Objective To investigate the expressions of plasminogen activator inhibitor-1 (PAI-1), activated protein C (APC) and the histology structures of the rat lung tissues in the different hypoxia time; and to investigate the effects of breviscapine to the above changes. Methods Eighty SD rats were randomly divided into A (control), B (hypoxia), C (hypoxia+low-dose breviscapine) and D (hypoxia+high-dose breviscopine) groups with 20 rats in each group. Each hypoxia group placed daily pressure (101 kpa, 10% O2) environment for 8 h, low-dose and high-dose breviscapine groups were given of 10 mg/kg, 40 mg/kg breviscapine by intraperitoneal injection. On the 3rd,7th,14th and 21st d, 5 rats were randomly taken from each group and were killed for examination. The hematoxylin and eosin stain (HE stain) was performed for observation on pathological changes in the rat lung tissues. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed for detection of the mRNA levels of transforming growth factor (TGF-β1) and Plasminogen activator inhibitor-1 (PAI-1). Western blot analysis was applied for detection of the expression of PAI-1. Besides, APC in the bronchoalveolar lavage fluid (BALF) was determined by ELISA. Results ① The HE stain demonstrated that compared with A group, the degree of thickening of alveolar septal the mRNA expressions of TGF-β1 and PAI-1, and the protein expressions of PAI-1 in B group were increased (PPPAI-1 and TGF-β1 (r=0.936, PTGF-β1 and PAI-1, and the protein expression of PAI-1 were decreased (PP
