Studies on Poisonous Metals. XI. Effect of Chelating Agents on Biliary Excretion of Cadmium in Rats

Abstract

The mechanism of the stimulatory effect of chelating agents, such as DL-penicillamine and citric acid, on the biliary excretion of cadmium in rats was studied. The results of Sephadex G-75 gel filtration of liver soluble fraction of rats administered cadmium with or without these chelating agents indicated that the chelating agents significantly depressed the binding of cadmium to a high molecular weight protein of liver tissue. The cumulative biliary excretion of DL-penicillamine and citric acid in a 9 h period after administration were about 1% and about 0.04% of the dose, respectively. It is suggested that the stimulatory effect of DL-penicillamine on the biliary excretion of cadmium was due to the formation of DL-penicillamine-cadmium complex, and that citric acid depressed the binding of cadmium to high molecular protein in the liver cytosol, resulting in enhanced biliary excretion of cadmium.