In vitro vascular responsiveness to norepinephrine in experimental portal hypertension.

It has been postulated that loss of response to norepinephrine accounts in part for the portal hypertension, systemic hypotension, and generalised vascular dilatation of chronic liver disease. The in vitro vascular responsiveness to norepinephrine was measured in aortic rings and portal veins excised from four different rat models of hepatic disease with and without portal hypertension, hepatocellular damage, and hyperbilirubinemia--the carbon tetrachloride (CCl4) cirrhotic rat with portal hypertension, the five-week chronic bile duct ligated and resected (CBDL) cirrhotic rat with portal hypertension and hyperbilirubinemia, the 10-day partial ligated portal vein (PVL) portal hypertensive rat without hepatocellular damage and hyperbilirubinemia, and the three-day bile duct ligated (ABDL) rat with acute hepatocellular damage and hyperbilirubinemia but without portal hypertension. Sham-treated or operated groups for each model were also prepared. Vascular reactivity of the aortic rings to norepinephrine was potentiated in the three portal hypertensive groups, and attenuated in the model of acute cholestasis. No consistent pattern of response to norepinephrine was evident in the portal veins. Based upon the presented in vitro data and the discussed limitations of an in vitro study, we conclude that it is unlikely that the loss of response to norepinephrine accounts for the portal hypertension, systemic hypotension, and generalised vascular dilatation of chronic liver disease.