Inhibition of the expression of pathology in dystrophic mouse leg muscles by immobilization.

Normal and dystrophic calf muscles of young mice of the Bar Harbor strain Re 129 were immobilized with the foot in an extended position. Two weeks after treatment the muscles were examined morphologically. Immobilization resulted in the inhibition of fibre necrosis and, consequently, of regeneration. In the contralateral leg these processes progressed unhampered and gave rise to typical dystrophic features. As a result of treatment there was some muscle fibre atrophy. The results clearly indicate that injury of muscle fibres is of a true "myogenic" nature, and that mechanical, i.e. contractive, activity is an important factor inducing damage to the sarcolemma of dystrophic muscle fibres.