Regulation of blood glucose concentration: response of liver to glucose administration

¹ Departments of Biochemistry, Medicine, and Surgery, School of Medicine, Western Reserve University, Cleveland, Ohio

Hepatic glucose output has been determined during the infusion of glucose in gradually increasing quantities into unanesthetized dogs with cannulas inserted in their aortas, hepatic veins and portal veins. Profound changes in hepatic response to the infusions were consequent to differences in the composition of the diets ingested by the dogs in the days prior to these experiments. Infusion of glucose into dogs maintained on a high protein diet resulted in a rise in blood glucose concentration, with a cessation of net hepatic glucose production only at hyperglycemic levels. In contrast, in carbohydrate-fed dogs the blood glucose concentration increased very little on glucose infusion, and there was a net uptake of glucose by the liver. Under these conditions the liver appears to play a dominant role in the regulation of the constancy of the blood glucose concentration, and the regulating mechanism appears to be particularly sensitive to small changes in glucose concentration.