Neural and hormonal control of pyloric sphincter function

Recent manometric studies suggest that the pylorus functions in conjunction with the stomach and duodenum to regulate gastric emptying of both solids and liquids. The opening of the pylorus is controlled intramurally by contractions in the antrum and either Immorally or neurally by the presence of food or acid in the duodenum. Vagal excitation of the pylorus is mediated by both cholinergic and non-cholinergic, non-adrenergic (NANC) (possibly enkephalinergic) pathways, whereas vagal relaxation is mediated by a NANC pathway with vasointestinal polypeptide (VIP) as the possible neurotransmitter. Sympathetic excitation of the pylorus is mediated by postganglionic cholinergic fibres and by beta-receptor acetylcholine release, whereas sympathetic inhibition is mediated by both alpha- and beta-receptors. Cholecystokinin administered in physiologic doses induces phasic contractions of the pylorus by a direct action and tonic contractions via a non-cholinergic pathway. Finally, disordered neural and hormonal control of the pylorus may result in disturbed pyloric activity, as seen in diabetic gastropareses and in hypertrophic pyloric stenosis.