Objective: To investigate the activity of coagulation and fibrinolysis systems in bronchoalveolar lavage fluid (BALF) in lung fibrosis in rats, and to study their role in diagnosis of lung fibrosis.
Methods: Thirty-six Sprague-Dawley rats were randomly divided into 2 groups (n=18 in each group ). Lung fibrosis and control models were made by tracheal instillation bleomycinA(5) (BLMA(5)) (5 mg/kg) and saline. On days 7, 14 and 28, the recalcification time points of normal pooled plasma for studying procoagulation activity (PCA), the levels of von Willebrand Factor (vWF), the activities of Antithrombin-III(AT-III) , plasminogen activity inhibitor-1 (PAI-1) and urokanise-type plasminogen activator (uPA) in BALF were measured respectively.
Results: (1) In BLM group,the recalcification time points in BALF were (56+/-10), (78+/-3) and (172+/-11) seconds respectively, they were (190+/-10), (186+/-8) and (184+/-6) seconds respectively in control group. The difference was significant (P<0.01) except on day 28; (2) The differences in level of vWF and activity of AT-III in BALF were not significant in BLM group versus control group; (3) Activities of PAI-1 in BALF in BLM group were (1.04+/-0.08), (1.47+/-0.06), (3.03+/-0.18) u/mL respectively, while they were (0.66+/-0.11), (0.71+/-0.09), (0.70+/-0.08) u/mL respectively in control group. The difference was significant (P<0.01); (4) Activities of uPA in BALF in BLM group were (0.19+/-0.03), (0.16+/-0.02), (0.12+/-0.05) u/mL respectively, while they were (0.26+/-0.05), (0.25+/-0.06), (0.24+/- 0.07) u/mL respectively. The difference was significant (P<0.01).
Conclusion: The PCA upregulation might be means to diagnose alveolitis. The activity of the fibrinolysis system was injured progressively by PAI-1 activity upregulation and uPA activity downregulation, which might be taken as means to study the occurrence of early lung fibrosis and its development,vWF and AT-III rendered no help in diagnosis of lung fibrosis.