Matsunaga Satoshi, Inashima Shuichiro, Yamada Takashi, Watanabe Hitoshi, Hazama Toshio, Wada Masanobu
Institute of Health and Sport Science, Osaka City University, Sugimoto, Osaka-shi, 558-8585 Osaka, Japan.
Pflugers Arch. 2003 Jun;446(3):394-9. doi: 10.1007/s00424-003-1040-0. Epub 2003 Apr 9.
Ca(2+)-ATPase and Ca(2+)-pumping activities by the sarcoplasmic reticulum (SR) and the amounts of sulphydryl and carbonyl groups contained in the SR protein were examined in the superficial portion of the gastrocnemius and vastus lateralis muscles of the rat after high-intensity treadmill runs to exhaustion (average time to exhaustion: 363 s). Exercise at the estimated maximal O(2) uptake rate led to 16% and 34% reductions in SR Ca(2+)-ATPase activity ( P<0.01) and Ca(2+) uptake rate ( P<0.01), respectively. The carbonyl group content in SR Ca(2+)-ATPase, assessed by immunoblotting analysis, was increased by 127% after exercise ( P<0.05), while the sulphydryl group content in the purified SR fraction was unchanged. Consistent with the unchanged sulphydryl group content, treatment of homogenates with dithiothreitol, the disulphide reducing reagent, failed to restore the decreased catalytic activity of SR Ca(2+)-ATPase in exercised muscles. These findings show clearly that high-intensity, exhaustive exercise causes oxidation of SR Ca(2+)-ATPase protein and suggest that oxidation of amino acids, other than cysteine, in the SR Ca(2+)-ATPase may be responsible, at least in part, for exercise-induced inactivation of this enzyme.
在大鼠进行高强度跑步机跑至力竭（平均力竭时间：363秒）后，检测了腓肠肌和股外侧肌表层中肌浆网（SR）的Ca(2 +)-ATP酶活性、Ca(2 +)泵浦活性以及SR蛋白中巯基和羰基的含量。以估计的最大摄氧量速率进行运动，导致SR的Ca(2 +)-ATP酶活性（P<0.01）和Ca(2 +)摄取速率（P<0.01）分别降低了16%和34%。通过免疫印迹分析评估，运动后SR的Ca(2 +)-ATP酶中的羰基含量增加了127%（P<0.05），而纯化的SR组分中的巯基含量未发生变化。与巯基含量不变一致，用二硫苏糖醇（一种二硫化物还原剂）处理匀浆未能恢复运动肌肉中SR的Ca(2 +)-ATP酶降低的催化活性。这些发现清楚地表明，高强度的力竭运动导致SR的Ca(2 +)-ATP酶蛋白氧化，并表明SR的Ca(2 +)-ATP酶中除半胱氨酸外的氨基酸氧化可能至少部分地导致了运动诱导的该酶失活。
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