Activation of 5-HT3 receptor subtypes causes rapid excitation of rabbit parasympathetic neurones

Intracellular recordings were made from parasympathetic neurones of the rabbit vesical pelvic ganglia maintained in vitro. 5-Hydroxytryptamine (5-HT) caused a membrane depolarization which was antagonized by ICS 205-930 ([3 alpha-tropanyl]-1H-indole-3-carboxylic acid ester) but not by methysergide. ICS 205-930 caused a parallel shift to the right of the dose-response curve for 5-HT. These results suggest that the 5-HT3 receptor is involved in the membrane depolarization.