EFFECT OF ECCENTRIC EXERCISE ON OXIDATIVE DNA DAMAGE IN RAT SKELETAL MUSCLES / 体力科学

ABSTRACT

Vigorous exercise induces a muscular oxidative DNA damage due to increased generation of reactive oxygen species (ROS). However, it is not fully understood how ROS induces muscular DNA damage after vigorous exercise. This study examined the relation between muscle damage and the muscular oxidative DNA damage in the gastrocnemius (GAS) and soleus (SOL) muscles of rats after eccentric exercise. All rats performed level (0 degree ; L) or downhill (—17 degrees ; DH) running on a treadmill for 1h at 20 m/min. In GAS, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) content, an indicator of DNA damage, showed a 2-3 times increase from that in the control after DH running, but not after L running (P<0.05). The 8-OHdG content was positively correlated with lipid peroxide (TBARS) (r=0.61, P<0.01). Moreover, plasma creatine kinase (CK) activity was positively correlated with 8-OHdG content (r=0.68, P<0.05) and TBARS (r=0.64, P<0.05) after both DH and L running. The 8-OHdG content in SOL showed larger changes than that in GAS during the 1-week recovery period following DH running. These findings show that the exercise-induced muscular DNA damage is reflected in plasma CK activity. Consequently, it is suggested that changes in plasma CK activity can also be useful as an indicator of muscular DNA damage.