Activation of pyruvate dehydrogenase in adipose tissue: role of insulin and pyruvate.

Abstract

This study was designed to investigate the relation between activation of pyruvate dehydrogenase in white adipose tissue and the intracellular pyruvate content. The intracellular pyruvate level was approximately 8 nmol/g wet weight when adipose tissue was incubated up to 20 min with fructose (1 mg/ml) as substrate. The addition of insulin to the incubation medium resulted in a 1.5-fold increase in the active form of pyruvate dehydrogenase after 20 min incubation without raising the intracellular pyruvate level at earlier time periods. Intracellular pyruvate contents were increased 1.5-fold by TMPD (75 μM), but in this case there was no concomitant activation of pyruvate dehydrogenase. We conclude that the insulin-induced activation of pyruvate dehydrogenase is caused by mechanism(s) in addition to an elevation of pyruvate concentration.