DTT recovers SR Ca2+-ATPase activity in rat skeletal muscle after high-intensity exercise, suggesting oxidation of critical sulfhydryl groups contributes to muscular fatigue.
Suggests reversible oxidation contributes to post-exercise SR Ca2+-ATPase impairment in rats; leaves open translation to human fatigue mechanisms.
Although the precise mechanisms underlying the dysfunction of sarcoplasmic reticulum (SR) that occurs during skeletal muscle fatigue remain obscure, it has been hypothesized that it may be attributable to oxidation of critical sulfhydryl groups residing in SR Ca2+-ATPase protein by endogenously produced reactive oxygen species. In order to test this hypothesis, SR Ca2+-ATPase activities in the absence or presence of the disulfide reducing agent, dithiothreitol (DTT), were examined in muscle homogenates of the soleus muscles (SQL) and the superficial portions of the vastus lateralis muscles (VS) from the rat subjected to exhaustive running at 50 m/min on a 10% grade. Immediately after exercise, the catalytic activity of SR Ca2+-ATPase was significantly depressed in VS, but not in SQL. The loss of SR Ca2+-ATPase activity observed in VS was fully recovered after treatment with DTT (1 mM) . These recovery effects of a potent disulfide reducing agent suggest that important proteins of SR Ca2+-ATPase may be oxidized during high-intensity exercise and that the onset of muscular fatigue may be delayed by the improved function of the cellular antioxidant
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Tsuchimochi et al. (2001) studied this question.
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