Fig. 4. Effects of CP1 on IKs channels.
a, b IKs currents in the absence (left) and presence of 2 µM CP1 (right) recorded with 100-s and −120-mV interval pulses between testing voltages. Holding potential: −80 mV; testing potential: −120 to +80 mV; returning potential: −40 mV (a). G–V relations (b). c, d IKs recorded at the same conditions as in (a), except for the interval pulses, was 20 s at −80 mV. e, f IKs in the absence or presence of 10 µM CP1. The voltage protocol was the same as in (b). g, h Current (g) and relative conductance (h) increases of IKs channels by 10 µM CP1. In h, the measured conductance in CP1 at all voltages was divided by the maximum measured conductance in control, and then normalized with the maximum measured conductance in control being 1. i Dose response for ΔV1/2 of G–V relations to different CP1 concentrations as compared with those of KCNQ1 (dashed line).