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Aging-Dependent Regulation of Antioxidant Enzymes and Redox Status in Chronically Loaded Rat Dorsiflexor Muscles

¹ Laboratory of Muscle Biology and Sarcopenia, Division of Exercise Physiology, West Virginia University School of Medicine, Morgantown.
² National Institute for Occupational Safety and Health, Morgantown, West Virginia.

Address correspondence to Stephen E. Alway, PhD, Division of Exercise Physiology, School of Medicine, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506-9227. E-mail: salway{at}hsc.wvu.edu

This study compares changes in the pro-oxidant production and buffering capacity in young and aged skeletal muscle after exposure to chronic repetitive loading (RL). The dorsiflexors from one limb of young and aged rats were loaded 3 times/week for 4.5 weeks using 80 maximal stretch-shortening contractions per session. RL increased H₂O₂ in tibialis anterior muscles of young and aged rats and decreased the ratio of reduced/oxidized glutathione and lipid peroxidation in aged but not young adult animals. Glutathione peroxidase (GPx) activity decreased whereas catalase activity increased with RL in muscles from young and aged rats. RL increased CuZn superoxide disumutase (SOD) and Mn SOD protein concentration and CuZn SOD activity in muscles from young but not aged animals. There were no changes in protein content for GPx-1 and catalase or messenger RNA for any of the enzymes studied. These data show that aging reduces the adaptive capacity of muscles to buffer increased pro-oxidants imposed by chronic RL.

Key Words: Exercise • Oxidative stress • Sarcopenia • Superoxide dismutase