Property of IK,n in inner hair cells isolated from guinea-pig cochlea

One of the potassium currents, I-K,I-n, is already activated at the resting potential of the cell and thus determines the membrane potential. KCNQ4 channel has been identified as the molecular correlate of I-K,I-n. In the present study, we measured I-K,I-n in acutely isolated IHCs of guinea-pig cochlea using the whole-cell voltage-clamp techniques, and investigated the properties of the currents. I-K,I-n was 70% activated around the resting potential of -60 mV and deactivated on hyperpolarization. I-K,I-n was blocked by the KCNQ-channel blockers, linopirdine (100 mu M) and XE991 (10 mu M), but was insensitive to both I-K,I-f blocker, tetraethylammonium (TEA), and I-K,I-s blocker, 4-aminopyridine (4-AP). There was no significant difference in the size of I-K,I-n between the apical and basal turn IHCs. (C) 2010 Elsevier B.V. All rights reserved.