Gastrointestinal absorption and organ distribution of oral cadmium chloride and cadmium‐metallothionein in mice

Body retention and tissue distribution of Cd from oral 109CdCl2 and 109Cd-metallothionein were studied in C57BL/6J mice given identical doses (60 microgram Cd and 2 muCi 109Cd). Measurement of 109Cd radioactivity in mice showed identical absorption but differences in tissue distribution of Cd from the two forms. A significantly greater deposition of Cd was observed in the kidney of mice fed Cd-metallothionein than in the CdCl2 group where a major portion of Cd was deposited in the liver. Most of the radioactive Cd in the renal and hepatic tissue and in the duodenum was bound to metallothionein 24 h after oral Cd-metallothionein, whereas only 30 and 38% of the cadmium in liver and kidney supernatants, respectively, were bound to metallothionein after oral CdCl2. These results suggest that the dietary form of Cd may influence the renal deposition of Cd.