The Effect of N–acetyJated DL–penicillamine and DL–homocysteine Thiolactone on the Mercury Distribution in Adult Rats,Rat Foetuses and Macaca Monkeys after Exposure to Methyl Mercuric Chloride

Abstract The distribution and excretion of mercury was studied in pregnant rats, given a single intravenous dose of 2 μmol/kg of CH₃²⁰³HgCl on the 13th day of pregnancy. Oral treatment for one week with N–acetyl–DL–penicillamine (4 mmol/kg per day) increased the mercury excretion in faeces (from 45 to 120 nmol) and urine (from 9 to 160 nmol). Such treatment mobilized mercury from all the organs tested, and the foetal and maternal brain levels of mercury were decreased to 1/5 and 1/3 of the controls, respectively. A four–day period of treatment with N–acetyl–DL–penicillamine started three days after the injection of methyl mercury reduced the foetal and maternal brain levels to 1/2 and 2/3 of the controls, respectively. The rapid removal of metal deposits following treatment with N–acetyl–DL–penicillamine is attributed to a free penetration of the complexing thiol into the tissue cells in question. No signs of toxicity were detected in monkeys given an effective daily dose of the agent (4 mmol/kg) for 6 days. In contrast N–acetyl–DL–homocysteine thiolactone was found to be toxic in the monkeys. In addition, the latter agent was ineffective in increasing the mercury elimination from the brains of monkeys, rats and rat foetuses.