Differences in the in vivo effects of cuprizone on superoxide dismutase activity in rat liver cytosol and mitochondrial intermembrane space.

Through aerobic NBT2+ photoreduction in the absence or in the presence of 10(-4) M EDTA and through o-dianisidine photooxidation superoxide dismutase (SOD) activity was differentiated as enzymatic and nonenzymatic. SOD activity in cytosol and mitochondrial matrix was enzymatic, while 50% of the SOD activity in the intermembrane space was nonenzymatic. Cuprizone inhibited by 40% the cytosolic SOD activity and by more than 50% the nonenzymatic SOD activity in intermembrane space without, however, changing the enzymatic SOD activity in the latter fraction. Single copper injection increased enzymatic SOD activity: the cuprizone-inhibited cytosolic dismutase activity restored to normal and the unaltered dismutase activity in the intermembrane space exceeded that in the controls.