Spiers D E
John B. Pierce Foundation Laboratory, Yale University School of Medicine, New Haven, Connecticut 06519.
J Appl Physiol (1985). 1988 May;64(5):2119-24. doi: 10.1152/jappl.1988.64.5.2119.
Immature rats were tested at 2, 7, 11, and 15 days of age to determine steady-state thermoregulatory responses during light (L) and dark (D) phases of the daily cycle. Pups were housed with dams in a vivarium illuminated from 0700 to 1900 h. During each phase tests began approximately 1 h after the change in the light conditions of the vivarium. Duration of each test was approximately 7 h. Rats were tested individually in temperature-controlled cylinders at ambient temperatures (Ta) = 25.0, 30.0, 32.5, and 35.0 degrees C. Both colonic (Tco) and tail skin temperatures of each animal were measured continuously. O2 content of effluent air from each cylinder was determined to provide an estimate of metabolic rate (M). Immature rats, at 2 to 11 days of age, exhibited significant L:D differences in M and Tco. However, no significant L:D differences in these responses were noted at 15 days of age. In every case, nocturnal increases in Tco were associated with a rise in M. L:D differences in Tco response were not attributed to a significant change in total thermal conductance. These data support the conclusion that the immature rat exhibits daily variation in metabolic rate, which is the primary contributor to L:D shifts in Tco.
对未成熟大鼠在2、7、11和15日龄时进行测试，以确定其在每日昼夜循环的光照（L）和黑暗（D）阶段的稳态体温调节反应。幼崽与母鼠一起饲养在一个从07:00至19:00有光照的动物饲养室中。在每个阶段，测试在饲养室光照条件改变后约1小时开始。每次测试持续约7小时。大鼠在温度控制的圆柱体中单独进行测试，环境温度（Ta）分别为25.0、30.0、32.5和35.0摄氏度。连续测量每只动物的结肠温度（Tco）和尾部皮肤温度。测定每个圆柱体排出空气中的氧气含量，以估算代谢率（M）。2至11日龄的未成熟大鼠在代谢率和结肠温度方面表现出显著的昼夜差异。然而，在15日龄时未观察到这些反应有显著的昼夜差异。在每种情况下，结肠温度的夜间升高都与代谢率的升高相关。结肠温度反应的昼夜差异并非归因于总热传导率的显著变化。这些数据支持这样的结论：未成熟大鼠的代谢率存在每日变化，这是导致结肠温度昼夜变化的主要因素。
