The funding source for the lab demonstration was NIGMS grant: GM077119. We thank Dr. Joseph R. Haywood and Dr. Peter Cobbett for their support of the Short Couse in Integrative and Organ Systems Pharmacology. We also thank Ms. Hannah Garver for her technical support of the laboratory demonstration.&#160;

Prior to any animal procedure, the institutional animal care and use committee (IACUC) must approve the protocol. This protocol was approved by the Michigan State University IACUC.
1. Pre-lab Preparation of FITC-inulin Solution
<ol>
	<li>Warm 20 ml of saline to 70 &#176;C and slowly stir in 100 mg of FITC-inulin (5 mg/ml FITC-inulin) until all inulin is dissolved.</li>
	<li>Cool solution to RT&#160;and add 800 mg of bovine serum albumin (40 mg/ml BSA, lyophilized powder, essentially globulin free, low endotoxin, &#8805;98% purity by agarose gel electrophoresis).</li>
	<li>Filter the inulin-BSA solution with filter paper (grade 1). Place the filtered solution in a 20 ml syringe with a syringe-tip filter (0.2 &#181;m) and cover with foil to protect from light.</li>
</ol>
2. Anesthesia and Surgery
<ol>
	<li>Place the rat in an induction chamber filled with 5% isoflurane to induce anesthesia. Record body weight (250-350 g) and place the rat on a heated surgical platform designed to maintain 37 &#176;C body temperature throughout the experiment. Gently secure the rat to the platform with laboratory tape over the paws.&#160;Maintain anesthesia with 1-2% isoflurane with medical grade 100% O2&#160;at airflow rate of 0.8-1.0 L/min.</li>
	<li>Insert a tapered catheter (intravascular tip O.D., 2.7F)&#160;into the femoral artery for blood pressure and heart rate monitoring, and blood sampling.</li>
	<li>Insert a catheter (PE-50) into the femoral vein for inulin infusion. Secure the catheter to surrounding tissue with 5-O braided silk surgical suture6.</li>
	<li>Attach the arterial catheter to a strain gauge pressure transducer. Record blood pressure and heart rate using data acquisition software and display on a computer screen in real-time. This technique is demonstrated in detail on video6.</li>
	<li>Expose the bladder via a suprapubic incision. Cut a small hole in the tip of the bladder and insert a cannula (PE-190) with a heat flared tip inside the bladder for urine collection. Secure the cannula to the bladder with a purse-string suture.</li>
</ol>
3. Urine and Blood Collection
<ol>
	<li>Place the syringe of FITC-inulin in a syringe pump with flow rate set of 1 ml/hr per 100 g of body weight (3 ml/hr for a rat weighing 300 g). Attach the syringe to the femoral vein catheter. Start the inulin infusion and allow a 1-2 hr equilibration period. Keep syringe covered with foil to protect from light.</li>
	<li>Determine if urine flow rate is stable and adequate for sample analysis (20 &#181;l/min) by collecting a urine sample in a pre-weighed collection vial for a period of 10 min. Determine urine volume gravimetrically with a digital scale. An adequate urine volume for a 10 min collection period is 0.2 ml. Continue to collect urine samples until two consecutive collections indicate a urine flow rate of 20 &#181;l/min or more.</li>
	<li>Pre-Drug Samples
	<ol>
		<li>Collect a urine sample during a 20 min period. Collect a blood sample (0.5 ml) from the arterial catheter at the midpoint of the urine collection period. Be careful to completely clear the arterial catheter of saline before collecting a blood sample in a collection vial containing 1 U heparin. Use collection vials with volume markings to facilitate the collection of 0.5 ml&#160;of arterial blood.</li>
		<li>Flush the arterial catheter with heparin-saline (20 U/ml) to clear the catheter of blood (approx. 0.1 ml). The length of the arterial catheter should be as short as possible to limit the volume of heparin-saline required to flush. 
		Note: Diluted blood samples produce inaccurate calculations of GFR and fractional excretion of Na and K.</li>
		<li>Wait 10 min, and repeat the collection of a second Pre-drug urine and blood sample.</li>
	</ol>
	</li>
	<li>Following the collection of two Pre-drug samples, administer a diuretic drug, furosemide (10 mg/kg), via the arterial catheter. Flush the arterial catheter with heparinized saline to clear the catheter of drug. Take care to prevent the injection of air through the arterial catheter. Record the time of the furosemide injection.</li>
	<li>Post-drug Samples: At each of the 3 time points below, collect a urine sample during a 10 min collection period, and a blood sample (0.5 ml) at the midpoint of the urine collection period.
	<ol>
		<li>For Post-Drug Sample 1 &#8211; collect five min after furosemide.</li>
		<li>For Post-Drug Sample 2 &#8211; collect ten min after furosemide.</li>
		<li>For Post-Drug Sample 3 &#8211; collect fifteen min after furosemide.</li>
	</ol>
	</li>
	<li>After all samples have been collected, euthanize the rat in accordance with institutional procedures by thoracotomy and removal of the heart. Remove both kidneys. Decapsulate (remove the surrounding membrane) and blot the kidneys to remove excess blood. Weigh the kidneys.</li>
</ol>
4. Sample Analysis
<ol>
	<li>Measure all urine sample volumes gravimetrically with a digital scale, and record weights.</li>
	<li>Centrifuge whole blood samples with a table-top centrifuge (1,800 x g) to separate plasma. Transfer plasma samples to small labeled vials.</li>
	<li>Analyze Na and K concentrations in urine and plasma samples with a sodium/potassium analyzer.</li>
	<li>Measurement of FITC-inulin in plasma and urine
	<ol>
		<li>Dilute pre-drug urine (from 1:200 to 1:400), and post-drug urine (1:10) with HEPES buffer (500 mM, pH 7.4).</li>
		<li>Add 40 &#181;l of standard or sample and 60 &#181;l of HEPES buffer in a 96 well plate (one sample per well) and allow to mix for 10 min while covered with aluminum foil.</li>
		<li>Generate a standard curve for FITC-inulin for concentrations of 6.25, 12.5, 25, 50, 100, 200, 400 &#181;g/ml&#160;(Figure 1). Determine FITC-inulin fluorescence in samples and standards using a microplate reader with excitation and emission wavelengths of 485 and 538 nm, respectively.</li>
		<li>Fit the fluorescent values for the standards to a 4-paramter logistic function regression analysis. The regression function parameters are used to calculate FITC-inulin concentration in plasma and urine samples (Table 1).</li>
	</ol>
	</li>
</ol>
5. Post-lab Analysis of Results: Calculations
<ol>
	<li>Calculate Urine Flow Rate (UV; ml/min): [volume of urine collected (ml)] &#247; [time of collection (min)]</li>
	<li>Calculate Glomerular Filtration Rate (GFR; ml/min): [Urine inulin concentration (&#181;g/ml) x UV (ml/min)] &#247; [Plasma inulin conc. (&#181;g/ml)]</li>
	<li>Calculate Filtered Sodium Load (&#181;mol/min): Plasma sodium concentration (&#181;mol/ml) x GFR (ml/min)</li>
	<li>Calculate Sodium Excretion Rate (UNaV; &#181;mol/min): Urine sodium concentration (&#181;mol/ml) x UV (ml/min)</li>
	<li>Calculate Fractional Excretion of Sodium (FE Na; %): [UNaV (&#181;mol/min)] &#247; [Filtered Sodium Load (&#181;mol/min)] x 100</li>
	<li>Calculate Filtered Potassium Load (&#181;mol/min): Plasma potassium concentration (&#181;mol/ml) x GFR (ml/min)</li>
	<li>Calculate Potassium Excretion Rate (UKV; &#181;mol/min): Urine potassium concentration (&#181;mol/ml) x UV (ml/min)</li>
	<li>Calculate Fractional Excretion of Potassium (FE K; %): [UKV (&#181;mol/min)] &#247; [Filtered Potassium Load (&#181;mol/min)] x 100</li>
</ol>

