Objective:To study the expression levels of thromboxane A2(TXA2) and prostacyclin (PGI2) in the plasma,endothelin-1(ET-1)in vascular endothelium,bronchial and alveolar epithelia of lungs,and hemodynamic changes in acute pulmonary thromboembolism(APTE) of rabbit,and to explore the effects of thrombolytic(urokinase,UK)on their expressions. Methods:Twenty four rabbits were randomly divided into a control group,a APTE model group,a UK therapy group,with 8 rabbits each. The APTE model was established by intravenous injection of autologous blood clots. The plasma’s concentrations of TXA2 and PGI2 were examined by radioimmunoassay before and 1 h,2 h,4 h,8 h after injection. The hemodynamic monitoring were used by float catheter. The expression levels of ET-1 in lung vascular endothelium,bronchial and alveolar epithelia were examined by immunohistochemistry. Results:①The radioimmunoassay showed that TXA2 and PGI2 had no diference in the control group at each point;TXA2 and PGI2 in the APTE group increased at 1 h,peaked at 2 h,decreased at 4 h,which also were higher than those in the control group at 1 h,2 h,4 h(P < 0.01). In the UK group,TXA2 and PGI2 increased at 1 h,peaked 2 h,decreased after 2 h,also decreased faster than those in the APTE group at 1 h,2 h and 4 h,respectively(P < 0.01). There were no differences in TXA2 and PGI2 before injection and 8 h after injectionin in each group(P > 0.05). ②Hemodynamic monitoring showed that the PAMP and CVP were no change in the control group;and PAMP and CVP in the APTE group and UK group increased immediately after embolism,peaked at 2 h,then decreased,which also were higher than those in the control group at 1 h,2 h,4 h,8 h(P < 0.01). In the UK group PAMP and CVP also decreased faster than those in the APTE group at 1 h,2 h respectively(P < 0.01). There were no differences at 4 h and 8 h between the APTE group and the UK group. ③The immunohistochemistry results showed in the APTE,the expression levels of ET-1 in lung vascular endothelium,bronchial and alveolar epithelia were significantly higher compared with those in the control group. The UK group was significantly lower in ET-1 as compared to the APTE group. Conclusion:After APTE,TXA2,PGI2,ET-1 participated increasing of pulmonary vascular resistance,and early thrombolytic treatment could decrease TXA2,PGI2,ET-1,also relieved pulmonary vascular resistance.