Variability of mitochondrial cytochemistry in human neuromuscular diseases

This study describes mitochondrial cytochemistry with reference to cytochrome c oxidase and NADH oxidase activities as well as calcium localization at subcellular level in a variety of human mitochondrial disorders. The enzyme activities, calcium homeostasis, and myofibrillary architecture were retained in the lipid storage myopathies with carnitine and carnitine palmityl transferase deficiency. The loss of enzyme reaction, excessive Ca++ deposit, and myonecrosis were the features of the group comprised of a variety of disorders with mitochondrial pathology (Kearns-Sayre's syndrome, chronic progressive ophthalmoplegia, polymyositis, neurogenic atrophy, and fascioscapulo humeral dystrophy). Based on these and our previous experimental study (Shah et al., 1985), we suggest that the human mitochondrial disorders may be grouped into two types: one in which the morphologically altered mitochondria retain the enzyme activities and Ca++ homeostasis and the other in which the altered mitochondria associated with muscle necrosis represent the loss/reduction of the enzyme activities as well as Ca++ homeostasis.