Sugimoto N, Shido O, Furuyama F, Sakurada S, Nishino H
Department of Physiology, School of Medicine, Faculty of Medicine, Kanazawa University, Japan.
Int J Biometeorol. 1999 Nov;43(3):119-23. doi: 10.1007/s004840050126.
FOK is an inbred rat strain with a genotypic adaptation to hot environments. The present study investigated the mechanism of the high heat tolerance of the FOK rat. Male FOK and WKAH rats were used. They were loosely restrained and placed individually in a direct calorimeter with an ambient temperature of 24 degrees C. Their hypothalamic temperature, evaporative and non-evaporative heat loss and heat production were measured. After thermal equilibrium had been attained, the rats were warmed for 30 min with a chronically implanted intraperitoneal electric heater (internal heating). At least 90 min after the heating, the jacket water temperature surrounding the calorimeter chamber was gradually raised from 24 degrees C to 36 degrees C in 80 min (external warming). During the internal heating, changes in the thermoregulatory parameters did not differ between the groups. During the external warming, the evaporative heat loss of the FOK rat was significantly greater than that of the WKAH rat, while changes in nonevaporative heat loss and heat production did not differ between the groups. The results suggest that in the FOK rat, the improved heat tolerance is attributable to an enhanced evaporative heat loss response, but not to a facilitation of nonevaporative heat loss or of metabolic depression.
FOK是一种对炎热环境具有基因型适应性的近交系大鼠品系。本研究探讨了FOK大鼠耐热性高的机制。使用雄性FOK和WKAH大鼠。将它们轻度束缚，单独置于环境温度为24℃的直接热量计中。测量它们的下丘脑温度、蒸发和非蒸发散热以及产热。达到热平衡后，用长期植入的腹腔内电加热器对大鼠进行30分钟的加热（内部加热）。加热后至少90分钟，将热量计腔室周围的夹套水温在80分钟内从24℃逐渐升高至36℃（外部加热）。在内部加热期间，两组的体温调节参数变化没有差异。在外部加热期间，FOK大鼠的蒸发散热量显著大于WKAH大鼠，而非蒸发散热量和产热的变化在两组之间没有差异。结果表明，在FOK大鼠中，耐热性的提高归因于蒸发散热反应的增强，而不是非蒸发散热的促进或代谢抑制。
