Figure 7.

Calcium signaling is involved in deciliation and TJ remodeling. (A) Ca²⁺ concentration was determined by digitized fluorescence microscopy of Fura-2–stained MDCK II cells incubated without or with 4 mM CH or NH₄SO₄ for indicated durations. n = 5 cells per condition; error bars, SEM. (B) Cells were preloaded with either 25 μM EGTA-AM or 25 μM BAPTA-AM before addition of 4 mM CH or 30 mM NH₄SO₄ or were left untreated (control). Twenty-four hours later, TER was measured and cultures were fixed and labeled with anti-acetylated tubulin antibodies. Note that preloading cells with calcium chelators largely prevented deciliation and blocked the associated rise in TER induced by CH, but had no effect on NH₄SO₄-induced deciliation and remodeling. Cilia were counted in five randomly selected fields per filter. n = 3 filters per condition; error bars, SEM. (C) Polarized MDCK II cells were cultured in HG-DMEM in the absence or presence of 1 μM thapsigargin for 24 h, at which time TER was measured and cultures were fixed and labeled with anti-acetylated tubulin antibodies. n = 3 filters per condition; error bars, SEM.