The effects of the triazolobenzodiazepine anxiolytic, alprazolam, on the incidence of ischemia- and reperfusion-induced ventricular arrhythmias was studied in the isolated buffer-perfused rat heart. Administration of alprazolam before and after myocardial ischemia resulted in a dosage-dependent reduction in the incidence and duration of reperfusion-induced ventricular fibrillation and was significant at a concentration of 1 X 10(-3) mol/l alprazolam. This cardioprotective effect was not extended to ischemia-induced ventricular dysrhythmias. In conclusion, our findings provide evidence that benzodiazepine drugs are able to provide a cardioprotective effect in the experimental setting of myocardial ischemia followed by coronary reperfusion.