Superoxide dismutase activity and lipid peroxidation of the rat liver during development.

The present work was an attempt to understand the effects of oxygen toxicity in the early neonatal period and was performed using rat liver homogenate and mitochondria as examples of superoxide dismutase (SOD) activity and lipid peroxidation. SOD activity of the liver was extremely low during the fetal period and approximately the 5th day after birth. However, a rapid increase in the level of activity was observed from about the 10th day after birth. By the 20th day, this had reached 88% of the level in the adult rat. Peroxidated lipids, in an inverse relation to SOD activity, occurred at high levels during the fetal and early neonatal period, but rapidly decreased after the 10th day. It can be considered, therefore, that protection against oxygen toxicity is inadequate in such rat livers during the fetal and early neonatal periods, but that it is well established by the 10th day after birth.