Stimulation of Pyruvate Dehydrogenase Activity in Intact Rat Adipocytes by Insulin Mediator from Rat Skeletal Muscle*
- 1 March 1985
- journal article
- research article
- Published by The Endocrine Society in Endocrinology
- Vol. 116 (3) , 1011-1016
- https://doi.org/10.1210/endo-116-3-1011
Abstract
The effects of insulin and insulin mediator from skeletal muscle of control and insulin-treated rats were compared on intact adipocyte pyruvate dehydrogenase. Increasing insulin concentrations stimulated pyruvate dehydrogenase activity in a biphasic manner with a maximal stimulation at 100 .mu.U/ml which was 2-fold and sustained for up to 1 h. The mediators from control or insulin-treated rats also stimulated pyruvate dehydrogenase of intact adipocytes with the effect increasing in a linear manner up to a 1:10 final dilution. The latter mediator had twice the stimulatory activity as the former. Peak stimulation of pyruvate dehydrogenase by the mediators was attained within 10 min of incubation. The enzyme activity rapidly declined thereafter, with the stimulation by mediator from control rats decreasing at a faster rate than that due to mediator from insulin-treated rats. The stimulatory effect of the mediators on adipocyte pyruvate dehydrogenase was found to be additive to that of insulin. Insulin mediator can act on mitochondrial pyruvate dehydrogenase of intact, functional adipocytes as it does on isolated, intact or broken mitochondria. The mediator is degraded by the adipocyte. The amount of mediator generated by insulin probably limits the stimulation of pyruvate dehydrogenase by insulin. The physiological relevance of this putative insulin second messenger was further substantiated.This publication has 18 references indexed in Scilit:
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