Studies of the effects and modes of action of autonomic drugs on portal hemodynamics

The effect of epinephrine, pitressin, and Arfonad on portal pressure has been studied in dogs with special emphasis on the role of the liver in determining pressure changes. The use of dogs with portacaval transposition allowed portal pressures to be studied with the exclusion of any hepatic vascular factor. With this preparation, vena caval pressures were brought under the influence of changes in hepatic vascular resistance. By this technique, the action of epinephrine in raising portal pressure primarily seemed to be due to an increase in hepatic vascular resistance. The action of pitressin in reducing portal pressure appeared to be due to a combination of reduction of splanchnic blood flow and a reduction in hepatic vascular resistance. The effect of Arfonad in lowering portal pressure appeared to be unrelated to any changes in the liver itself. © 1962