Biliary excretion of cadmium in rat. VI. Mobilization of cadmium from metallothionein by 2,3-dimercaptopropanol.

Cadmium was preferentially bound to metallothionein in tissues 24 h after CdCl2 injection. Of a number of chelating agents examined, only 2,3-dimercapto-1-propanol (BAL) was effective in mobilizing Cd from metallothionein into bile. Structurally similar dithiols such as 1,3-dimercaptopropanol and 2,3-dimercapto-1-propanesulfonic acid were not effective. Diethylenetriamine pentaacetic acid increased only the urinary excretion of Cd. Biliary excretion of Cd increased with increasing dose of BAL, and there was a concurrent decrease in hepatic Cd levels without any increase in renal concentration. BAL was effective even 14 d after Cd injection. The form of Cd excreted in the bile after BAL injection in chronic exposure has not yet been characterized. Initial studies suggested that it was not metallothionein but was a low-molecular-weight Cd complex, probably with BAL.