Superoxide dismutase in the rat and mouse as a function of age and longevity.

Superoxide dismutase was assayed in extracts of a variety of tissues in relatively short-lived (A/J) and long-lived (LP/J) male mice. At 9 mo of age the brains and lungs of LP/J mice contained more of this activity than did those of A/J mice. No significant differences were seen in the other tissues investigated. It was also found that specific activities of total superoxide dismutase in extracts of the brain and liver of male CD Sprague-Dawley rats did not diminish during aging; however, the cyanide-insensitive superoxide dismutase, which reflects the mitochondrially localized enzyme and which constitute only a fraction of total activity, did diminish somewhat with age in liver, but not in brain.