Can high-intensity training protect against exercise-induced oxidation of sarcoplasmic reticulum Ca^<2+>-ATPase?

点击翻译按钮获取中文摘要

The cytosolic free Ca^<2+> concentration ([Ca^<2+>]_f) plays a central role in muscle contraction and relaxation. In skeletal muscle, the regulation of [Ca^<2+>]f is accomplished primarily by the kinetics of Ca^<2+> release and uptake by the sarcoplasmic reticulum (SR). Although the fatigue process involves multiple factors and mechanisms, recent evidence implies that functional impairment of the SR is a major contributor to muscle fatigue. We previously observed that a loss of SR function may be attributed, at least partly, to protein oxidation by reactive oxygen species, generation of which is elevated during muscle contraction. However, no published data presently exists that examines whether high-intensity training could protect against deteriorating SR Ca^<2+>2+-ATPase activity and oxidation of Ca^<2+>-ATPase with acute exercise. The purpose of this study was to investigate the influence of high-intensity training and/or a single bout exercise on SR function and oxidation of Ca^<2+>-ATPase.Our in vitro measures on the superficial region of the vastus lateralis revealed that 8 weeks of running training elicited an increase in SR Ca^<2+>-uptake rate without concomitant changes in SR Ca^<2+>-ATPase activity and Ca^<2+>-release rate. These results implicate training-induced decreases in Ca^<2+> efflux from the SR lumen. Despite the extension of the run time to exhaustion, no differences existed in exhaustive exercise-induced reductions in SR Ca^<2+>-uptake ability and increases in carbonyls contained in Ca^<2+>-ATPase between trained and untrained muscles. These findings suggest that high-intensity training might protect Ca^<2+>-ATPase enzyme against oxidative modification that occurs during vigorous muscle contraction.