Cell cultures
Human embryonic kidney 293 (HEK 293) cells were used. The cells were grown in high-glucose Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum and 1% streptomycin at 37°C in a 5% CO2 atmosphere. The cells were transfected with the pcDNA3.1 vector containing either WT Nav1.5 cDNA (1𝛍 g) or Nav1.5/Q1491H and G1481V mutants with the pIRES2/EGFP vector containing β1 subunit cDNA (1 𝛍 g) in 10-cm cell culture dishes using the calcium phosphate method as previously reported14.