Abstract
In a previous paper, it was reported that doxapram (DOP) has a stimulating effect on the central nervous system in mice, rats, rabbits and dogs. As a follow up study, peripheral pharmacological effects of DOP were examined. In the isolated phrenic nerve-diaphragm preparation of the rat, DOP increased muscle contractions elicited by electrical stimulation both directly and indirectly. Systemic administration of DOP (1 ?? 10 mg/kg i.v.) did not affect on the neuro-muscular transmission in sciatic nerve-gastrocnemius muscle preparation of the rat. On isolated smooth muscle preparations, such as ileum, taenia coli, colon and vas deferens in guinea-pigs and uterus in non-pregnant rats, DOP showed inhibitory effects in concentrations as high as 10-5 g/ml. Spontaneous intestinal movement in anesthetized rabbits was also temporarily inhibited after DOP administration (10 mg/kg i.v.). DOP facilitated spontaneous movement of an isolated strip of smooth muscle from the uterus of a pregnant rat, but had no effect on the movement of an intact pregnant uterus in situ.
