DOCSLIB.ORG

A Comparison of Patterns of Changes in Urine Flow and Urine Electrical Conductivity Induced by Exogenous ADH in Hydrated Rats

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Comparison of Patterns of Changes in Urine Flow and Urine Electrical Conductivity Induced by Exogenous ADH in Hydrated Rats Tohoku J. exp. Med., 1973, 109, 281-296 A Comparison of Patterns of Changes in Urine Flow and Urine Electrical Conductivity Induced by Exogenous ADH in Hydrated Rats TOKIHISA KIMURA* and RYUZO YOKOYAMA•õ Department of Physiology, Tohoku University School of Medicine , S endai KIMURA,T. and YOKOYAMA,R. A Comparisonof Patterns of Changesin Urine Flow and Urine Electrical ComductivityInduced by ExogenousADH in HydratedRats. Tohoku J. exp. Med., 1973, 109 (3), 281-296 Both urine flowrate and urine electrical conductivitywere recorded continuouslyin hydrated alcohol-anesthetizedrats, and the patterns of changesin these two induced by intravenous injection of ADH were compared. Although ADH-inducedchanges in urine flow rate and conductivity were reciprocallyrelated, significantdeviation from a simple reciprocal relation was found when a relatively high dose of ADH was given. Dose response curves as obtained by using the maximummagnitude or the time-integralof the response as the index of the response revealed that the urine-flowmethod has higher sensitivity to ADH in a relatively low dose range, whereas the conductivity method is superior for the assay of relatively high dose of ADH. Saluresis induced by NaCl-loadingor by administration of Furosemide produced parallel increases in both urine flow and conductivity, while a reduction of blood pressure caused parallel decreases. Asphyxia and pentobarbital sodium produced ADH-like (reciprocaltype) pattern of changes, but these changes were interpreted as the results of a liberation of endogenous ADH. Diuretic effect of a low dose of ADH, saluretic effect of a moderate dose of ADH, and vascular effect of a high dose of ADH werecharacterized by the dual recording of urine flow rate and conductivity. It is concludedthat the dual reocrdingof urine flow rate and conductivity is recommendablefor the assay of ADH of a wide range of dose since the renal effect of ADH is of compositenature, and the single recordingof either of these urinary factors cannot characterize the ADH action. urinary responses to ADH; ADH bioassay; flow rate measuring method; conductivity measuring method Measurements of changes in either urine flow rate or urine conductivity in hydrated ethanol-anesthetized rats have currently been widely used in the bioassay of ADH (see Fitzpatrick and Bentley 1968). There seem to be controvertial views as to which method be more recommendable for the ADH bioassay, one measuring urine flow rate and the other measuring urine conductivity. Sawyer (1958) argued the superiority of the former, whereas Yoshida et al. (1963) and Bonjour and Malvin (1970) recommended to use the latter. Received for publication, August 17, 1972. * Present address: The Second Department of Medicine, Tohoku University School of Medicine, Sendai. Present•õ address: Department of Electronic Engineering, Faculty of Engineering, Iwate University, Morioka. 281 282 T. Kimura and R. Yokoyama Principally, if ADH causes only a reduction of free water clearance of animals, these two methods should be entirely equivalent, since both measure reciprocally related phenomena. ADH, however, is known to have additional effects in rats, e.g., a diuretic effect in its low dose range (Kramar et al. 1966), natriuretic and kaliuretic effects over a wide range of dose (Chan 1965) and a vasopressor effect in a high dose range (Dekanski 1952). Furthermore, a conducti vity-measuring system usually has a small but significant dead space. All these factors may greatly modify the simple reciprocal relationship between changes in urine flow rate and urine conductivity and also affect the practical usefulness of these two methods in ADH bioassay. The aim of the present study is to compare the two methods above mentioned in an attempt to examine