The Effect of Glucagon on Hepatosplanchnic Hemodynamics, Functional Capacity, and Metabolism of the Liver in Gats

Abstract

Abstract Glucagon in doses of 0.1, 0.5, and 5.0, μg/kg/min infused i.v. caused a marked increase in portal blood flow (up to 300 %) due to a dose‐dependent increase in conductance‐of gastrointestinal vessels, and an increase in the conductance in the hepatic low pressure vessels (up to 30 %), but only slight changes in hepatic arterial conductance and flow. Glucagon caused a decrease in the hepatic extraction of Indocyanine Green (ICG), no change in ICG clearance, an increase in bile acid secretion, but only minor changes in bile flow and ICG excretion. The splanchnic glucose output and ketone production were increased by glucagon. The cytoplasmic redox level was not affected, but the mitochondrial redox level was changed to a more oxidized state together with a 30 % rise in hepatic oxygen consumption and a correlated increase in ethanol elimination. These last effects were not dose‐dependent. It is concluded that the marked changes in splanchnic hemodynamics found during glucagon infusions, are not a consequence of the metabolic effects of the hormone on the liver, but rather a direct effect of non‐physiological concentrations of glucagon on gastrointestinal vessels. The results exclude any marked influence of glucagon on the intrahepatic distribution of blood flow and functional liver mass.