Effects of metal ions and sulfhydryl inhibitors on glucose metabolism by adipose tissue

Abstract

Effect of divalent metal ions and sulfhydryl compounds on the metabolism of glucose by rat adipose tissue (epididymal fat pad) has been studied with carbon 14-labeled glucose. Co and Ni ions enhanced glucose uptake, its oxidation to carbon dioxide and incorporation into fat-pad lipids, thus simulating the action of insulin. In addition Ni ion increased glucose incorporation into glycogen. Co did not have this effect In vitro addition of insulin antiserum did not influence the action of Co, as was the case with insulin. Co, like insulin, enhanced the oxidation of C-1 glucose, but not of C-6 glucose. Sulfhydryl inhibitors varied in their effect; at certain concentrations p-hydroxymercuribenzoate, arsenite, and Cd increased the oxidation of C-l glucose to carbon dioxide; however, at higher concentrations they either inhibited or did not affect glucose metabolism. N-ethylmaleimide (NEM) and iodoacetate, at all concentrations tested, inhibited or had no effect on the metabolism of glucose. Prior treatment of the fat pad with NEM effectively blocked both insulin and Co action on the fat pad,.