The effects of intravenous, intra-arterial and intra-portal administration of prostaglandin E₁ (PGE₁) on hepatic artery (HA) and portal vein (PV) flows were studied in anaestetized dogs. Intravenous administration of PGE₁ (1 µg/kg) produced an increase in HA flow, PV flow and PV pressure concomitant with a significant decrease in systemic arterial pressure, whereas, the injection of the same dose of PGE₁ into the portal vein caused essentially no change in PV flow, PV pressure, or systemic arterial pressure. Intra-arterial injection of PGE₁ increased HA flow and decreased its resistance, with no change in systemic arterial pressure. The hepatic arterial effect of PGE₁ was dose-dependent and was not abolished after β-adrenoceρtor blockade by propranolol 1 mg/kg i.v. It is concluded that PGE, possesses a direct dilator action on HA and indirectly influences the portal venous circulation.

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