目的观察博莱霉素（ＢＭ）致肺间质纤维化大鼠肺泡上皮通透性（ＬＥＰ）的改变及糖皮质类固醇（ＧＣ）对其的影响。方法将５８只成年雄性Ｗｉｓｔａｒ大鼠分为对照组及疾病组（包括７天、１４天非治疗组及ＧＣ治疗组）。气管内一次性注入ＢＭ，制作肺间质纤维化模型，雾化吸入９９ｍＴｃＤＴＰＡ气溶胶测定ＬＥＰ。结果ＧＣ治疗组第７天时，ＬＥＰ较非治疗组降低，支气管肺泡灌洗液中白蛋白及碱性磷酸酶较非治疗组明显下降，但仍高于对照组；ＬＥＰ与支气管肺泡灌洗液中白蛋白及碱性磷酸酶呈正相关（ｒ＝０７８和０７６，Ｐ均＝００１）。结论ＧＣ可降低ＢＭ致肺间质纤维化早期的ＬＥＰ；ＬＥＰ愈高，肺泡上皮的损伤愈重，ＬＥＰ可作为检测肺泡上皮损伤的敏感、无创性指标 Objective To observe the changes of alveolar epithelial permeability (LEP) in bleomycin (BM) -induced pulmonary interstitial fibrosis and the effects of glucocorticoid (GC) on it. Methods Fifty - eight adult male Wistar rats were divided into control group and disease group (including 7 days, 14 days non - treatment group and GC treatment group). One-time tracheal injection of BM, making pulmonary interstitial fibrosis model, inhaled 99mTc DTPA aerosol determination of LEP. Results On the seventh day after GC treatment, the LEP was lower than that of the non-treatment group and the level of albumin and alkaline phosphatase in bronchoalveolar lavage fluid was significantly lower than that of the non-treatment group, but still higher than that of the control group. LEP and bronchoalveolar lavage fluid Albumin and alkaline phosphatase were positively correlated (r = 078 and 076, P = 001). Conclusions GC can reduce the LEP in the early stages of pulmonary fibrosis induced by BM. The higher the LEP is, the more damage the alveolar epithelium. The LEP can be used as a sensitive and noninvasive index to detect alveolar epithelial injury