The effect of endurance training on glutathione (GSH) status and antioxidant enzyme system was investigated in skeletal muscle, heart, and liver of female Sprague-Dawley rats pair fed an isocaloric diet. Ten weeks of treadmill training (25 ml/min, 10% grade for 2 h/day, 5 days/wk) increased citrate synthase activity in the deep vastus lateralis (DVL) and soleus muscles by 79 and 39%, respectively (P < 0.01), but not in the heart or liver. In DVL, GSH content was increased 33% (P < 0.05) with training, accompanied by a 64% (P < 0.05) increase in glutamate content but no change in cysteine. Trained rats showed a 62 and 27% higher GSH peroxidase (GPX) and superoxide dismutase (SOD) activity, respectively (P < 0.05), in DVL compared with control rats. In contrast, GSH content and glutathione reductase (GR) activity in soleus declined with training (P < 0.05), whereas activities of GPX and SOD remained unchanged. Training did not alter GSH status in the liver or plasma but significantly decreased the GSH-to-glutathione disulfide ratio in the heart. In addition, GR activity in the liver and GSH sulfur- transferase activity in the heart and DVL were significantly lower in the trained vs. control rats. DVL muscle had threefold higher γ-glutamyl- transpeptidase activity compared with other tissues; however, no significant alteration was observed in the activity of γ-glutamyltranspeptidase or γ- glutamylcysteine synthetase in the liver, heart, or skeletal muscle. These data indicate that endurance training can cause tissue- and muscle fiber- specific adaptation of antioxidant systems and that GSH homeostasis in extrahepatic tissues may be determined by utilization and uptake of GSH via the γ-glutamyl cycle.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|Issue number||1 41-1|
|State||Published - 1997|
- antioxidant enzymes
- oxidative enzymes
- skeletal muscle