Effect of Atropine on Local Skin Wettedness and Sensible Heat Loss

摘要

This study examined arm skin wettedness (w) and dry heat loss (arm R+C) responses during atropine injection (2 mg im, vastis lateralis) or saline injection in heat acclimated subjects. Six male subjects dressed in shorts and sneakers, each exercised (1h to 1 1/2h) on a treadmill (1.34 m/s) in three different environments which facilitated evaporative heat exchange (T sub g = 41 C; P sub w = 12 Torr), impeded dry heat loss T sub g - 35 C; P sub w = 22 Torr) or allowed both sensible and insensible heat exchange (T sub g = 32 C; P sub w = 22 Torr). Local skin wettedness was measured by dew point sensors and arm R+C by analysis of radiative and convective heat exchange components. Rectal T sub re, mean skin temperatures bar T sub sk, V02, and heart rate was measured. A significant decrement (P<0.05) in w (50% reduction) occurred after atropine injection. Whereas control experiments always resulted in minimal heat loss or a frank heat gain depending on environmental condition, arm (R+C) after atropine injection was significantly increased with skin wettedness depression. Two patterns of response in arm (R+C) were apparent: one related to rapid increases in arm (R+C) occurring with net changes in delta T sub re < 0.3 C above that due to exercise alone and a more prolonged response exhibited at delta T sub re > 0.4 to 1.2 C. The results show that injection of atropine in heat acclimated individuals at three discrete environments apparently causes equal inhibition of local sweating but differential local heat loss responses which are affected by state of vasomotor activity and humidity.