<ol>
	<li>Silverthorn, D. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Human Physiology: An integrated approach. , (2012).</li><li>Hall, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Guyton and Hall Textbook of Medical Physiology. , 303-344 (2011).</li><li>Levey, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+renal+function+in+chronic+renal+disease.">Measurement of renal function in chronic renal disease.</a> Kidney International. 38 (1), 167-184 (1990).</li><li>Thurau, K., Valtin, H., Schnermann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kidney.">Kidney.</a> Annual Review of Physiology. 30, 441-524 (1968).</li><li>Shannon, J. A., Smith, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+excretion+of+inulin,+xylose,+and+urea+by+normal+and+phoriziniaed+man.">The excretion of inulin, xylose, and urea by normal and phoriziniaed man.</a> Journal of Clinical Investigation. 14, 393-401 (1935).</li><li>Jespersen, B., Knupp, L., Northcott, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+arterial+and+venous+catheterization+for+blood+sampling,+drug+administration+and+conscious+blood+pressure+and+heart+rate+measurements.">Femoral arterial and venous catheterization for blood sampling, drug administration and conscious blood pressure and heart rate measurements.</a> Journal of Visualized Experiments. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conventional+measurement+of+renal+function+utilizing+serum+creatinine,+creatinine+clearance,+inulin+and+para-aminohippuric+acid+clearance.">Conventional measurement of renal function utilizing serum creatinine, creatinine clearance, inulin and para-aminohippuric acid clearance.</a> Current Opinion in Nephrology and Hypertension. 4 (6), 505-509 (1995).</li><li>Matavelli, L. C., Kadowitz, P. J., Navar, L. G., Majid, D. 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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assay+of+inulin+in+tissues+using+anthrone.">Assay of inulin in tissues using anthrone.</a> Clinical Biochemistry. 8 (1), 67-70 (1975).</li><li>Shalmi, M., Lunau, H. E., Petersen, J. S., Bak, M., Christensen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suitability+of+tritiated+inulin+for+determination+of+glomerular+filtration+rate.">Suitability of tritiated inulin for determination of glomerular filtration rate.</a> Americam Journal of Physiology. 260 (2 Pt 2), F283-F289 (1991).</li><li>Denton, K. M., Anderson, W. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glomerular+untrafiltration+in+rabbits+with+superficial+glomeruli.">Glomerular untrafiltration in rabbits with superficial glomeruli.</a> EUropean Journal of Physiology. 419 (3-4), 235-242 (1991).</li><li>Jobin, J., Bonjour, J. -. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+glomerular+filtration+rate+in+conscious+unrestrained+rats+with+inulin+infused+by+implanted+osmotic+pumps.">Measurement of glomerular filtration rate in conscious unrestrained rats with inulin infused by implanted osmotic pumps.</a> Americam Journal of Physiology. 248 (5 Pt 2), F734-F738 (1985).</li><li>Lorenz, J. N., Gruenstein, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple,+nonradioactive+method+for+evaluating+single-nephron+filtration+rate+using+FITC-inulin.">A simple, nonradioactive method for evaluating single-nephron filtration rate using FITC-inulin.</a> Americam Journal of Physiology. 276 (1 Pt 2), F172-F177 (1999).</li><li>Qi, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serial+determination+of+glomerular+filtration+rate+in+conscious+mice+using+FITC-inulin+clearance.">Serial determination of glomerular filtration rate in conscious mice using FITC-inulin clearance.</a> Americam Journal of Physiology. 286 (3), F590-F596 (2004).</li><li>Bivona, B. J., Park, S., Harrison-Bernard, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glomerular+filtration+rate+determinations+in+conscious+type+II+diabetic+mice.">Glomerular filtration rate determinations in conscious type II diabetic mice.</a> Americam Journal of Physiology. 300 (3), F618-F625 (2011).</li><li>Rosen, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+anaesthesia+and+surgery+on+renal+hemodynamics.">Effects of anaesthesia and surgery on renal hemodynamics.</a> British Journal of Anesthesiology. 44, 252-258 (1972).</li><li>Cousins, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anesthesia+and+the+kidney.">Anesthesia and the kidney.</a> Anaesthesia and intensive care. 11 (4), 292-320 (1983).</li><li>Walter, S. J., Zewde, T., Shirley, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+anaesthesia+and+standard+clearance+procedures+on+renal+function+in+the+rat.">The effect of anaesthesia and standard clearance procedures on renal function in the rat.</a> Quarterly Journal of Experimental Physiology. 74, 805-812 (1989).</li><li>Rieg, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-throughput+method+for+measurement+of+glomerular+filtration+rate+in+conscious+mice.">A high-throughput method for measurement of glomerular filtration rate in conscious mice.</a> Journal of Visualized Experiments. (75), (2013).</li></ol>

