The effect of body heating on the circulation in skin and muscle

The blood flow in the human forearm increases when the body temperature is raised by heating. The problem is to determine whether the increase is occurring in skin, or in muscle, or in both. Barcroft, Bonnar & Edholm (1947) studied the effect ofbody heating on the forearm blood flow after the cutaneous circulation had been suppressed by the iontophoresis of adrenaline. They came to the conclusion that the greater part of the increased flow was due to dilatation of the muscle blood vessels. Subsequently, similar experiments, with some modification in technique, showed that the increase in the skin blood flow on body heating was apparently much greater than the earlier work suggested (Cooper, Edholm, Fletcher, Fox & Macpherson, 1954). In fact, the increase in the skin blood flow was so large it seemed possible that with further refinements of technique the whole of the increase might be found to be passing through the skin. The experiments to be described were performed in an attempt to decide this point.