Fate of heavy metal in animals : quantitative change of metallothionein in the liver, kidney and intestinal mucosa of rat after a single injection of 109CdCL2

Periodical and quantitative changes in the amount of metallothionein, formed by a single administration of cadmium, were examined. Male Wistar rats were given intravenous injection of 109CdCl2 solution (1 mg Cd/kg) or subcutaneous injection (3 mg Cd/kg) and, 0.5, 1, 6, and 24 hr after intravenous injection or 1, 2, 4, 8, 16, 32, and 64 days after subcutaneous injection, liver, kidney, and small intestinal mucosa supernatant (s) were fractionated by Sephadex G-75 column. (1) In the liver, a larger amount of cadmium was bound to high molecular proteins rather than as metallothionein 1 hr after the administration of 109CdCl2 but the situation was reversed after 6 hr and almost all cadmium was present as metallothionein which increased rapidly thereafter, reaching a maximum on 8 th day. Subsequently, it decreased with time and became about 1/3 after 64 days. (2) In the kidneys, almost all cadmium was present as metallothionein in the initial stages after the administration but its increase was smaller than that in the liver, though reaching a maximum on 8 th day. Subsequent decrease was extremely gradual and 4/5 of the 8-day value was present even after 64 days, being in the same level as that in the liver. (3) In the small intestinal mucosa, cadmium was bound to both metallothionein and high-molecular protein 1 hr after the administration, but most of it was present as metallothionein after 6 hr. Cadmium decreased with time thereafter.