Daltroban (BM-13505) (1 mg/kg; i.v.; per hour) exerts protective effect in reperfusion injury following acute myocardial ischemia in cats. In comparison with vehicle (physiological saline)-treated cats, Daltroban (20 mg/kg per hour i.v.) reduces the ischaemia-induced rise in the ST segment and prevented the development of a Q-wave in the ECG during reperfusion. Daltroban protects the myocardium from ischaemic injury and that this effect involves prevention of ischaemia-induced leukocytosis.