The aim of our study was to evaluate the acute effect of epirubicin (EPI), an anthracycline anticancer drug, on the evolution of cardiac functional parameters and production of reactive oxygen/nitrogen species (RONS). Isolated perfused rat hearts were subjected to 70 minutes of EPI (10.3 microM) infusion and to 5 minutes of isoproterenol (ISO, 0.1 microM) at the end of the protocol. Coronary flow (CF), left ventricular developed pressure (LVDP), and lactate dehydrogenase (LDH) release in the coronary effluents were evaluated throughout the protocol. RONS were detected in the coronary effluents by electron spin resonance spectroscopy with a spin probe, 1-hydroxy-3-carboxy-pyrrolidine (CP-H, 0.1 mM). EPI induced a reduction in CF and in LVDP (P < 0.001). ISO infusion enhanced CF and RPP in the control group; in the EPI group, these increases were significantly impaired. Release of LDH was significantly increased during EPI infusion (P < 0.001). RONS was 2.5 times greater in the EPI group than in the control group (P < 0.05). In conclusion, a significant deterioration in cardiac function was observed after EPI perfusion and was associated with cellular injury and the generation of myocardial RONS. Further investigations are now needed to determine whether new cardioprotective agents targeting oxidative stress may reduce the incidence of anthracycline-induced cardiotoxicity.