Relationship between oxygen metabolism, aging and development

Evidence concerning the involvement of metabolic rate, prooxidants and antioxidants in processes of aging and development of animals is examined. Life span of poikilotherms and homeotherms is apparently dependent on a genetically-determined metabolic potential (i.e., total amount of energy expended during life per unit weight) and the rate of metabolic expenditure. Metabolic potential may vary in different species and under different environmental conditions. The relationship between metabolic potential, metabolic rate and duration of life is most demonstrable in organisms with a variable basal metabolic rate, such as poikilotherms and mammalian hibernators. Experimental regimes which reduce metabolic rate prolong life span and tend to retard the rate of age-related physiological and biochemical changes and vice versa. Effects of metabolic rate on aging may be mediated by oxygen free radicals. Antioxidant defenses tend to decline during aging, whereas, free radical induced damage seems to increase with age. Intracellular environment becomes progressively less reducing during the course of development and aging. We have postulated that such a shift in redox potential may play a role in the modulation of gene activity during development and aging.