The vasodilator role of endogenous nitric oxide in the rat gastric microcirculation.

The role of endogenous nitric oxide (NO) in the gastric microcirculation of the anaesthetised rat was investigated using the selective inhibitor of NO synthesis, NG-monomethyl-L-arginine (L-NMMA). L-NMMA (12.5-50 mg kg-1 i.v.) induced a dose-dependent increase in systemic arterial blood pressure (BP) and fall in resting gastric mucosal blood flow (MBF), as estimated by hydrogen-gas clearance. The effects of L-NMMA on BP and MBF were abolished by concurrent administration of L-arginine. The enantiomer D-NMMA had no effect on resting BP or MBF. These findings indicate that endogenous NO, derived from L-arginine, plays a local vasodilator role in the gastric mucosal microvasculature.