Ensemble-fluctuation analysis of IHC Ca2+ currents
| Cell | NCa [mean ± SEM (n)] | iCa [mean ± SEM (n)] | pmax [mean ± SEM (n)] |
|---|---|---|---|
| 1 | 1776 ± 157 (n = 2) | 0.53 ± 0.03 (n = 3) | 0.87 ± 0.04 (n = 2) |
| 2 | 1635 ± 133 (n = 2) | 0.63 ± 0.02 (n = 4) | 0.89 ± 0.01 (n = 2) |
| 3 | 1894 ± 177 (n = 3) | 0.59 ± 0.01 (n = 10) | 0.86 ± 0.02 (n = 3) |
| 4 | 2030 (n = 1) | 0.57 ± 0.02 (n = 6) | 0.81 (n = 1) |
| 5 | 1909 ± 77 (n = 4) | 0.60 ± 0.01 (n = 2) | 0.76 ± 0.01 (n = 4) |
| 6 | 1449 ± 213 (n = 3) | 0.87 ± 0.01 (n = 3) | 0.82 ± 0.02 (n = 3) |
| 7 | 1262 ± 67 (n = 5) | 0.62 ± 0.03 (n = 5) | 0.72 ± 0.01 (n = 5) |
| 8 | 1580 ± 59 (n = 6) | 0.63 ± 0.01 (n = 6) | 0.79 ± 0.01 (n = 6) |
| 9 | 1867 (n = 1) | 0.60 (n = 1) | 0.84 (n = 1) |
| All | 1711 ± 83 (n = 9) | 0.63 ± 0.03 (n = 9) | 0.82 ± 0.02 (n = 9) |
Fluctuation analysis of Ca2+ channels quantifies NCa, single-channel current (iCa), and pmax, determined by nonstationary fluctuation analysis in nine apical IHCs as described in Figure 1. In seven IHCs, we acquired at least two ensembles of 500 current sweeps and obtained average estimates of the channel parameters. The maximal open probability could be slightly underestimated because we had to limit tail current analysis to start only 100 μs after the repolarization as a result of contaminating capacitative currents. The grand averages represent equally weighted means of the results of the individual cells.