Document Detail

Influence of endogenous angiotensin II on control of sympathetic nerve activity in human dehydration.
MedLine Citation:
PMID:  19805740     Owner:  NLM     Status:  MEDLINE    
Arterial blood pressure can often fall too low during dehydration, leading to an increased incidence of orthostatic hypotension and syncope. Systemic sympathoexcitation and increases in volume regulatory hormones such as angiotensin II (AngII) may help to maintain arterial pressure in the face of decreased plasma volume. Our goals in the present study were to quantify muscle sympathetic nerve activity (MSNA) during dehydration (DEH), and to test the hypothesis that endogenous increases in AngII in DEH have a mechanistic role in DEH-associated sympathoexcitation. We studied 17 subjects on two separate study days: DEH induced by 24 h fluid restriction and a euhydrated (EUH) control day. MSNA was measured by microneurography at the peroneal nerve, and arterial blood pressure, electrocardiogram, and central venous pressure were also recorded continuously. Sequential nitroprusside and phenylephrine (modified Oxford test) were used to evaluate baroreflex control of MSNA. Losartan (angiotensin type 1 receptor (AT1) antagonist) was then administered and measurements were repeated. MSNA was elevated during DEH (42 +/- 5 vs. EUH: 32 +/- 4 bursts per 100 heartbeats, P = 0.02). Blockade of AT1 receptors partially reversed this change in MSNA during DEH while having no effect in the control EUH condition. The sensitivity of baroreflex control of MSNA was unchanged during DEH compared to EUH. We conclude that endogenous increases in AngII during DEH contribute to DEH-associated sympathoexcitation.
J A Rabbitts; N A Strom; J R Sawyer; T B Curry; N M Dietz; S K Roberts; S M Kingsley-Berg; N Charkoudian
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-10-05
Journal Detail:
Title:  The Journal of physiology     Volume:  587     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-11-16     Completed Date:  2010-07-26     Revised Date:  2013-05-31    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  5441-9     Citation Subset:  IM    
Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA.
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MeSH Terms
Angiotensin II / physiology*
Blood Pressure / physiology
Dehydration / physiopathology*
Heart Rate / physiology
Receptor, Angiotensin, Type 1 / physiology
Sympathetic Nervous System / physiology*
Water-Electrolyte Balance / physiology
Young Adult
Grant Support
Reg. No./Substance:
0/Receptor, Angiotensin, Type 1; 11128-99-7/Angiotensin II

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