Mutation S652L accelerates voltage-dependent inactivation and reduces persistent currents. (a, b) Inactivation kinetics of WTL vs S652LL (A) and WTS vs S652LS (B) during a prolonged (5-s) depolarization to Vmax with Ca2+ (CDI and VDI) or Ba2+ (VDI only; dim colors) as a charge carrier. Data are presented as mean ± SEM for the n-numbers indicated; for statistics see Table 2. c, d Persistent currents were determined after 5-s long depolarizations to different potentials and are expressed as % of the peak current amplitude measured by a preceding 20 ms pre-pulse to Vmax. Statistics: two-way ANOVA followed by Bonferroni post hoc test, *p < 0.05, ***p < 0.001. Data are represented as mean ± SEM for the n-numbers indicated.