##Iron assay
Renal tissue samples (10 mg) from each group were washed with cold normal saline after incision. A vibrating homogenizer was immediately applied to add cold brine for tissue homogenization. In addition, the collected cells were homogenized with ultrasonic cell interfering agent. After centrifugation for 10 min, the supernatant was collected, and the iron concentration in tissues and cells was determined with an iron content determination kit (BioAssay, Hayward, CA, USA). According to the manufacturer’s instructions, a sufficient amount of the working reagents was prepared, the working reagents were transferred with 96-well plate, and supernatant was collected from a 96-well plate. The optical density determination wavelength of the iron content determination kit was 590 nm.