[Radioimmunoassay and immunohistochemical study of myoglobin in neuromuscular diseases].

The localization of myoglobin (Mb) in skeletal muscle was studied by an immunoperoxidase technique and the serum Mb was measured by radioimmunoassay in 38 patients with various neuromuscular diseases. The positive rate of Mb immunoreactivity was significantly different between the muscular disorders and the motor neuron diseases. It was 44-77% in Duchenne dystrophy and polymyositis, and was 90-99% in motor neuron diseases. Serum myoglobin was markedly elevated in all the patients with muscular disorders, especially Duchenne dystrophy and polymyositis at the level of 329-330 ng/ml. It was found to increase slightly or normally in motor neuron diseases. Marked decrease or loss of Mb immunoreactivity was observed in muscle fibers with hyaline degeneration or floccular necrosis. It suggested that the elevation of serum Mb in patients with these diseases was ascribable to its leak through the injured plasma membrane of diseased muscle fibers or release from the necrotic muscle fibers.