Study On Renal Toxicity Of Combined Effect Of Lead And Cadmium On Rats

Objective: Combined effect of lead and cadmium on kidneys of rats was explored and principle of combined effect was researched through the study on the assessment of kidneys in rats by Pb and Cd co-exposure. It could provide toxicological data for humans and animals to formulate the health standard for Pb and Cd co-exposure.Methods: The control group was lavaged with distilled water, while the lead exposure group was lavaged with lead of 0.88% in lead acetate, the cadmium exposure group was lavaged with cadmium of 0.3% in cadmium chloride, the combined exposure group was lavaged with the mixture of the lead exposure group and the cadmium exposure group. All of these treatments were done to SPF Wistar rats weighted from 180-200g once a day for 90 days. The changes in avoirdupois and morphology were observed. Urinary albumin(UALB), urinary N-acetyl-p-glucosaminidase(UNAG) were determined after 90 days. Then the rats were sacrificed and kidneys obtained in -20℃. Coefficient of viscera, Malondialdehyde, Glutathione, Superoxide Dismutase, Xanthine Oxidase, Superoxide Dismutase were determined. The change in histology of kidney was observed through light microscope. Contents of lead and cadmium in kidneys and blood were also determined.Result: Lead exposure group, cadmium exposure group and combined exposure group all had toxic symptom. Avoirdupois of cadmium exposure group and co-exposure group were less than control group. Coefficient of viscera, urinary albumin(UALB), urinary N-acetyl-p-glucosaminidase(UNAG) decreased from co-exposure group, lead(cadmium) exposure group and control group. The content of lead in kidneys(KPb), blood(BPb) and urine(UPb) of lead exposure group and co-exposure group were obvious higher than control group. The KPb and UPb in co-exposure group were obvious higher than lead exposure group. The content of cadmium in kidneys(KCd), blood(BCd) and urine(UCd) of cadmium exposure group and co-exposure group were obvious higher than control group, but there were not significant differences between these two group. Compared with the control group, SOD and GSH were decreased, MDA, XOD and NO were increased in all of the poisoned groups, especially in combined exposure group. The changes in morphology of kidney were little between lead(cadmium)-treated group and co-exposure group.Conclusion: Lead and cadmium all have toxicity to renal function and morphology, especially in combined exposure. Cadmium has higher toxicity than lead in tubule, lead has higher toxicity than cadmium in glomerulus. The renal function decreased from control group, lead(cadmium) exposure group and co-exposure group, but there were little changes between lead(cadmium)-treated group and co-exposure group in pathology, it indicated that the changes in renal function were before the changes in pathology. Lead and cadmium accumulate in kidney, blood and urine, especially in co-exposure group, the contents were positive correlation to poisoned dose. Cadmium could heighten the accumulation of lead in kidneys and urine, but lead had little effect. The accumulation of lead and cadmium in kidneys and blood could cause effect of peroxidation of endoirine, especially in combinedexposure group. The content of accumulations were positive correlation to the changes of peroxidationof endoirine. These may the mechanism of the toxicity caused by lead and cadmium. The interaction oflead and cadmium in UNAG and UALB represented additivity, while in peroxidation of endoirinerepresented synergism and additivity. It indicated that the interaction of lead and cadmium didn't haverule.