MT channel Ca2+ permeability in cochlear hair cells of wild-type and Tmc mutants
| Hair cell location | Wild type | Tmc1dn/dn | Tmc2−/− | Tmc1dn/dn Tmc2−/− |
| OHC apex | 6.1 ± 0.7a (7) | 5.9 ± 0.2 (3) | 4.4 ± 0.1 (5) | 1.9 ± 0.07 (6) |
| OHC base | 4.6 ± 0.5 (12) | 6.3 ± 0.2 (4) | 3.9 ± 0.2 (6) | 1.8 ± 0.04 (3) |
| IHC apex | 5.7 ± 0.4a (13) | 6.6 ± 0.6 (3) | 4.5 ± 0.2 (6) |
| Hair cell location | Wild type | Tmc1dn/dn | Tmc2−/− | Tmc1dn/dn Tmc2−/− |
| OHC apex | 6.1 ± 0.7a (7) | 5.9 ± 0.2 (3) | 4.4 ± 0.1 (5) | 1.9 ± 0.07 (6) |
| OHC base | 4.6 ± 0.5 (12) | 6.3 ± 0.2 (4) | 3.9 ± 0.2 (6) | 1.8 ± 0.04 (3) |
| IHC apex | 5.7 ± 0.4a (13) | 6.6 ± 0.6 (3) | 4.5 ± 0.2 (6) |
Mean ± SEM (number of measurements) of MT channel permeability to Ca2+ relative to Cs+ (PCa/PCs) for OHCs and IHCs in wild-type, Tmc1dn/dn, Tmc2−/−, and Tmc1dn/dn Tmc2−/− double mutants in neonatal mice of P2–P6. Data are summarized from Kim and Fettiplace (2013) and Kim et al. (2013).
In mice older than P6, the Ca2+ permeability decreases to 4.6 ± 0.1 (n = 6) in apical OHCs, the same as that at the base, but the Ca2+ permeability in IHCs remains high at 5.8 ± 0.4 (n = 5).