The actions of histamine in cat and rabbit superior cervical ganglia.

Depolarization of the cat superior cervical ganglion (SCG) evoked by histamine was antagonized by mepyramine. Histamine-induced depolarization, indicated by changes in the negative and positive afterpotentials of ganglionic action potentials, was decreased by pretreatment with aminophylline. In the cat SCG, histamine evoked stimulus bound decremental oscillatory potentials (SBDOP). In the rabbit SCG, only depolarization and no SBDOP were observed after the administration of histamine. Histamine-induced SBDOP were increased by isoprenaline and decreased by Leu-enkephalin pretreatment. Our results indicate that histamine evokes depolarization and an increase in excitability of the cat SCG which seems to be mediated by H1-receptors.