Measurement of superoxide dismutase (SOD) activity

The total SOD activity in LV myocardium was determined using the hydroxylamine method. Fresh-frozen LV myocardium was converted to homogenates in a homogenizer filled with precooled normal saline (NS). The homogenates were centrifuged at 4°C for 15 mins with a speed of 2000 r/min. The supernatant were mixed with the reagents supplied in a SOD Assay Kit (Nanjing Jiancheng Bioengineering Corporation, China, A001-3). The mixture was incubated at room temperature for 10 min, and the absorbance of the compound was then measured at 550 nm. All operations were according to the manufacturer’s instructions. Each preparation was tested in triplicate. SOD activity was expressed as U/mg prot.