Oxidation of Specifically Labeled Glucose by Rat Adipose Tissue. ∗

Summary

The in vitro oxidation of glucose-1-C¹⁴ and glucose-6-C¹⁴ by liver and adipose tissues of the rat has been studied. 1) In adipose tissues from normal animals, the yield of C¹⁴O₂ from glucose-6-C¹⁴ averaged about 18% of that obtained from glucose-1-C¹⁴, indicating the extensive occurrence of extraglycolytic catabolism of glucose. Liver slices from these animals showed a corresponding C¹⁴O₂ ratio of 68%. 2) Starvation (from 18 to 192 hours) depressed the C¹⁴O₂ yield from glucose-1-C¹⁴ without affecting the yield from glucose-6-C¹⁴ in adipose tissues. Similar changes were seen in adipose tissues from alloxan diabetic and cortisone-treated animals. In all these cases, the C-6/C-1 ratio was significantly elevated above normal. In the liver, prolonged starvation (96 to 192 hours) lowered the C¹⁴O₂ yields from both substrates without affecting their ratio. Marked depressions of C¹⁴O₂ yields were seen in diabetic livers, but no changes in C-6/C-1 ratio were evident in these, as well as in livers