Figure 4.

Concomitant responses to PIP₂ of cotransfected hERG and KCNE1-KCNQ1. (A) Measured currents of a representative cell (protocol shown in the inset). hERG current was computed from the recovery from inactivation (KCNE1-KCNQ1 does not inactivate); KCNE1-KCNQ1 current was computed from the current increase during the prepulse (hERG current is stable after a few milliseconds at high potential). Currents are shown after excision (control, t = 5 s), after rundown (t = 290 s), and after PIP₂ addition (t = 780 s; 5 μmol/L PIP₂ is added at t = 315 s). (B) Kinetics of hERG (solid circles) and KCNE1-KCNQ1 (open circles) currents of a representative cell (the same as in A). (Upper graph) Current amplitudes. (Lower graph) Current amplitudes after PIP₂ addition normalized to their steady-state values after complete PIP₂ effect. (C) hERG versus KCNE1-KCNQ1 normalized current amplitudes during PIP₂ application (N = 11 cells). hERG and KCNE1-KCNQ1 currents are normalized to their steady state after PIP₂ addition.