scholarly journals Glomerular filtration rate and salt and water reabsorption during pregnancy in the conscious rat.

1983 ◽  
Vol 334 (1) ◽  
pp. 493-504 ◽  
Author(s):  
J C Atherton
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Water Reabsorption ◽  
Conscious Rat

THE EFFECT OF HYPOPHYSECTOMY AND CORTICOTROPHIN ON THE RENAL SENSITIVITY TO ANTIDIURETIC HORMONE

1967 ◽  
Vol 38 (2) ◽  
pp. 107-114 ◽  
Author(s):  
J. W. BAUMAN
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Antidiuretic Hormone ◽  
Plasma Flow ◽  
Filtration Rate ◽  
Normal Values ◽  
Renal Plasma Flow ◽  
Free Water ◽  
Water Reabsorption ◽  
Hypophysectomized Rats

SUMMARY Glomerular filtration rate (GFR), renal plasma flow (RPF) and solute-free water reabsorption (TcH2O) were measured in anaesthetized intact and hypophysectomized rats and in hypophysectomized rats treated with corticotrophin (ACTH). GFR and RPF were measured by [14C]inulin and [3H]p-aminohippuric acid clearances. In agreement with previous reports, these two functions were found to be reduced by hypophysectomy. Infusion of vasopressin increased TcH2O in the intact rat but failed to produce a significant change in the hypophysectomized rat. Treatment of hypophysectomized rats with ACTH restored the effects of vasopressin on TcH2O. ACTH also increased the RPF of hypophysectomized rats to normal values, but only partially restored GFR.

Measuring dynamic kidney function in an undergraduate physiology laboratory

2013 ◽  
Vol 37 (4) ◽  
pp. 384-391 ◽  
Author(s):  
Scott Medler ◽  
Frederick Harrington
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Urine Concentration ◽  
Renal Physiology ◽  
Water Reabsorption ◽  
Laboratory Courses ◽  
Physiological Processes ◽  
Estimate Glomerular Filtration Rate ◽  
Physiology Laboratory

Most undergraduate physiology laboratories are very limited in how they treat renal physiology. It is common to find teaching laboratories equipped with the capability for high-resolution digital recordings of physiological functions (muscle twitches, ECG, action potentials, respiratory responses, etc.), but most urinary laboratories still rely on a “dipstick” approach of urinalysis. Although this technique can provide some basic insights into the functioning of the kidneys, it overlooks the dynamic processes of filtration, reabsorption, and secretion. In the present article, we provide a straightforward approach of using renal clearance measurements to estimate glomerular filtration rate, fractional water reabsorption, glucose clearance, and other physiologically relevant parameters. The estimated values from our measurements in laboratory are in close agreement with those anticipated based on textbook parameters. For example, we found glomerular filtration rate to average 124 ± 45 ml/min, serum creatinine to be 1.23 ± 0.4 mg/dl, and fractional water reabsorption to be ∼96.8%. Furthermore, analyses for the class data revealed significant correlations between parameters like fractional water reabsorption and urine concentration, providing opportunities to discuss urine concentrating mechanisms and other physiological processes. The procedures outlined here are general enough that most undergraduate physiology laboratory courses should be able to implement them without difficulty.

EFFECT OF DEHYDRATION PRODUCED BY WATER DEPRIVATION, DIARRHEA AND VOMITING ON RENAL FUNCTION IN INFANTS

PEDIATRICS ◽  
1951 ◽  
Vol 7 (3) ◽  
pp. 328-340
Author(s):  
PHILIP L. CALCAGNO ◽  
MITCHELL I. RUBIN
Keyword(s):  
Renal Function ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Intravenous Administration ◽  
Water Conservation ◽  
Filtration Rate ◽  
Water Deprivation ◽  
Diarrheal Disease ◽  
Normal Values ◽  
Water Reabsorption

Dehydration when of sufficient severity depresses the glomerular filtration rate significantly. The high inulin and creatinine U/P ratios during dehydration indicate water conservation by the tubules. Depressed glomerular filtration rates may enhance this mechanism. The tendency to the lower than expected rise in U/P ratio with low urine flows during dehydration in diarrheal disease suggests disturbed tubular mechanism for water reabsorption. Glomerular filtration rate is rapidly restored with the intravenous administration of fluid. Restoration to normal values may proceed at a slower pace in the sick infant.

Physical Factors Influencing Fluid Reabsorption from Henle's Loop

1975 ◽  
Vol 53 (2) ◽  
pp. 224-230 ◽  
Author(s):  
A. D. Baines ◽  
C. K. Wu
Keyword(s):  
Glomerular Filtration Rate ◽  
Flow Velocity ◽  
Glomerular Filtration ◽  
Transit Time ◽  
Filtration Rate ◽  
Physical Factors ◽  
Water Reabsorption ◽  
Fluid Reabsorption ◽  
Henle's Loop ◽  
Loop Volume

