Nitric oxide is involved in the mediation of gastric blood flow and tissue oxygenation

Endogenous nitric oxide which is enzymatically formed by endothelial cells from L-arginine has been implicated in the control of gastrointestinal circulation. Its role in the mediation of gastric tissue oxygenation has not been studied. We investigated the role of NO in the control of gastric blood flow and oxygen uptake. In anesthetized dogs, total gastric blood flow, gastric mucosal blood flow, systemic arterial and portal venous pressures and the arteriovenous oxygen content difference were studied. From these measurements gastric vascular resistance and oxygen consumption were calculated. Administration of NG-nitro-L-arginine (L-NNA) induced gastric tissue ischemia and hypoxia. Both, systemic arterial pressure and gastric vascular resistance were increased. Above hemodynamic and metabolic effects of L-NNA were significantly attenuated when administration of L-NNA was combined with L-arginine. Our findings suggest that endogenous NO is a tonic vasodilator modulating gastric blood flow and oxygen uptake through influence on the gastric microcirculatory structures responsible for vascular resistance and the nutrient circulation.