Cutaneous vasodilatation elicited by body heating in calf, forearm, cheek, and ear

¹ Department of Physiology, Saint Louis University School of Medicine, Saint Louis, Missouri

When seminude subjects were exposed to a slowly rising ambient temperature (25–45 C), the onset of cutaneous vasodilatation occurred simultaneously in the calf, forearm, cheek, and ear, and the further progress of the vasodilatation was similar in the last three regions. That in the calf and toe often differed from that in the forearm. Either the vasodilatation in the calf was small or it stabilized early while the forearm vessels continued to dilate markedly. One subject repeatedly presented an exception in that a marked vasodilatation in the calf considerably exceeded that in the forearm. He was a poor sweater and exhibited unusually high skin temperatures. The usual failure of the skin temperature to rise as much in the calf as in the forearm appeared to be closely related to the lesser cutaneous vasodilatation. There was no evidence that local sweating elicited local vasodilatation; on the contrary, evaporative cooling seemed to decrease the vasodilatation, particularly in the calf. The cutaneous vascular events were followed continuously in each region by means of photoelectric plethysmography.