Identification of thermo-receptor and elucidation of the functional mechanism

草履虫细胞对从培养温度下降的温度做出反应，并短暂地使膜去极化，从而引发游动方向的变化。我们发现，当细胞对温度下降有反应时，细胞内Ca^<2+>瞬间升高。Ca^<2+>的增加局限于细胞前部，对应于对温度下降敏感的部分。结果表明，Ca^<2+>的增加是由外部Ca^<2+>的流入引起的。一些似乎抑制前列腺素（PG）合成的化学物质也抑制草履虫对温度下降的反应。另一方面，当一些PG作用于细胞时，细胞对温度下降的反应恢复了。草履虫细胞对PG敏感，当作用于细胞前部时表现出短暂的反应。这些结果提示热接受可能与前列腺素受体有一定的关系。这种关系的细节必须进一步研究。采用胞内Ca^<2+>测定大鼠肥大细胞系RBL-2H3对温度下降的响应。当外部培养基中加入ATP时，细胞开始对温度下降做出反应，细胞内Ca^<2+>出现短暂升高。Ca^<2+>的增加是由内部Ca^<2+>的释放引起的。药理分析表明，ATP受体对温度下降具有敏感性。ATP受体的激活机制有待在分子水平上进一步阐明。

Paramecium cells respond to a temperature drop from the culture temperature and transiently depolarize the membrane, which triggers the directional changes in the swimming. We found that when the cells respond to the temperature drop, the intracellular Ca^<2+> transiently increased. The Ca^<2+> increase was restricted to the anterior part of the cell, corresponding to the sensitive part to the temperature drop. It was shown that the Ca^<2+> increase was caused by an influx of external Ca^<2+>.Some chemicals which seem to inhibit prostaglandin (PG) synthesis of Paramecium also inhibited the response to the temperature drop. On the other hand, when some PG were applied to the cell, the response to the temperature drop was recovered. The Paramecium cell has a sensitiviy to PG and showed a transient response when applied to the anterior part of the cell. These results suggest the possibility that the thermo-reception has some relationship to the prostaglandin receptor. Details of the relationship must be studied further.Rat mast cell line (RBL-2H3) was tested for the response to the temperature drop by the measurements of intracellular Ca^<2+>. When ATP was added in the external medium, the cells became to respond to the temperarure drop, and showed a transient increase in the intracellular Ca^<2+>. The Ca^<2+> increase was caused by the liberation from internal Ca^<2+> stores. Pharmacological analyzes showed that the ATP receptor has the sensitivity to the temperature drop. Activation mechanism of the ATP receptor remains to be elucidated further in the molecular level.