Lead transport and binding by human erythrocytes in vitro.

Transport and binding of Pb2+ by human erythrocytes were examined for cell Pb contents in the 1-10 microM range, using the 203Pb isotope. Pb2+ crosses the erythrocyte membrane by the anion exchanger, and can also leave erythrocytes by a vanadate-sensitive pathway, identified with the Ca2+ pump. However, Pb2+ exit is very much less than expected from earlier experiments with resealed erythrocyte ghosts [Simons TJB (1988) J Physiol (Lond) 405:105-113] and the distribution of Pb2+ across the erythrocyte membrane is close to equilibrium. The high ratio of erythrocyte to plasma Pb seen in vivo appears to be due to the presence of a labile Pb(2+)-binding component present in erythrocyte cytoplasm.