The authors declare that they have no competing financial interests. The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

An appropriate marker for GFR measurement must meet four criteria: be freely filtered at the glomerulus, be unbound to plasma proteins, and neither be absorbed nor secreted in the nephron. Inulin is a fructose polymer which satisfies these criteria. As a result, the renal clearance of inulin is considered the gold standard for measuring GFR7. The demonstrated technique represents the traditional approach of determining the renal clearance of inulin using timed urine collections during a constant infusion of in...

The most important function of the kidney is the homeostatic regulation of extracellular water and electrolyte content. The kidneys closely regulate extracellular water, sodium (Na) and potassium (K) to maintain normal physiological levels. Disturbances in renal function can result in serious metabolic disorders which can be fatal. The basic renal process occurs in the nephron and begins with the filtration of plasma at the glomerulus and ends with the excretion of urine. Other processes that determine the final concentration of water, Na and K in the urine are secretion and reabsorption within the nephron. Measurements of glomerular filtration rate (GFR) and the fractional excretion of Na and K are critical in assessing renal function in health and disease. The reader is referred to previously published review articles and textbooks for a more thorough discussion of kidney function1-4. 
GFR can be measured as the steady state renal clearance of inulin which is filtered at the glomerulus, but not secreted or reabsorbed along the nephron5. While this technique requires anesthesia, surgical preparation, and a terminal experiment, it is considered the gold standard of GFR measurement. Using inulin that is tagged with fluorescein-isothiocyanate (FITC), plasma and urine concentration of FITC-inulin can be easily measured in small volumes and used to calculate GFR during multiple time points of an experiment. The fractional excretion of Na and K can be determined from the concentration of Na and K in plasma and urine. 
The conceptual understanding of how to measure renal function can easily be demonstrated in a short lab designed to allow students to actively participate in some aspects of the experiment. This video depicts the pre-lab preparation, the renal function demonstration, and the post-lab evaluation of results. The surgical techniques necessary for making measurements of GFR are demonstrated in an anesthetized rat. In addition, example calculations for GFR, and the fractional excretion of Na and K are shown before and after administration of a diuretic drug.

