Effect of downhill running on muscular DNA damage in rats

Abstract

  The aim of this study was to determine oxidative stress in skeletal muscle and examine the effect of exercise on tissue oxidative stress. Male wistar rats (8 weeks old, n = 30) were used in this study. Rats performed an intermittent downhill running exercise (DH) at -17 degree incline, 25 m/min for a total of 90 min (5-min bouts separated by 2-min rest, 18 bouts). Blood lactate level slightly increased after the DH (p < 0.05). Plasma CK increased 2-3 times immediately after DH and did not return to the pre- value in 2-day recovery period (p < 0.01). Muscle glycogen decreased by 39.2% in soleus (SOL) whereas there was no difference in medial gastrocnemius white portion (GMW) and red portion (GMR) (p < 0.05). Muscular DNA damage (8-OHdG/dG) increased at 24 h after DH in both GMW and GMR, but not in SOL (p < 0.05). Lipid hydroperoxide content increased at 24 h after DH in SOL, but not in GMW and GMR (p < 0.05). SOD activity increased at 24 h after DH in all muscles. Glutathione peroxidase activity increased immediately after DH in GMW. However, glutathione reductase activity reduced at 24 h and 48 h after DH in GMW. These results indicate the effect of exercise on muscular oxidative stress suggesting involvement of massive mechanical stress in enlargement of oxidative stress in fast-twitch fibers.