Figure 1

Effect of zinc acetate on hydrogen peroxide-induced intestinal damage and Stx2 translocation in T84 cells. T84 cells grown to confluency in Transwell inserts were treated with various concentrations of hydrogen peroxide and barrier function monitored by measuring trans-epithelial electrical resistance (TER) and translocation of Stx2 across the monolayers. Stx2 itself does not damage T84 cells due to lack of expression of the Gb₃ receptor in this cell line. Panel A, time course of TER in response to H₂O₂ added to final concentrations of 1 to 5 mM. Panel B, effect of H₂O₂ on translocation of Stx2 and on fluorescein-labeled dextran-4000. Stx2 was added to the upper chamber 2 hours after the addition of H₂O_2, and Stx2 was measured by EIA in the lower chamber. H₂O₂ at concentrations of 3 mM and higher induced significant translocation of Stx2 into the lower chamber. The amount of Stx2 translocated to the lower chamber after 24 in response to 5 mM H₂O₂ was 3.5% of the total Stx2 added. Panel B, Inset, shows that H₂O₂ also triggers a translocation of FITC-dextran-4000 across the monolayer, which is abolished by addition of 1200 U/mL of catalase; *significant compared to H₂O₂ alone. Panels C, effect of zinc acetate on Δ TER in undamaged T84 cell monolayers. Δ TER is defined as the TER_final – TER_initial, which is determined separately for each well, then averaged. Using the Δ TER helps to compensate for well-to-well variation in the starting TER, because each well serves as its own control. Panel D, effect of zinc acetate on Δ TER in cells treated with 2% DMSO. Panel E, effect of zinc on T84 cell monolayers treated with 3 mM H₂O₂. Panel F, protection by zinc against Stx2 translocation induced by exposure to H₂O₂.