Production of Glucose by the Liver during Hyperglycæmia

Abstract

THE effect of hyperglycæmia on hepatic glucose output has been studied employing an isotope dilution technique. Glucose labelled with carbon-14, of the same specific activity as the blood glucose, was injected in amounts sufficient to produce hyperglycæmia. The selection of the appropriate specific activity for this glucose ‘load’ was made easier by a procedure in which an infusion of labelled glucose (in ‘weightless’ amount) was continued throughout the experiment. During such an experiment the blood glucose specific activity remains relatively constant so long as the flow of unlabelled glucose from the liver continues at a uniform rate. On the other hand, the specific activity of the blood glucose rises if the flow of unlabelled glucose from the liver stops or decreases¹. The present technique avoids the misleading values for plasma glucose specific activity which might result from slow mixing of injected unlabelled glucose with a labelled body glucose pool¹.