Enhanced and inhibited biotransformation of methyl mercury in the rat spleen

Biotransformation of methyl mercury in rats was studied by enhancing or inhibiting its biotransformation with various procedures. A new sensitive method developed to determine specifically inorganic mercury in the presence of organic mercury was used. Biotransformation was enhanced by treating the rat with phenylhydrazine. The increase of inorganic mercury was highest (four to five times) and rapid in the spleen. Inhibited biotransformation of methyl mercury was observed in splenectomized rats. The inorganic portion of total mercury in the macrophage-rich fraction of spleen cells was clearly higher than that in unfractionated spleen cells. The biotransformation of methyl mercury was inhibited by treating the rat with carrageenan, a well-known substance blocking macrophage function. These results suggest that the spleen is an important site for the formation of inorganic mercury, and that the macrophage participates in this biotransformation.