which is more reliable or useful as the procedure of ADH bioassay. Additionally, it was examined whether or not simultaneous recording of both changes in urine flow rate and conductivity has some advantages in detecting or measuring the urinary response to exogenous ADH given in rats under various diuretic conditions. METHODS Preparation of animals: Male albino rats weighing 200-250g were used. Methods for anesthesiaand prehydrationwere almost the same as those reported by Czaczkes and Kleeman(1964). Briefly, 12% ethanol solution amounting 3% of body weight was given twice through stomach tube at an interval of 30 min. 20 min after the second infusion, warmed tap water amounting 2% of body weight was supplemented. The total amount of water, thus given, was 8% of body weight. The abdominalwall was openedby the mid-lineincision to exposethe urinary bladder. A short (2cm long)soft silicone-rubbertube of 1 mm inner diameter was inserted into the bladder through a cut made at the upper part of its ventral wall, then the tube was tied together with the bladder to fix it. The urethra was obstructed by ligating the penis. The jugular vein was catheterizedwith a thin polyethylene cannula, through which the maintenanceinfusion was carried out with a hypotonic saline (0.3% NaCl) containing2% ethanoland 1.6%glucose. The rate of infusionwas fixed at 0.1ml/minin most experiments. Atropine sulfate (0.01mg/kgbody weight) was administered subcutaneously in order to inhibit secretionof excesssputa during experiments. Tracheal cannulationwas made with a short polyethylene tube and pure oxygen gas was supplied onto the opening of the cannula. Declineof body temperature of animalswas prevented by warming their body with an electriclamp. Recordingof urine conductivityand urine flow rate: Conductivity-measuringsystem used is essentiallysimilar to those employedby Share (1961)and Yoshida et al. (1963). The conductivitywas measuredbetween two small stainless-steeltubes interposed along the courseof a polyethylenecannula which was connectedto the rubber tube inserted into the bladder. Each stainless-steelpipe had 1cm in length and 0.9mm in inner diameter, and both werefixed 8mm apart. The electrodeswere connectedto a Wheatstonebridge with fine lead wires, and the part of the electrodes was molded with epoxy resin. Alternating current of 1 kHz was supplied to the bridge from a oscillator, and the bridge output was amplifiedby a differentialamplifier. A devicewas made to obtain voltage outputs linear to fluid conductivity in the similar way to that reported by Rothe et al. (1967). The electrical circuit was shown in Fig. 1. Recording system for urine flow rate used is principally the same as those employedby Sawyer (1958), Tata and Gauer (1966) and Forsling et al. (1968). It consistsof a drop counter, a pulse generator and an integrator ADH Action on Urine Conductivity and Urine Flow Rate 283 Fig. 1. Electrical circuit of the apparatus for measuring urine electrical conductivity . Alternating current of 1 kHz is supplied to a Wheatstone bridge , and the bridge output is amplified by a differential amplifier so as to give voltage output linear to electrical conductivity of urine. Fig. 2. Electrical circuit of the apparatus for recording urine flow rate continuously. Urine drops are converted to electrical pulses of constant voltage and constant duration, and the pulses thus generated are integrated by an integrator which is reset every minute with a timer (not illustrated in this figure) by short-circuiting S. of pulses. Generation of pulses with constant duration and constant voltage was made synchronized with urine drops flowing out of the cannula from the bladder, and the integrator was reset every minute. The electrical circuit of the system was illustrated in Fig. 2. Both urine flow rate and conductivity were recorded on a two-pen ink-writing recorder (Towa Denpa Co., EPR-3T) or a multichannel ink-writing recorder (Watanabe Sokki Co., WA621-1). Administration of ADH: In most experiments, arginine vasopressin (Sigma Co.) was used. Synthetic lysine vasopressin (Sandoz) was also used in some experiments. Both were dissolved in 0.9% NaCl solution containing 0.03% acetic acid. 0.1ml of diluted ADH solutions was slowly injected into the jugular vein in about 30 sec. During this interval, the infusion pump was stopped. An injection of 0.1ml isotonic saline had no detectable effect on either urine flow or conductivity. Experiments in rats during osmotic diuresis: In experiments where ADH effects were observed during mannitol diuresis, maintenance infusion was carried out with 10% mannitol solution containing 2% ethanol. When necessary, systemic blood pressure was recorded from the common carotid artery by the use of an electrosphygmomanometer (Sanei Sokki Co., E-044). Other procedures were same as in experiments during water diuresis. 284 T. Kimura and R. Yokoyama Chemical analyses of urine: Urine collection was made during three successive phases: during 10 min prior to ADH administration, during antidiuretic response, and during 10 min after the restoration of urine flow rate. For each urine sample, Na+ and K+ concentrations and volume were determined. Determination of Na+ and K+ concentrations were carried out by the use of a flame photometer (Elma). RESULTS 1) Patterns of responses of urine flow and urine conductivity to ADH in water diu retic rats In rats anesthetized with ethanol, the prehydration and the subsequent maintenance infusion of the hypotonic saline brought animals to a steady water diuresis within 30-60 min after the start of the maintenance infusion, when urine flow reached about the same rate as that of the infusion (100ƒÊl/min). At this stage, urine osmolality and urine conductivity were stabilized at 178•}27 mOsm/kg H2O (mean•}S.E., n=4) and about 10mM equivalent NaCl, respectively. Fig. 3 shows a typical example of responses to graded doses of ADH given during such steady water diuresis. In this particular experiment, 100, 75, 50 and 25ƒÊU of ADH were administered in sequence. Urine flow began to decrease within 2-3 min, and the maximum reduction occurred after 5-10 min, depending on the dose. The response in urine flow had a relatively simple time course, an initial rapid decrease followed by a gradual recovery. Urine conductivity began to increase with a time lag corresponding to 4 urine drops.
Load more

Recommended publications
  • Renal Effects of Atrial Natriuretic Peptide Infusion in Young and Adult ~Ats'
    003 1-3998/88/2403-0333$02.00/0 PEDIATRIC RESEARCH Vol. 24, No. 3, 1988 Copyright O 1988 International Pediatric Research Foundation, Inc. Printed in U.S.A. Renal Effects of Atrial Natriuretic Peptide Infusion in Young and Adult ~ats' ROBERT L. CHEVALIER, R. ARIEL GOMEZ, ROBERT M. CAREY, MICHAEL J. PEACH, AND JOEL M. LINDEN WITH THE TECHNICAL ASSISTANCE OF CATHERINE E. JONES, NANCY V. RAGSDALE, AND BARBARA THORNHILL Departments of Pediatrics [R.L.C., A.R.G., C.E.J., B. T.], Internal Medicine [R.M.C., J.M. L., N. V.R.], Pharmacology [M.J.P.], and Physiology [J.M.L.], University of Virginia, School of Medicine, Charlottesville, Virginia 22908 ABSTRAm. The immature kidney appears to be less GFR, glomerular filtration rate responsive to atrial natriuretic peptide (ANP) than the MAP, mean arterial pressure mature kidney. It has been proposed that this difference UeC~pV,urinary cGMP excretion accounts for the limited ability of the young animal to UN,V, urinary sodium excretion excrete a sodium load. To delineate the effects of age on the renal response to exogenous ANP, Sprague-Dawley rats were anesthetized for study at 31-32 days of age, 35- 41 days of age, and adulthod. Synthetic rat A* was infused intravenously for 20 min at increasing doses rang- By comparison to the adult kidney, the immature kidney ing from 0.1 to 0.8 pg/kg/min, and mean arterial pressure, responds to volume expansion with a more limited diuresis and glomerular filtration rate, plasma ANP concentration, natriuresis (I). A number of factors have been implicated to urine flow rate, and urine sodium excretion were measured explain this phenomenon in the neonatal kidney, including a at each dose.
