Correlation of hepatic metallothionein concentrations with acute cadmium toxicity in the mouse

Dose-dependent induction of metallothionein by cadmium was measured by gel filtration of liver supernatants prepared from mice 48 hr following single doses of 0.2–2.0 mg of Cd/kg (ip). Hepatic metallothionein concentrations increased in proportion to the cadmium pretreatment dose. A dose-dependent tolerance to acute cadmium toxicity was simultaneously evidenced by elevated LD50 values in cadmium-pretreated mice. A positive correlation between dose-related increases in hepatic metallothionein and cadmium LD50 suggests a protective function for metallothionein. The data suggest that a threshold dose of cadmium must be exceeded in order to induce concentrations of metallothionein adequate to ameliorate acute cadmium toxicity.