Glycogen and histological changes in muscle grafts of rats during fasting or exercise.

The metabolic integrity of skeletal muscle grafts must be restored, along with histological regeneration, if muscle transplants are to be clinically acceptable. The purpose of the present study was to contrast glycogen changes in muscle grafts after exercise or fasting with those in normal muscles. The extensor digitorum longus (EDL) and soleus (SOL) muscles were switched to each other's muscle bed in one leg of male Sprague-Dawley rats. Fifty days later, some of the rats were fasted for 48 h and sacrificed either immediately or after 4 h of refeeding. Other rats were run on a treadmill for 30 min ( 1 mi/h (0.447 m/s)) and sacrificed either immediately or after 4 h of resting. Muscle grafts and contralateral normal muscles of these experimental, as well as control animals (neither exercised nor fasted), were removed for determination of glycogen concentration. The results show that glycogen in muscle grafts, as in normal muscles, decreases with exercise or fasting. After 4 h of rest or refeeding, glycogen is restored in both grafts and normal muscles. It is concluded, therefore, that muscle grafts are metabolically active and that their pattern of utilization and restoration of glycogen in response to physiological events, such as exercise or fasting, is similar to that of normal muscle.U