Figure 4. RIRR-mediated arrhythmias in intact myocardium.

A, representative O₂⁻ responses to OS in P2 (–) and P2 (+) hearts. Contour maps of O₂⁻ indicating absence (top) and presence (bottom) of increased O₂⁻ levels in hearts perfused with different concentrations of H₂O₂. B, volume-conducted ECG traces recorded from P2 (+) but not P2 (–) hearts exhibit incidence of sustained arrhythmias. Arrhythmia severity was quantified as an arrhythmia score in hearts challenged by increasing concentrations of H₂O₂ for 10 min (bottom, left). P2 (–) hearts exhibited a significantly lower AS value compared to P2 (+) hearts (bottom, right).