ENHANCEMENT OF INHIBITORY AND EXCITATORY EFFECTS OF CATECHOLAMINES

¹ Department of Physiology and Pharmacology, Graduate School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

Enhancement of both excitatory and inhibitory responses to epinephrine, l-norepinephrine and isoproterenol was demonstrated with cocaine, ephedrine, 2-amino-4-(diethyl-aminoethylanlino) - 6, 7 - diphenvlpteridine (McN-537), and 1 - 2 - imino - 3,4 - dimethyl- 5 - phenylthiazolidine hydrochloride (McN-X-l90). Excitatory responses studied included blood pressure and contraction of the nictitating membrane of the cat; the inhibitory responses were blood pressure and uterine relaxation in the cat, and bronechodilatation in the dog. None of the four compounds produced enhancement of the inhibitory effects of the catecholamines on the isolated guinea pig traeheal chain or rabbit ileum. Consideration is given to possible mechanisms involved in producing the observed enhancement of the effects of the catecholamines in situ.