Decreased Na_v1.5 expression in <i>Scn5a</i>^+/− mice.

<p><b>A.</b> Representative Western blots showing the expression levels of Na_v1.5 in WT mice and <i>Scn5a</i>^+/− mice (mean age = 18±1 weeks) with a mild or a severe phenotype. Protein loading was controlled by anti-actin immunoblotting. <b>B.</b> Quantification of Na_v1.5 expression in WT mice (open bars) and <i>Scn5a</i>^+/− mice with mild (grey bars) and severe (black bars) phenotype was performed on Western blots from 10 mice in each group by normalizing the intensities of the Na_v1.5 bands to the actin bands. ***, p<0.001 <i>versus</i> WT; †, p<0.05 <i>versus</i> mild <i>Scn5a</i>^+/− mice. <b>C.</b> Confocal images of Na_v1.5 in ventricular cardiomyocytes isolated from WT mice (left panel) and <i>Scn5a</i>^+/− mice with mild (middle panel) and severe (right panel) phenotype. Scale bar, 20 µm. In <i>Scn5a</i>^+/− images presented, a WT cardiomyocyte is also included in the image frame (yellow arrows) to illustrate the clear difference in WT <i>versus Scn5a</i>^+/− intercalated disc staining intensities.