ROLE OF PROSTACYCLIN IN HEMODYNAMIC-ALTERATIONS IN CONSCIOUS RATS WITH EXTRAHEPATIC OR INTRAHEPATIC PORTAL-HYPERTENSION

Although prostaglandins are thought to be involved in the hyperdynamic circulation of portal hypertension, the role of this substance has no t been elucidated. Dose-response curves, the hemodynamic effects of pr ostacyclin (20 mug/kg) and its inhibitor indomethacin and measurements of plasma and urinary levels of 6-keto-prostaglandin F1alpha were com pared in three groups of six rats each: normal, with portal vein steno sis and with secondary biliary cirrhosis. Plasma and urinary levels of 6-keto-prostaglandin F1alpha were higher in rats with portal vein ste nosis and cirrhotic rats than in normal rats. Dose-response curves sho wed similar maximal decreases in arterial pressure in the three groups , whereas the maximal increase in portal pressure was less marked in c irrhotic rats than in normal rats and rats with portal vein stenosis. In normal rats, prostacyclin increased cardiac output by 21% and porta l pressure by 41%. Similar increases were observed in rats with portal vein stenosis. In contrast, prostacyclin did not affect cardiac outpu t and portal pressure in cirrhotic rats. Indomethacin induced a more m arked vasoconstrictive effect in normal rats than in cirrhotic rats. T his study shows that prostacyclin plays a role in the hemodynamic alte rations in portal hypertension. Moreover, the hyporeactivity observed in cirrhotic rats suggests that prostacyclin plays a major role in the circulatory changes of portal hypertension due to chronic liver disea se.