Figure 5. Sensitivity of I_h to ZD7288.

A, currents elicited by hyperpolarizing voltage steps (1 s duration, from −60 to −130 mV) before and during the bath application of ZD7288 (10-200 μm). B, spontaneous discharges recorded in the current-clamp mode before (Ba) and during (Bb) the bath application of ZD7288 (100 μm). Note that ZD7288 induced a marked decrease in the spontaneous discharge rate and the membrane hyperpolarization (about 4 mV). Bc, the trajectory of the slow depolarization between two spikes before (dark trace) and during (light trace) the application of ZD7288. Note that blockade of I_h by ZD7288 caused a slower time course of the depolarization towards the second spike. C, mean values for the frequency of action potentials before and during the application of ZD7288 (* P < 0.01, n = 6).