Ih contributes to neonatal (P1–8) SGN membrane responses. (A) Comparison of resting membrane potential (Vrest) before and after treatment with 100 µM ZD7288 in WT SGNs. Note that ZD7288 hyperpolarizes WT SGN Vrest to potentials comparable with that of Hcn1−/− SGNs. (B) Representative current-clamp recordings in WT SGNs (P3) in response to 2-s hyperpolarizing current (5 pA) injections. Note the depolarizing sag and rebound potential at the end of hyperpolarizing current step in the control condition (black trace). In the presence of 100 µM ZD7288, the depolarization sag and rebound potential are abolished (red trace). (C) Quantification of sag amplitude before and after treatment with 100 µM ZD7288 from the same cells. Sag amplitude was measured as the difference between the peak hyperpolarization and the steady-state potential near the end of the current step. Error bars equal +1 SD. *, P < 0.05; ***, P < 0.001.
