Hypoxic cutaneous vasodilation is sustained during brief cold stress and is not affected by changes in CO2
| Autor: | Christopher T. Minson, Grant H. Simmons, John R. Halliwill, Sarah M. Fieger |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Adult
Male medicine.medical_specialty Physiology Cold exposure Hemodynamics Vasodilation Hypercapnia Young Adult Oxygen Consumption Stress Physiological Physiology (medical) Internal medicine Cutaneous vasodilation medicine Humans Cold stress Skin Skin blood flow Chemistry Articles Carbon Dioxide Hypoxia (medical) Cell Hypoxia Cold Temperature Endocrinology Regional Blood Flow Anesthesia medicine.symptom Blood Flow Velocity |
| Zdroj: | J Appl Physiol (1985) |
| ISSN: | 1522-1601 8750-7587 |
| Popis: | Hypoxia decreases core body temperature in animals and humans during cold exposure. In addition, hypoxia increases skin blood flow in thermoneutral conditions, but the impact of hypoxic vasodilation on vasoconstriction during cold exposure is unknown. In this study, skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as red blood cell flux/mean arterial pressure and normalized to baseline ( n = 7). Subjects were exposed to four different conditions in the steady state (normoxia and poikilocapnic, isocapnic, and hypercapnic hypoxia) and were cooled for 10 min using a water-perfused suit in each condition. CVC increased during all three hypoxic exposures (all P < 0.05 vs. baseline), and the magnitude of these steady-state responses was not affected by changes in end-tidal CO2 levels. During poikilocapnic and hypercapnic hypoxia, cold exposure reduced CVC to the same levels observed during normoxic cooling ( P > 0.05 vs. normoxia), whereas CVC remained elevated throughout cold exposure during isocapnic hypoxia ( P < 0.05 vs. normoxia). The magnitude of vasoconstriction during cold stress was similar in all conditions ( P > 0.05). Thus the magnitude of cutaneous vasodilation during steady-state hypoxia is not affected by CO2 responses. In addition, the magnitude of reflex vasoconstriction is not altered by hypoxia, such that the upward shift in skin blood flow (hypoxic vasodilation) is maintained during whole body cooling. |
| Databáze: | OpenAIRE |
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