Variation of the Level of Mercury and Metallothionein in the Kidneys and Liver of Rats with Time of Exposure to Sodium Selenite

Sodium selenite was administered to rats before, after, and simultaneously with mercuric chloride. In all animal groups, mercury was administered intravenously in doses of 0.5 mg/kg every other day for two weeks. Selenium was given intragastrically either in a single dose of 7.0 mg Se/kg or in repeated doses of 0.1 mg Se/kg every day for weeks. It was demonstrated that, depending on the administration schedule, selenium induced significant changes in the binding of mercury by soluble fraction proteins both in the kidneys and in the liver. In every exposure, the mercury content decreased mainly in the low-molecular weight proteins, and the level of metallothionein-like proteins was diminished in the both organs. In the kidneys, the mercury content showed a correlation with the level of metallothionein (r=0.78). Amounts of mercury below 10 μg/g kidney do not stimulate metallothionein biosynthesis in this organ. A distinct interaction effect was observed in the case of a simultaneous administration of equimolar amounts of both the metals in question.