Superoxide dismutases of muscle in mitochondrial encephalomyopathies

Muscle Nerve. 1995 Nov;18(11):1265-71. doi: 10.1002/mus.880181108.


Immunohistochemical analyses were made of the superoxide dismutases (Mn-SOD and Cu/Zn-SOD) in biopsied muscles from 7 patients with mitochondrial encephalomyopathies that included mitochondrial encephalomyopathy, lactic acidosis and strokelike episodes (MELAS), and chronic progressive external ophthalmoplegia (CPEO). Mn-SOD mainly was present in the subsarcolemmal region, but it also was found in a coarsely granular, reticular, or diffuse pattern of staining within the muscle fibers. These Mn-SOD-positive fibers corresponded almost completely to the ragged-red fibers. The immunoreaction for Cu/Zn-SOD was weakly positive in some of the muscle fibers positive for Mn-SOD. In CPEO, Mn-SOD-positive fibers predominantly showed decreased cytochrome c oxidase (COX) activity. In MELAS, Mn-SOD-positive fibers tended to be stained deeply for COX although a few were COX-negative. These findings suggest that Mn-SOD-positive fibers can be used to make a differential diagnosis between CPEO and MELAS and that in mitochondrial encephalomyopathies Mn-SOD in the ragged-red fibers may protect against oxidative stress.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Child
  • Electron Transport Complex IV / metabolism
  • Female
  • Humans
  • Immunohistochemistry / methods
  • MELAS Syndrome / enzymology*
  • Male
  • Middle Aged
  • Muscle Fibers, Skeletal / enzymology
  • Muscles / enzymology*
  • Ophthalmoplegia, Chronic Progressive External / enzymology*
  • Staining and Labeling
  • Superoxide Dismutase / metabolism*


  • Superoxide Dismutase
  • Electron Transport Complex IV