Figure 1.

Effect of CaMKII inhibition on arrhythmogenicity of metabolic acidification. Representative recordings of epicardial MAPs from hearts perfused with control solution or solution causing metabolic acidification in the absence (a) or presence (b) of CaMKII inhibition (2 μm KN-93). Panels (a) and (b) show recordings during regular 8 Hz pacing and during intrinsic rhythm. Stimulations are indicated by squares under traces. No arrhythmic tendencies were observed during control conditions in the presence or absence of KN-93 (c). Panels (d)–(f) show the numbers of hearts that fired spontaneous APs (d), developed VT during regular pacing (e) and precipitated to VT during intrinsic rhythm (f) during metabolic acidification in the presence and absence of KN-93. *Significant difference between the absence and presence of KN-93 as assessed using Fisher’s exact test.