Fate of erythrocyte Cd-metallothionein in mice.

Degradation of metallothionein (MT), which appears in erythrocytes following cadmium (Cd) administration, was investigated in mice. Cd-MT underwent only slight decomposition by hemolysate in an in vitro experiment unlike an 800g supernatant fraction of the liver homogenate. In an in vivo study, [3H]diisopropylfluorophosphate was given to mice which had received 109CdCl2 to investigate the relationship between the decay of 109Cd-MT in the erythrocyte and the life span of the erythrocyte. A similar reduction pattern of radioactivity of 109Cd and 3H was observed. Erythrocytes containing 109Cd-MT obtained from mice preadministered with 109CdCl2 was transfused to normal mice. The 109Cd radioactivity of erythrocytes decreased in a manner similar to Cd in erythrocytes of 109CdCl2-administered mice. Contrary to this decrease of erythrocyte Cd in the transfused mice, Cd concentration of the spleen increased markedly. Cd increased also in the liver. These results indicate that erythrocyte MT degrades along with the erythrocyte. The Cd from this MT is deposited in the spleen and liver where blood cells are catabolized.