Lead ions but not other metallic ions increase resistance to hypotonic lysis in prenatal hemopoiesis red blood cells

RESUMO

Metals known to have toxic effects on exposed individuals (Aluminum (Al), Cadmium (Cd), Zinc (Zn) and lead (Pb)) were selected. Umbilical cord erythrocytes from normal newborns were incubated in isotonic media alone or with addition of Pb (20 microM), Cd, Zn or Al (concentration range 20-250 microM). Red cells were then placed in media of diminishing tonicity, to measure cellular lysis and volume; the regression curves of percent lysis as a function of osmolarity were determined for each data set and the break points calculated. Resistance to lysis increased significantly in Pb treated cells whereas cells treated with the other metals did not differ from controls, even at concentrations ten times higher than that of Pb. Lead produced a reduction in cellular volume corrected by addition of quinidine (an inhibitor of potassium channels activation) to the cell suspension; on the other hand, quinidine did not modify the effect of lead on lysis sensitivity. These results suggest that the effect of lead on cell resistance to lysis might be mediated by changes in membrane structure. The other metals examined did not affect the variables studied.