Role of nitric oxide in the control of the gastric motility within the nucleus ambiguus of rats.

This study aims to investigate whether exogenous nitric oxide (NO) plays a role in controlling gastric motility within the nucleus ambiguus (NA). Experiments were performed on male Wistar rats anaesthetized with chloral hydrate. A latex balloon, connected to a pressure transducer, was inserted into the pylorus through the fundus for continuous recording of the change of gastric smooth muscle contractile curves. Microinjection of the NO-donor sodium nitroprusside (SNP; 5 nmol) or L-arginine (L-Arg; 5 nmol) into the NA significantly inhibited gastric motility, whereas the treatment of NO-synthase inhibitor N-nitro-L-arginine methylester (L-NAME) increased gastric motility remarkably. The negative effect of SNP or L-Arg on gastric motility was abolished by bilateral subdiaphragmatic vagotomy as well as by intravenous injection of ganglionic blocker, hexamethonium bromide (Hb). These results demonstrated that NO inhibited gastric motility by activating the cholinergic preganglionic neurons in the NA and through the mediation of vagus nerves.