抄録
In the present study, we examined the effect of hyperoxia on skin vasomotor and sudomotor responses in heat-stressed human. Eleven healthy male subjects breathed 21% (room air) or 100% O2 during normothermia and heat stress produced by hot water-perfused suits. Skin blood flow (SkBF) in forearm was monitored by laser-Doppler flowmetry. Cutaneous vascular conductance (CVC) was calculated as the ratio of SkBF to blood pressure. Local sweating rate (SR) in forearm was monitored by ventilated capsule method. Breathing 100% O2 increased (P<0.001) arterial O2 saturation during normothermia and heat stress, while end-tidal CO2 was maintained at a constant level throughout the O2 inhalation in the two thermal conditions. Breathing 100% O2 did not alter core or skin temperatures. Breathing 100% O2 decreased (P<0.05) CVC under normothermic and heat-stressed conditions. Blockade of adrenergic vasoconstrictor function by using bretylium (BT) iontophoresis did not diminish the reduction of CVC during 100% O2 breathing under the two thermal conditions. The hyperoxia-induced reductions in CVC did not statistically differ between the BT-treated and untreated sites. Breathing 100% O2 did not change SR from the normoxic baseline level. From these findings, it was suggested that hyperoxia induces skin vasoconstriction via non-adrenergic mechanisms but does not alter sudomotor activity. [J Physiol Sci. 2007;57 Suppl:S191]
