Chelation of cadmium from metallothionein in vivo and its excretion in rats repeatedly injected with cadmium chloride.

Chelation and removal of cadmium from rats which were exposed to cadmium by multiple injections were studied in vivo after injection of two different compounds, 2,3-dimercaptopropanol (BAL) and diethylenetriamine pentaacetic acid (DTPA). Rats were injected i.p. with 1 mg of Cd/kg as 109CdCl2 daily for 4 days and 3 days after the last injection, they were treated with the chelating agents alone or in combination 5 days in a week for 2 weeks. BAL (50 mg/kg) alone or in combination with DTPA (50 mg/kg) was effective in removing cadmium from the body without increasing the level of cadmium in the kidney, the critical organ in cadmium toxicity. After treatment with BAL alone and BAL-DTPA, cadmium was excreted mainly in the feces with marked decrease in hepatic and renal concentrations of both cadmium and metallothionein. Injection of DTPA alone increased the urinary excretion of cadmium without any significant change in tissue cadmium. Although the urinary excretion of zinc was increased after injection of DTPA and also BAL-DTPA, there was no change in the tissue levels of zinc and copper. The results of this study suggest the potential use of BAL or BAL-DTPA combination as a mode of chelation of cadmium from the body under proper experimental conditions in chronic cadmium poisoning. It may be possible to prevent tubular damage in the kidney, the critical organ in cadmium toxicity by this treatment.