Figure 4.

Effect of Pb removal from exponentially growing cells. Cells were cultured in 24-well plates until they reached 30–40% confluence. At that time, two plates were counted as time zero control (C0) and other plates were treated, in duplicates, for 24, 48 or 72 h with medium alone (C) or two concentrations of Pb (10 μM or 50 μM) for 24, 48 or 72 h. To analyze recovery, in other plates after 24 h treatment with 10 or 50 μM Pb, the medium was changed to a medium free of Pb for another 24 h or 48 h (R10 or R50) as indicated in this figure. At the end of these treatments, cells were trypsinized and counted in Neubauer chamber as indicated in methods. Results are expressed relative to C0, which is set to 1 and represent mean ± SE of three independent experiments. Asterisk significantly different from C at the corresponding time, P < 0.05; plus sign represents significantly different from 10 μM Pb for 48 or 72 h, P < 0.05 and double plus sign represents significantly different from 50 μM Pb for 48 h or 72 h, P < 0.05 (ANOVA).