The influence of administered mass on the subcellular distribution and binding of mercury in rat liver and kidney.

The influence of the administered mass on the tissue and sub-cellular distribution of mercury (Hg) was investigated in rats, using 203Hg. The fraction of the dose deposited in liver increased threefold over the dose range 0.17-1.65 mg Hg X kg-1, while the retention in the kidney decreased by a factor of 2. The uptake in other organs, lung, spleen, brain, thymus, salivary glands showed no dose-dependent variation. Subcellular fractionation studies showed a dose-dependent increase in the Hg content of the liver cytosol, with corresponding decreases in the deposition in the lysosomal and nuclei-cell debris fractions. In contrast, no clear changes in the distribution of Hg amongst the subcellular organelles of the kidney were observed. The amount of Hg bound to metallothionein in the liver cytosol rose steeply with increasing dose. However, in the kidney cytosol the mass of Hg bound to metallothionein increased with dose up to 0.55 mg Hg X kg-1, thereafter remaining approximately constant. These observations suggest that the Hg-binding metallothionein in the kidney was saturated by administered doses greater than 0.55 mg Hg X kg-1, whereas in liver saturation levels of the metal were not reached even at the highest dose tested, 1.65 mg Hg X kg-1.