Altered expression and insulin-induced trafficking of Na+, K+-ATPase in rat skeletal muscle: effects of high fat diet and exercise

Skeletal muscle Na+-K+-ATPase plays a central role in the clearance of K+ from the extracellular fluid, therefore maintaining blood [K+]. Na+-K+-ATPase activity in peripheral tissue is impaired in insulin resistant states. We determined effects of high-fat diet (HFD) and exercise training (ET) on skeletal muscle Na+-K+-ATPase subunit expression and insulin-stimulated translocation. Skeletal muscle expression of Na+-K+-ATPase isoforms and transcription factor DNA binding was determined before or after 5 days of swim training in Wistar rats fed chow or HFD for 4 or 12 wk. Skeletal muscle insulin resistance was observed after 12 wk of HFD. Na+-K+-ATPase α1-subunit protein expression was increased 1.6-fold (P < 0.05), whereas α2- and β1-subunits and protein expression were decreased twofold (P < 0.01) in parallel with decrease in plasma membrane Na+-K+-ATPase activity after 4 wk of HFD. Exercise training restored α1-, α2-, and β1-subunit expression and Na+-K+-ATPase activity to control levels and reduced β2-s...