<table border="0" cellpadding="0" cellspacing="0" width="1011">
	<colgroup>
		<col />
		<col />
		<col />
	</colgroup>
</table>
<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>5-0 Braided Silk Surgical Suture</td>
			<td>Surgical Specialties Corp</td>
			<td>SP1033</td>
			<td></td>
		</tr>
		<tr>
			<td>Assay Plate, 96-Well</td>
			<td>Costar&#160;</td>
			<td>3922</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma Chemical Co</td>
			<td>A2934-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Beckman Coulter</td>
			<td>MicroFuge 18, 357160</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical Sample Tubes</td>
			<td>Dot Scientific Inc.&#160;</td>
			<td>#711-FTG</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton Tipped Applicators</td>
			<td>Solon Manufacturing Co</td>
			<td>56200</td>
			<td></td>
		</tr>
		<tr>
			<td>Data Acquisition Software</td>
			<td>ADInstruments</td>
			<td>LabChart Pro 7.0</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital Scale&#160;</td>
			<td>Denver Instrument</td>
			<td>APX-4001</td>
			<td></td>
		</tr>
		<tr>
			<td>FITC-Inulin</td>
			<td>Sigma Chemical Co</td>
			<td>F3272-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze Sponges</td>
			<td>Covidien</td>
			<td>2146</td>
			<td></td>
		</tr>
		<tr>
			<td>Heated Surgical Bed</td>
			<td>EZ-Anesthesia</td>
			<td>EZ-212</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Sagnet</td>
			<td>NDC 25021-402-10</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma Chemical Co</td>
			<td>H3375</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Abbott Animal Health</td>
			<td>IsoFlo, 5260-04-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane Vaporizer</td>
			<td>EZ-Anesthesia</td>
			<td>EZ-190F</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Dissecting Forceps</td>
			<td>Biomedical Research Instruments Inc.</td>
			<td>70-1020</td>
			<td></td>
		</tr>
		<tr>
			<td>Microplate Reader - Fluoroskan</td>
			<td>ThermoScientific</td>
			<td>Ascent FL, 5210460</td>
			<td></td>
		</tr>
		<tr>
			<td>NOVA 5+ Sodium/Potassium Analyzer</td>
			<td>NOVA BioMedical</td>
			<td>14156</td>
			<td></td>
		</tr>
		<tr>
			<td>Olsen-Hegar Needle Holders with Scissors</td>
			<td>Fine Science Tools</td>
			<td>12002-12</td>
			<td></td>
		</tr>
		<tr>
			<td>PE-190 (for bladder catheter)</td>
			<td>BD Medical</td>
			<td>427435</td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure Transducer&#160;</td>
			<td>ADInstruments</td>
			<td>MLT1199</td>
			<td></td>
		</tr>
		<tr>
			<td>Pyrex Culture Tubes</td>
			<td>Corning Inc.</td>
			<td>99445-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat Femoral Tapered Artery Catheter</td>
			<td>Strategic Applications Inc.</td>
			<td>RFA-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Salix Furosemide 5%</td>
			<td>Intervet</td>
			<td>#34-478</td>
			<td></td>
		</tr>
		<tr>
			<td>Strabismus Scissors</td>
			<td>Fine Science Tools</td>
			<td>14075-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Student Surgical Scissors</td>
			<td>Fine Science Tools</td>
			<td>91402-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Gloves</td>
			<td>Kimberly-Clark</td>
			<td>Sterling Nitrile Gloves</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>Razel Scientific</td>
			<td>R99-E</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Forceps</td>
			<td>Fine Science Tools</td>
			<td>91121-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Scissors</td>
			<td>George Tiemann&#160; Co</td>
			<td>105-420</td>
			<td></td>
		</tr>
	</tbody>
</table>
5-0 Braided Silk Surgical Suture Surgical Specialties Corp SP1033 Assay Plate, 96-Well Costar&#160; 3922 Bovine Serum Albumin Sigma Chemical Co A2934-25G Centrifuge Beckman Coulter MicroFuge 18, 357160 Conical Sample Tubes Dot Scientific Inc.&#160; #711-FTG Cotton Tipped Applicators Solon Manufacturing Co 56200 Data Acquisition Software ADInstruments LabChart Pro 7.0 Digital Scale&#160; Denver Instrument APX-4001 FITC-Inulin Sigma Chemical Co F3272-1G Gauze Sponges Covidien 2146 Heated Surgical Bed EZ-Anesthesia EZ-212 Heparin Sagnet NDC 25021-402-10 HEPES Sigma Chemical Co H3375 Isoflurane Abbott Animal Health IsoFlo, 5260-04-05 Isoflurane Vaporizer EZ-Anesthesia EZ-190F Micro Dissecting Forceps Biomedical Research Instruments Inc. 70-1020 Microplate Reader - Fluoroskan ThermoScientific Ascent FL, 5210460 NOVA 5+ Sodium/Potassium Analyzer NOVA BioMedical 14156 Olsen-Hegar Needle Holders with Scissors Fine Science Tools 12002-12 PE-190 (for bladder catheter) BD Medical 427435 Pressure Transducer&#160; ADInstruments MLT1199 Pyrex Culture Tubes Corning Inc. 99445-12 Rat Femoral Tapered Artery Catheter Strategic Applications Inc. RFA-01 Salix Furosemide 5% Intervet #34-478 Strabismus Scissors Fine Science Tools 14075-11 Student Surgical Scissors Fine Science Tools 91402-12 Surgical Gloves Kimberly-Clark Sterling Nitrile Gloves Syringe pump Razel Scientific R99-E Tissue Forceps Fine Science Tools 91121-12 Tissue Scissors George Tiemann&#160; Co 105-420

