Figure 3. Real-time HEK-293 cell I_bck subtraction in a dAPC experiment, using a WT SCN5A cDNA-transfected HEK-293 cell.

A, step-ramp voltage protocol and the first AP elicited in a subepicardial model cell. The maximum diastolic potential (MDP) during dAPC was −90 mV (top); Middle: I_Na in the presence of I_bck (arrows) and after I_bck removal (bottom). Note the transient WT late I_Na during AP repolarization. Broken line shows zero current level. B, I–V relationship of I_bck in the experiment shown in A, fit with the scaled polynomial equation (P= 0.39) (see text for details).