Hypokinesia Causes Oxidative Damage and Mitochondrial DNA Deletion in Rat Skeletal Muscle

The present study was conducted to determine effects of oxidative stress on mitochondrial genome caused by disuse atrophy of skeletal muscles by hindlimbs suspension. We used rats as subjects, and produced hypokinesia by hindlimbs (tail) suspension. With electron microscopy, confirming previous results, we found mitochondrial swelling, accompanied by blurred matrix changes in the soleus muscle. Surprisingly, in these muscles, we were able to detect two types of large-scale deletions (about 3.9 and 5.2 kb) of mitochondrial DNA (mtDNA) by the polymerase chain reaction. Our study showed that hypokinesia for two weeks caused not only oxidative damage to the histology of skeletal muscular mitochondoria and but also deletion of mtDNA. Situated close to the energy-generating system, mtDNA is susceptible to oxidative stress and is likely to generate mutations.