Changes in the forms of the components of the troponin complex during regeneration of injured skeletal muscle.

Using the immunoperoxidase technique, antibodies to the fast components of the troponin complex stained all regenerating cells after localized alcohol injury to rat skeletal muscle. Antibodies to slow troponin components stained only some of these cells. About 6 weeks after injury with the nerve intact, the fast and slow forms of the troponin components were located in different cells. During the later stages of regeneration, staining for myosin ATPase correlated with the staining with antibodies to fast and slow troponin components. A similar staining pattern was also observed in the early stages of regeneration of muscle denervated at the time of injury. In this case, antibodies to fast skeletal muscle troponin components continued to stain all the cells 10 weeks after injury. Injured denervated muscle cells stained equally dark by myosin ATPase after preincubation at pH 9.4 over this period. None of the regenerating myotubes in denervated muscle stained for myosin ATPase after preincubation at pH 4.3.