ON THE MECHANISM OF OXIDATIVE PHOSPHORYLATION. IX. ENERGY-DEPENDENT REDUCTION OF NICOTINAMIDE ADENINE DINUCLEOTIDE BY ASCORBATE AND UBIQUINONE OR MENADIONE

31P NMR study of improvement in oxidative phosphorylation by vitamins K3 and C in a patient with a defect in electron transport at complex III in skeletal muscle

The bioenergetic capacity of skeletal muscle in a 17-year-old patient with a severe defect in complex III of the electron transport chain has been examined by 31P NMR measurements of the molar ratio of phosphocreatine to inorganic phosphate (PCr/Pi). Resting ratios were 1.3-2.5, which can be compared with roughly 8.6 for a young, normal female control at rest. Quantitative evaluation of the activity of oxidative metabolism was afforded by the rate of recovery of PCr/Pi from exercise and was found to be 2.5% of normal. After administration of menadione and ascorbate, we found a 21-fold increase of the recovery rate relative to the pretherapy value, to within 56% of the recovery rate of the young female control. Thus, NMR examinations of skeletal muscle at rest and in recovery from activity document marked improvement to specific drug therapy in the electron transport capabilities and the ATP synthesis rate of a patient with a deficiency in a cytochrome b-containing complex III. Improvements in functional ability, although not as dramatic as biochemical changes, are also apparent.