An Effect of Insulin on Production of Glucose during Hepatic Glycogenolysis

Abstract

IN earlier work the effect of a prolonged intravenous infusion of insulin on the utilization and production of circulating glucose was investigated in the trained, unanæsthetized normal dog in the post-absorptive state with the aid of intravenously administered ¹⁴C-glucose¹. The plasma glucose concentration and specific activity were determined at frequent intervals, and from these values were calculated the rates of production of hepatic ¹²C -glucose and total glucose-uptake by the tissues². It was shown that insulin brought about a hypoglycæmia primarily by increasing the uptake of glucose by the tissues. The rate of production of hepatic ¹²C-glucose, although temporarily somewhat reduced soon after the insulin infusion was begun, usually rose during the course of the infusion to higher than normal levels, but not sufficiently to restore the plasma glucose concentration to its pre-insulin level. When the insulin infusion was stopped, there was a marked further increase in the production of hepatic ¹²C-glucose which restored the plasma glucose concentration to its control-level. From these findings it was concluded that, during the period of insulin infusion, the production of ¹²C-glucose was restrained in spite of severe hypoglycæmia¹.