Figure 2. Amalgam toxicity, but not mercury toxicity, was blocked by the metal chelator, CaEDTA, while the mercury chelator, DMPS, blocked mercury toxicity but not amalgam toxicity. (A) Amalgam, 0.010 + 0.002 mg; DMPS, 100 µM 2,3-dimercaptopropane-1-sulphonate; CaEDTA, 1 mM calcium disodium ethylenediaminetetraacetate. Amalgam was placed in tissue culture inserts so that it was exposed to the same media as the cells but was not in direct physical contact with the cells. Bars show % cell death (mean + SEM, n = 12). (B) Hg; 5 µM HgCl₂. Bars show % cell death (mean + SEM, n = 8-16). Cell death was quantified by the measurement of release of LDH, 24 hrs after the beginning of the insult. Sham wash values were subtracted, and results were scaled to the level measured in sister cultures exposed to 10 µM A23187 for 24 hrs (n = 100; this exposure induced near-complete cell death). * indicates significant difference from control amalgam or mercury toxicity.