Similar in vitro fatigue patterns of normal and BIO 40.54 dystrophic hamster extensor digitorum longus muscle.

Fatigue patterns of normal and BIO 40.54 dystrophic hamster extensor digitorum longus (EDL) muscles were studied in vitro (22°C) at 60, 120, 170, and 320 days of age. The diseased muscle showed similar rates of tension decline compared to their normal counterparts when stimulated intermittently (a twitch or tetanus every 90 s) for 3 h or in rapid succession (1-s tetanus every 5 s) until tetanic tension was decreased 50%. Electron microscopic observations revealed a subsarcolemmal accumulation of enlarged mitochondria in dystrophic muscle compared to normal EDL. These results suggest that the availability of adenosine triphosphate for cross-bridge formation may not be impaired in dystrophic hamster muscles.