physiology lab demonstration: glomerular filtration rate in a rat

Measurements of glomerular filtration rate (GFR), and the fractional excretion of sodium (Na) and potassium (K) are critical in assessing renal function in health and disease. GFR is measured as the steady state renal clearance of inulin which is filtered at the glomerulus, but not secreted or reabsorbed along the nephron. The fractional excretion of Na and K can be determined from the concentration of Na and K in plasma and urine. The renal clearance of inulin can be demonstrated in an anesthetized animal which has catheters in the femoral artery, femoral vein and bladder. The equipment and supplies used for this procedure are those commonly available in a research core facility, and thus makes this procedure a practical means for measuring renal function. The purpose of this video is to demonstrate the procedures required to perform a lab demonstration in which renal function is assessed before and after a diuretic drug. The presented technique can be utilized to assess renal function in rat models of renal disease.

The diuretic used in the lab demonstration was furosemide which very quickly inhibits the reabsorption of Na and K filtered by the kidney resulting in increased Na, K, and water excretion within minutes of drug administration. By its primary mechanism, furosemide should have minimal effects on GFR and the filtered load of Na and K, but will increase urine flow, and fractional excretion of Na and K.
The representative results in Table 3 show that in an anesthetized rat, the ave...

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Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat

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.

Measurements of glomerular filtration rate (GFR), and the fractional excretion of sodium (Na) and potassium (K) are critical in assessing renal function ...

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17.2K Views.  U.S. Army Institute of Surgical Research. 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. 

Video: Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat

Large Volume (20L+) Filtration of Coastal Seawater Samples

The workflow begins with the collection of coastal marine waters for downstream microbial community, nutrient and trace gas analyses. For this method, samples were collected from the deck of the HMS John Strickland operating in Saanich Inlet. This video documents large volume (&ge;20 L) filtration of microbial biomass, ranging between 0.22&mu;m and 2.7&mu;m in diameter, from the water column. Two 20L samples can be filtered simultaneously using a single pump unit equipped with four rotating heads. Filtration is done in the field on extended trips, or immediately upon return for day trips. It is important to record the amount of water passing through each sterivex filter unit. To prevent biofilm formation between sampling trips, all filtration equipment must be rinsed with dilute HCl and deionized water and autoclaved immediately after use. This procedure will take approximately 5 hours plus an additional hour for clean up.

Large Volume 20L+ Filtration of Coastal Seawater Samples

This video documents large volume (&ge;20 L) filtration of microbial biomass, ranging between 0.22&mu;m and 2.7&mu;m in diameter, from the water column.

The workflow begins with the collection of coastal marine waters for downstream microbial community, nutrient and trace gas analyses. For this method, ...

Small Volume (1-3L) Filtration of Coastal Seawater Samples

The workflow begins with the collection of coastal marine waters for downstream microbial community, nutrient and trace gas analyses. For today s demonstration samples were collected from the deck of the HMS John Strickland operating in Saanich Inlet. This video documents small volume (~1 L) filtration of microbial biomass from the water column. The protocol is an extension of the large volume sampling protocol described earlier, with one major difference: here, there is no pre-filtration step, so all size classes of biomass are collected down to the 0.22 &mu;m filter cut-off. Samples collected this way are ideal for nucleic acid analysis. The set-up, filtration, and clean-up steps each take about 20-30 minutes. If using two peristaltic pumps simultaneously, up to 8 samples may be filtered at the same time. To prevent biofilm formation between sampling trips, all filtration equipment must be rinsed with dilute HCl and deionized water and autoclaved immediately after use.

