Comparative effects of three chelating agents on distribution and excretion of cadmium in rats

Sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC), which was newly synthesized, 2,3-dimercaptopropanol (BAL), and N-methyl-D-glucamine dithiocarbamate (NMG-DTC) were compared for their relative efficacies in the distribution and excretion of cadmium in rats exposed to cadmium. Rats were injected ip with 109CdCl2 (1 mg Cd and 10 microCi 109Cd/kg) and 3 days later, they were treated with the chelating agents (400 mumol/kg) every other day for 2 weeks. These chelating agents were effective in removing cadmium from the body without increasing the amount of cadmium in the kidney. After treatment with these chelating agents, cadmium was excreted mainly in the feces through the bile and the fecal excretion of cadmium by NBG-DTC was significantly larger than that by BAL or NMG-DTC. The hepatic cadmium content after treatment with NBG-DTC was much more decreased than that with BAL or NMG-DTC. The renal cadmium content was decreased only after treatment with NBG-DTC. These chelating agents did not result in the redistribution of cadmium to brain, testes, and heart. The growth of rats was little retarded by treatment with NBG-DTC and NMG-DTC, but was retarded by treatment with BAL. The treatment with NBG-DTC decreased the tissue amounts of Zn, Fe, and Mn to a small extent as compared with the treatment with cadmium alone. The results of this study reveal that the injection of NBG-DTC to rats pretreated with cadmium can more effectively remove cadmium from the body without the mobilization of cadmium to the kidney, the critical organ in cadmium toxicity, and without redistribution of cadmium to other tissues such as brain, testes, and heart, than injection of BAL and NMG-DTC.