Effect of Adrenal Steroids on Glucose Kinetics in Normal and Diabetic Dogs

Abstract

The rates of endogenous glucose production, utilization, the amount of the intermixing glucose ("pool") and the apparent distribution space were measured in conscious, trained normal and depancreatized dogs by the method of successive measured injections of tracer. During the intravenous infusion of hydrocortisone or methylprednisolone both the rates of glucose production and utilization fell in normal dogs. Since the same effect was obtained during the infusion of hydrocortisone in depancreatized dogs this effect of adrenal steroids does not seem to be due to an extra release of insulin. In normal dogs, daily injections of 4 mg/kg of methylprednisolone for 1 week significantly increased the rates of glucose production and utilization and also the amount of intermixing glucose and the apparent glucose space, without any signficant change in the concentration of glucose in the blood plasma. Prolongation of methylprednisolone treatment for a 2nd week caused a further increase in all 4 parameters again with no change in plasma glucose level. The intravenous infusion of glucose was found to diminish the rate of endogenous glucose production to the same degree before as after 1 week of methylprednisolone treatment. In diabetic dogs deprived of insulin, 2 daily injections of methylprednisolone increased the rate of glucose production and the plasma concentration but not the apparent distribution space of glucose. These experiments indicate that in dogs the homeostasis of plasma glucose level is maintained in spite of markedly increased gluconeogenesis if pancreatic function is unimpaired.