Electrophysiological Phenotype of the Cardiac Sodium Channel when CoExpressed with V14I-CAV3, T78M-CAV3, or L79R-CAV3 Mutations. Late INa was measured with a testing -40 mV potential of 700 ms duration for a holding potential of -140 mV. A) Demonstrates the persistent and increased sodium channel late INa current associated with coexpressed wild-type SCN5A and mutant CAV3. B) Summarized is the late INa current represented as a percent (% ± SD) of peak INa. All the values were analyzed by one-way ANOVA across pcDNA3 (SCN5A alone), WT Cav3 (SCN5A + Cav3) and three Cav3 mutants (SCN5A + mutant Cav3). *Statistically significant values (p<0.05). The amount of late current is comparable to other functionally characterized LQT3-associated SCN5A mutations (i.e. ∆KPQ-SCN5A, white box, Nagatomo et al. Am J Physiol 1998; 275(6 Pt 2):H2016-2024)