FIGURE 7.

IL-13-induced claudin-2 expression alters tight junction ion selectivity in vivo. A, 12 h after intraperitoneal injection of 1 μg of murine IL-13, immunofluorescent staining revealed increased claudin-2 (green) expression compared with saline-injected control mice. F-actin (red) is shown for orientation. Bar, 20 μm. B, immunoblots show that colonocytes isolated from IL-13-treated mice express 209 ± 21% as much claudin-2 relative to controls (n = 5, saline; n = 5, IL-13 injected). Actin was used as a loading control. C, PNa⁺/PCl⁻, calculated from stable apical dilution potentials after changing apical NaCl concentration from 118 to 59 mm, was increased after IL-13 injection (n = 6, saline, white; n = 5, IL-13 injected, green). D, paracellular FITC flux was unchanged after IL-13 injection (n = 5, saline, white; n = 5, IL-13 injected, green) (*, p ≤ 0.05, S.E.).