Effects of separate and combined chronic mercuric chloride and sodium selenate administration in rats: histological, ultrastructural, and x-ray microanalytical studies of liver and kidney.

The separate administration of mercuric chloride (HgCl2) and sodium selenate (Na2SeO4) to male rats in drinking water or a combined administration of both (50 ppm Hg, 15 ppm Se) caused different signs of toxicity over a 22 week period. The HgCl2 group showed histopathological and ultrastructural lesions as evidenced by periportal fatty degeneration and cell necrosis in the liver and tubular necrosis with proteinaceous casts in the kidney. The Na2SeO4 group showed the most severe depression of growth and food and water consumption, but no pathological changes were seen in the liver or kidney. Simultaneous administration of both toxicants produced a protective effect on weight loss and histopathology. These effects were associated with the formation of electron dense nuclear inclusions in kidney proximal tubule cells and similar electron dense formations in the reticuloendothelial cell cytoplasm and in the extracellular space of Disse in the liver. These formations were shown to contain both Se and Hg by energy dispersive X-ray microanalysis. The basis of the protective interaction of these two elements appears to result from an alteration of the chemical form or association of the mercury and selenium.