Fine structural histochemistry of myosin-ATPase activity in the skeletal muscles of Duchenne muscular dystrophy.

Myosin ATPase activity was fine-structurally examined in various skeletal muscle lesions including atrophy, degenerations, necrosis, "deltashaped subsarcolemmal lesion", and apparently normal fibers from seven patients of Duchenne muscular dystrophy (D M D). The enzyme activity was almost completely lost in the foci of necrosis, and more or less markedly diminished in various kinds of degenerations, while it was well preserved in the apparently normal and simply atrophic fibers. The results suggested that there were two different lesions in wasting of the skeletal muscles in D M D; necrotic process with degenerations in which myosin-ATPase activity was affected and simply atrophic process which had little influence on the enzyme activity. The former lesion might be related with direct or indirect damages such as proteolysis, while the latter seemed to be an expression of basically different process such as disuse or denervation, or a more mild expression basically of the same process ultimately resulting in necrosis.