RESUMO
<p><b>OBJECTIVE</b>To investigate how transient low dose of hydroperoxide pretreatment prevents cardiac ischemia/reperfusion injury.</p><p><b>METHODS</b>SD rats were divided into 4 groups: sham operation (Sham), standard ischemia/reperfusion (I/R), ischemic preconditioning (IPC) and IR preceded by low H2O2 treatment. Cardiac function and injury parameter were compared among groups.</p><p><b>RESULTS</b>IPC protected reperfusion injury and improved cardiac function. Low H2O2 treatment played a role in cardioprotection similar to IPC. Low H2O2 was indeed generated in the early phase of simulated ischemia and attenuated cytochrome c release induced by high Ca2+ in isolated mitochondria.</p><p><b>CONCLUSION</b>Low H2O2 plays a critical role in cardioprotection probably by inhibiting mitochondrial permeability transition.</p>