Document Detail


Peripheral vasoconstriction shortly after onset of moderate exercise in humans.
MedLine Citation:
PMID:  7836159     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The immediate cardiovascular responses at the onset of supine dynamic leg exercise were studied by noninvasive methods in healthy humans. Total peripheral conductance (TPC), heart rate, and cardiac output increased very rapidly at the onset of exercise. Mean arterial pressure (MAP) showed a moderate anticipatory increase during a 10-s countdown to exercise and then decreased (but not below resting level) during the first 10 s of exercise. The TPC response was biphasic, and TPC started to fall from its peak value approximately 12 s after onset of exercise. This peripheral vasoconstriction increased MAP. After 25 s, the cardiovascular variables were stable for the rest of the 2-min exercise period. In the same subjects, cholinergic blockade was induced by atropine sulfate (0.035 mg/kg) and resting cardiac output, MAP, and TPC increased considerably. The exercise protocol was repeated after atropine, and the increase in heart rate at onset of exercise was slower and smaller. MAP decreased and remained depressed throughout the exercise period. A monophasic increase in TPC was seen. We suggest that, in the normal situation, the biphasic response in TPC reflects a baroreflex sympathetic vasoconstriction very shortly after onset of exercise and that this response is due to a rapid increase in set point for arterial pressure control at the onset of exercise. After cholinergic blockade, MAP was probably continuously well above the set point for arterial pressure control both before and during exercise and no reflex vasoconstriction was observed in this situation.
Authors:
K Toska; M Eriksen
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  77     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1994 Sep 
Date Detail:
Created Date:  1995-02-28     Completed Date:  1995-02-28     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1519-25     Citation Subset:  IM; S    
Affiliation:
Department of Physiology, University of Oslo, Norway.
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MeSH Terms
Descriptor/Qualifier:
Adult
Atropine / pharmacology
Baroreflex / drug effects,  physiology
Cardiac Output / drug effects,  physiology
Exercise / physiology*
Female
Heart Rate / drug effects,  physiology
Hemodynamics / drug effects,  physiology
Humans
Leg / physiology
Male
Regional Blood Flow / drug effects,  physiology
Stroke Volume / drug effects,  physiology
Supine Position / physiology
Vasoconstriction / drug effects,  physiology*
Chemical
Reg. No./Substance:
51-55-8/Atropine

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


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