Figure 3.

Oxidative stress plays a significant role in IR-induced ΔΨ instability.A, cytosolic GSH oxidized during ischemia. On reperfusion, GSH oxidized further early during reperfusion and then partially recovered. CytoGRX ratio (GSSG:GSH) is shown in three cardiomyocytes in the center of a monolayer during IR. The dashed line shows the beginning of reperfusion 60 min. B, transient ΔΨ oscillations during reperfusion do not seem to correlate with the changes in cytosolic glutathione redox potential; however, sustained depolarization of the mitochondrial network of the cardiomyocyte is followed by a further increase in cytosolic oxidative stress. C and D, postischemic ΔΨ oscillations correspond with mitochondrial GSH redox potential. ΔΨ depolarization correlates with GSH oxidation, and ΔΨ recovery correlates with GSH reduction. E, a section of a cell in the center of the reperfused region of a monolayer loaded with TMRM (50 nM) and transfected with mitoGRX. The images correspond with the first oscillation in ΔΨ and mitochondrial redox status in (E) at t0 and t1. The emission signals for each excitation wavelength are shown on the right. F, scatter plot of normalized TMRM measurements versus normalized mitoGRX ratios during reperfusion; aggregate data for nine mitochondrial clusters in separate monolayers subjected to IR are shown. IR, ischemia and reperfusion; TMRM, tetramethylrhodamine methyl ester.