Cholinergic effects on human gastric motility

Background-Cholinergic regulation of chronotropic (frequency) and inotropic (force) aspects of antral contractility and how these impact on gastric em ptying are not well delineated. Aims-To determine the effects of cholinergi c stimulation and inhibition on myoelectric, contractile, and emptying para meters of gastric motility. Methods-Ten normal subjects underwent three studies each, using simultaneou s electrogastrography (EGG), antroduodenal manometry, and gastric emptying with dynamic antral scintigraphy (DAS). After 30 minutes of baseline fastin g manometry and EGG, subjects received saline intravenously, atropine (0.6 mg then 0.25 mg/hour intravenously), or bethanechol (5 mg subcutaneously). This was followed by another 30 minutes' recording and by three hours of po stprandial recording after ingestion of a technetium-99m labelled solid mea l. Results-During fasting, atropine decreased, whereas bethanechol increased, the antral manometric motility index and EGG power. Postprandially, atropin e decreased the amplitude of antral contractions by DAS, decreased the post prandial antral manometric motility index, and slowed gastric emptying. Atr opine caused a slight increase in postprandial frequency of antral contract ions by DAS and gastric myoelectrical activity by EGG. Bethanechol slightly increased the amplitude, but slightly decreased the frequency of antral co ntractions by DAS and decreased the frequency of gastric myoelectrical acti vity by EGG, with no significant increase in the motility index or gastric emptying. Conclusions-Cholinergic antagonism with atropine reduces antral contractili ty and slows gastric emptying. Cholinergic stimulation with bethanechol inc reases antral contractility, but decreases the frequency of antral contract ions, without altering the antral motility index or gastric emptying.