    [Show full text]
  • Urate-2- C Transport in the Rat Nephron
    Urate-2-14C transport in the rat nephron Ronald A. Kramp, … , William E. Lassiter, Carl W. Gottschalk J Clin Invest. 1971;50(1):35-48. https://doi.org/10.1172/JCI106482. Research Article Intrarenal transport of urate-2-14C was studied in anesthetized rats using the microinjection technic. During saline diuresis, small volumes of urate-2-14C (0.24-0.48 mM) and inulin-3H were injected into surface proximal and distal convoluted tubules, and ureteral urine was collected serially. Total (74-96%) and direct (57-84%) urate recovery increased significantly the more distal the puncture site. Delayed recovery (±20%) remained approximately the same regardless of localization of the microinjection. After proximal injections, total and direct recoveries of urate-2-14C were significantly higher in rats treated with probenecid, pyrazinoate, or PAH than during saline diuresis alone, while the excretion rates were comparable after distal injection. Delayed recovery was not altered by drug administration. The decreased proximal reabsorption of urate is presumably due to an effect of the drugs on the luminal membrane of the nephron. For perfusion at high urate concentrations, nonradioactive urate was added to the injectate (0.89-1.78 mM). Urate-2-14C recovery was almost complete and there was no delayed excretion, demonstrating saturation kinetics. These findings are compatible with a carrier-mediated mechanism for urate transport probably located at the luminal border of the proximal tubular epithelium. No definitive evidence for urate secretion was found in these studies. Find the latest version: https://jci.me/106482/pdf Urate-2-14C Transport in the Rat Nephron RONALD A.
    [Show full text]
  • Atrial Natriuretic Peptide and Blood Volume During Red Cell Transfusion
    Archives ofDisease in Childhood 1991; 66: 395-397 395 Atrial natriuretic peptide and blood volume during Arch Dis Child: first published as 10.1136/adc.66.4_Spec_No.395 on 1 April 1991. Downloaded from red cell transfusion in preterm infants W Rascher, N Lingens, M Bald, 0 Linderkamp Abstract 1710 g (range 650-2660). All infants were in Because raised plasma concentrations of good clinical condition. Four were mechanically atrial natriuretic peptide indicate volume ventilated through an intratracheal tube. None expansion, we studied the effect of red cell had renal disease, shock, sepsis or were being transfusion on plasma atrial natriuretic pep- treated with diuretics. The volume of trans- tide concentration, packed cell volume, and fused red cells was calculated to raise the packed intravascular volume in eight preterm infants. cell volume to 0-45 (haemoglobin to 155 g/l). Red cell transfusion increased red cell mass, The transfusion rate averaged 0-05 (0 01) packed cell volume and erythrocyte count, ml/min/kg. but decreased plasma volume. Total blood Before and one hour after red cell transfusion volume, plasma atrial natriuretic peptide con- blood was drawn in EDTA coated tubes (1 5-2 centration, urine flow rate, and urinary ml) for determination of plasma atrial natriur- sodium excretion did not change. etic peptide and haemoglobin concentrations We conclude that a slow transfusion of packed cell volume, haemoglobin F concentra- less than 10 ml red cells/kg body weight does tion, and plasma osmolality. In addition 0 5 ml not cause volume expansion with subsequent blood was drawn in plastic tubes for measure- atrial natriuretic peptide release thereby ment of serum sodium, potassium and creati- affecting the cardiovascular system.
