Figure 1.

Effects of isoprenaline (ISO) on rapid delayed rectifier K⁺ (I_Kr) current. (A–C) I_Kr current traces showing tail currents as relaxation of current during repolarization to −40 mV under control conditions (A), following exposure to 100 nM ISO (B) and after washing the cells in ISO-free solution (C). (D) Representative experiment demonstrating the effect of 100 nM ISO on I_Kr and the full suppression of the ISO-induced current by 1 µM E-4041. (E) Voltage-dependence of the activation of I_Kr in control and in the presence of 100 nM ISO. Tail current amplitudes measured at each test potential was normalized to the respective tail current obtained at +20 mV. Symbols and bars are means ± SEM, n= 4.