Superoxide dismutase provides protection against the hyperoxia in the retina of the rainbow trout (Salmo gairdneri).

A modified hydroxylamine oxidation assay method coupled with a parallel line analysis to detect endogenous interfering substances, was used to determine superoxide dismutase (SOD). Retinal SOD activities in trout, frog and rat were compared. SOD activity in liver and brain tissues was also determined. Based on estimates of superoxide anion production there appears to be excess SOD protection in the rainbow trout retina, which could, at least in part, account for its resistance to oxygen toxicity.