The expression of dystrophin and alpha 1-syntrophin during skeletal muscleregeneration

The expression of dystrophin and alpha1-syntrophin in rat tibialis anterior muscles were evaluated during a cycle of regeneration after myonecrosis in duced by the injection of cardiotoxin. Immunohistochemical studies were per formed in cryosections of muscles on days 1, 3, 5, 7, 10, 14, 21 and 28 aft er injection of cardiotoxin. Western blot analysis was also examined in mus cle on days 1, 3, 5, 7, 10, 14, 21 and 28. In immunohistochemical studies, dystrophin was stained weakly at the sarcolemma of some regenerating muscle fibers on day 3, and by day 10 it was stained strongly on almost all regen erating muscle fibers. alpha1-syntrophin was stained weakly at the sarcolem ma of some regenerating fibers on day 5, and by day 14 it was detected on a ll regenerating muscle fibers. In Western blot analysis, dystrophin (DYS1) and alpha1-syntrophin (alpha 1S) were completely absent on day 1. Re-expres sion of DYS1 and alpha 1S was visible by day 5 and accelerated thereafter. The Western blots of DYS1 and alpha 1S were densitometrically analyzed on e ach day. The protein levels on each day were converted to the percentage of the protein level on day 28, which was taken as 100%. From the sequential line based on these data, the following results were obtained on the chrono logical course of DYS1 and alpha 1S. DYS1: 25% of the protein level on day 28 was reached by 3.5 days, 50% was reached by 5.3 days, and 90% was reache d by 6.9 days. alpha 1S: 25% of the protein level on day 28 was reached by 4.6 days, 50% was reached by 6.0 days, and 90% was reached by 12.5 days. In this study, DYS1 regenerated earlier than alpha 1S at the sarcolemma of re generating muscle fibers.