急性肺栓塞大鼠肺泡Ⅱ型上皮细胞形态及功能变化

Morphological and functional changes of type Ⅱ pneumonocytes in rats after acute pulmonary embolism

目的探讨急性肺栓塞大鼠肺泡Ⅱ型上皮细胞功能及形态的变化。方法 16只雄性SD大鼠以随机数字表法随机分为对照组、栓塞组,每组8只。栓塞组以明胶海绵溶液经颈静脉注入制备大鼠肺栓塞模型,经右心导管测定肺动脉压、心率、呼吸频率,并行动脉血气分析;对照组手术过程同栓塞组,颈静脉注入同等体积生理盐水。实验大鼠于造模后24 h时处死,取肺组织制备病理切片,HE染色光镜下观察肺组织病理变化,电镜下观察Ⅱ型上皮细胞形态学改变;留取支气管肺泡灌洗液(BALF)行磷脂测定,肺组织行肺表面活性物质相关蛋白A(SPA)蛋白及mRNA水平测定。结果对照组和栓塞组大鼠肺动脉平均压、动脉血氧分压(单位:mmHg)比较均有统计学差异(14.2±4.1 vs 26.1±7.5,P<0.05;94.1±8.8 vs 80.5±5.8,P<0.05)。对照组和栓塞组肺泡灌洗液磷脂水平分别为(374.17±36.55)mg/100 ml、(311.67±48.56)mg/100 ml(P<0.05)。栓塞组肺组织SPA蛋白、mRNA水平均明显低于对照组(P<0.05)。光镜下24 h时栓塞组大鼠肺组织可见多个血管腔有明胶海绵栓塞;电镜下,对照组大鼠肺泡Ⅱ型上皮细胞形态规则,线粒体、内质网等细胞器丰富,板层小体排列整齐,肺泡表面活性物质层连续完整;栓塞组大鼠Ⅱ型上皮细胞形态欠规则,线粒体肿胀、嵴断裂,板层小体空泡化,肺泡表面活性物质层连续性中断。结论急性肺栓塞后大鼠肺泡Ⅱ型上皮细胞功能及形态均发生明显变化,产生表面活性物质能力显著降低,可能在肺栓塞动脉低氧血症中起重要作用。

Objective To explore the changes of morphology and function of type Ⅱ pneumonocytes in rats with acute pulmonary embolism.Methods Sixteen male SD rats were randomized into control group（n=8） and embolism group（n=8）.The rats were injected with medical gelfoam microspheres via jugular vein to induce PE model in embolism group,while in control group the rats were injected with saline instead of gelfoam granule solution.They were sacrificed at 24 h after establishing PE model.Pulmonary artery pressure,heart rate and respiratory rate were detected by right heart catheterization and artery blood gas was analyzed at 24 h.Bronchoalveolar lavage fluid（BALF） was collected for detecting the levels of phospholipid.Lung tissue was dyed with HE and the morphology of type Ⅱ pneumonocytes was observed under electric microscope.RT-PCR and Western blot were used to study the expression of SPA mRNA and SPA protein in lung tissues.Results The mean pulmonary pressure and artery oxygen blood pressure were significantly different between control group and embolism group[（14.2±4.1）mmHg vs（26.1±7.52）mmHg,P〈0.05;（94.1±8.8）mmHg vs（80.5±5.8）mmHg,P〈0.05].The levels of phospholipid in BALF were（374.17±36.55）mg/100 ml and 311.67±48.56）mg/100 ml in control group and embolism group,respectively（P0.05）.The expression of SPA mRNA and protein was significantly lower in embolism group than in control group（0.83±0.33 vs 1.43±0.51,P〈0.05;0.44±0.18 vs 1.00±0.00,P〈0.05）.At 24 h,pulmonary arteries were seen emboliation with gelfoam under microscope.The microvillus of type Ⅱ pneumocytes reduced and desquamated under eletromicroscope,the mitochondria was bulged with fractured ridge and irregular empty lamina bodies,and the continuity of surfactant layer was interrupted.Conclusion The morphology and function of type Ⅱ pneumonocytes are changed significantly in acute pulmonary embolism rats,with decreased production of surfactant,which may play an important role in hypoxemia of pulmonary embolism.