Abstract

The aim of the study was twofold: 1) to examine the exercise training-induced changes in oxidative and antioxidant enzyme activity in skeletal muscle of old rats; and 2) to critically analyze the relationship between oxidative and antioxidant enzyme activities in skeletal muscle in both trained and untrained senescent rats. Female Fischer-344 rats (24-mo) were divided into 1) exercised trained (ET) and 2) sedentary (S). ET rats performed a 10-wk training program of treadmill exercise (60 min, 5 d/wk). Training significantly improved VO2max in the ET rats. Further, the ET group had significantly elevated activities of succinate dehydrogenase (SDH) in the soleus and red gastrocnemius (RG) muscles as well as greater 3-hydroxyacyl-CoA dehydrogenase (HADH) activity in the RG compared to the S group. However, training did not alter HADH activity within the white gastrocnemius (WG) or soleus muscles. Activity of the antioxidant enzyme, glutathione peroxidase (GPX) was higher in the soleus and RG in ET rats than in S rats; in contrast, training did not alter GPX activity in the WG. Finally, the correlation coefficients between SDH and GPX activities (combined ET and S groups) for the RG, WG, and soleus muscles were r=.73, .17 and .36, respectively. We conclude that endurance training in senescent rats elevates both SDH and GPX activities in hindlimb muscles containing a high percentage of type I or type IIa fibers; however, endurance training does not result in increases in oxidative and antioxidant enzyme activities in aged rats. Verf.-Ref.