Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle

Benziane B, Widegren U, Pirkmajer S, Henriksson J, Stepto NK, Chibalin AV. Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle. Am J Physiol Endocrinol Metab 301: E456-E466, 2011. First published June 7, 2011; doi:10.1152/ajpendo.00533.2010.-Phospholemman (PLM, FXYD1) is a partner protein and regulator of the Na+-K+-ATPase (Na+-K+ pump). We explored the impact of acute and short-term training exercise on PLM physiology in human skeletal muscle. A group of moderately trained males (n = 8) performed a 1-h acute bout of exercise by utilizing a one-legged cycling protocol. Muscle biopsies were taken from vastus lateralis at 0 and 63 min (non-exercised leg) and 30 and 60 min (exercised leg). In a group of sedentary males (n = 9), we determined the effect of a 10-day intense aerobic cycle training on Na+-K+-ATPase subunit expression, PLM phosphorylation, and total PLM expression as well as PLM phosphorylation in response to acute exercise (1 h at similar to 72% (V) over dot(O2peak)). Biopsies were taken at rest, immediately following, and 3 h after an acute exercise bout before and at the conclusion of the 10-day training study. PLM phosphorylation was increased both at Ser(63) and Ser(68) immediately after acute exercise (75%, P < 0.05, and 30%, P < 0.05, respectively). Short-term training had no adaptive effect on PLM phosphorylation at Ser(63) and Ser(68), nor was the total amount of PLM altered posttraining. The protein expressions of alpha(1-), alpha(2-),and beta(1)-subunits of Na+-K+-ATPase were increased after training (113%, P < 0.05, 49%, P < 0.05, and 27%, P < 0.05, respectively). Whereas an acute bout of exercise increased the phosphorylation of PKC alpha/beta II on Thr(638/641) pre- and posttraining, phosphorylation of PKC zeta/lambda on Thr(403/410) was increased in response to acute exercise only after the 10-day training. In conclusion, we show that only acute exercise, and not short-term training, increases phosphorylation of PLM on Ser63 and Ser68, and data from one-legged cycling indicate that this effect of exercise on PLM phosphorylation is not due to systemic factors. Our results provide evidence that phosphorylation of PLM may play a role in the acute regulation of the Na+-K+-ATPase response to exercise.