[On the thermal alteration in the receptors of the vas deferens].

This study was made to clarify chemical properties of a-receptor and acetylcholine receptor. The isolated was deferenses of rats and guinea pigs were heated in organ bath, and the receptor activity was examined. 1) The heat treatments of the was deferenses of a guinea pig (46 • Ž or 47 • Ž, 20 min) and of a rat (45 • Ž or 46 • Ž, 20min) produced no change in the response to K.C1. On the other hand, the responses to noradrenaline and acetylcholine were depressed significantly. 2) The reversible denaturations of the acetylcholine receptor of a guineas pig was deferens by heat treatment were observed. 3) In the guinea pig was deferens received heat treatment the response to acetylcholine was significantly larger than the responses to noradrenaline. 4) The a-receptor of the rat was deferens was heat-labile and the thermal alteration produced irreversible changes of the receptor activity. 5) In the rat was deferens, the heat treatment caused a decrease in the maximum response of the dose response curve of noradrenaline without the parallel shift.