Effects of insulin and alloxan diabetes on glucose metabolism in rabbit aortic tissue

Abstract

Tubular sections of rabbit thoracic aorta, free of adventitia, were incubated in vitro with uniformly labeled glucose-C¹⁴ in Krebs bicarbonate buffer. Lactate production accounted for the major portion of glucose uptake, oxidation to CO₂ and incorporation of glucose carbon into glycogen and total lipid, for progressively smaller fractions. Insulin in vitro had no effect on glucose uptake or lactate production by tissue from normal or alloxan diabetic rabbits. Glucose uptake, lactate production, and the incorporation of glucose carbon in CO₂, glycogen, and total lipid were markedly decreased by alloxan diabetes, and were not increased in insulin in vivo until after 18 hr of therapy. Marginal but consistent increases in the incorporation of carbon 14 into total lipid occurred in tissue from normal and diabetic rabbits with insulin in vitro; similar increases in the incorporation of glucose carbon into glycogen were observed. The bulk of the cellular components of the intima and media of the rabbit aorta appear to be insensitive to a direct or immediate insulin effect, but their glucose utilization is impaired by the diabetic state.