. A polarized epithelial preparation was initially perfused on both sides with 0 Na^+^ Ringer\'s solution containing 000 mM NMDG-Cl (pH 0.0). (A) Temporal changes in F~000~ of Na-green--loaded TRCs were monitored while the apical membrane was perfused with Ringer\'s solution containing 000 mM NaCl + 0 μM Bz 