Effect of AMPK activation on monocarboxylate transporter (MCT)1 and MCT4 in denervated muscle.

It is now evident that exercise training leads to increases in monocarboxylate transporter (MCT)1 and MCT4, but little is known about the mechanisms of coupling muscle contraction with these changes. The aim of this study was to investigate the effect of 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) induced activation of AMP-activated protein kinase (AMPK) on MCT1, MCT4, and GLUT4 in denervated muscle. Protein levels of MCT4 and GLUT4 after 10 days of denervation were significantly decreased in mice gastrocnemius muscle, while MCT1 protein levels were not altered. AICAR treatment for 10 days significantly increased MCT4, and GLUT4 protein levels in innervated muscle as shown in previous studies. We found that the MCT1 protein level was also increased in AICAR treated innervated muscle. AICAR treatment prevented the decline in MCT4 and GLUT4 protein levels in denervated muscle. Thus, the current study suggests that MCT1 and MCT4 protein expression in muscles, as well as GLUT4, may be regulated by AMPK-mediated signal pathways, and AMPK activation can prevent denervation-induced decline in MCT4 protein.