Fig. 3
From: Late Na+ current produced by human cardiac Na+ channel isoform Nav1.5 is modulated by its β1 subunit
Effects of the β subunits on the I NaL produced by the heterologously expressed human cardiac NaCh isoform α subunit (Nav1.5). a Representative examples of superimposed current traces recorded in tsA201 cells transfected with cDNA encoding human cardiac NaCh α-subunit alone or together with β1 (α + β1) or β2 (α + β2). Shown are averaged (10–20) currents with a single-exponential fit to I NaL decay (solid lines) starting 200 ms after the onset of depolarization. The time constant (τ) values are given in the panel. The current amplitudes are relative to the peak I NaT. The voltage-clamp procedure given in the inset. b, c Statistical analysis of the I NaL/I NaT ratio (b) and the decay time course (c) changes in response to coexpression of α with β subunits. The statistically significant difference (P) in panels b and c was evaluated by ANOVA followed by the Bonferroni’s post hoc test. Bars in panels b and c represent means ± SE, n number of cells. There was no significant difference between α + β1-GFP compared with α + β1 (1:5 cDNA ratio) or for α alone compared with α + β2-GFP for both b and c panels