CPVT cells demonstrated rightward and leftward shifts in the voltage-dependent activation and inactivation of <i>I_Ca</i>, respectively.

<p><i>A</i>. Activation kinetics of <i>I_Ca</i> over the whole voltage range were not significantly different between WT (open symbols) and CPVT (filled symbols) cells. <i>B</i>. The time course of inactivation of <i>I_Ca</i>, which encompass slow and fast components, were similar in WT and CPVT cells at all voltages studied. <i>C.</i> Superimposed voltage-dependence of <i>I_Ca</i> activation and inactivation. <i>I_Ca</i> activationis shifted to more positive values in CPVT <i>vs</i> WT cells, whereas inactivation of <i>I_Ca</i> is shifted to more hyperpolarized potential in CPVT cells compared with WT cells. <i>D</i>. Voltage dependence of <i>I_Ca</i> window current () display a bell-shaped voltage-dependence, however, the peak of is reduced in CPVT cells (continuous line) compared to WT cells (dashed line). * P<0.05 and ** P<0.005.