Fig. 5.

Membrane stability in mutant muscle fibers before and after injury. Evans blue dye (EBD) was used to evaluate sarcolemmal integrity within the TA muscles of mice that were uninjured or mice that were injured by high-strain lengthening contractions. A and B: cryosections of TA muscles from EBD-injected DKO mice showing EBD and DAPI before (A) and after (B) injury. Sarcolemmal damage is indicated by the presence of myoplasmic EBD. As shown in C, without injury (black bars) the number of EBD-positive (EBD+) fibers was not significantly different from WT in any of the mutant muscles. All animals showed a significant increase (*) in the number of positively labeled fibers after injury (gray bars), but this increase was significantly higher in the DKO muscles (†) compared with all other groups (P < 0.05; n = 3 for all groups).