Effects of Lead and/or Cadmium on the Oxidative Damage of Rat Kidney Cortex Mitochondria

Lead acetate (300 mg/L) and/or cadmium chloride (50 mg/L) were administered as drinking water to Sprague-Dawley rats for 8 weeks to investigate the possible combined effects of these metals on the damage in renal cortex mitochondria. Increased malonaldehyde levels due to exposure to these metals were detected by colorimetric method, which demonstrated the lipid peroxidation in the renal cortex. Ultrastructural observations and real-time quantitative PCR analyses were performed on kidney cortex pieces to identify the mitochondrial damage and quantify the relative expression levels of cytochrome oxidase subunits (COX-I/II/III), respectively. The most striking ultrastructural modifications involved distortion of mitochondrial cristae and an unusual arrangement, which were more evident when the mixture was ingested. There were significant differences in the expression levels of COX-I, II, and III between the control group and the exposed groups, whereas those in the (lead+cadmium) group were all significantly lower than that in the lead or cadmium group. In conclusion, there was an obvious synergistic oxidative damage effect of lead combined with cadmium on rat kidney cortex mitochondria, which increased defects in mitochondrial oxidative metabolism.