Document Detail

Forelimb postischaemic reactive hyperaemia is impaired by hypotensive low body negative pressure in healthy subjects.
MedLine Citation:
PMID:  16494605     Owner:  NLM     Status:  MEDLINE    
Local metabolic conditions adapt blood supply to metabolic requirement by a direct effect on vascular smooth muscles and indirectly by modulating sympathetic vasoconstrictor effectiveness. During exercise, sympathetic nervous activity could in turn interfere on local metabolic control of vascular tone and restrain blood flow to active muscles. In order to investigate that interaction non-invasively, we measured postischaemic reactive hyperaemia (RH) in the forelimb of eight healthy young men (22.7 +/- 2.1 years) at rest and during two levels of sympathetic stimulation using low body negative pressure (LBNP -15 and -30 mmHg). During every stages, RH was measured after 40, 60, 90 and 180 s of arterial occlusion, respectively. In control conditions, RH rose with duration of ischaemia (18.9, 24.2, 30.4, 33.1 ml min(-1) per 100 ml(-1) for 40, 60, 90 and 180 s of ischaemia, respectively). During non-hypotensive LBNP (-15 mmHg) sympathetic activation was associated with decreased forelimb blood flow (6.4 +/- 0.9 versus 3.9 +/- 0.6 ml min(-1) per 100 ml(-1), P<0.01), but RH were not significantly different from control conditions. During hypotensive tachycardia LBNP (-30 mmHg), RH were significantly lower than under the previous LBNP stage. This fall in RH was greater after the shortest gap of ischaemia and tapered off as arterial occlusion gap increased (-22.3, -13.1, -10.5 and -8.7% for 40, 60, 90 and 180 s of ischaemia, respectively). These results suggested that vascular tone adaptation to local metabolic conditions was modified by sympathetic nervous activation. This was particularly marked when an hypotensive-mediated sympathetic stimulation was opposed to short gaps of ischaemia.
Marc Charles; Vincent Pichot; Jean-Claude Barthelemy; Frederic Roche; Frederic Costes
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Clinical physiology and functional imaging     Volume:  26     ISSN:  1475-0961     ISO Abbreviation:  Clin Physiol Funct Imaging     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-02-23     Completed Date:  2006-07-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101137604     Medline TA:  Clin Physiol Funct Imaging     Country:  England    
Other Details:
Languages:  eng     Pagination:  132-7     Citation Subset:  IM    
Research Unity Physiology Physiopathology of Exercise and Handicap and CHU Saint-Etienne, North Hospital, EFCR Unity, University Jean Monnet, Saint-Etienne, France.
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MeSH Terms
Exercise / physiology*
Forearm / blood supply*
Hyperemia / physiopathology*
Ischemia / physiopathology
Lower Body Negative Pressure*
Regional Blood Flow
Supine Position
Sympathetic Nervous System / physiology
Tachycardia / physiopathology
Vascular Resistance / physiology*

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