The Hepatic Response to Glucagon in the Unanesthetized Dog1

Intravenous administration of crystalline glucagon 02 mg.⁄kg. was used to study hepatic glycogenolysis and associated events in the unanesthetized dog. An increase in hepatic blood flow and hepatic glucose output regularly occurred following glucagon administration. Approximately 9.6 gm, of glucose were released from the liver during the first hour after a single intravenous injection of glucagon; this represents a net increase over control values of about 6 gm. Depletion of glycogen stores induced by fasting was associated with a decreased or absent response of hepatic blood flow and hepatic glucose output to glucagon. Hepatic uptake of alpha amino nitrogen increased after glucagoninduced glycogenolysis; this increase began promptly and reached a maximum about 45 minutes after glucagon administration. These changes were interperted as reflecting increased gluconeogenesis following depletion of liver glycogen stores. GLYCOGENOLYSIS may be induced in the liver in a controlled fashion by means of glucagon administration.