Abstract 361: The Augmentation of Oxygen-sensitive Generation of Oxygen Radicals in Mitochondria and the Attenuation of Hyperoxia-induced Oxidative Stress After Cardiac Arrest

Introduction: Hyperoxia can induce oxidative stress resulting in organ injuries after cardiac arrest (CA). Mitochondrial reactive oxygen species (ROS) are key to understanding its mechanism, however the augmentation of oxygen-sensitive ROS generation caused by CA ( Fig 1 ) has not been well described. Methods: Rats were assigned into: 1) sham with normoxia, 30% O2; 2) sham with hyperoxia, 100% O2; 3) CA with normoxia; and 4) CA with hyperoxia (n=15 for each group). CA was induced by 10-minute asphyxia and CPR was delivered. Neurological deficit score (NDS), histological lung injury score (LIS), survival time were obtained from the CA groups. Carbonyl protein as an oxidative stress indicator was measured at 2 hrs after resuscitation. H2O2 generation from isolated mitochondria were measured ex vivo at a normoxic and hyperoxic condition set up with nitrogen and air saturated medium. Results: Between the CA groups, the normoxia group had a higher 48hr-survival rate (77%), lower NDS (359±140), and lower LIS (4.3±2.9) compared to those (28%, 452±85, 14±2, respectively) of the hyperoxia group (p Conclusions: The normoxic therapy may attenuate organ damage and improve survival of CA. The reduction of augmented mitochondrial ROS generation, which is oxygen-sensitive, would be an important mechanism and therapeutic target of post-CA care.