The addition of a zinc chelator, CaEDTA, did not reverse the effect of zinc of glutamate uptake. Astrocytes were exposed for 30 min to Zn2+ at the designated concentrations, and glutamate uptake was measured three hours later. The cultures were also treated with 1 mM of the zinc chelator CaEDTA or, as a control, ZnEDTA, for 5 min prior to initiation of the glutamate uptake assay. Data points are means of three independent experiments (n = 3), each with measurements from two to three culture wells. *P < 0.05 compared with zero (0) zinc-exposed control.