Inactivation kinetics of I1495F. A, Time constant of fast inactivation for WT (filled circles, n = 39) and I1495F (open circles, n = 14) showing an additional slow component (open squares,n = 14) for the HyperKPP mutant channels.B, Steady-state fast inactivation. HEK 293 cells were subjected to a protocol described in Materials and Methods to generate the inactivation curves for WT (filled circles,n = 43) and I1495F (open circles,n = 31).