DIFFERENT THERMAL DEPENDENCY OF CUTANEOUS SYMPATHETIC OUTFLOW TO GLABROUS AND HAIRY SKIN IN HUMANS

We investigated the effects of ambient temperature on the sudomotor an d vasoconstrictor components of skin sympathetic nerve activity (SSNA) . The sympathetic traffic was measured by simultaneous microneurograph ic recording from post-ganglionic nerve fibres in the tibial and the p eroneal nerves. When the ambient temperature was raised from 25 degree s C to 34 degrees C, both sudomotor and vasoconstrictor components of SSNA were enhanced in the peroneal nerve but were suppressed in the ti bial nerve. The sudomotor and vasoconstrictor sympathetic outflows wer e elevated in both nerves when the temperature was lowered from 34 deg rees C to 18 degrees C. Our results suggested that the sudomotor and t he vasoconstrictor components of SSNA are differently modulated by amb ient temperature. The difference in sudomotor and vasoconstrictor comp onents of SSNA in the tibial and the peroneal nerves at different ambi ent temperature may have been responsible for the differences observed in sweating and vasoconstriction in glabrous and hairy skin.