Summary Effects of local skin temperature on sweat gland activity were analyzed quantitatively by measuring changes in the rates of thermal sweating and of drug-induced sweating by local heating. The data indicates that a rise in local temperature causes an accelerated increase in the rate of sweat production, the Q10 being around 2.5 regardless of the basal sweat rate with some individual variations. Local heating apparently facilitates transmitter release at the neuroglandular junction and augments glandular responsiveness, their significances being comparable.Key words : sweating, sweat gland activity, local skin temperature.The activity of eccrine sweat glands is controlled largely by centrally-derived sudomotor neural activity, but may be modified by local conditions. It has been shown that the rise in local skin temperature caused accelerated increments in local sweat rate: NADAL et al. (1971) proposed a model describing major influences on local sweat rate, where the effect of local skin temperature was determined to be exponential. The Q10 of sweat gland activity was calculated to be 3 (subject range 2.6-3.5), while the value calculated from the data of BULLARD et al. (1970) ranged between 2 and 5. As for its mechanism, MACINTYRE et al. (1968) maintained that transmitter substance released per neural impulse at the neuroglandular junction is increased by local heating. One of the present authors (OGAWA, 1970) showed that the threshold concentration of an intradermally injected sudorific agent for inducing local sweating is reduced by local heating in a cool environment. It was also demonstrated that local heating caused localized increase in the rate of druginduced sweating on an area under nerve block as well as in a cool environment (OGAWA and BULLARD, 1970). These observations suggest that the responsiveness of glandular cells to a given amount of transmitter substance is affected by local temperature.The present study was proposed to reevaluate quantitatively the sweat-facili-

It has been demonstrated by Takagi and his colleagues that

Effects of sweat gland training by daily local heating were examined and its significance in heat acclimatization was evaluated.Training by 2-hr immersion of an arm in hot water of 43°C caused distinct augmentation of sweat gland activity in the trained area, with reduc-

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