Investigations into the physiological expression of UCP1 and UCP3

Abstract

Previous studies have indicated that acute exercise induces large increases in uncoupling protein 3 in skeletal muscle, whereas endurance training results in marked decreases in skeletal muscle uncoupling protein 3 at both mRNA and protein levels. Using an uncoupling protein 3 specific antibody we confirm that uncoupling protein 3 protein is expressed in rat skeletal muscle mitochondria. In addition, we show that absolute uncoupling protein 3 expression is elevated in gastrocneumis and plantaris muscle homogenates following acute exercise (2 weeks). Furthermore, we show the novel finding that uncoupling protein 3 protein expression per unit mass of mitochondria is increased by acute exercise (2 weeks) in gastrocnemius muscle of mice. We also show that the increase in uncoupling protein 3 protein expression is transient with levels returning to pre-exercise levels 22 hours after the final exercise bout. Acute exercise is shown to have no effect on uncoupling protein 3 protein expression in plantaris, soleus or extensor digitorum longus muscle homogenates. Furthermore, we present novel results illustrating that endurance exercise (17 weeks) results in no significant changes in uncoupling protein 3 protein expression in whole muscle homogenates gastrocnemius, soleius, plantaris or extensor digitorum longus.