Abstract: Objective: To evaluate the thrombolytic effects of recombinant staphylokinase and compare it with those of recombinant streptokinase. Methods: Thirty Chinese experimental miniature pigs were divided into five groups, namely, solvent control group, positive drug control group and three recombinant staphylokinase groups, six in each group. The thrombus of coronary artery was formed by surgical thoracotomy and direct current stimulation in anesthetized animals. Intravenous administration was started after the thrombus of coronary artery was formed for 30 minutes, and the method of first injection and then constant speed infusion by peristaltic pump was used. The solvent control group was injected intravenously with solvent, the positive drug control group was given recombinant streptokinase 4 mg·kg^-1 intravenously, and the three recombinant staphylokinase groups were given recombinant staphylokinase at the doses of 4, 2 and 1 mg.kg^-1 intravenously. The volume of intravenous injection was 5 ml, which was completed within 1 min, the speed of infusion was 0.5 ml·min^-1, which was completed within 60 min, and the animals were sacrificed 120 minutes later. Before and 30, 60 and 120 min after administration, the venous blood samples were collected. At the end of the experiment, the coronary artery segments of the thrombosis site were taken, and the euglobulin dissolution time (ELT), blood fibrinogen content (FBG), fibrinogen degradation product (FDP) and wound bleeding volume were measured respectively. The coronary thrombolysis rate, myocardial ischemia degree and ischemia range were measured.Results: Compared with the solvent control group, ELT in the experimental group was significantly shortened (P＜0.05 or P＜0.01), FBG degradation in a few experimental animals was more than 20%, FDP was significantly increased (P＜0.05 or P＜0.01), and there was no significant effect on blood pressure and heart rate of small pigs. Compared with the control group, the maximum thrombus area was decreased by 34.3% and 15.4% (P＜0.05) in the high and middle dose groups of the experimental group. Compared with the same dose of recombinant streptokinase, recombinant staphylokinase had stronger thrombolytic effect (P＜0.05 or P＜0.01) on the coronary thrombus caused by electrical stimulation, less bleeding side effects and the same effect on the degree and range of myocardial infarction as recombinant streptokinase. Conclusion: Compared with recombinant streptokinase, recombinant staphylokinase has faster thrombolysis speed, higher fibrin specificity and less bleeding side effects. In general, 2 mg.kg^-1 recombinant staphylokinase has better efficacy and safety.

Key words: recombinant staphylokinase, recombinant streptokinase, thrombolysis, miniature pigs