I_Kr elicited by voltage clamp conditions (top) in wild-type (left) and N588K/KCNE2 mutant (right) M cell modelling. Notice the different scaling. The voltage clamp protocol and the measurement data [12] are shown in the insets. The currents were elicited by 800 ms lasting depolarizing pulses from a holding potential of −80 mV. The amplitude of the pulses was between −50 and 50 mV with increments of 10 mV. To investigate the deactivating inward tail currents, a repolarizing voltage to −100 mV followed. In the mutant ionic model, the amplitude of the potassium current at depolarizing pulses was increased. The repolarizing voltage step generated a small tail current with an accelerated decay. Normalized current–voltage relationships are shown at the bottom. Amplitudes of the steady-state I_Kr currents are normalized to their values at 0 mV. Short QT mutation abolished rectification of I_Kr and induced a linear relationship for positive potentials.