Figure 3. Pharmacological characterization of the two outward currents I_r and I_s.

I_r was analysed at the potential +70 mV, whereas I_s was tested at +20 mV to avoid contamination by I_r (see Methods). A, effects of the K⁺ channel blockers Ba²⁺ (1 mm), 4-aminopyridine (4-AP, 3 mm), E-4031 (5 μm), HMR1556 (1 μm), linopirdine (10 μm) and of the chloride channel blocker DIDS (200 μm). Outward current amplitudes in the presence of blockers were normalized to predrug amplitudes. Numbers in columns give the number of cells tested. B, effects of tetraethylammonium on outward current amplitudes. The effects of all compounds were reversible upon washout. *P < 0.05, **P < 0.01, ***P < 0.001; Student's paired t test.