Shido O, Sakurada S, Sugimoto N, Furuyama F, Nagasaka T
Department of Physiology, School of Medicine, Faculty of Medicine, Kanazawa University, Japan.
Am J Physiol. 1998 Mar;274(3):R604-9. doi: 10.1152/ajpregu.1998.274.3.R604.
The FOK is an inbred rat strain with a genotypic adaptation to hot environments. The present study compared the thermoeffector thresholds and preferred ambient temperatures (Tpref) of the FOK rat with those of other rat strains. Male FOK, WKAH, and Donryu rats were used. First, they were loosely restrained and placed individually in a metabolic chamber with an ambient temperature of 26.0 degrees C. Their hypothalamic temperature (T(hy)), tail skin temperature (Tsk), and heat production (M) were measured. After thermal equilibrium had been attained, the rats were gradually warmed and then cooled using an intravenous thermode. The threshold T(hy) values for tail skin vasodilation and cold-induced thermogenesis were defined as the points at which sharp increases in Tsk and M occurred, respectively. The two thresholds of the FOK rat were lower than those of the WKAH and Donryu rats. In a second set of experiments, the FOK and WKAH rats were placed individually in a thermocline. Their intra-abdominal temperatures (T(ab)) were measured by a biotelemetry system, and the rats' Tpref values were estimated with the thermal gradient. Mean T(ab) and Tpref over a 24-h period for the FOK rat were significantly lower than those of the WKAH rat. The results suggest that in the FOK rat the control ranges of autonomic and behavioral thermoregulation are lower than those of the other rat strains examined. This contributes to the maintenance of core temperature at low levels.
FOK是一种对炎热环境具有基因型适应性的近交系大鼠。本研究比较了FOK大鼠与其他大鼠品系的温度效应器阈值和偏好环境温度（Tpref）。使用了雄性FOK、WKAH和唐育大鼠。首先，将它们轻度束缚并单独置于环境温度为26.0℃的代谢室中。测量它们的下丘脑温度（T(hy)）、尾皮肤温度（Tsk）和产热（M）。达到热平衡后，使用静脉内热电极逐渐加热然后冷却大鼠。尾皮肤血管舒张和冷诱导产热的阈值T(hy)值分别定义为Tsk和M急剧增加的点。FOK大鼠的这两个阈值低于WKAH和唐育大鼠。在第二组实验中，将FOK和WKAH大鼠分别置于温度梯度仪中。通过生物遥测系统测量它们的腹腔内温度（T(ab)），并利用热梯度估计大鼠的Tpref值。FOK大鼠在24小时内的平均T(ab)和Tpref显著低于WKAH大鼠。结果表明，FOK大鼠自主神经和行为性体温调节的控制范围低于所检测的其他大鼠品系。这有助于将核心温度维持在较低水平。
