rat model.

Early Detection of Drug-Induced Renal Hemodynamic Dysfunction Using Sonographic Technology in Rats

The purpose of this protocol is to demonstrate the principles and techniques for measuring and calculating glomerular filtration rate, urine flow rate, and excretion of sodium and potassium in a rat. This demonstration can be used to provide students with an overall conceptual understanding of how to measure renal function.

Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat

Determination of glomerular filtration rate (GFR) is the gold standard to assess overall kidney function. However, traditional procedures to measure this parameter are cumbersome and require a large investment of time. Here we describe a faster and minimally invasive method to determinate GFR transcutaneously.

Transcutaneous Assessment of Renal Function in Conscious Rodents

Anesthetized mice exhibit non-physiological systemic blood pressure, which precludes meaningful assessment of autonomic tone given the intimate relationship between blood pressure and the autonomic nervous system. Thus, a novel method to simultaneously record renal sympathetic nerve activity and blood pressure with intravenous infusion in conscious mice is outlined.

Novel Approach for Simultaneous Recording of Renal Sympathetic Nerve Activity and Blood Pressure with Intravenous Infusion in Conscious, Unrestrained Mice.

Here we describe a protocol to measure glomerular filtration rate (GFR) in conscious, freely moving mice using a transdermal GFR monitor.

Transdermal Measurement of Glomerular Filtration Rate in Mice

Here a protocol for continuous blood sampling during PET/CT imaging of rats to measure the arterial input function (AIF) is described. The catheterization, the calibration and setup of the system and the data analysis of the blood radioactivity are demonstrated. The generated data provide input parameters for subsequent bio-kinetic modeling.

Continuous Blood Sampling in Small Animal Positron Emission Tomography/Computed Tomography Enables the Measurement of the Arterial Input Function

This article demonstrates the use of laser Doppler flowmetry to evaluate the ability of the cerebral circulation to autoregulate its blood flow during reductions in arterial blood pressure.

Evaluation of Cerebral Blood Flow Autoregulation in the Rat Using Laser Doppler Flowmetry

Learn long-term continuous measurement of renal blood flow in conscious rats for hypertension research using implanted catheters. This method enables chronic 24-hour monitoring in naturalistic home environments.

Long-Term Continuous Measurement of Renal Blood Flow in Conscious Rats

Explore More Videos