Variations of activities in the segments of respiratory chain among tissues in a patient with mitochondrial encephalomyopathy.

Enzymatic activities of NADH cytochrome c reductase and cytochrome c oxidase were determined in the mitochondria from various tissues of a patient with mitochondrial encephalomyopathy and compared with those of controls. NADH cytochrome c reductase in the present patient decreased significantly in the liver and spleen and to a less extent in the kidneys. On the other hand, cytochrome c oxidase of the patient decreased severely in the skeletal muscle and kidneys and partially in the heart. Difference spectrum of reduced-minus oxidized form of mitochondria from patient's skeletal muscle and heart showed a decrease of cytochrome aa3 peak in the alpha region at 605 nm. These results indicate that there are cryptic deficiencies in the segments of the respiratory chain in the mitochondria from several tissues of the present patient, such as liver, kidney, spleen without any clinical manifestation. The weakness and atrophy of skeletal muscle was, however, well correlated to the biochemical analysis.