大鼠注射内毒素后１～７２ｈ６个时相点，肺组织主要病变为充血、瘀血、水肿，不同程度的肺萎陷；肺泡Ⅱ型上皮（ＰⅡ）肿胀、退变。肺组织匀浆表面活性物质（ＰＳ）含量及活性下降，肺泡隔面积密度相应增加，二者呈显著负相关（ｒ＝－０．９３９５，Ｐ＜０．０１）。于注射内毒素后１～４８ｈ改变最为明显。结果表明，内毒素可直接或间接致ＰⅡ及ＰＳ系统受损，进而促进肺水肿、肺萎陷的发生和呼吸窘迫综合征的形成。 At 1 hour and 72 hours after endotoxin injection, the main pathological changes in lung tissues were congestion, blood stasis, edema and varying degrees of lung collapse. The swelling and degeneration of type Ⅱ alveolar epithelium (PⅡ) were observed. The content and activity of surfactant (PS) and the density of alveolar septa in lung tissue homogenate increased significantly (r = -0.9395, P <0.01). 1 to 48h after injection of endotoxin changes the most obvious. The results showed that endotoxin could directly or indirectly lead to impaired PII and PS system, and then promote pulmonary edema, lung collapse and respiratory distress syndrome.