Fig. 2. Time constant of verapamil blockade of hKv1.5 current during depolarization. (A) Superimposed hKv1.5 currents recorded during the depolarizing step to 0 mV in the absence and presence of verapamil (upper panel). The current ratio was obtained by dividing hKv1.5 current in the presence of verapamil (IVerapamil) by that in control (IControl) and fitted with a single exponential function, yielding the time constant for channel blockade (t). (B) Time constant (t) for channel blockade at various test potentials. *, P<0.05 versus -10 mV.