Document Detail


Ischemic muscle chemoreflex response elevates blood flow in nonischemic exercising human forearm muscle.
MedLine Citation:
PMID:  10444489     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We tested the hypothesis that forearm blood flow (FBF) might be reduced during forearm exercise when a vasoconstrictor response was evoked by calf exercise during calf ischemia (CE + I). In nine healthy subjects, brachial artery FBF and finger-cuff mean arterial pressure (MAP) were measured beat by beat during rest and forearm exercise. CE + I initiated before 5 min of forearm exercise (condition A) increased MAP by 24% and reduced resting forearm vascular conductance (FVC) by 24% such that FBF remained at the same level as without CE + I (control, condition C). With the onset of forearm exercise, the difference in FVC between condition A and condition C was abolished; consequently, the FBF adaptation to exercise was greater after 3 min of exercise in condition A (247.0 +/- 14.8 ml/min) than in condition C (197.1 +/- 9.4 ml/min, P < 0. 05) because of the elevated MAP. Gradual stimulation of the chemoreflex by the addition of CE + I at 3 min of a 9-min bout of forearm exercise (condition B) did not affect FVC such that progressive elevations in MAP resulted in proportional increases in FBF. We concluded that chemoreflex-mediated increases in systemic sympathetic nervous activity appear to affect resting FVC. Evidence from this study suggests that local factors responsible for initiating and maintaining vasodilation during moderate, small-muscle mass exercise can quickly override this vasoconstrictor influence such that FBF is elevated during exercise in direct proportion to the elevation in MAP.
Authors:
M E Tschakovsky; R L Hughson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  277     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1999 Aug 
Date Detail:
Created Date:  1999-09-23     Completed Date:  1999-09-23     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H635-42     Citation Subset:  IM; S    
Affiliation:
Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Adult
Chemoreceptor Cells / physiopathology*
Exercise / physiology*
Forearm
Homeostasis
Humans
Ischemia / physiopathology*
Male
Muscle, Skeletal / blood supply*
Reflex / physiology*
Regional Blood Flow

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


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