Induction of metallothionein after lead administration by three injection routes in mice.

The amount of induced hepatic metallothionein (MT) and the alterations of calcium (Ca) and lead (Pb) concentrations in plasma, liver, kidney, and spleen were compared in male mice after iv, ip, and sc injections of lead acetate at a dose of 30 mg Pb/kg body wt. The amount of hepatic MT at 1 day was in the order of ip greater than iv greater than sc injection approximately 0, despite the hepatic Pb concentration in the order of iv greater than ip greater than sc injection. Heat-stable Pb-binding MT was not detected following any injection route. After the iv injection, a transitory hypercalcemia with hyperphosphatemia was observed. As for the tissue Pb concentration after the iv and ip injections, liver and spleen showed a high concentration, while kidney concentration was relatively low. The high tissue Pb was accompanied by an increase of tissue Ca in most cases. Only 10 to 15% of the total Pb accumulated in the liver at 1 day was recovered from the supernatant fraction after ultracentrifugation. The increase of hepatic Ca was ascribed to that in the sediment fraction. After the sc injection, the tissue Pb concentration was very low and no alterations were observed in tissue Ca concentrations.