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The effect of isocapnic hypoxia on reflex cutaneous vasoconstriction
Author(s) -
Simmons Grant H.,
Minson Christopher T.,
Halliwill John R.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.956.13
Subject(s) - vasoconstriction , hypoxia (environmental) , anesthesia , medicine , reflex , vasodilation , hypoxic pulmonary vasoconstriction , laser doppler velocimetry , blood flow , chemistry , oxygen , organic chemistry
We have previously shown that isocapnic hypoxia increases skin blood flow in thermoneutral humans, but the effect of hypoxic vasodilation on reflex cutaneous vasoconstriction is unknown. In this study, we tested the hypothesis that reflex cutaneous vasoconstriction is blunted during isocapnic hypoxia. Ten healthy volunteers (7 men, 3 women) underwent 10 minutes of progressive whole body cooling (water‐perfused suit) while breathing from a scuba mouthpiece during both normoxia and isocapnic hypoxia. Skin blood flow was assessed using laser Doppler flowmetry and cutaneous vascular conductance (CVC) was calculated as red cell flux/mean arterial pressure and normalized to normoxic baseline. During normoxia (SaO 2 = 98.4 ± 0.3%), cold stress decreased CVC from 99.9 ± 0.6 to 71.4 ± 4.3 %baseline ( P <0.05). During isocapnic hypoxia (SaO 2 = 79.9 ± 0.4%), baseline CVC was elevated ( P <0.05 vs. normoxia) and cold stress decreased CVC from 124.3 ± 4.5 to 86.9 ± 6.5 %baseline ( P <0.05). Since the change in CVC was not different between normoxic and hypoxic conditions (−28.6 ± 4.4 vs. −37.4 ± 4.2 %baseline; P =0.11), the resulting CVC was lower during cold exposure in normoxic vs. hypoxic conditions ( P <0.05). Thus, although reflex cutaneous vasoconstriction is functional during isocapnic hypoxia, skin blood flow during cold exposure remains elevated by isocapnic hypoxia relative to values observed in normoxic conditions.