Adrenergic reactivity of visceral veins in hypoxia and hypothermia.

Adrenoreactivity of veins in skeletal muscle to norepinephrine decreased, while reactivity of intestinal veins remained virtually unchanged during combined exposure to hypoxia and hypothermia. In skeletal muscles cooling enhanced the direct effect of hypoxia on vascular smooth muscle cells, while in the intestine hypothermia prevented hypoxia-induced endothelial dysfunction, as it did under normothermic conditions. The results of experiments on the intestine indicated possible protective effect of hypothermia with respect to hypoxia-induced damage, and experimental findings on muscles showed potentiation of the direct effect of oxygen deficiency on venous smooth muscles.