Figure 3.

Ca²⁺-activated Cl⁻ currents in supporting cells from a region of the olfactory epithelium near the transition zone with the respiratory epithelium. (A) Representative whole-cell currents recorded from different supporting cells with pipette solutions containing the indicated [Ca²⁺]_i. The holding potential was 0 mV, and voltage steps from −80 mV to +80 mV with 20-mV increments, followed by a step to −80 mV, were applied as indicated at the top of the panel. (B) Average ± SEM of steady-state I-V relations in the presence of the following [Ca²⁺]_i: nominally 0 (n = 17), 0.5 µM (n = 5), 1.5 µM (n = 33), and 3.8 µM (n = 7). (C) Average ± SEM of ratios between the currents measured at +80 and −80 mV at different [Ca²⁺]_i from the same experiments shown in B (**, P < 0.01; ***, P < 0.001, Dunn–Holland–Wolfe test after Kruskal–Wallis test). (D) Comparison of dose–responses at +80 and −80 mV, from the same experiments shown in B, fitted to the Hill equation (Eq. 1). The error bars indicate SEM. (E and F) Representative whole-cell currents recorded with pipette solution containing 1.5 µM Ca²⁺. (E and G) Extracellular ion concentrations were modified by replacing 140 mM NaCl in the Ringer’s solution with sucrose, reducing the extracellular [Cl⁻] to the indicated concentrations (E) or with NMDG-Cl (G). (F–H) Current amplitudes measured at the end of voltage pulses versus the test potential from the cells shown respectively in E–G.