A, effects of different channel blockers on the late-onset response elicited by MFB stimulation, as follows: ZD7288 (2 μm), Cs+ (2 mm), SKF96365 (30 μm), co-application of ZD7288 (2 μm) and SKF96365 (30 μm). In this and the following recordings the holding potential was maintained at −80 mV by adjusting the holding current. B, effect of ZD7288 (2 μm) and SKF96365 (30 μm) on the voltage response elicited by hyperpolarizing current step injection. C, effects of sequential application of nimodipine (20 μm) and mibefradil (10 μm) alone and in combination. The inset shows that the depolarizing ramp did not change significantly after nimodipine and mibefradil (20 min application), at least until the pre-potential just below spike threshold.