Superoxide dismutase activity of normal murine liver, regenerating liver, and H6 hepatoma

By means of both direct assay and gel electrophoresis, normal A/J mouse liver was shown to possess both Cu-Zn and Mn superoxide dismutase (SD) activity. H6 hepatoma cells contained Cu-Zn SD activity, but no Mn SD activity was detectable. Isolated mitochondria from normal liver contained both forms of the enzyme, but isolated mitochondria from H6 hepatoma cells contained no SD activity. To ascertain whether this loss of Mn SD activity was characteristic of these tumor cells or was simply a property of rapidly dividing cells, SD activity was measured in regenerating liver. Mn SD activity was present in the regenerating liver at all times after surgery. Hence loss of the Mn SD activity seemed to be a characteristic of some tumor cells but not of corresponding rapidly dividing normal cells.