Figure 6. Role of IMAC in RIRR and arrhythmias in intact myocardium.

A, average normalized O₂⁻ responses of control (blue, n = 4) and 64 μm 4′-Cl-DZP (red, n = 4)-treated hearts to perfusion with 200 μm H₂O₂ for 10 min. In the treatment group, 4′-Cl-DZP perfusion was introduced 10 min prior to the H₂O₂ challenge and maintained throughout the entire protocol. The timing of H₂O₂ challenge is indicated by the red arrow. B, representative volume-conducted ECG traces from control and 4′-Cl-DZP-treated hearts challenged with an identical H₂O₂ perfusion protocol indicating the presence and absence of sustained VT in control and 4′-Cl-DZP-treated hearts, respectively. Time of onset of VT/VF in control (black), CsA- (blue), and 4′-Cl-DZP- (red) treated hearts is plotted. Open red circles indicate absence of arrhythmias at the end of the experimental protocol in 4′-Cl-DZP hearts. 100% of CsA- and 50% of 4′-Cl-DZP-treated hearts exhibited VT/VF. Time of onset was earlier in CsA-treated hearts.