Myoglobin content and enzymatic activity of muscle and altitude adaptation

Quantitative determinations of myoglobin were made in the sartorius muscle of healthy human subjects native to sea level and high altitude. The specific activities of the reduced form of diphosphopyridine nucleotide oxidase (DPNH-oxidase), DPNH- and the reduced form of triphosphopyridine nucleotide (TPNH)-cytochrome c reductases, transhydrogenase, and isocitric and lactic dehydrogenases were also examined. There was found a significantly higher myoglobin concentration in the muscle of the high-altitude native as compared with the sea-level resident. The enzyme systems DPNH-oxidase, TPNH-cytochrome c reductase, and transhydrogenase similarly showed a significantly higher activity in the altitude resident. It was concluded that the respiratory capacity of the muscle was apparently higher in the altitude native than in the sea-level one. The enhanced enzymatic activity was probably related to the higher pigment content of the skeletal muscle. Results on myoglobin determinations in several other muscles from certain sea-level patients are discussed. Submitted on July 24, 1961