HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 295/3/R727    most recent 00144.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mueller, P. J. Search for Related Content PubMed PubMed Citation Articles by Mueller, P. J.

CALL FOR PAPERS
Physiological and Molecular Mechanisms Implicated in the Neural Control of Circulation

Influence of sedentary versus physically active conditions on regulation of plasma renin activity and vasopressin

Dalton Cardiovascular Research Center and Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, Missouri; and Department of Physiology, Wayne State University, School of Medicine, Detroit, Michigan

Submitted 27 February 2008 ; accepted in final form 27 May 2008

Physical inactivity is an independent risk factor for cardiovascular disease. Sedentary animals compared to physically active controls exhibit enhanced sympathoexcitatory responses, including arterial baroreflex-mediated sympathoexcitation. Hypotension-induced sympathoexcitation is also associated with the release of vasoactive hormones. We hypothesized that sedentary conditions may enhance release of the vasoactive hormones AVP and ANG II. To test this hypothesis, the humoral response to hypotension was examined in conscious rats after 9–12 wk of sedentary conditions or "normally active" conditions. Normally active conditions were produced by allowing rats access to running wheels in their home cages. Running distance peaked after 4 wk (4.5 ± 0.7 km/day), and the total distance run after 9 wk was 174 ± 23 km (n = 25). Similar levels of hypotension were induced in conscious sedentary or physically active animals with the arterial vasodilator, diazoxide (25 mg/kg iv). Control experiments used a saline injection of equivalent volume. Plasma samples were collected and assayed for plasma AVP concentration and plasma renin activity (PRA). Sedentary conditions significantly enhanced resting and hypotension-induced PRA relative to normal physical activity. In contrast, resting and hypotension-induced AVP levels were not statistically different between groups. These data suggest that baroreflex-mediated activation of the renin-angiotensin system, but not AVP secretion, is enhanced by sedentary conditions. We speculate that augmented activation of the renin-angiotensin system may be related to enhanced sympathetic outflow observed in sedentary animals and may contribute to increased risk of cardiovascular disease in the sedentary population.

physical activity; physical inactivity; neurohumoral control; angiotensin II