Effects of l- or d-cysteine coadministration on short-term distribution of inorganic mercury in the rat

Abstract

Male Sprague-Dawley rats received iv injections of mercuric chloride alone or in combination with l-cysteine or d-cysteine. Mercury concentrations in kidney, liver, and cerebrum 5 min after injection increased linearly over the dose range of 0.1, 0.5, 1.0, and 2.0 μmol of mercury/kg. Over this dose range, coadministration of l-cysteine or d-cysteine at a 2-to-1 molar ratio relative to mercury increased renal mercury concentrations and reduced mercury accumulation in the liver, cerebrum, and erythrocytes. Renal mercury concentrations were highly correlated with plasma mercury concentrations 5 min after injection and coadministration of l-cysteine or d-cysteine did not alter this relationship. Hepatic and cerebral mercury concentrations were also highly correlated with plasma mercury concentrations but coadministration of either thiol compound altered the relationship between plasma and tissue mercury concentrations. These data suggested that different processes underlie short-term mercury accumulation in different tissues. Investigations of the effects on tissue distribution of various molar ratios of l- or d-cysteine relative to mercury further suggested that direct complexation of mercury by either thiol may be a critical factor in the control of mercury deposition in these tissues.