Interaction of Mercury with Human Erythrocytes

The binding of mercury to red blood cells was measured in terms of Hg²⁰³ uptake and desorption. The significant features of the binding are: (a) rapid achievement of equilibrium (3 to 5 minutes); (b) release of a Hg-complexing material from the red cells themselves which distorts the binding curves at low concentrations of metal (2.5 x 10^-7 to 5.0 x 10^-6 M); (c) prevention of binding by cysteine, glutathione, penicillamine, and EDTA but not by imidazole or histidine; (d) binding of mercury in amounts up to 7 times the reduced glutathione concentration of the cells before combination with glutathione itself; (e) binding primarily to sulfhydryl groups of hemoglobin and to a small number of stromal sulfhydryl groups, but also to other non-sulfhydryl cellular ligands after saturation of the sulfhydryl groups. Associated with the binding is inhibition of glucose uptake, induction of loss of K⁺, and decrease in osmotic fragility. These effects increase over the range of concentrations (1 x 10^-17 to 1 x 10^-15 moles of Hg/RBC) well below those that result in saturation of the cellular binding sites; above 1 x 10^-15 moles/RBC, the effects decrease as the cells become saturated.