Mitochondrial functions in five cases of human neuromuscular disorders.

We determined the respiration, respiratory control, and Pi:O ratios with different substrates in mitochondria isolated from five cases of human neuromuscular disorders (two cases of central core disease, two cases of neuropathy of Dejerine-Sottas, and one case of Kugelberg-Welander's disease) and compared them with normal human muscle. In all the myopathies studied, a severe derangement of the respiratory control with variable derangement of oxidative phosphorylation was found. This supports the idea that a group of neuromyopathies shares the same biochemical lesion as the so-called mitochondrial myopathies, forming with them a group of myopathies which may be related through a similar biochemical lesion of varying degree. Alternatively, disturbance of mitochondrial functions in a number of myopathies could be considered as a non-specific finding.