A kinetic analysis of the interaction between methylmercury and selenium

Guinea pigs were given radiolabelled methyl(203)mercuric chloride at a dose of 3 mg/kg p.o. alone or with an equimolar dose of sodium selenite, every second day for 3 weeks (10 doses). Whole-body mercury levels were measured during the course of the study and multi-compartment analysis carried out by computer least-squares curve fitting. Results indicated that mercury given alone behaved according to a single compartment model with half-life of 23.6 days, while in the presence of selenium a two-compartment behaviour resulted with one clearing rapidly (half-life 8.7 +/- 5.3 days) and the other clearing more slowly (half-life 40.8 +/- 13.0 days). Selenium decreased excretion of mercury in feces (2-fold) and urine (7-fold). Approximately 70% of the total mercury in the feces and 90% of that in the urine was in organic form. Tissue distribution of total, organic and inorganic mercury was determined 1, 14 and 28 days after the final dose. Selenium decreased the levels of mercury 1 day after the final dose, but produced a slower clearance after that. In all organs examined most of the mercury was in the organic form, except in the kidney which had over 70% inorganic mercury. Selenium increased the relative amounts of inorganic mercury in the liver, spleen, pancreas, large and small bowels, but not in the kidney.