Bishop B, Silva G, Krasney J, Nakano H, Roberts A, Farkas G, Rifkin D, Shucard D
State University of New York at Buffalo, Department of Physiology and Biophysics, Sherman Hall/South Campus, Buffalo, NY 14214, USA.
Am J Physiol Regul Integr Comp Physiol. 2001 Apr;280(4):R1190-6. doi: 10.1152/ajpregu.2001.280.4.R1190.
When rats, acclimated to an ambient temperature (T(a)) of 29 degrees C, are exposed to 10% O(2) for 63 h, the circadian rhythms of body temperature (T(b)) and level of activity (L(a)) are abolished, T(b) falls to a hypothermic nadir followed by a climb to a hyperthermic peak, L(a) remains depressed (Bishop B, Silva G, Krasney J, Salloum A, Roberts A, Nakano H, Shucard D, Rifkin D, and Farkas G. Am J Physiol Regulatory Integrative Comp Physiol 279: R1378-R1389, 2000), and overt brain pathology is detected (Krasney JA, Farkas G, Shucard DW, Salloum AC, Silva G, Roberts A, Rifkin D, Bishop B, and Rubio A. Soc Neurosci Abstr 25: 581, 1999). To determine the role of T(a) in these hypoxic-induced responses, T(b) and L(a) data were detected by telemetry every 15 min for 48 h on air, followed by 63 h on 10% O(2) from rats acclimated to 25 or 21 degrees C. Magnitudes and rates of decline in T(b) after onset of hypoxia were inversely proportional to T(a), whereas magnitudes and rates of T(b) climb after the hypothermic nadir were directly proportional to T(a). No hyperthermia, so prominent at 29 degrees C, occurred at 25 or 21 degrees C. The hypoxic depression of L(a) was least at 21 degrees C and persisted throughout the hypoxia. In contrast, T(a) was a strong determinant of the magnitudes and time courses of the initial fall and subsequent rise in T(b). We propose that the absence of hyperthermia at 21 and 25 degrees C as well as a persisting hypothermia may protect the brain from overt pathology.
当适应环境温度（Ta）为29℃的大鼠暴露于10%氧气环境63小时后，其体温（Tb）和活动水平（La）的昼夜节律被消除，Tb降至低温最低点，随后攀升至高温峰值，La持续降低（毕晓普B、席尔瓦G、克拉斯尼J、萨卢姆A、罗伯茨A、中野H、舒卡德D、里夫金D和法卡斯G。《美国生理学杂志：调节、整合与比较生理学》279卷：R1378 - R1389，2000年），并且检测到明显的脑病理学变化（克拉斯尼JA、法卡斯G、舒卡德DW、萨卢姆AC、席尔瓦G、罗伯茨A、里夫金D、毕晓普B和鲁维奥A。《神经科学学会摘要》25卷：581，1999年）。为了确定Ta在这些缺氧诱导反应中的作用，对适应25℃或21℃的大鼠，在空气中通过遥测每15分钟检测一次Tb和La数据，持续48小时，随后在10%氧气环境中检测63小时。缺氧开始后Tb下降的幅度和速率与Ta成反比，而低温最低点后Tb攀升的幅度和速率与Ta成正比。在25℃或21℃时未出现29℃时那么明显的高温现象。La的缺氧性降低在21℃时最小，且在整个缺氧过程中持续存在。相比之下，Ta是Tb初始下降和随后上升的幅度及时间进程的重要决定因素。我们提出，21℃和25℃时不存在高温以及持续的低温可能保护大脑免受明显的病理学损害。
