Pharmacological studies of doxapram

Certain pharmacological properties of doxapram (DOP; 1-ethyl-(2-morpholinoethyl)-3, 3-diphenyl-2-pyrrolidinon hydrochloride hydrate) were studied in various preparations. Results were obtained as follows: The transient effects such as respiratory stimulation, rise in blood pressure and increase in coronary blood flow were observed with i. v. administration of DOP or dimorpholamine in anesthetized dogs. In the isolated heart of the guinea-pig, the coronary flow was not affected by DOP but both the heart rate and the cardiac contractile force were slightly decreased by DOP. The same results were obtained in the isolated atria of the guinea-pig. The contractions induced by direct (muscle) or indirect (nerve) electrical stimulations in the isolated diaphragm of the rat, were increased by DOP (>10-4g/ml) or dimorpholamine (>10-5g/ml). The isolated trachea of the guinea-pig was relaxed by DOP (10-4 g/ml), while it was contracted by dimorpholamine (10-7_??_2×10-4g/ml). Neither the secretory volume nor the components of the gastric juice were affected by s. c. administration of DOP or dimorpholamine in the Shay rat. The rectal temp. of rabbits was not affected by DOP. Inhibitory effects of DOP and dimorpholamine (both>3×10-4g/ml) on the oxygen consumption of the cortex slice of the guinea-pig were observed.