Cholinergic and adrenergic innervations of the muscularis mucosae in guinea-pig esophagus.

Transmural stimulation of the isolated muscularis mucosae from guinea-pig esophagus induced contraction, which was completely inhibited by the pretreatment with atropine (o.1 microM) or tetrodotoxin (0.1 microM). In the presence of atropine, muscularis mucosae which contracted with histamine 2 microM slightly relaxed by transmural stimulation in 8 out of 20 preparations. The relaxation was inhibited by an addition of guanethidine (10 microM) or propranolol (2 microM). The vagal stimulation or an addition of nicotine also induced contractions of muscularis mucosae which were blocked by hexamethonium (20-50 microM), tetrodotoxin (0.1 microM) or atropine (0.1 microM). Using the formaldehydeinduced fluorescence technique, a few catecholamine-containing nerve fibres were observed in muscularis mucosae or in the wall of small blood vessels of guinea-pig esophagus. From these results, it is suggested that muscularis mucosae in guinea-pig esophagus is innervated mostly with excitatory cholinergic nerves, and sparsely with inhibitory adrenergic nerves, but not with non-adrenergic and non-cholinergic nerves.