LOCALIZATION AND AMOUNT OF MYOGLOBIN AND MYOGLOBIN MESSENGER-RNA IN RAGGED-RED FIBER OF PATIENTS WITH MITOCHONDRIAL ENCEPHALOMYOPATHY

The localization and amounts of myoglobin (Mb) and Mb mRNA in ragged-r ed fibers (RRF) in skeletal muscle of 6 patients with mitochondrial en cephalomyopathy were examined immunohistochemically and by in situ hyb ridization. The amounts of Mb and Mb mRNA were expressed in terms of o ptical densities (ODs) of Mb immunostaining and Mb mRNA signals. In no natrophic RRF, Mb was predominantly seen in the ragged-red region and Mb mRNA signals were increased throughout the sarcoplasm. The amounts of Mb and Mb mRNA in nonatrophic RRF were greater than those in nonatr ophic non-RRF. In contrast, the localization and amount in atrophic RR F were similar to those in atrophic non-RRF. Thus, Mb synthesis in non atrophic RRF may increase to compensate for mitochondrial dysfunction and to supply sufficient oxygen to mitochondria, but this compensatory function may be impaired in atrophic RRF. (C) 1996 John Wiley & Sons, Inc.