[Na+ + K+] Mg2+-ATPase of muscle plasma membranes in Duchenne muscular dystrophy.

The activity of [Na+ + K+] Mg2+-ATPase of muscle surface membrane was investigated in 20 cases of the Duchenne type of progressive muscular dystrophy; it was found to be diminished and to have a changed reactivity to ouabain. There was nothing like it in cases of limb-girdle dystrophy and neurogenic muscular atrophies investigated for the purpose of comparisons, whereas in some cases of myotonic dystrophy and myotonia congenita the activity of the ATPase was indeed depressed, but the response to ouabain invariably remained normal.