Effect of starvation on muscle glucose metabolism: studies with the isolated perfused rat hindquarter

Studies in man and experimental animals suggest that the metabolism of glucose by skeletal muscle is depressed during starvation. To investigate the basis for this, the effect of starvation on the uptake and disposition of glucose in skeletal muscle was studied in the isolated perfused rat hindquarter. In contrast to earlier work carried out in heart, neither glucose uptake, whether stimulated by insulin or exercise, nor glycolysis were depressed by 48 hr of starvation or by perfusion of the hindquarter with acetoacetate, palmitate, or octanoate. Glucose oxidation, assessed from the oxidation of 1-[14C]lactate, was depressed by approximately 75% in starved rats and by 30% in fed rats perfused with acetoacetate. Exercise increased lactate oxidation 10-fold in both fed and starved rats; however, the relative difference between the groups persisted. In general, changes in lactate oxidation were paralleled by changes in the activity of pyruvate dehycrogenase (active form). The data suggest that glucose metabolism in skeletal muscle is inhibited during starvation at the step of pyruvate oxidation and that this inhibition persists during exercise. The also suggest that the diminution of glucose uptake that occurs in skeletal muscle of intact organisms during starvation may not be related to the presence of high concentrations of free fatty acids and ketone bodies.