Thiol antidote to inorganic mercury toxicity with an uncharacteristic mechanism

alpha-Mercapto-beta-(2-furyl)acrylic acid (MFA) significantly reduced the lethality of mercuric chloride to rats (2.2 mg Hg/kg, ip) when administered (25 mg/kg, po) at 1, 24, 48, and 72 hr. Daily administration of MFA (25 mg/kg, po) significantly reduced the lethality of daily injection of increasing amounts of mercuric chloride (1 mg Hg/kg X 7 days, 2 mg Hg/kg X 7 days, 4 mg Hg/kg X 14 days, ip). Mercury concentration in kidneys of MFA-treated rats was significantly higher than in vehicle-treated controls, whereas concentration in liver was (nonsignificantly) lower. Enhanced mercury deposition in kidney as a manifestation of antidotal effect is not characteristic of thiol chelators used in practice for mercury poisoning.