Regional similarities and differences in thermoregulatory vaso‐ and sudomotor tone.

Abstract

Skin nerve sympathetic activity was recorded simultaneously from the following pairs of nerves: left and right median, median and peroneal, left and right peroneal, posterior cutaneous antebrachial and superficial radial, posterior cutaneous antebrachial and median. The recordings were performed on healthy subjects exposed to different ambient temperatures. Electrodermal responses and pulse plethysmograms were recorded from the neural innervation zones. Vasoconstrictor impulse bursts recorded simultaneously from the median and peroneal nerves during exposure to a cold environment showed a striking similarity with respect to the timing and strength of individual bursts. A similar strong correlation was observed also among sudomotor bursts recorded simultaneously from the posterior cutaneous antebrachial and superficial radial nerve during exposure to a warm environment. On some occasions, such as during exposure to a moderately warm environment or emotional stress, a temporal correlation was also observed between vasoconstrictor bursts recorded from the median and sudomotor bursts recorded simultaneously from the posterior cutaneous antebrachial nerve. The double nerve recordings provided evidence that in the distal glabrous skin areas, reflex thermoregulatory functions are mainly executed via vasoconstrictor fibers whereas sudomotor fibers are brought into action only at relatively high temperature. In the hairy skin on the dorsal side of forearm and hand, reflex thermoregulation is to a large extent executed via sudomotor fibers.