VASODILATOR RESPONSES TO NITRIC-OXIDE ARE ENHANCED IN MESENTERIC-ARTERIES OF PORTAL HYPERTENSIVE RATS

Nitric oxide (NO) is discussed as a mediator of the splanchnic hyperae mia in portal hypertension. We assessed the vasorelaxation by the NO-d ependent vasodilator acetylcholine, the NO donor 3-morpholino-sydnonim ine (SIN-1) and forskolin, a stimulator of the adenylate cyclase pathw ay in potassium-preconstricted isolated perfused mesenteric arteries o f portal vein-ligated and sham-operated rats. Dilator responses to ace tylcholine and SIN-1 were significantly enhanced in vessels of portal vein-ligated rats as compared to sham-operated rats, whereas no differ ence was found in forskolin-induced vasodilatation. This suggests enha nced reactivity of the vasculature to NO in experimental portal hypert ension.