Inhibition of Ih in vestibular hair cells. A, A representative family of traces from a wild-type vestibular hair cell. B, C, Representative families of currents from wild-type cells after application of 100 μM ZD7288 (B) or 10 μM Cilobradine (C). While the fast inward rectifier IK1 remained, Ih was completely blocked in both cases. D, A representative family of currents from a GFP-positive cell with residual Ih after transfection with the HCN2-AYA construct. In 12 of 16 cells, Ih was completely absent and the currents resembled those seen in B and C. In the remaining 4 cells, the current was significantly reduced. E, Representative currents from a neighboring GFP-negative cell. The cell was not transfected and the currents resembled those recorded from wild-type controls, as shown in panel A. F, DIC image of a GFP-positive cell. Scale bar = 10 μm. G, Bar graph summarizing the conductance values from 63 wild-type cells, 5 cells after application of ZD7288, 7 cells after application of Cilobradine, 16 cells GFP-positive for HCN2-AYA, and 8 GFP-negative cells. Asterisks mark statistically significant differences (p<0.001) relative to wild-type (WT).