Abstract
Transmission through the cat superior cervical ganglion was studied by recording the response of the nictitating membrane to both pre- and postganglionic cervical sympathetic nerve stimulation. The intra-arterial injection of central depressant drugs to the ganglion through the lingual artery depressed transmission through the ganglion. The central depressant drugs tested were (in decreasing order of activity): amylobarbitone, pentobarbitone, carbromal, benactyzine, mephobarbitone, hydroxyzine, phenobarbitone, azacyclonol, methylpentynol carbamate, paraldehyde, phenytoin, mephenesin, chlorbutol, troxidone, methylpentynol and barbitone. All were weaker ganglion-blocking agents than tetraethylammonium. The intra-arterial injection of the central stimulant drugs leptazol, bemegride, amiphenazole and 5-(1,3-dimethylbut-2-enyl)-5-ethylbarbituric acid (McN 481) also depressed ganglionic transmission. Leptazol or bemegride did not antagonize the ganglion-blocking action of amylobarbitone or troxidone. The intra-arterial injection of pecazine and perphenazine, and the intravenous injection of barbitone, benactyzine, azacyclonol, hydroxyzine, mephenesin, methylpentynol and paraldehyde impaired the response of the nictitating membrane to both post- and preganglionic stimulation. The implications of these observations are discussed.