Elementary Ca²⁺ currents recorded in cell-attached configuration.

<p><b>A</b>, Representative unitary currents recorded from adult IHCs positioned in the middle region of the gerbil cochlea using a high-K⁺ extracellular solution (High_K⁺; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0113750#s4" target="_blank">Methods</a>). The pipette solution contained 5 mM Ca²⁺ and 5 µM BayK 8644. Transmembrane patch potentials are shown next to the traces. The inter-stimulus interval in all cell-attached recordings was 2 s. Grey lines indicate the channel closed state (here and in the other figures Ca²⁺ channel openings are indicated by a downward deflection of the current trace). Arrows and arrowheads show single brief and long-lasting openings, respectively. In several cases clusters of openings were seen, which were interrupted by short closing periods (asterisk). <b>B</b>, Average current-voltage (<i>I</i>-<i>V</i>) data for single Ca²⁺ channel currents recorded in High_K⁺ from eight IHCs (4≤<i>n</i>≤8 patches). Mean channel conductance values was 14.9±0.1 pS. <b>C</b>, Average single Ca²⁺ channel recordings from IHCs in high_Na⁺ extracellular solution (High_Na⁺; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0113750#s4" target="_blank">Methods</a>) plotted on the fit from panel B. Number of IHCs tested is shown. Note that the slope of the linear fit was virtually identical to that shown in panel <b>B</b>.