Small Volume 1-3L Filtration of Coastal Seawater Samples

This video documents small volume (~1 L) filtration of microbial biomass from the water column.

The workflow begins with the collection of coastal marine waters for downstream microbial community, nutrient and trace gas analyses. For today s ...

A Video Demonstration of Preserved Piloting by Scent Tracking but Impaired Dead Reckoning After Fimbria-Fornix Lesions in the Rat

Piloting and dead reckoning navigation strategies use very different cue constellations and computational processes (Darwin, 1873; Barlow, 1964; O&#x2019;Keefe and Nadel, 1978; Mittelstaedt and Mittelstaedt, 1980; Landeau et al., 1984; Etienne, 1987; Gallistel, 1990;
Maurer and S&#233;guinot, 1995). Piloting requires the use of the relationships between relatively stable external (visual, olfactory, auditory) cues, whereas dead reckoning requires the integration of cues generated by self-movement. Animals obtain self-movement information from vestibular receptors, and possibly muscle and joint receptors, and efference copy of commands that generate movement. An animal may also use the flows of visual, auditory, and olfactory stimuli caused by its movements. Using a piloting strategy an animal can use geometrical calculations to determine directions and distances to places in its environment, whereas using an dead reckoning strategy it can integrate cues generated by its previous movements to return to a just left location. Dead reckoning is colloquially called "sense of direction" and "sense of distance."

Although there is considerable evidence that the hippocampus is involved in piloting (O&#x2019;Keefe and Nadel, 1978; O&#x2019;Keefe and Speakman, 1987), there is also evidence from behavioral (Whishaw et al., 1997; Whishaw and Maaswinkel, 1998; Maaswinkel and Whishaw, 1999), modeling (Samsonovich and McNaughton, 1997), and electrophysiological (O&#x2019;Mare et al., 1994; Sharp et al., 1995; Taube and Burton, 1995; Blair and Sharp, 1996; McNaughton et al., 1996; Wiener, 1996; Golob and Taube, 1997) studies that the hippocampal formation is involved in dead reckoning. The relative contribution of the hippocampus to the two forms of navigation is still uncertain, however. Ordinarily, it is difficult to be certain that an animal is using a piloting versus a dead reckoning strategy because animals are very flexible in their use of strategies and cues (Etienne et al., 1996; Dudchenko et al., 1997; Martin et al., 1997; Maaswinkel and Whishaw, 1999). The objective of the present video demonstrations was to solve the problem of cue specification in order to examine the relative contribution of the hippocampus in the use of these strategies. The rats were trained in a new task in which they followed linear or polygon scented trails to obtain a large food pellet hidden on an open field. Because rats have a proclivity to carry the food back to the refuge, accuracy and the cues used to return to the home base were dependent variables (Whishaw and Tomie, 1997). To force an animal to use a a dead reckoning strategy to reach its refuge with the food, the rats were tested when blindfolded or under infrared light, a spectral wavelength in which they cannot see, and in some experiments the scent trail was additionally removed once an animal reached the food. To examine the relative contribution of the hippocampus, fimbria&#x2013;fornix (FF) lesions, which disrupt information flow in the hippocampal formation (Bland, 1986), impair memory (Gaffan and Gaffan, 1991), and produce spatial deficits (Whishaw and Jarrard, 1995), were used.

In a piloting scent tracking task, the ability of the rats to return to a refuge with food using visual an odor trail or using dead reckoning in infrared light, the integrated record of previous movements, demonstrates that the hippocampus is necessary for dead reckoning.

Piloting and dead reckoning navigation strategies use very different cue constellations and computational processes (Darwin, 1873; Barlow, 1964; ...

Historical View and Physiology Demonstration at the NMJ of the Crayfish Opener Muscle

Here we present some of the key important discoveries made with the opener neuromuscular (NMJ) preparation of crustaceans and illustrate that there is still much to learn from this model preparation. In understanding the history one can appreciate why even today this NMJ still offers a rich playground to address questions regarding pre- and post-synaptic function and plasticity. The viability and ease of access to the terminal for intracellular as well as extracellular electrophysiology and imaging are significant advantages. The mechanisms behind the modulation of vesicular kinetics and fusion within the high- and low-output terminals are begging for investigation. The preparation also offers a testable model system for computational assessments and manipulations to examine key variables in theoretical models of synaptic function, for example calcium dynamics during short-term facilitation. The synaptic complexity of active zone and statistical nature of quantal release is also an open area for future investigation both experimentally and computationally.

The opener muscle of the crayfish leg is presented for its historical importance and experimental versatility in muscle phenotype, synaptic physiology and plasticity.