    [Show full text]
  • Hypernatremia Due to Urea-Induced Osmotic Diuresis: Physiology at The
    Educational Forum Hypernatremia due to Urea-Induced Osmotic Diuresis: Physiology at the Bedside Sonali Vadi, Kenneth Yim1 Private Practitioner, Mumbai, Maharashtra, India, 1Director of Inpatient Hemodialysis‑Davita Dialysis, University of Maryland Midtown Campus, Maryland, USA Abstract Hypernatremia secondary to urea‑induced solute diuresis is due to the renal excretion of electrolyte‑free water. This concept is explained here step‑wise physiologically with the help of a clinical vignette. Keywords: Electrolyte‑free water clearance, hypernatremia, hypertonicity, osmotic diuresis, urea BACKGROUND Her initial laboratory data are presented in Table 1 and electrolyte trends during the hospital stay are summarized in Equation between solutes and water determines serum sodium Table 2. levels. Increased urinary solute load in the form of urea nitrogen leads to urea‑induced osmotic diuresis with increased Acute issues at hand free water loss and ensued hypernatremia. Diagnostic 1. What is the cause of her renal dysfunction? CLINICAL VIGNETTE 2. Why is she hypernatremic? A 70‑year‑old woman was found unconscious at home. As Treatment per her family members, she complained of abdominal pain 1. Should she be urgently dialyzed? and diarrhea for 1 week’s duration. Her baseline mental 2. How should her hypernatremia be managed? status was noted to be alert and oriented three days prior to presentation. Her medical history was significant for DISCUSSION hypertension and osteoarthritis. There was no prior history of renal dysfunction. She has been a heavy alcohol drinker. This complex pathological situation has been de‑coded Her medications included ibuprofen and cyclobenzaprine step‑wise in a question format, with answers to each in two for osteoarthritis; lisinopril and felodipine for hypertension; parts.
    [Show full text]
  • The Use of Selected Urine Chemistries in the Diagnosis of Kidney Disorders
    CJASN ePress. Published on January 9, 2019 as doi: 10.2215/CJN.10330818 The Use of Selected Urine Chemistries in the Diagnosis of Kidney Disorders Biff F. Palmer1 and Deborah Joy Clegg2 Abstract Urinary chemistries vary widely in both health and disease and are affected by diet, volume status, medications, and disease states. When properly examined, these tests provide important insight into the mechanism and therapy of 1Division of various clinical disorders that are first detected by abnormalities in plasma chemistries. These tests cannot be Nephrology, interpreted in isolation, but instead require knowledge of key clinical information, such as medications, physical Department of examination, and plasma chemistries, to include kidney function. When used appropriately and with knowledge of Medicine, University of Texas Southwestern limitations, urine chemistries can provide important insight into the pathophysiology and treatment of a wide Medical Center, variety of disorders. Dallas, Texas; and Clin J Am Soc Nephrol 14: ccc–ccc, 2019. doi: https://doi.org/10.2215/CJN.10330818 2Department of Internal Medicine, University of California, Los Introduction values ,15 mEq/L. On the other hand, volume Angeles School of Urine chemistries can provide valuable insight into a expansion suppresses effector mechanisms and stimu- Medicine, Los wide range of clinical conditions. These tests are often lates release of atrial natriuretic peptide, leading to a Angeles, California underutilized because of the difficulty many physi- reduction in sodium reabsorption, causing urinary so- Correspondence: cians find in their interpretation. Whereas a basic dium concentration to be high. Thus, the urine sodium fi Dr. Biff F. Palmer, metabolic pro le obtained from a blood sample has concentrationisanindirectmeasureofvolumestatusand Department of Internal well defined normal values, there are no such values reflects the integrity of the kidney to regulate that status.
