SKELETAL-MUSCLE AND LIVER GLUTATHIONE HOMEOSTASIS IN RESPONSE TO TRAINING, EXERCISE, AND IMMOBILIZATION

Female beagle dogs were treadmill trained 40 km/day at 5.5-6.8 km/h, 15% upgrade, 5 days/wk for 55 wk. With training, hepatic and red gastrocnemius (RG) total glutathione increased, glutathione peroxidase (GPX) and glutathione reductase (GRD) increased in all the leg muscles studied, and hepatic glutathione S-transferase (GST) activity increased. Joint immobilization (11 wk) did not affect GPX, GRD, and GST of RG, but total glutathione decreased. Male Han Wistar rats were treadmill trained 2 h/day at 2.1 km/h, 5 days/wk for 8 wk. With training, hepatic total glutathione and leg muscle GPX increased but GRD of RG decreased, perhaps because of an increased muscle flavoprotein breakdown during exhaustive training. gamma-Glutamyl transpeptidase was higher in the trained leg muscles. Exhaustive exercise decreased muscle gamma-glutamyl transpeptidase of only control leg muscle, depleted muscle (lesser extent in trained rats) and liver total glutathione of both groups, decreased GRD only in untrained RG, and increased hepatic GST. Endurance training elevated the antioxidant and detoxicant status of muscle and liver, respectively.