Here we present some of the key important discoveries made with the opener neuromuscular (NMJ) preparation of crustaceans and illustrate that there is ...

Ovariectomy and 17&beta;-estradiol Replacement in Rats and Mice: A Visual Demonstration

Estrogens are a family of female sexual hormones with an exceptionally wide spectrum of effects. When rats and mice are used in estrogen research they are commonly ovariectomized in order to ablate the rapidly cycling hormone production, replacing the 17&beta;-estradiol exogenously. There is, however, lack of consensus regarding how the hormone should be administered to obtain physiological serum concentrations. This is crucial since the 17&beta;-estradiol level/administration method profoundly influences the experimental results1-3. We have in a series of studies characterized the different modes of 17&beta;-estradiol administration, finding that subcutaneous silastic capsules and per-oral nut-cream Nutella are superior to commercially available slow-release pellets (produced by the company Innovative Research of America) and daily injections in terms of producing physiological serum concentrations of 17&beta;-estradiol4-6. Amongst the advantages of the nut-cream method, that previously has been used for buprenorphine administration7, is that when used for estrogen administration it resembles peroral hormone replacement therapy and is non-invasive. The subcutaneous silastic capsules are convenient and produce the most stable serum concentrations. This video article contains step-by-step demonstrations of ovariectomy and 17&beta;-estradiol hormone replacement by silastic capsules and peroral Nutella in rats and mice, followed by a discussion of important aspects of the administration procedures.

Ovariectomy and 17&#946;-estradiol Replacement in Rats and Mice: A Visual Demonstration

Ovariectomy and subsequent replacement of 17&beta;-estradiol by means of silastic capsules and peroral Nutella are demonstrated in rats and mice.

Estrogens are a family of female sexual hormones with an exceptionally wide spectrum of effects. When rats and mice are used in estrogen research they are ...

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

The measurement of glomerular filtration rate (GFR) is the gold standard in kidney function assessment. Currently, investigators determine GFR by measuring the level of the endogenous biomarker creatinine or exogenously applied radioactive labeled inulin (3H or 14C). Creatinine has the substantial drawback that proximal tubular secretion accounts for ~50% of total renal creatinine excretion and therefore creatinine is not a reliable GFR marker. Depending on the experiment performed, inulin clearance can be determined by an intravenous single bolus injection or continuous infusion (intravenous or osmotic minipump). Both approaches require the collection of plasma or plasma and urine, respectively. Other drawbacks of radioactive labeled inulin include usage of isotopes, time consuming surgical preparation of the animals, and the requirement of a terminal experiment. Here we describe a method which uses a single bolus injection of fluorescein isothiocyanate-(FITC) labeled inulin and the measurement of its fluorescence in 1-2 &mu;l of diluted plasma. By applying a two-compartment model, with 8 blood collections per mouse, it is possible to measure GFR in up to 24 mice per day using a special work-flow protocol. This method only requires brief isoflurane anesthesia with all the blood samples being collected in a non-restrained and awake mouse. Another advantage is that it is possible to follow mice over a period of several months and treatments (i.e. doing paired experiments with dietary changes or drug applications). We hope that this technique of measuring GFR is useful to other investigators studying mouse kidney function and will replace less accurate methods of estimating kidney function, such as plasma creatinine and blood urea nitrogen.

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.

The measurement of  glomerular filtration rate (GFR) is the gold standard in kidney function  assessment. Currently, investigators determine GFR by ...

Rapid Isolation And Purification Of Mitochondria For Transplantation By Tissue Dissociation And Differential Filtration

Previously described mitochondrial isolation methods using differential centrifugation and/or Ficoll gradient centrifugation require 60 to 100 min to complete. We describe a method for the rapid isolation of mitochondria from mammalian biopsies using a commercial tissue dissociator and differential filtration. In this protocol, manual homogenization is replaced with the tissue dissociator&#8217;s standardized homogenization cycle. This allows for uniform and consistent homogenization of tissue that is not easily achieved with manual homogenization. Following tissue dissociation, the homogenate is filtered through nylon mesh filters, which eliminate repetitive centrifugation steps. As a result, mitochondrial isolation can be performed in less than 30 min. This isolation protocol yields approximately 2 x 1010 viable and respiration competent mitochondria from 0.18 &#177; 0.04 g (wet weight) tissue sample.

A method for rapid isolation of mitochondria from mammalian tissue biopsies is described. Rat liver or skeletal muscle preparations were homogenized with a commercial tissue dissociator and mitochondria were isolated by differential filtration through nylon mesh filters. Mitochondrial isolation time is &#60;30 min compared to 60 - 100 min using alternative methods.

Previously described mitochondrial isolation methods using differential centrifugation and/or Ficoll gradient centrifugation require 60 to 100 min to ...

