NOS2 and myocardial ischemia: However, in response to myocardial ischemia, enhanced iNOS/NO production led to the formation of peroxynitrite and its associated oxidative stress, which mediated the detrimental effects of iNOS/NO, whereas ischemic preconditioning markedly enhances the ability of the heart to withstand a subsequent ischemic injury and is closely associated with the upregulation of antioxidant defense system, which eliminates the increased oxidative stress [63].