Oxygen toxicity is not related to mammalian body size

Abstract

1. 1. Small mammals have been used to study the effects of O 2 toxicity. The aim of the present study was to investigate whether body size should be considered when applying the results of these studies to man. 2. 2. Oxygen toxicity is enhanced as perfusion and metabolism increase: specific animal tissues of high perfusion are more susceptible to O 2 toxicity. Exercise, high metabolic rate, and increased brain blood flow enhance O 2 toxicity. 3. 3. Increased specific O 2 consumption and perfusion as body mass decreases may enhance O 2 toxicity in small mammals. 4. 4. Survival time in normobaric hyperoxia (1 atm O 2) and the time to first appearance of convulsions in hyperbaric oxygen (4–5 atm) were collected from the literature and showed no relation to body size. 5. 5. Known difference in antioxidant enzyme activity cannot explain the findings. 6. 6. Independence of tissue P O 2 on body size, or equal rates of free radical formation and degradation, are suggested as possible mechanisms. 7. 7. Small mammals can serve as a good model for O 2 toxicity in man.