Fuller A, Carter R N, Mitchell D
Department of Physiology, University of the Witwatersrand, Medical School, Parktown 2193, Johannesburg, South Africa.
J Appl Physiol (1985). 1998 Mar;84(3):877-83. doi: 10.1152/jappl.1998.84.3.877.
We measured brain and abdominal temperatures in eight male Sprague-Dawley rats (350-450 g) exercising voluntarily to a point of fatigue in two hot environments. Rats exercised, at the same time of the day, in three different trials, in random order: rest 23 degrees C, exercise 33 degrees C; rest 23 degrees C, exercise 38 degrees C; and rest 38 degrees C, exercise 38 degrees C. Running time to fatigue was 29.4 +/- 5.9 (SD), 22.1 +/- 3.7, and 14.3 +/- 2.9 min for the three trials, respectively. Abdominal temperatures, measured with intraperitoneal radiotelemeters, at fatigue in the three trials (39.9 +/- 0.3, 39.9 +/- 0.3, and 39.8 +/- 0.3 degrees C, respectively) were not significantly different from each other. Corresponding brain temperatures, measured with thermocouples in the hypothalamic region (40.2 +/- 0.4, 40.2 +/- 0.4, and 40.1 +/- 0.4 degrees C), also did not differ. Our results are consistent with the concept that there is a critical level of body temperature beyond which animals will not continue to exercise voluntarily in the heat. Also, in our study, brain temperature was higher than abdominal temperature throughout exercise; that is, selective brain cooling did not occur when body temperature was below the level limiting exercise.
我们在两种炎热环境中，对八只雄性斯普拉格-道利大鼠（体重350 - 450克）进行了测量，这些大鼠自愿运动至疲劳状态。大鼠在一天中的同一时间进行了三次不同的试验，试验顺序随机：休息（23摄氏度）、运动（33摄氏度）；休息（23摄氏度）、运动（38摄氏度）；休息（38摄氏度）、运动（38摄氏度）。三次试验中，大鼠运动至疲劳的时间分别为29.4±5.9（标准差）分钟、22.1±3.7分钟和14.3±2.9分钟。通过腹腔内无线电遥测仪测量的三次试验中大鼠疲劳时的腹部温度（分别为39.9±0.3摄氏度、39.9±0.3摄氏度和39.8±0.3摄氏度）彼此之间无显著差异。在下丘脑区域用热电偶测量的相应脑温（分别为40.2±0.4摄氏度、40.2±0.4摄氏度和40.1±0.4摄氏度）也无差异。我们的结果与以下概念一致，即存在一个关键体温水平，超过该水平动物将不会在炎热环境中继续自愿运动。此外，在我们的研究中，整个运动过程中脑温高于腹温；也就是说，当体温低于限制运动的水平时，未发生选择性脑冷却。
