Muscle-contractile activity increases fatty acid metabolism and transport and FAT/CD36

We have examined whether 1) fatty acid (FA) uptake, 2) FA transporter expre ssion, and 3) FA metabolism are increased when the oxidative capacity of sk eletal muscle is increased. The oxidative capacities of red and white tibia lis anterior and extensor digitorum longus muscles were increased via chron ic stimulation (10 Hz, 24 h/day for 7 days). The contralateral muscles serv ed as-controls. After 7 days of increased muscle activity 1) palmitate upta ke by giant sarcolemmal vesicles was increased twofold (P < 0.05), 2) the e xpression of FA translocase (FAT)/CD36 was increased at both the mRNA (3.2- to 10-fold) and protein (3.4-fold) levels, and 3) palmitate oxidation and esterification into triacylglycerols and phospholipids were increased 1.5-, 2.7-, and 1.7-fold, respectively (P < 0.05). These data show that when the oxidative capacity of muscle is increased, there is a;parallel increase in the rate of FA transport and FA transporters at the sarcolemmal membrane, which is associated with the enhanced expression of the membrane: transport er FAT/CD36.