Experimental studies on the humoral and nervous control of the hepatic circulation--effects of epinephrine and nor-epinephrine and of splanchnic nerve stimulation.

Abstract

(1) Hepatic and portal venous blood flows were measured by a electromagnetic flowmeter in dogs for studying the effects of epinephrine and nor-epinephrine and of the greater splanchnic nerve stimulation on the hepatic and portal circulation.(2) Epinephrine and nor-epinephrine administered into the portal vein or hepatic artery caused a decrease in hepatic venous blood flow in spite of a slight increase in arterial pressure, indicating that these catecholamines had vasoconstrictor effects on the hepatic circulation. It was shown that the effects were somewhat greater when they were administered into the hepatic artery than when administered into the portal vein.(3) Administration of epinephrine or nor-epinephrine into the femoral or portal vein caused a decrease in portal venous blood flow associated with an increase in mesenteric vascular resistance (MR) and portal venous vascular resistance of hepatic side (HR). Administration into the femoral vein was followed by a more marked increased of MR than that of HR, however, administration into the portal vein caused a more marked increase of HR than that of MR. These observations suggested that the mechanisms of the decrease in portal venous blood flow by epinephrine and norepinephrine were different according to the route of their administration.(4) The greater splanchnic nerve stimulation caused an arterial pressure rise of diphasic pattern. The first peak of arterial pressure was consistently accompanied by an increase of hepatic venous blood flow and pressure, and the second peak was accompanied by a decrease of hepatic venous blood flow and pressure.(5) By the stimulation of the greater splanchnic nerve portal venous blood flow was increased initially in some cases and decreased subsequently in accordance with the second peak of arterial pressure in all cases. MR and HR were markedly increased with the decrease of portal venous flow, and the changes in MR were greater than those in HR. Therefore, the mechanism of the decrease in portal venous blood flow induced by the stimulation of the greater splanchnic nerve is considered to be reflected by the changes in the mesenteric blood vessels and to be similar to that induced by the administration of epinephrine or nor-epinephrine into the femoral vein.