Fig. 3.

Effect of treatment of postconfluent populations of wild-type Madin-Darby canine kidney (MDCK) cells (A), occludin knockdown (Occ KD) MDCK cells (B), or zonula occludens-1 knockdown (ZO-1 KD) MDCK cells (C) with various H₂O₂ concentrations on paracellular calcein flux. Average flux rates for each condition were calculated and normalized to the control flux rate for each cell line (D). Cells were pretreated with 0 μM, 44 μM, 55 μM, or 66 μM H₂O₂ for 1 h before initiation of the calcein flux assay. Calcein flux was measured periodically over the next 4 h. Data are presented as means (SD) of triplicate independent samples. These are representative experiments of at least 3 separate experiments for each cell line. Content of tight junction proteins, occludin, ZO-1, and ZO-2 was determined by Western blotting (E) and was normalized to the content of β-actin in the same sample. Images shown are representative of the results obtained from at least 3 separate lysates.