The figure shows that the uptake of the fluorescent dye procion orange as a marker of membrane damage is not different in the stretch (+) vs nonstretch (-) condition for the young control,mdx, or mdx:utrn-/- mice aged 9-12 d, but is different for mdx-old mice aged ~110 d. *Greater than control (P < 0.05). †Stretch condition greater than nonstretch condition (P < 0.05). EDL muscles were subjected to a stretch injury protocol in vitro (⁹). These data suggest that dystrophic membranes of early maturing dystrophic mice may not be as susceptible to membrane damage as older dystrophic mice. (Reprinted from Grange, R.W., T.G. Gainer, K.M. Marschner, R.J. Talmadge, and J.T. Stull. Fasttwitch skeletal muscles of dystrophic mouse pups are resistant to injury from acute mechanical stress. Am. J. Physiol. Cell Physiol. 283: C1090-C1101, 2002 (4). Copyright ® 2002 The American Physiological Society. Used with permission.)