Effects of emphysema and training on glutathione oxidation in the hamster diaphragm

Loading of skeletal muscles is associated with increased generation of oxid ants, which in turn may impair muscle contractility. We investigated whethe r the load on the hamster diaphragm imposed by pulmonary emphysema induces oxidative stress, as indicated by glutathione oxidation, and whether the de gree of glutathione oxidation is correlated with contractility of the diaph ragm. In addition, the effect of 12 wk of treadmill exercise training on co ntractility and glutathione content in the normal (NH) and emphysematous ha mster (EH) diaphragm was investigated. Training started 6 mo after elastase instillation. After the training period, glutathione content and in vitro contractility of the diaphragm were determined. Twitch force and maximal te tanic force were significantly reduced (by similar to 30 and similar to 15% , respectively) in EH compared with NH. In sedentary hamsters, the GSSG-to- GSH ratio was significantly elevated in the EH compared with the NH diaphra gm. A significant inverse correlation was found between GSSG-to-GSH ratio a nd twitch force in the diaphragm (P < 0.01). Training improved maximal teta nic force and reduced fatigability of the EH diaphragm but did not alter it s glutathione content. In conclusion, 1) emphysema induces oxidative stress in the diaphragm, 2) training improves the contractile properties of the E H diaphragm, and 3) this improvement is not accompanied by changes in gluta thione redox status.