Relationship of hepatic potassium efflux to phosphorylase activation induced by glucagon

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Abstract
Hepatic biopsies were obtained from intact, anesthetized dogs before and at 6- to 15-sec intervals after intravenous administration of glucagon. Simultaneously, blood samples were taken from the hepatic vein at 3-sec intervals and the plasma potassium concentration measured. The time course of phosphorylase activation in hepatic biopsies was observed and compared with the time course of potassium release into the hepatic efflux. Measurements were made in normothermic (38 C) animals and in animals subjected to hypothermia (21–25 C). Maximum phosphorylase activation was reached in an average of 79 sec in normothermia and in 144 sec in hypothermia. Maximum hepatic venous potassium concentrations were observed in an average of 41 sec in normothermia and 108 sec in hypothermia. The increased hepatic potassium release which preceded the activation of phosphorylase suggested that electrolyte shifts may be involved in the primary action of glucagon upon hepatic glycogenolytic systems.