    [Show full text]
  • Atrial Natriuretic Peptide and Furosemide Effects on Hydraulic Pressure in the Renal Papilla
    Kidney International, Vol. 34 (1988), pp. 36—42 Atrial natriuretic peptide and furosemide effects on hydraulic pressure in the renal papilla RAMON E. MENDEZ, B. RENTZ DUNN, JULIA L. TROY, and BARRY M. BRENNER The Harvard Center for the Study of Kidney Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA Atrial natriuretic peptide and furosemide effects on hydraulic pressure pre-renal arterial clamping prior to, or during, ANP administra- in the renal papilla. Atrial peptides (ANP) have been shown to prefer- tion has been shown to markedly blunt or abolish the natriuresis entially increase blood flow tojuxtamedullary nephrons and to augment vasa recta blood flow. To determine the effect of this alteration in[1,9,4]. Since clamping also prevented an ANP-induced rise in intrarenal blood flow distribution on pressure relationships in innerGFR, the enhancement of GFR by ANP was felt to be a primary medullary structures and their significance as a determinant of ANP- factor responsible for its natriuretic effect [11. However, several induced natriuresis, we measured hydraulic pressures in vascular and studies have demonstrated increases in renal sodium excretion tubule elements of the renal papilla exposed in Munich-Wistar rats in in the absence of discernable changes in whole kidney hemo- vivo during an euvolemic baseline period and again during an experi- mental period. Rats in Group 1 received intravenous infusion of rANP dynamics [6, 7, 10]. On the other hand, an additional hemody- [4-27], administered as a 4 sg/kg prime and 0.5 gIkg/min continuous namic mechanism which might be operative lies in the renal infusion, and were maintained euvolemic by plasma replacement.vasodilatory properties of ANP, in particular its ability to Infusion of ANP resulted in significant natriuresis, diuresis and increase increase vasa recta blood flow [11, 10].
    [Show full text]
  • Effect of Flow Rate and the Extracellular Fluid Volume on Proximal Urate and Water Absorption
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Kidney International, Vol. /7(1980), pp. 155 -16/ Effect of flow rate and the extracellular fluid volume on proximal urate and water absorption HARRY 0. SENEKJIAN, THOMAS F. KNIGHT, STEVEN C. SANSOM, and EDWARD J. WEINMAN Rena! Section, Department of Internal Medicine, Veterans Ad,ninist ration Medical Center and Baylor College of Medicine, Houston, Texas Effect of flow rate and the extracellular fluid volume on proximal laboratory. It has been demonstrated previously urate and water absorption. The in vivo microperfusion tech- nique was used to examine the effect of variations in tubular flow that the state of hydration of the extracellular fluid rate and the extracellular fluid volume on [2-14C]-urate and water volume (ECV) affects urate transport [1—4]. Spe- absorption in the proximal tubule of the rat. In nondiuretic ani- cifically, expansion of the ECV with isotonic saline mals, fractional urate absorption was highest at the lowest per- fusion rate examined and decreased as the rate of perfusion was resulted in an increase in urate excretion and an in- increased. Increasing the initial concentration of urate in the per- creased recovery of radioactive urate microinjected fusion solution had no effect on the fractional absorption of directly into the proximal tubule [1]. By analogy to urate. Fractional water absorption was also inversely related to the rate of perfusion. Expansion of the extracellular fluid volume the known changes in sodium reabsorption induced with isotonic saline resulted in rates of urate absorption similar by expansion of the ECV, we suggested a possible to control values at any given microperfusion rate.
    [Show full text]
  • Management of Severe Hyponatremia: Infusion of Hypertonic Saline and Desmopressin Or Infusion of Vasopressin Inhibitors? Antonios H
    Marshall University Marshall Digital Scholar Biochemistry and Microbiology Faculty Research 2014 Management of Severe Hyponatremia: Infusion of Hypertonic Saline and Desmopressin or Infusion of Vasopressin Inhibitors? Antonios H. Tzamaloukas MD Joseph I. Shapiro MD Marshall University, [email protected] Dominic S. Raj MD Glen H. Murata MD Deepak Malhotra MD, PhD See next page for additional authors Follow this and additional works at: http://mds.marshall.edu/sm_bm Part of the Medical Sciences Commons, and the Medical Specialties Commons Recommended Citation Tzamaloukas AH, Shapiro JI, Raj DS, Murata GH, Glew RH, Malhotra D. Management of severe hyponatremia: infusion of hypertonic saline and desmopressin or infusion of vasopressin inhibitors? The American Journal of the Medical Sciences, 2014;348(5):432-9. This Article is brought to you for free and open access by the Faculty Research at Marshall Digital Scholar. It has been accepted for inclusion in Biochemistry and Microbiology by an authorized administrator of Marshall Digital Scholar. For more information, please contact [email protected], [email protected]. Authors Antonios H. Tzamaloukas MD; Joseph I. Shapiro MD; Dominic S. Raj MD; Glen H. Murata MD; Deepak Malhotra MD, PhD; and Robert H. Glew PhD This article is available at Marshall Digital Scholar: http://mds.marshall.edu/sm_bm/214 REVIEW ARTICLE Management of Severe Hyponatremia: Infusion of Hypertonic Saline and Desmopressin or Infusion of Vasopressin Inhibitors? Antonios H. Tzamaloukas, MD, Joseph I. Shapiro, MD, Dominic S. Raj, MD, Glen H. Murata, MD, Robert H. Glew, PhD and Deepak Malhotra, MD, PhD 7 Abstract: Rapid correction of severe hyponatremia carries the risk of of osmotic demyelination syndrome is high.
