Dissociation of potassium and glucose efflux in isolated perfused rat liver

Abstract

The dissociation of K and glucose movement during glucagon-induced glycogenolysis was studied in the isolated rat liver utilizing a small volume perfusion apparatus. When glucagon was added to a preparation assumed to be insulin deficient and depleted of a fraction of liver K+ after 60-min. perfusion, a marked outflow of glucose occurred in the absence of an early efflux of liver K+. However, when glucagon was administered to a liver pretreated with insulin to restore intracellular K+, a large efflux of K occurred during the onset of glycogenolysis. The administration of insulin after glucagon effected a recovery of K previously lost from the liver and reduced the outflow of glucose. These findings indicate that a fraction of K dependent upon insulin for retention within the liver moves independently of glucose and suggests that the early release of K during glucagon-induced glycogenolysis involves an inhibition of the effect of insulin on maintaining K within the cell.