Alterations in Enzymes and Metabolites Resulting From Adaptation to Low Oxygen Tensions

Abstract

Succinoxidase activity has been demonstrated to be significantly higher in the tissues of guinea pigs native to altitudes of 14,000–14,900 feet than in sea level guinea pigs. Desoxyribonucleic acid content is higher in the tissues of the altitude animals, indicating a larger number of cells per gram of tissue with a constant amount of succinoxidase activity per cell. ‘Antimycin A titer,’ which varies little with altitude, and cytochrome c oxidase, which is increased in some tissues of altitude guinea pigs, indicate that altitude acclimatization may be aided by increases in key reactions of enzyme series, avoiding the necessity for changes at all of the steps of the series. Altitude animals have increased glycolysis and adenosinetriphosphatase capacities and accumulate higher levels of high energy phosphate. Animals moved from one altitude to the other show changes in enzyme concentrations indicative of acclimatization.