Document Detail

Reduced sensitivity of the renal circulation to angiotensin II in pregnant rats.
MedLine Citation:
PMID:  9322985     Owner:  NLM     Status:  MEDLINE    
The renal circulation undergoes significant changes during pregnancy and pregnancy-induced hypertension. Although numerous studies indicate that the pressor response to angiotensin II (Ang II) is reduced during pregnancy, it is unclear as to whether this altered sensitivity to Ang II occurs in the renal circulation. The first aim of this study was to determine whether the renal vascular responsiveness to exogenous Ang II is altered in the midterm pregnant rat. All rats were pretreated with an intravenous infusion of the converting-enzyme inhibitor captopril (20 microg x kg(-1) x min(-1)) to block endogenous Ang II formation. Following a control period, Ang II was infused at a dose of 10 ng x kg(-1) x min(-1) for 50 minutes into the renal arteries via a suprarenal aortic catheter. In anesthetized virgin rats, Ang II markedly decreased renal plasma flow (RPF) by 39% (5.0+/-0.4 to 3.1+/-0.4 mL/min), glomerular filtration rate (GFR) by 39% (1.9+/-0.1 to 1.16+/-0.2 mL/min), and urine flow by 47% (22.1+/-5.6 to 12.3+/-4.8 microL/min). In contrast, Ang II had no significant effect on RPF, GFR, and urine flow in the anesthetized pregnant rats. Since nitric oxide (NO) has been previously reported to modulate the renal vascular actions of Ang II in normal animals and NO synthesis is thought to be elevated in pregnancy, this study examined the role of NO in the attenuated renal response to Ang II. In pregnant rats pretreated with L-NAME, the arterial pressure was higher and RPF was lower than in the control pregnant rats. However, the renal response to Ang II in the L-NAME-pretreated pregnant rats was similar to control pregnant rats. These data indicate that the renal circulation has a reduced sensitivity to Ang II during pregnancy. We also found that NO synthesis inhibition does not alter the attenuated renal response to Ang II in the anesthetized pregnant rats.
J Novak; J Reckelhoff; L Bumgarner; K Cockrell; S Kassab; J P Granger
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Hypertension     Volume:  30     ISSN:  0194-911X     ISO Abbreviation:  Hypertension     Publication Date:  1997 Sep 
Date Detail:
Created Date:  1997-10-16     Completed Date:  1997-10-16     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  580-4     Citation Subset:  IM    
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505, USA.
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MeSH Terms
Angiotensin II / pharmacology*
Glomerular Filtration Rate / drug effects
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / physiology
Pregnancy, Animal / physiology*
Rats, Sprague-Dawley
Renal Circulation / drug effects*
Grant Support
Reg. No./Substance:
10102-43-9/Nitric Oxide; 11128-99-7/Angiotensin II; 50903-99-6/NG-Nitroarginine Methyl Ester

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