Abstract
Since 1956, Takasaki et al. (1956, 1957) have studied the mechanism of the reflex apnea caused by nicotine and diphenhydramine in cats or rabbits and concluded that it may be due to the “pulmonary respiratory chemoreflex” described by Dawes et al. (1954). Further, the blocking effects of several drugs on the reflex were reported (Nakano et al., 1957).In the present paper, the blocking effects of several drugs on the respiratory and circulatory reflexes in dogs were examined.