Excitatory effects of 5-hydroxytryptamine, veratridine and phenyl diguanide on sensory ganglion cells of the nodose ganglion of the cat

Abstract

5-hydroxytryptamine (5-HT), phenyl diguanide (PDG) and veratridine, injected into the common carotid artery in doses of 5–10 μg, caused action potentials to be generated in small bundles dissected from the infranodose vagus nerve of cat. These excitatory effects persisted following transection of the supranodose vagus nerve. 5-HT and PDG also produced action potentials in fibers dissected from the supranodose vagus, before and after transection of the cervical vagus nerve; veratridine was not tested on these fibers. Not all infranodose or supranodose fibers were excited by these drugs in the doses used. Susceptibility of the fibers to 5-HT, PDG or veratridine did not appear to be related to the type of sensory modality transmitted by the fibers, as fibers subserving different modalities were excited. Pentobarbital, 1–4 mg/kg injected intravenously, depressed responses to 5-HT (responses that the reflexes produced by 5-HT, PDG and veratridine through an action on the nodose ganglion probably result from direct excitatory effects of these drugs on sensory ganglion cells.