Sugimoto N, Shido O, Sakurada S
Department of Physiology, School of Medicine, Kanazawa University, Japan.
J Appl Physiol (1985). 1995 May;78(5):1720-4. doi: 10.1152/jappl.1995.78.5.1720.
Body core temperature of rats acclimated to heat given daily at a fixed time falls during the previous heat exposure time. In the present study, thermoregulatory responses of heat-acclimated rats were examined during the specific period. Heat-acclimated rats were subjected to an ambient temperature of 32 degrees C for approximately 5 h in the first half or last half of the dark phase for 14 days while control rats were kept at 24 degrees C. Then the rats were placed in a direct calorimeter and were warmed for 30 min with an intraperitoneal electric heater. Measurements were made twice in the first and last halves of the dark phase. Body warming significantly increased body core temperature in all rats. In the heat-acclimated rats, heat production (M) was significantly depressed during the previous heat exposure time but not during the other period. Body warming had little effect on M in the control rats during either period. The results suggest that rats acclimated to heat given at a fixed time daily respond to an acute heat load with a pronounced reduction of M. However, such a response was observed only during the period when the rats had been previously exposed to heat.
每天在固定时间适应热环境的大鼠，其体核温度在之前的热暴露时间内会下降。在本研究中，在特定时间段内检测了热适应大鼠的体温调节反应。热适应大鼠在黑暗期的前半段或后半段，于32℃环境温度下暴露约5小时，持续14天，而对照大鼠则饲养在24℃环境中。然后将大鼠置于直接热量计中，用腹腔内电加热器加热30分钟。在黑暗期的前半段和后半段各测量两次。身体升温使所有大鼠的体核温度显著升高。在热适应大鼠中，产热（M）在之前的热暴露时间内显著降低，但在其他时间段则没有。在两个时间段内，身体升温对对照大鼠的M几乎没有影响。结果表明，每天在固定时间适应热环境的大鼠对急性热负荷的反应是M显著降低。然而，这种反应仅在大鼠之前暴露于热的时间段内观察到。
