ABSTRACT
The objective of the present study was to investigate the effects of eccentric training on the activity of mitochondrial respiratory chain enzymes, oxidative stress, muscle damage, and inflammation of skeletal muscle. Eighteen male mice (CF1) weighing 30-35 g were randomly divided into 3 groups (N = 6): untrained, trained eccentric running (16°; TER), and trained running (0°) (TR), and were submitted to an 8-week training program. TER increased muscle oxidative capacity (succinate dehydrogenase and complexes I and II) in a manner similar to TR, and TER did not decrease oxidative damage (xylenol and creatine phosphate) but increased antioxidant enzyme activity (superoxide dismutase and catalase) similar to TR. Muscle damage (creatine kinase) and inflammation (myeloperoxidase) were not reduced by TER. In conclusion, we suggest that TER improves mitochondrial function but does not reduce oxidative stress, muscle damage, or inflammation induced by eccentric contractions.
Subject(s)
Animals , Male , Mice , Rats , Mitochondria, Muscle/physiology , Muscle, Skeletal/physiology , Oxidative Stress/physiology , Physical Conditioning, Animal/physiology , Creatine Kinase/blood , Lipid Peroxidation/physiology , Mitochondria, Muscle/metabolism , Muscle, Skeletal/metabolism , Oxidation-Reduction , Physical Exertion , Peroxidase/blood , Succinate Dehydrogenase/bloodABSTRACT
In this study, we investigated the possibility that GLUT4 protein concentration and mitochondrial enzyme activity is coregulated by muscle contractile activity. In the first experiment, male rats were trained by treadmill running or swimming for 3 wks and training effects in upper-and hind-limb muscle were investigated. Treadmill training program induced increases of 30% in citrate synthase activity, 51% in hexokinase activity, and 35% in GLUT4 protein concentration in hind-limb soleus muscles without causing training effects in upper-limb epitrochlearis muscles. On the other hand, swimming training program induced increases of 67% in citrate synthase activity, 139% in hexokinase activity, and 89% in GLUT4 protein concentration in epitrochlearis muscle without causing training effects in soleus muscles. These results suggest that muscle contractile activity which raises mitochondrial enzyme activity increases GLUT4 protein concentration in skeletal muscle. In a second set of experiment, we investigated relationship between muscle GLUT4 protein concentration and mitochondrial enzyme activity by use of the various type of rat muscles (soleus, plantaris, red gastrocnemius, white gastrocnemius, epitrochlearis and heart), which possese different contractile activity level. Significant correlation was observed between GLUT4 protein concentration and citrate synthase activity among different muscles (r=0.936) . They suggest that muscle GLUT4 protein concentration and mitochondrial enzyme activity level may be coregulated according to muscle contractile activity level.