Document Detail


Effect of angiotensin II receptor blockade on proximal tubular fluid reabsorption.
MedLine Citation:
PMID:  9277533     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of physiological concentrations of angiotensin II on proximal tubular fluid reabsorption remains controversial. To investigate the effect of blockade of intratubular AT1 receptors on tubular reabsorption, losartan (10(-5) M) was administered by microperfusion into an early proximal convolution of halothane-anesthetized Sprague-Dawley rats. Four parameters that depend on the rate of proximal fluid reabsorption were measured: proximal intratubular pressure (Pprox), early and late proximal flow rate, and early distal NaCl concentration. Pprox decreased by 0.5 +/- 0.1 mmHg, late proximal flow rate decreased by 2.0 +/- 0.8 nl/min, and early distal NaCl concentration decreased by 4.3 +/- 0.8 mM (mean +/- SE). No changes were observed after microperfusion with saline. Because the tubuloglomerular feedback mechanism was operating in the closed-loop mode, the decreased NaCl load to the macula densa will be compensated by an increase in the single-nephron glomerular filtration rate. In agreement with this, the early proximal flow rate, measured proximal to the site of losartan administration, increased by 5.7 +/- 1.3 nl/min. The increase in the rate of proximal reabsorption between the early and late proximal convolutions was estimated to be 7.8 nl/min (approximately 36%). It is concluded that a decrease in local luminal angiotensin II levels and/or AT1 receptor activity under free flow conditions increases the rate of proximal tubular fluid reabsorption.
Authors:
P P Leyssac; F M Karlsen; N H Holstein-Rathlou
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Aug 
Date Detail:
Created Date:  1997-09-25     Completed Date:  1997-09-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R510-7     Citation Subset:  IM    
Affiliation:
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
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MeSH Terms
Descriptor/Qualifier:
Absorption / drug effects
Animals
Biphenyl Compounds / pharmacology
Body Fluids / metabolism*
Imidazoles / pharmacology
Kidney Tubules, Proximal / drug effects,  metabolism*,  physiology
Losartan
Male
Perfusion
Pressure
Rats
Rats, Sprague-Dawley
Receptors, Angiotensin / antagonists & inhibitors*
Sodium Chloride / metabolism
Tetrazoles / pharmacology
Chemical
Reg. No./Substance:
0/Biphenyl Compounds; 0/Imidazoles; 0/Receptors, Angiotensin; 0/Tetrazoles; 114798-26-4/Losartan; 7647-14-5/Sodium Chloride

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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