Abstract: Objective To study the expression changes of catecholamine metabolism related enzymes COMT and MAO in the lung tissues of a rat acute pulmonary embolism (PE) model. Methods We constructed a rat acute PE model. The blood samples were collected by intracardiac puncture at different time points 1h, 8h, 24h and 48h. The mRNA level changes of COMT, MAO-A and MAO-B were identified by semi-quantitative RT-PCR, and the protein level changes of COMT, MAO-A and MAO-B were validated by western blot methods. The serum concentrations of catecholamine were determined by HPLC methods. Results At different time points, the mRNA and protein expression levels of COMT, MAO-A and MAO-B decreased gradually after acute PE. On the contrary, the serum concentrations of epinephrine (EPH) and norepinephrine (NE) increased gradually compared with controls. Conclusion The serum concentrations of catecholamine increased after acute PE because its degradation was suppressed. The study of their expression changes may be helpful to uncover the molecular mechanisms of pulmonary artery hypertension involved in acute PE.