【作者】 何勇；

【导师】 匡凤梧； 许峰；

【作者基本信息】 重庆医科大学 ， 儿科学， 2003， 硕士

【摘要】 目的　新生儿呼吸窘迫综合症（NRDS）主要是由于早产导致肺表面活性物质（PS）缺乏所致，急性肺损伤(ALI)和急性呼吸窘迫综合症(ARDS)是否也存在PS代谢的变化，PS的改变是否作为重要的发病机理，参与了ALI/ARDS的发生发展尚不清楚。本文通过内毒素（LPS）诱导建立大鼠ALI模型，动态观察总磷脂（TPL）和磷脂各组分的变化，以及肺组织表面活性物质蛋白(SP-A、SP-B)的基因表达，以探索PS在ALI/RADS发生发展中的作用，为我们使用PS制剂治疗ALI/ARDS提供理论依据。材料和方法　成年Wistar 大鼠56只，随机分为两组：对照组(NS组)和肺损伤组（ALI组）。肺损伤组采用LPS诱导建立ALI模型。用定磷法和高效液相色谱法动态监测了NS组和ALI组第1、3、5、7hr大鼠支气管肺泡灌洗液（BALF）中的TPL和磷脂各组分，采用逆转录聚合酶链反应（RT-PCR）的方法检测肺组织SP-A、SP-B的表达情况。此外对肺系数（肺干/湿重比）、BALF中蛋白含量、动脉血PaO2以及肺组织病理学改变也进行了对比分析。结果 与NS组比较，ALI组大鼠出现明显的中毒症状，表现为活动减少，呼吸急促，鼻腔流出泡沬状血性分泌物。动脉PaO2进行性下降。不同时间点的病理切片改变显示出肺间质水肿、炎性细胞浸润、肺泡出血，肺泡内纤维物沉积。肺系数在1、3、5、7hr明显低于NS组（P<0.05），BALF蛋白含量在1、3、5、7hr明显高于NS组（P<0.05）。BALF中TPL在1、3、5、7hr明显低于NS组（P<0.05），卵磷酯胆碱（PC）在3、5、7hr明显低于NS组（P<0.05），TPL、PC呈进行性下降趋势；溶血卵磷脂（LPC）在1、3、5、7hr明显高于NS组（P<0.05），呈进行性升高趋势。肺组织SP-A、SP-BmRNA表达在3、5、7hr明显低于NS组（P<0.05），呈进行性下降趋势。<WP=5>结论　1、注射LPS后动物表现为进行性缺氧、呼吸困难，血PaO2下降，肺系数下降、BALF总蛋白增加及病理学检查提示严重肺水肿、肺泡毛细血管膜通透性增加，肺泡塌陷, 以上均符合ALI改变。说明采用大剂量LPS可成功复制出ALI动物模型。2、ALI存在PS的代谢改变，主要表现在TPL的下降和磷脂组分的改变（PC下降、LPC增高），以及SP-A、SP-BmRNA的表达降低。3、LPS诱导ALI模型中，PS含量的降低和组分的改变是导致肺顺应性下降、肺萎缩塌陷和难以纠正的低氧血症的重要原因之一。4、早期PS替代治疗可能对遏制ALI/ARDS的发生发展有重要意义。更多还原

【Abstract】 Objective Pulmonary surfactant(PS) deficiency is the main cause of neonatal respiratory distress syndrome (NRDS), and surfactant-replacement therapy has achieved great success. Whether the alteration of PS is the main cause of acute lung injury(ALI)/ acute respiratory distress syndrome (ARDS) has not understood clearly. In our experiment, the aim is to study the alterative trend of PS in rats with endotoxin-induced acute lung injury. Methods Fifty-six adult Wistar rats were randomly divided into normal saline (NS) group and ALI group. An equal number of animals in each group were sacrificed after sublingual venous injection of NS or LPS at 1hr, 3hr, 5hr, and 7hr. The levels of mRNA of the surfactant-associated protein-A,-B（SP-A,-B）were measured by reverse transcription polymerase chain reaction (RT-PCR). The content and component of PS in the bromchoalveolar lavage fluid (BALF) were measured by high performance liquid chromatography (HPLC). In addition, lung dry/wet weight ratio, the protein content of BALF, alveolar oxygen partial pressure (PaO2) and histological changes were performed.Results Compared to NS group, in ALI group were observed that the serious intoxical symptom: activity decreace, tachypnoea, and lower PaO2. The histological changes in ALI group show that diffuse alveolar damage, inflammatory cells were found increasingly in capillaries, interstitial tissue, airspaces. Interstitial edema and alveolar haemorrhagia can be found. Lung dry/wet weight ratio at 1、3、5、7hr were lower than the NS group(P<0.05). the content of BALF protein at 1、3、5、7hr were higher than the NS group(P<0.05), PaO2 at 3、5、7hr were lower than NS group(P<0.05). TPL of BALF at 1、3、5、7hr were lower than the NS group(P<0.05), phosphatidylcholine(PC) at 3、5、7hr were lower than the NS group(P<0.05) and decreased<WP=7>progressively. Lysophosphatidylcholine (LPC) at 1、3、5、7hr were higher than the NS group(P<0.05) , and increased progressively. the expression contents of SP-A, SP-B, mRNA at 3、5、7hr were less than the NS group(P<0.05), and decreased progressively.Conclusion 1. After injection of LPS, the rats were observed that the tachypnoea, and the blood gas show that decreased PaO2 remarkedly, the histological changes show that interstitial oedema and alveolar haemorrhagia which were coincided with human ALI clinical criteria. The current research successfully established a rat model of LPS-induced acute lung injury(ALI).2. The changed metabolism of PS exists in the pathogenesis of ALI, which mainly shows that the decreased TPL、PC , increased LPC and the decreased expression of SP-A, SP-B mRNA .3. The decreased content and changed components of PS maybe play an important role in a further decrease in pulmonary compliance, lead to the alveoli collapse, atelectasis and severe hypoxemia in ALI.4. PS replacement therapy may be an effective method for ALI/ARDS.更多还原