RESEARCH ARTICLE Reversible Blockade of Complex I or Inhibition of PKCb Reduces Activation and Mitochondria Translocation of p66Shc to Preserve Cardiac Function after Ischemia

Aim: Excess mitochondrial reactive oxygen species (mROS) play a vital role in cardiac ischemia reperfusion (IR) injury. P66Shc, a splice variant of the ShcA adaptor protein family, enhances mROS production by oxidizing reduced cytochrome c to yield H2O2. Ablation of p66 Shc protects against IR injury, but it is unknown if and when p66Shc is activated during cardiac ischemia and/or reperfusion and if attenuating complex I electron transfer or deactivating PKCb alters p66Shc activation during IR is associated with cardioprotection. Methods: Isolated guinea pig hearts were perfused and subjected to increasing periods of ischemia and reperfusion with or without amobarbital, a complex I blocker, or hispidin, a PKCb inhibitor. Phosphorylation of p66Shc at serine 36 and levels of p66Shc in mitochondria and cytosol were measured. Cardiac functional variables and redox states were monitored online before, during and after ischemia. Infarct size was assessed in some hearts after 120 min reperfusion