Comparative changes in antioxidant enzymes and oxidative stress in cardiac, fast twitch and slow twitch skeletal muscles following endurance exercise training.

The aim of this study was to evaluate exercise-induced transcriptional and protein responses of heart, soleus (slow oxidative), and plantaris (fast glycolytic) muscle in response to ten days of endurance exercise training. Four-month old female Sprague-Dawley rats were assigned to either a sedentary (SED) or endurance exercise-training (EXE) group (n=8 per group). The heart, plantaris, and soleus were excised and used for biochemical analyses. Our results show that heart and plantaris from EXE animals had higher protein levels of superoxide dismutase 2 (SOD2) compared to SED animals (P<0.05). Also, the protein levels of catalase were higher in plantaris of EXE animals compared to SED animals (P<0.05). No significant differences existed for 4 hydroxynonenal (4HNE) conjugated proteins (index of oxidative damage) in the three tissues between SED and EXE animals. mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) were higher in plantaris of EXE animals compared to SED animals (P<0.05), and mRNA levels of estrogen-related receptor alpha (ERRα) were lower in the heart of EXE animals compared to SED animals. In conclusion, heart and plantaris are responsive to ten days of treadmill training, while greater exercise intensities or durations may be needed to elicit alterations in soleus.