Figure 4. Pharmacological profile of I_CCh.

A, examples of actual traces. Zn²⁺ (500 μm) was added shortly before application of CCh, as it blocks cation channels almost immediately. In contrast, the inhibitory effects of 100 μm 9-AC on I_CCh take much longer to develop and so 9-AC was applied > 20 min before CCh. B, summary of inhibition by various blockers. Vertical axis shows the amplitude of I_CCh in the presence of the blockers normalized to their controls. Note that the values for DIDS, 9-AC and niflumic acid were obtained 20–30 min after the start of application to confirm their maximal effects. The data in Ca²⁺-free solution (0.1 mM EGTA) were obtained 5 min after its introduction. Repeated activation of I_CCh in Ca²⁺-free solution resulted in a gradual decline in amplitude (not shown). Asterisks indicate significant differences with Student's paired t test (P < 0.005).