STIMULATION BY CARBACHOL OF MUCUS GEL THICKNESS IN RAT STOMACH INVOLVES NITRIC-OXIDE

Instillation of carbachol (150 mu g/kg) into the gastric lumen in vivo increased the thickness of the mucus gel layer. Intravenous administr ation of the inhibitor of nitric oxide (NO) synthase, N-G-nitro-L-argi nine methyl ester (L-NAME, 0.4-5 mg/kg) dose-dependently reduced the s timulation by carbachol, the half-maximal inhibitory dose being 0.57 m g/kg. This effect of L-NAME was abolished by administration of L-argin ine but not by D-arginine (100 mg/kg i.v.). By contrast L-NAME (5 mg/k g) did not reduce the stimulatory effect of intraluminal 16,16-dimethy l prostaglandin E(2) (50 mu g/kg) on mucus gel thickness. These result s implicate NO in the cholinergic activation of gastric mucus secretio n.