STUDIES OF THE CELLULAR-DISTRIBUTION OF SUPEROXIDE DISMUTASES IN ADULT AND FETAL-RAT TISSUES

Activities of three types of superoxide dismutase in tissue fractions were significantly lower in fetal and adult brain and fetal limb prepa rations than in fetal and adult heart preparations. An exception was t he cytoplasmic fraction of adult brain that had levels of Cu, Zn-super oxide dismutase activity comparable to those in cyto-plasmic fractions of heart. In addition, Mn superoxide dismutase activity appeared to b e very low in all fetal mitochondrial matrix fractions and cyto-plasmi c fractions as well as in adult brain. Finally, the results of these s tudies emphasize the importance of two antioxidant defense systems in the tissues studied, one associated with the mitochondrial electron tr ansport system and the other, the cytosolic Cu, Zn enzyme.