Cutaneous vascular responses in finger and forearm during rising ambient temperatures

¹ Department of Physiology, St. Louis University School of Medicine, St. Louis, Missouri

During slowly rising ambient temperatures, digital vasodilatation often preceded that in forearm skin; the two vasodilatations proceeded together in spring but not in summer experiments. The curvilinear relation of local skin temperature to local skin blood flow in the forearm often showed an abrupt inflection, suggesting the appearance of an additional influence on the vessels; however, a regular relation to local sweating was not apparent, vasodilatation in forearm skin often continued to increase even when local skin temperature had stabilized or fallen slightly, and the forearm vascular events were prevented by local cooling. During repeat cycles of ambient temperature, complete dissociation of the cutaneous vascular events in finger and forearm and of forearm vasodilatation and sweating often occurred. Digital vasomotor waves were not accompanied by similar waves in forearm skin. Of multiple factors possibly controlling the forearm skin circulation, the local temperature seemed most important. The maximum vasodilatation in forearm during heat exposure was not augmented by acetyl-ß-methylcholine.