Effect of Chelating Agents on Accumulation and distribution of Mercury in Tissues and Subcellular Fractions of Methylmercuric Chloride Injected Rats

The effect of dimercaptosuccinic acid (DMSA), D-penicillamine (DPA), N-acetyl-D, L-homocysteine thiolactone (NAHCTL), and sodium selenite (Se) on the accumulation and distribution of mercury in tissues and subcellular fractions in methylmercuric chloride injected rats were studied. 1. Hg-lowering effect was in the order of DMSA>DPA>NAHCTL in liver and brain, and DMSA≒DPA>NAHCTL in kidney and blood. Se indicated the effect lower than DMSA and DPA in liver and kidney and the lowest in blood. Se caused remarkable increase (145%) in Hg value of brain as compared with control. 2. Hg-lowering effect on subcellular fractions was observed in a similar manner, DMSA>DPA>NAHCTL>Se. Se caused the increase in Hg values of subcellular fractions of brain except neuronal nuclei, nuclei of kidney, plasma, and stroma. Nucleoli of liver showed a tendency to resist reduction in Hg in common with four kinds of agents. 3. In cytosol of kidney the increase in the ratio of inorganic mercury was observed as a result of agent-dosing, suggestive of stimulation of biotransformation by administration of chelating agents. 4. From gel filtration of kidney cytosol the following results were obtained; increase in the amount of protein-bound Hg localized to void volume resulting from Se-dosing; increase in inorganic mercury bound to metallothionein peak in NAHCTL-dosing which showed the highest ratio of inorganic mercury in cytosol; appearance of a new peak in low-molecular weight region in DMSA-dosing which was assumed as DMSA-Hg complex. 5. It is concluded that DMSA is most effective in reduction of Hg accumulation in tissues and its subcellular fractions in methylmercuric chloride injected rats and is most recommendable agent also from a view point of its low toxicity