Document Detail


The persistent effect of long-term enalapril on pressure natriuresis in spontaneously hypertensive rats.
MedLine Citation:
PMID:  9249597     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Long-term angiotensin-converting enzyme inhibitor treatment has been shown to have a persistent antihypertensive effect in spontaneously hypertensive rats (SHR) long after discontinuation of treatment. To test the hypothesis that this persistent effect involves a shift in the pressure-natriuresis relation, we performed experiments in male, anesthetized SHR at 18 wk of age with fixed neural and hormonal influences on the kidney. Renal function was assessed at various levels of arterial pressure using standard clearance techniques. Enalapril (25 mg.kg-1.day-1 in drinking water) was administered from 4 to 14 wk of age and again 3 days before renal function studies. The following four groups of SHR were studied: 1) 10-wk treatment, 2) 10-wk + 3-day treatment, 3) 3-day treatment, and 4) untreated. Groups 1 and 4 had an intact renin-angiotensin system; groups 2 and 3 had the renin-angiotensin system blocked. Mean arterial pressure (MAP, mmHg; means +/- SE) under Inactin anesthesia was 139 +/- 4 (n = 9), 109 +/- 3 (n = 8), 149 +/- 1 (n = 9), and 181 +/- 7 mmHg (n = 9) for each of the four groups, respectively. Glomerular filtration rate was similar in all groups at resting levels of MAP, whereas renal blood flow was elevated in all treatment groups when compared with that in untreated SHR. Pressure-natriuresis, pressure-diuresis, and pressure-fractional sodium excretion curves for the 10-wk treatment group and 3-day only treatment group were shifted leftward to significantly lower pressures by approximately 25 mmHg, compared with the untreated group. The curves for the treated +3-day group were shifted an additional 30 mmHg to the left. The relationship between renal artery pressure (RAP) and renal interstitial hydrostatic pressure was also shifted 25-30 mmHg but only in rats that received the long-term treatment with enalapril. Three-day enalapril had no significant effect on this relationship. These data indicate that the persistent effect of long-term enalapril treatment on arterial pressure in SHR is the result of a shift in the pressure-natriuresis relationship. The mechanism for this effect involves hemodynamic changes that act to improve transmission of RAP to the interstitium, resulting in enhanced sodium excretion for a given level of RAP.
Authors:
S A Dukacz; M A Adams; R L Kline
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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 Jul 
Date Detail:
Created Date:  1997-09-03     Completed Date:  1997-09-03     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:  F104-12     Citation Subset:  IM    
Affiliation:
Department of Physiology, University of Western Ontario, London, Canada.
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MeSH Terms
Descriptor/Qualifier:
Angiotensin-Converting Enzyme Inhibitors / pharmacology*
Animals
Blood Pressure / drug effects,  physiology*
Enalapril / pharmacology*
Glomerular Filtration Rate / drug effects
Hypertension / physiopathology*
Kidney / blood supply,  drug effects*,  physiopathology
Male
Natriuresis / drug effects,  physiology*
Rats
Rats, Inbred SHR
Regional Blood Flow / drug effects
Renal Artery / drug effects,  physiopathology
Renal Circulation / drug effects
Renin-Angiotensin System / drug effects,  physiology
Chemical
Reg. No./Substance:
0/Angiotensin-Converting Enzyme Inhibitors; 75847-73-3/Enalapril

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


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