BIOCHEMICAL CHARACTERISTICS OF RAT SUPEROXIDE-DISMUTASE AND THE EFFECT CAUSED BY PARAQUAT INJECTION ON THE ENZYME-ACTIVITY IN VARIOUS TISSUES

Rat superoxide dismutase (SOD) prepared from the rat was not found by sedimentation in sucrose gradients or isoelectric focusing to consist of > 1 molecular form. On polyacrylamide gels, 1 major and 1 minor activity form could be demonstrated. The sedimentation constant and corresponding MW of the enzyme determined by sucrose gradient centrifugation were 3.0 .+-. 0.36 (34,300 .+-. 4023) and the isoelectric point 4.75. These characteristics did not differ for SOD prepared from different rat tissues and were not affected by a single dose of 40 mg/kg paraquat [a herbicide] given s.c. 48 h prior to sacrifice. The protein contents of various tissues based on both wet and dry weight did not deviate from normal during 5 days following a single exposure of paraquat up to 40 mg/kg. Experiments based on SOD activity measurements in different tissues as a function of time following single exposures of paraquat revealed the presence of a very high induction capability of the SOD protein in the rat. The results were correlated to autoradiographic studies. A correlation between SOD induction and tissues showing high paraquat retention could be demonstrated. This was especially expressed for the lung. Due to a difference in the induction pattern following exposure to 5 and 10 mg/kg paraquat, respectively, it was suggested that the ability of the rat to bear paraquat loads might be related to the SOD induction capability in various tissues.