    [Show full text]
  • 00-Mcqs from Books.Pdf
    Physiology Team 436 Renal Block MCQs File 1 (from books) ُ ُ ُ (وﻗ ِﻞ ا ْﻋ َﻤﻠﻮا َﻓ َﺴﯿَ َﺮى ا ﱠ 0ُ َﻋ َﻤﻠَﻜ ْﻢ ُ ْ َو َر ُﺳﻮﻟ ُﻪ َواﻟ ُﻤ ْﺆ ِﻣ ُﻨﻮ َن ) ﺻﺪق ﷲ اﻟﻌﻈﯿﻢ Done by: Reviewed by: Laila Mathkour Lulwah Alshiha دﻋﻮاﺗﻜﻢ ﻟﻨﺎ ﺑﺎﻟﺘﻮﻓﯿﻖ 1 This work was done by students, so if there are any mistakes please inform us. MCQ’S for renal block (include all lecture) Questions 1 and 2 Use the following clinical laboratory test results for questions 1 and 2: Urine flow rate = 1 ml/min Urine inulin concentration = 100 mg/ml Plasma inulin concentration = 2 mg/ml Urine urea concentration = 50 mg/ml Plasma urea concentration = 2.5 mg/ml 1. What is the glomerular filtration rate (GFR)? A. 25ml/min B. 50 ml/min C. 100 ml/min D. 125ml/min E. None of the above 2. What is the net urea reabsorption rate? A. 0 mg/min B. 25 mg/min C. 50 mg/min D. 75 mg/min E. 100 mg/min 3. Which of the following solutions when infused intravenously would result in an increase in extracellular fluid volume, a decrease in intracellular fluid volume, and an increase in total body water after osmotic equilibrium? A. 1 L of 0.9% sodium chloride solution B. 1 L of 0.45% sodium chloride solution 3=C C. 1 L of 3% sodium chloride solution 2=D D. 1 L of 5% dextrose solution 1=B E. 1 L of pure water Answer: 2 The Explanation of the answers will be in slide 19 Cont.