An Experimental and Bioinformatics Protocol for RNA-seq Analyses of Photoperiodic Diapause in the Asian Tiger Mosquito, Aedes albopictus

Photoperiodic diapause is an important adaptation that allows individuals to escape harsh seasonal environments via a series of physiological changes, most notably developmental arrest and reduced metabolism. Global gene expression profiling via RNA-Seq can provide important insights into the transcriptional mechanisms of photoperiodic diapause. The Asian tiger mosquito, Aedes albopictus, is an outstanding organism for studying the transcriptional bases of diapause due to its ease of rearing, easily induced diapause, and the genomic resources available. This manuscript presents a general experimental workflow for identifying diapause-induced transcriptional differences in A. albopictus. Rearing techniques, conditions necessary to induce diapause and non-diapause development, methods to estimate percent diapause in a population, and RNA extraction and integrity assessment for mosquitoes are documented. A workflow to process RNA-Seq data from Illumina sequencers culminates in a list of differentially expressed genes. The representative results demonstrate that this protocol can be used to effectively identify genes differentially regulated at the transcriptional level in A. albopictus due to photoperiodic differences. With modest adjustments, this workflow can be readily adapted to study the transcriptional bases of diapause or other important life history traits in other mosquitoes.

An Experimental and Bioinformatics Protocol for RNA-seq Analyses of Photoperiodic Diapause in the Asian Tiger Mosquito, Aedes albopictus

RNA-Seq analyses are becoming increasingly important for identifying the molecular underpinnings of adaptive traits in non-model organisms. Here, a protocol to identify differentially expressed genes between diapause and non-diapause Aedes albopictus mosquitoes is described, from mosquito rearing, to RNA sequencing and bioinformatics analyses of RNA-Seq data.

Photoperiodic diapause is an important adaptation that allows individuals to escape harsh seasonal environments via a series of physiological changes, ...

Microperfusion Technique to Investigate Regulation of Microvessel Permeability in Rat Mesentery

Experiments to measure the permeability properties of individually perfused microvessels provide a bridge between investigation of molecular and cellular mechanisms regulating vascular permeability in cultured endothelial cell monolayers and the functional exchange properties of whole microvascular beds. A method to cannulate and perfuse venular microvessels of rat mesentery and measure the hydraulic conductivity of the microvessel wall is described. The main equipment needed includes an intravital microscope with a large modified stage that supports micromanipulators to position three different microtools: (1) a beveled glass micropipette to cannulate and perfuse the microvessel; (2) a glass micro-occluder to transiently block perfusion and enable measurement of transvascular water flow movement at a measured hydrostatic pressure, and (3) a blunt glass rod to stabilize the mesenteric tissue at the site of cannulation. The modified Landis micro-occlusion technique uses red cells suspended in the artificial perfusate as markers of transvascular fluid movement, and also enables repeated measurements of these flows as experimental conditions are changed and hydrostatic and colloid osmotic pressure difference across the microvessels are carefully controlled. Measurements of hydraulic conductivity first using a control perfusate, then after re-cannulation of the same microvessel with the test perfusates enable paired comparisons of the microvessel response under these well-controlled conditions. Attempts to extend the method to microvessels in the mesentery of mice with genetic modifications expected to modify vascular permeability were severely limited because of the absence of long straight and unbranched microvessels in the mouse mesentery, but the recent availability of the rats with similar genetic modifications using the CRISPR/Cas9 technology is expected to open new areas of investigation where the methods described herein can be applied.

The modified Landis technique enables paired measurement of the hydraulic conductivity of individual microvessels in the mesentery of normal and genetically modified rats under control and test conditions using microperfusion techniques. It provides a convenient method to evaluate mechanisms that regulate microvessel permeability and transvascular exchange under physiological conditions.

Experiments to measure the permeability properties of individually perfused microvessels provide a bridge between investigation of molecular and cellular ...

Filtration Isolation of Nucleic Acids:  A Simple and Rapid DNA Extraction Method

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad to extract cellular DNA from whole blood in less than 2 min. The blood specimen is treated with detergent, mixed briefly and applied by pipet to the separation membrane. The lysate wicks into the blotting pad due to capillary action, capturing the genomic DNA on the surface of the separation membrane. The extracted DNA is retained on the membrane during a simple wash step wherein PCR inhibitors are wicked into the absorbent blotting pad. The membrane containing the entrapped DNA is then added to the PCR reaction without further purification. This simple method does not require laboratory equipment and can be easily implemented with inexpensive laboratory supplies. Here we describe a protocol for highly sensitive detection and quantitation of HIV-1 proviral DNA from 100 &#181;l whole blood as a model for early infant diagnosis of HIV that could readily be adapted to other genetic targets.

We describe here a simple and rapid paper-based DNA extraction method of HIV proviral DNA from whole blood detected by quantitative PCR. This protocol can be extended for use in detecting other genetic markers or using alternative amplification methods.

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad ...