Action potentials (APs) were triggered by FCCP-enhanced Ca_i²⁺ waves.

<p><b>A</b>. A line-scan image along the long axis of the cell (A-a), whole-cell Ca fluorescence intensity (A-b), and membrane potential (A-c), were recorded simultaneously from a ventricular myocyte. CaWs (W) and sub-theshold depolarizations (SD) were exacerbated by FCCP (100 nM) so that triggered APs/activities (TA) and Ca transients (T) were induced. <b>B</b>. Summary data showing that FCCP (100 nM) markedly increased the incidence of TAs (**<i>p</i> < 0.01 vs. control, n = 4).