Document Detail

Regional vascular responses to prolonged lower body negative pressure in normal subjects.
MedLine Citation:
PMID:  2750938     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to determine the effects of sustained unloading of baroreceptors in humans. The regional hemodynamic responses to lower body negative pressure (LBNP) were determined in 20 normal subjects. LBNP at -10 mmHg for 1 h decreased central venous pressure (CVP) without affecting blood pressure or heart rate, suggesting that only cardiopulmonary baroreceptors were unloaded. Forearm blood flow (FBF) and splanchnic blood flow (SBF) both decreased. Renal blood flow (RBF) did not change, but glomerular filtration rate (GFR) increased. Plasma renin activity rose slightly, whereas plasma norepinephrine levels did not change. Peak LBNP (either -20 or -40 mmHg for 1 h) caused a further decline in CVP and narrowed pulse pressure, thus unloading both arterial and cardiopulmonary baroreceptors. FBF returned to base-line values and SBF decreased further. RBF fell and the GFR remained increased. Plasma renin activity increased further, and plasma norepinephrine level rose. Thus the forearm and splanchnic circulations are sensitive to sustained unloading of cardiopulmonary baroreceptors; renal vasoconstriction occurs with additional unloading of arterial baroreceptors. Renin-angiotensin system activation during LBNP may be pertinent to the preservation of glomerular filtration.
A T Hirsch; D J Levenson; S S Cutler; V J Dzau; M A Creager
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  257     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1989 Jul 
Date Detail:
Created Date:  1989-08-16     Completed Date:  1989-08-16     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H219-25     Citation Subset:  IM; S    
Division of Vascular Medicine and Atherosclerosis, Brigham and Women's Hospital, Boston, Massachusetts 02115.
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MeSH Terms
Extremities / blood supply
Hormones / blood
Kidney / physiology
Lower Body Negative Pressure*
Pressoreceptors / physiology*
Regional Blood Flow
Renal Circulation
Splanchnic Circulation
Grant Support
Reg. No./Substance:

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