2.8. Bronchoalveolar Lavage and Determination of Protein Content

The mice were anesthetized and fixed. The chest of the mice was cut open. The trachea and lungs were exposed. The trachea was cut open and a catheter was inserted and fixed. A total of 0.3 mL PBS (pH 7.4) was injected into the lung through a catheter for 30 s, the lavage solution was extracted, and this injection and extraction process was repeated three times. The obtained alveolar lavage fluid was centrifuged at 1500× g r/min at 4 °C for 10 min to obtain the supernatant, which was stored in a refrigerator at −20 °C for measurement [11]. The protein content of alveolar lavage fluid was measured by BCA protein quantitative method.