THE INFLUENCE OF HORMONAL FACTORS AND OF DIET UPON HEPATIC GLUCOSE-6-PHOSPHATASE ACTIVITY

Abstract

It is well known that the hepatic utilization of glucose is impaired in alloxan diabetes, and evidence exists which suggests that in diabetes the conversion of glucose to glucose-6-phosphate is impaired (1). It has been suggested that the enzyme hexokinase is less active in the diabetic animal (2). The presence in liver of a specific glucose-6-phosphatase has been dem- onstrated by Swanson (3) and by de Duve and coworkers (4, 5). Pre- sumably this enzyme is responsible for contributing free glucose to the blood from the liver glycogen pool and from other precursors of glucose-6- phosphate. Since the net rate of formation of glucose-6-phosphate depends upon the relative velocities of the hexokinase and glucose-6-phosphatase reactions, it appeared possible that an increased activity of glucoseS- phosphatase in the liver might be responsible for decreased net utilization of glucose by this tissue, even if the hexokinase reaction were functioning normally. In this paper is presented evidence that there is greatly in- creased activity of glucose-6-phosphatase in the livers of alloxan-diabetic rats, and that this increased activity appears to be related rather specifi- cally to the diabetic state.