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Forelimb postischaemic reactive hyperaemia is impaired by hypotensive low body negative pressure in healthy subjects
Author(s) -
Charles Marc,
Pichot Vincent,
Barthelemy JeanClaude,
Roche Frederic,
Costes Frederic
Publication year - 2006
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2006.00665.x
Subject(s) - medicine , hyperaemia , cardiology , ischemia , blood pressure , blood flow , occlusion , reactive hyperemia , anesthesia , sympathetic nervous system , vasodilation , endocrinology
Summary 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.