FIGURE 5.

With reduced external Ca²⁺, PC2 current is insensitive to Ca²⁺ buffering. (A) The recordings shown were made at +60 mV immediately following a prepulse of 10 s to the voltages shown. The internal solution contained 0.1 mM BAPTA and 15 nM free Ca²⁺ and the external solution 0.1 µM free Ca²⁺. (B) Transient current amplitudes for cilia tested with either 2 mM (n = 15 cilia) or 0.1 µM (n = 9 cilia) external free Ca²⁺; the internal solution contained 0.1 mM BAPTA. Voltages were chosen that gave the greatest transient current. Prepulse voltages ranged from −140 mV to −40 mV and postpulse voltages from +40 mV to +80 mV. The values for cilia in 2 mM external Ca²⁺ are taken from Figure 1D. *p < 0.001. (C) Paired mean steady-state currents for 10 cilia, each tested in both 0.1 and 2 mM internal BAPTA; the external solution contained 0.1 µM free Ca²⁺. Voltages were chosen that gave the greatest difference in mean current between 0.1 and 2 mM BAPTA and were either +40 or +60 mV. (D) Mean steady-state currents for cilia tested with either 2 mM (n = 13 cilia) or 0.1 µM (n = 10 cilia) external free Ca²⁺; the internal solution contained 0.1 mM BAPTA. The values for cilia in 2 mM and 0.1 µM external Ca²⁺ are taken from Figure 2D and Figure 5C, respectively. In the box plots, the individual data are shown as filled circles. The top, middle, and bottom lines indicate the 75th, 50th, and 25th percentile values, respectively. Whiskers indicate the 90th and 10th percentile values. A blue square is shown at the level of the mean value. *p = 0.0099.