Defect in glucose metabolism in aortic tissue from alloxan diabetic rabbits

Abstract

The glucose, raffinose, and inulin spaces in tubular sections of rabbit thoracic aorta were compared. The glucose space exceeded the raffinose and inulin spaces in tissue from normal rabbits. Insulin in vitro did not alter the relative sizes of the glucose and raffinose spaces in tissue from normal animals. In aortic tissue from alloxan diabetic rabbits, the glucose space exceeded the raffinose space, and the ratio of these spaces was unaltered by insulin in vitro. Hexokinase activity was significantly reduced in tissue from diabetic rabbits. Aortic hexokinase activity was inhibited by glucose 6-phosphate, and no activity resembling hepatic glucokinase was detected. Phosphohexose isomerase and phosphohexokinase activities were not significantly different in normal and diabetic tissues. Transport into cells does not appear to be a rate-limiting step in glucose utilization by aortic tissue from normal or diabetic rabbits incubated in vitro. The impaired glucose utilization previously observed in tissue from diabetic rabbits appears to be related to decreased glucose phosphorylation which may be localized at the hexokinase reaction.