Figure 2. Dose dependence of ROS-induced ROS release in intact myocardium.

Average O₂⁻ responses of individual hearts subjected to a short (10 min) episode of OS by perfusion with 50 μm (n = 4), 100 μm (n = 4), 200 μm (n = 4) and 400 μm (n = 4) H₂O₂ followed by reperfusion with normal Tyrode solution. The timing of H₂O₂ perfusion is indicated by the double arrow for each heart. The delayed second peak (P2) is clearly evident in 1/4 (50 μm), 2/4 (100 μm), 4/4 (200 μm), and 4/4 (400 μm) H₂O₂ protocols. The arrhythmia score (AS) for each heart is also indicated. All hearts exhibiting P2 had an AS of 5, reflecting incidence of sustained VT/VF.