INTRODUCTIONPortal hypertension is a common clinical syndromecharacterized by an abnormal increase in portalblood to the systemic circulation, bypassing theliver. Recent studies have reported that humoralsubstances play an important role in thepathogenesis of portal hypertension, either byincreasing vascular resistance at both theintrahepatic and porto-collateral sites or affectingsplanchnic vasodilation with a concomitant increasein parto-collateral blood flow[1-6]