Force and stiffness of old dystrophic (mdx) mouse skeletal muscles.

It has recently been suggested, based on studies of tissue pathology, that the limb muscles of old mdx mice may be a good model for the muscular changes seen in human Duchenne muscular dystrophy. To test this hypothesis, we measured force and stiffness of soleus and extensor digitorum longus (EDL) muscles of old (20-21 months) mdx mice and age-matched controls. The mdx and control muscles generated similar twitch, tetanic, and eccentric forces. They were also equally stiff. The results show that the mechanics of aged mdx limb muscles differ greatly from Duchenne muscular dystrophy in humans, and disagree with the hypothesis.