Fig. 2.

Incidences of arrhythmic activity in WT, Scn5a+/Δ and Scn5a+/− hearts subjected to the extrasystolic stimulation procedure. Percentage of WT (a), Scn5a+/Δ (b) and Scn5a+/− (c) hearts demonstrating arrhythmic activity during regular stimulation (i) and during the extrasystolic stimulation procedure (ii). In both these cases, MAPs were obtained during treatment with control solution (A) and with solutions containing 1 μM flecainide (B), 1 μM quinidine (C) and 10 μM quinidine (D). Hashing indicates hearts demonstrating arrhythmic activity, and dots indicate hearts not demonstrating such activity