Neural control of human skin blood flow.

The paper reviews recent studies on neural control of skin blood flow, with special emphasis on the interaction between vasoconstrictor and vasodilator mechanisms. Intraneural electrical stimulation, mental stress, arousal and deep breaths have been found to cause cutaneous reflex vasodilatation in cold and vasoconstriction in warm subjects. The vasoconstrictions are probably due to increases of sympathetic vasoconstrictor nerve traffic, but whether vasodilatation is due to inhibition of vasoconstrictor nerve traffic or active (= impulse-induced) vasodilatation is unclear. The latter alternative is a possibility since electrical stimulation of the lumbar sympathetic chain may result in skin vasodilatation, suggesting that active vasodilatation is present in the skin of the human foot. Body cooling, which causes a reflex increase of cutaneous sympathetic vasoconstrictor activity, leads to reduction of cutaneous axon reflex vasodilatation. This may be due to competition between vasoconstrictor and vasodilator mechanisms at the blood vessel level.