呼气末正压通气对海水型呼吸窘迫综合征兔呼吸功能和肺泡表面活性蛋白表达的影响

Effects of positive end expiratory pressure ventilation upon respiratory function and hydrophobic surfactants proteins in rabbit with seawater respiratory distress syndrome

目的探讨呼气末正压（PEEP）通气对海水型呼吸窘迫综合征（SW-RDS）兔呼吸功能和肺泡表面活性物质相关蛋白质B（SP-B）／SP-C表达的影响。方法健康雌性新西兰兔24只，随机分为常规通气组、PEEP通气组（PEEP组）和对照组，每组8只。均于麻醉后气管插管行常规机械通气20min，用人工海水经气管插管灌肺法制备SW-RDS。常规通气组维持原参数通气6h；PEEP组在原通气参数设置基础上给予PEEP（8cmH2O）通气治疗2h，之后恢复原参数通气4h；对照组模型制作成功后，撤去呼吸机，不进行任何治疗。通气过程中持续监测氧合指数和肺顺应性。机械通气结束后处死动物（对照组取自然死亡动物），收集左肺支气管肺泡灌洗液测定肺泡表面张力，取右肺组织提取RNA及蛋白，分别以实时PCR和蛋白质印迹法测定肺组织SP-B／SP-C mRNA及SP-B蛋白的表达。结果SW-RDS建模成功后3组兔氧合指数和肺顺应性均明显下降，组间差异无统计学意义。对照组动物脱离呼吸机后15min内全部死亡。PEEP组经PEEP通气治疗30min氧合指数和肺顺应性即明显改善，而常规通气组无明显改善，组间差异有统计学意义（P〈0.05）。常规通气组肺泡最小表面张力（mN／m，30.8±6.3）明显高于PEEP组（21.1±4.4，P〈0.05）和对照组（23.6±4.6，P〈0.05）；SP-B／SP-C mRNA相对表达量（0.37±0.15／0.60±0.19）和SP-B蛋白相对丰度（0.38±0.17）明显低于PEEP组（0.73±0.15／0.92±0.40，0.52±0.22，均P〈0.05）。结论PEEP通气能明显改善SW-RDS兔的氧合指数和肺顺应性，这不仅与其单纯机械作用有关，同时与其促进SP-B／SP-C基因转录和翻译密切相关。

Objective To investigate the effects of positive end-expiratory pressure （PEEP） ventilation upon respiratory function and lung surfactant protein B （SP-B）/ SP-C in seawater respiratory distress syndrome （SW-RDS） rabbit. Methods Twenty-four female New Zealand rabbits were randomly equally divided into three groups：conventional mechanical ventilation （CMV） group, PEEP group, and control group. After anesthesia and tracheal intubation followed by 20 minutes of CMV, SW-RDS model was established by lung perfusion of artificial seawater through tracheal intubation. Then the CMV group ventilated for 6 hours （ each parameter unchanged） ; PEEP group ventilated with PEEP of 8 cm H20 for 2 hours based on prior parameters and subsequently with CMV for 4 hours; control group without ventilation after modeling. Oxygenation indices and lung compliance were continuously monitored during ventilation. After ventilation, the rabbits in study groups were sacrificed while those dying a natural death in the control group selected. Bronchoalveolar lavage fluid of the left lung was collected to determine the alveolar surface tension and the right lung was harvested to measure the mRNA expression of SP-B/SP-C by real-time PCR as well as SP-B protein by Western blotting. Results After modeling, the data of lung compliance and oxy, genation indices became significantly worse in every group but without statistical difference in three groups. All rabbits in control group died within 15 minutes of ventilator withdrawal. After receiving PEEP ventilation for 30 minutes, these indices significantly improved compared with CMV group in which there was no significant change of the indices （ P 〈 0.05 ）. Minimal alveolar surface tension in CMV group （mN/m, 30.8±6.3） was greater than in PEEP group （21.1±4.4,P 〈0.05） and control group （23.6±4.6, P 〈 0.05） ;SP-B/SP-C mRNA relative expression （0.37±0.15/0.60±0.19） and SP-B relative protein abundance （0.38±0.17）in CMV group were obviously lower than in PEEP group （0.73±0.15/0.92±0.40, 0.52±0.22, P 〈 0.05）. Conclusions PEEP ventilation can improve the oxygenation indices and lung compliance in SW-RDS animals. And such an effect is correlated with both the mRNA exnressions of SP-B/SP-C and mechanical distension.