Effects of SB203580 on I_Ca,V.A, Action of SB203580 on peak I_Ca,V for the entire duration of the experiment. Time course of the peak current during intracellular dialysis with SB203580 (20 μm), at the end of which BK and Leu-Enk were applied sequentially (bars, both at 0.1 μm). Between 0 and 20 min, I_Ca,V was activated every 30 sec. In the remaining portion of the time course, every 10 sec. Other parameters are as in Figure 1. B, C, Action of the inhibitor over a broad range of membrane potentials. They show peak I_Ca,V–voltage relations in two cells, before (open circles) and during (closed circles) application of BK (0.1 μm), and after intracellular dialysis of SKF106978 (B, 20 μm) or SB203580 (C, 20 μm). The current–voltage curves were obtained using a series of 50 msec commands (V_t) of increasing amplitude, at 5 sec intervals. The other explanations are as in Figure 1.