Our objective was to produce reductions in the luminal volume of Henle's loop and increases in linear flow velocity through the loop. We did this in a recollection micropuncture study by collecting fluid with and without suction from early distal tubules. With suction, transit time of fast green dye through the loop decreased by 34%, calculated loop volume decreased by 28%, and fractional water reabsorption fell from 73.6 to 70.3% (p < 0.025) in water diuretic rats. Absolute water reabsorption did not decrease significantly. In urea–saline diuretic rats transit time decreased 25%, calculated loop volume decreased 22%, fractional reabsorption fell from 59.0 to 51.7% (p < 0.001), and absolute reabsorption decreased by 2.3 nl/min(p < 0.025). Single nephron glomerular filtration rate, distal tubular sodium concentration, and osmolality were unaffected. The less pronounced effect of collection with suction in water diuretic rats may be related to the lower medullary fluid osmolality, which was 338 ± 9(S.E.)mOsmol/kg as compared to497 ± 35 in urea–saline diuretic rats. Collecting fluid with suction from late proximal tubules did not alter glomerular filtration rate or fractional water reabsorption. Stumpe et al. ((1970) J. Clin. Invest. 49, 1200–1212) noted an inverse correlation between fluid reabsorption from Henle's loop and flow velocity in rats with hypertension or congestive heart failure. One can reproduce this correlation by artificially altering the transmural pressure gradient in the loop.

Renal water reabsorption during saline and urea osmotic diuresis in the dog

1963 ◽  
Vol 205 (3) ◽  
pp. 477-482 ◽  
Author(s):  
David L. Maude ◽  
Laurence G. Wesson
Keyword(s):  
Glomerular Filtration Rate ◽  
Steady State ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Free Water ◽  
Conscious Dogs ◽  
Water Reabsorption ◽  
Osmotic Diuresis ◽  
Sodium Salts

Free water reabsorption (Twc) was measured in conscious dogs during a long-term, reasonably steady-state osmotic diuresis induced either by sodium salts or by urea. After 4 to 8 hr the original solute was partially replaced by urea or by sodium salts. Both the replacement of sodium salts by urea and the converse procedure were associated with an augmentation in Twc. During sodium diuresis Twc always fell during the first 2 or 3 hr, a change which appeared unrelated to glomerular filtration rate (GFR) or to osmolar clearance. During the course of urea diuresis Twc steadily increased and showed a positive correlation with GFR. A possible basis for such a correlation is discussed.

Hemodynamic mechanisms in CNS-induced natriuresis in the conscious rat

1983 ◽  
Vol 244 (4) ◽  
pp. F376-F382 ◽  
Author(s):  
S. L. Bealer
Keyword(s):  
Blood Pressure ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Urine Volume ◽  
Sodium Concentration ◽  
Potassium Excretion ◽  
Conscious Rat ◽  
Electrolytic Lesions ◽  
Sodium And Potassium

These experiments were designed to determine 1) the effects of increased CSF sodium concentration on renal hemodynamics in the conscious rat, and 2) the role of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) in the natriuretic and hemodynamic responses during this treatment. After electrolytic lesions of AV3V periventricular tissue or control surgery, blood pressure, glomerular filtration rate, effective renal blood flow, urine volume, and sodium and potassium excretion were measured before and during intraventricular (IVT) infusion of either isotonic or hypertonic saline solutions in conscious hydrated rats. Blood pressure, glomerular filtration rate, and sodium and potassium excretion increased during IVT infusion of concentrated sodium solutions in control rats but not in animals with lesions in the AV3V region. These data support the hypothesis that the natriuretic response to increased CSF sodium concentration in the rat is due to a pressor response and/or increased glomerular filtration rate and demonstrate that ablation of AV3V periventricular tissue blunts the natriuretic response, possibly through diminished central pressor mechanisms and/or decreased central control of glomerular filtration rate.

The effect of vasopressin and oxytocin on glomerular filtration rate in the conscious rat: contribution to the natriuretic response

1994 ◽  
Vol 141 (1) ◽  
pp. 59-67 ◽  
Author(s):  
M L Forsling ◽  
J M Judah ◽  
R J Windle
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Plasma Concentrations ◽  
Fractional Excretion ◽  
Conscious Rat ◽  
Arterial Blood ◽  
Fractional Excretion Of Sodium ◽  
Dose Dependent ◽  
Higher Doses

Abstract Urine flow, sodium excretion, mean arterial blood pressure and glomerular filtration rate (GFR) were detennined in the conscious unrestrained rat infused with hypotonic saline. The effects of vasopressin infused at 24 and 160 pmol/min and oxytocin infused at 30 and 200 pmol/min were determined. The lower doses of each hormone gave plasma concentrations within the physiological range whereas the higher doses produced plasma concentrations equivalent to those seen following dehydration. Vasopressin produced dose-dependent antidiuretic and natriuretic responses. Hormone infused at both rates increased the clearance of sodium, but only the higher dose caused a significant increase in GFR. Fractional excretion of sodium was significantly elevated by both doses. Oxytocin produced dose-dependent diuretic and natriuretic responses. Again both rates of infusion increased the clearance of sodium, but only the higher dose caused a significant increase in GFR. The lower dose caused a significant increase in the fractional excretion of sodium. It appears, therefore, that increases in GFR may have a role in the natriuretic response to both hormones. However, this response can also be seen when GFR remains unchanged. This fact, together with the observed increases in the fractional excretion of sodium, indicates that these hormones have additional tubular actions. Journal of Endocrinology (1994) 141, 59–67

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