Peroxynitrite Produced During Cardiac Ischemia‐Reperfusion Injury Induces Nitration of Mitochondrial Voltage‐Dependent Anion Channel

Excess superoxide (O 2 •− ) and nitric oxide (NO • ) produced during cardiac ischemia‐reperfusion (IR) injury react to form peroxynitrite (ONOO − ). ONOO − induces protein tyrosine nitration (tyr N ) that may alter protein structure and cause dysfunction. The voltage‐dependent anion channel (VDAC) plays a crucial role in regulating mitochondrial bioenergetics and contributes to apoptosis. We previously reported VDAC tyr N during IR injury, but whether VDAC tyr N is due to overproduction of O 2 •− and NO •− is unknown. In this study, we determined if resveratrol (O 2 •− scavenger) and /or L‐NAME (NOS inhibitor) reduced VDAC tyr N induced by IR. Isolated guinea pig hearts were perfused with KR buffer for 40 min (time control; TC), or for 30 min of ischemia plus 10 min of reperfusion (IR) with or without resveratrol and/or L‐NAME treatment. Mitochondria were isolated after each treatment. VDAC tyr N were detected by western blot using anti‐nitrotyrosine antibody with mitochondrial protein lysate. We also determined if VDAC could be nitrated by exogenous ONOO − using recombinant VDAC in vitro. We found higher VDAC tyr N in IR than in TC. L‐NAME + resveratrol treatment decreased the VDAC tyr N compared to the IR alone. We also showed that ONOO − induced recombinant VDAC tyr N in a dose‐dependent manner. These results indicate that VDAC tyr N during IR injury results from overproduction of O 2 •− and NO • , yielding the deleterious product ONOO − .