Gender difference of the sweating responses to iontophoretically applied acetylcholine

Abstract

It is well known that males sweat more compared to females, however the mechanism is still not fully understood. To elucidate the peripheral mechanisms of the gender difference in thermal sweating, sweating responses to acetylcholine (ACh), a primary transmitter of the sudomotor innervation, were compared between college-age male (n=10) and female (n=11) subjects. Ten percent ACh was iontophoretically administered on the forearm with the direct currents of 1.0, 1.5, 2.0 and 2.5 mA (Quantitative sudomotor axon reflex test). With the higher current the sweat latency tended shorter in both sex, but gender difference was not apparent. Directly activated and axon reflex-mediated sweating responses reached the maximum at a current of 1.5 or 2.0 mA in both sex, and those in the male were larger than those in the female though not significant because of the big individual variations. Iodine-pregnated paper method revealed that activated sweat gland density on the forearm in male was not lesser than in female although the expected larger forearm surface area. Sweat output per single gland was significantly large in the male than in the female. These results indicate that gender difference of thermal sweating is attributed to peripheral sweating mechanism at least in part, through both of the larger sweat output per single gland and the more number of active sweat gland on the forearm in male. [Jpn J Physiol 54 Suppl:S236 (2004)]