Fig. 1.

Effects of Nedd4–2 overexepression on short-circuit current (I_sc), transepithelial electrical resistance (TER), and conductance in mpkCCD_c14 cells. A and B: mpkCCD_c14 cells were transduced with Nedd4–2 or empty virus while subconfluent in culture dishes (plastic) or 24 h after being plated on transwell inserts (filters). Cells transduced on plastic were then plated into transwell filters. Forty-eight hours after being plated on filters, I_sc and TER were measured in Ussing chambers at 37°C and conductance was calculated from TER. Nedd4–2 significantly reduced I_sc in both groups compared with empty virus, although the effect was more robust in the first group. Nedd4–2 significantly increased conductance (∼3-fold) compared with empty virus but only in cells transduced on plastic; n = 12–14, means ± SE. C: time course of developing resistance in cells transduced on plastic and then plated on filters. Nedd4–2 significantly reduces TER at 46 h after being plated which is no longer evident at 70 h; n = 6, means ± SE. D and E: effect of benzamil, Ba²⁺, and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) on I_sc and TER in mpkCCD_c14 cells; n = 4, means ± SE. **P < 0.001; *P < 0.05 Tukey's pairwise multiple comparison.