    [Show full text]
  • Effect of Expansion of Extracellular Fluid Volume on Renal Phosphate Handling
    Effect of expansion of extracellular fluid volume on renal phosphate handling Wadi N. Suki, … , Diane Rouse, Arthur Terry J Clin Invest. 1969;48(10):1888-1894. https://doi.org/10.1172/JCI106155. Research Article To examine the specific effect of extracellular fluid (ECF) volume expansion on phosphate excretion studies were performed in thyroparathyroidectomized dogs receiving saline solution intravenously. The natriuresis resulting from ECF volume expansion was consistently accompanied by an increase in phosphate excretion. The possible role of increased filtered load of phosphate was eliminated in experiments in which the filtered load of phosphate was reduced by acute reduction in the glomerular filtration rate. Despite considerable reductions in filtered phosphate, ECF volume expansion resulted in a consistent increase in phosphate excretion. Furthermore, the possible contribution of alteration in blood composition was investigated in experiments in which saline was infused during thoracic inferior vena cava constriction. In these experiments saline infusion failed to increase sodium or phosphate excretion. Cessation of saline infusion and release of caval constriction resulted in a prompt natriuresis and increased phosphate excretion. It is concluded from these studies that extracellular fluid volume expansion results in an increased phosphate excretion in the parathyroidectomized dog. This effect is the specific consequence of ECF volume expansion and is not due to increase in the filtered load of phosphate or alterations in blood
    [Show full text]
  • Renal Clearance
    Faculty version with model answers Clearance Bruce M. Koeppen, M.D., Ph.D. University of Connecticut Health Center 1. Inulin is used in an experiment to measure the glomerular filtration rate (GFR). Inulin is continuously infused to achieve a steady-state concentration in the plasma of 1.0 mg/dL. Urine is collected over a 10 hour period. The total volume of urine is 1.5 L, and the urinary concentration of inulin is 440 mg/L. What is the GFR, as determined from the inulin clearance? Inulin Clearance = GFR = _____110____ ml/min Calculations: Urine flow rate = 1,500 ml/600 min = 2.5 ml/min Urine [inulin] = 440 mg/L = 0.44 mg/ml Plasma [inulin] = 1.0 mg/dL = 0.01 mg/ml Inulin clearance = GFR = (2.5 ml/min x 0.44 mg/ml)/0.01 mg/ml = 110 ml/min 2. In clinical situations the GFR of a patient is usually determined by measuring the clearance of creatinine. Like inulin, creatinine is freely filtered at the glomerulus. However, in contrast to inulin, a small amount is also secreted (approximately 10% of all creatinine excreted in the urine reflects this secretory component). Therefore creatinine is not an ideal marker for GFR. Despite this error, creatinine is used to measure GFR because it is produced endogenously by skeletal muscle, and does not require an infusion. Therefore it is easy to do a creatinine clearance, because the patient can do it at home by simply collecting their urine (usually over a 24 hr period), and having a single blood sample obtained to measure the plasma [creatinine].
    [Show full text]
  • L3-Renal Clearance [PDF]
    At the end of this session, the students should be able to: Describe the concept of renal plasma clearance Use the formula for measuring renal clearance Use clearance principles for inulin, creatinine etc. for determination of GFR Explain why it is easier for a physician to use creatinine clearance Instead of Inulin for the estimation of GFR Describe glucose and urea clearance Explain why we use of PAH clearance for measuring renal blood flow Mind map Concept of clearance rate of glomerular filtration Clearance is the volume of plasma that is completely Assess severity of renal cleared of a substance each damage minute. Tubular secretion&reabsorption of renal clearance renal different substances. The important of important The Clearance Equation Clearance tests CX = (UX X V)/ PX endogenous where creatinine Urea Uric acid CX = Renal clearance (ml/min) UX X V = excretion rate of substance X exogenous U = Concentration of X in urine X Inulin Para amino Diodrast (di-iodo V = urine flow rate in ml/min hippuric acid pyridone acetic acid) Px= concentration of substance X in the plasma Measurement of glomerular Measurement of renal Measurement of renal filtration rate (GFR) plasma flow (RPF) blood flow (RBF) GFR is measured by the RPF can be estimated from RBF is calculated from clearance of a glomerular maker the clearance of an organic the RPF and hematocrit like Creatinine & Inulin . acid Para-aminohippuric acid (PAH) The formula used to calculate GFR or RPF is CX = (UX X V)/ PX X could be PAH , creatinine and inulin The formula used to calculate RBF is RBF= RPF \ 1-Hct Or RBF=RPF% \ 100-Hct Hematocrit is the fraction of blood volume that is occupied by red blood cells and 1-Hct or 100-Hct is the fraction of blood volume that is occupied only by plasma Criteria of a substance used Criteria of a substance used for for GFR measurement renal plasma flow measurement 1.freely filtered 1.freely filtered 2.not secreted by the tubular cells 2.rapidly and completely secreted by the renal tubular cells 3.not reabsorbed by the tubular cells.
    [Show full text]