Figure 3.

Action potential clamp reveals erg current activation during a ramp pulse. A, Recordings of action potentials elicited with a ramp pulse before (Aa) and during (Ab) application of 5 μm E-4031. A Purkinje cell was depolarized by injecting a 1 s ramp pulse from 0 to 200 pA followed by a 200 ms constant current injection of 200 pA (see pulse protocol beneath membrane potential recording of Ab). Dashed lines indicate threshold potential. B–D, Action potential clamp. B, The membrane potential changes shown in Aa were used as a potential template. C, Superimposed membrane currents recorded before (gray) and during (black) application of 5 μm E-4031. Outward and inward currents were cut at 400 and 0 pA, respectively. D, E-4031-sensitive current obtained by subtracting the current trace recorded in the presence of E-4031 from the control.