The biochemical assays were carried out according to the instructions of kits
purchased from Nanjing Jiancheng Bioengineering Institute. Briefly, SOD activity
was measured through the inhibition of hydroxylamine oxidation by the superoxide
radicals generated in the xanthine–xanthine oxidase system. GSH-Px activity
was measured on the basis of the reaction of GSH and 5, 50-dithiobis-(2-nitrobenzoic
acid). CAT activity was determined by measuring the absorbance of the yellow
H2O2–ammonium molybdate complex at 405 nm. All above activities were expressed
as unit per milliliter (U/ml) in serums or unit per milligram of protein
(U/mg protein) in livers and hearts. The protein contents in the supernatants of
livers and hearts were determined by the Bradford method using bovine serum
albumin as the standard.