INVESTIGATION OF SYMPATHETIC ACTIVITY RESULTING FROM A DOSE OF ACETYLCHOLINE PRODUCING A HYPERTENSIVE RESPONSE

¹ Departments of Pharmacology and Anesthesiology and the Wiseman Animal Research Laboratories, Ohio, State University College of Medicine, Columbus, Ohio

Acetylcholine given i.v. in a dose of 1 mg/kg induced both pre-and postganglionic asynchronous firing in the superior cervical nerve of the cat anesthetized with pentobarbital and treated with 1 mg/kg of atropine sulfate. The origin of this activity is assumed to arise from the chemoreceptors. Pre-and postganglionic activity and contraction of the nictitating membrane after injections of acetylcholine were reduced or abolished by N, N-diisopropyl-N'-isoamyl-N'-diethylaminoethylurea (P-286) or by sectioning the preganglionic fibers. However, contraction of the nictitating membrane and the postganglionic action potential induced by electrical stimulation of the preganglionic nerve were not significantly altered by this compound. Thus, the nicotinic response to 1 mg/kg of acetylcholine (i.v.) in the intact animal was produced without direct stimulation of sympathetic ganglia and was antagonized by P-286 in the absence of ganglioplegia.