【作者】 陈淼； 谢海辉； 屈献峰；

【Author】 Chen Miao,Xie Hai-Hui.(Department of ICU Affiliated Hospital of Zunyi Medical College,Zunyi 563003 China)

【机构】 遵义医学院附属医院ICU；

【摘要】 目的探讨N-乙酰半胱氨酸(N-acetylcysteine,NAC)对犬体外循环(Cardiopulmonary bypass,CPB)后肺组织的转化生长因子-β1(TGF-β1)影响及机制。【方法】健康成年杂种犬24条,严格控制体重:15±0.2kg,随机分为三组:损伤对照组(C组)8条;预防组(N1组)8条;治疗组(N2组)8条。三组动物腹腔内注射戊巴比妥钠(25mg/kg),待麻醉生效后,插入内径(Inner diameter, ID)9.5mm带套囊气管导管,行右侧股动、静脉插管分别用于监测平均动脉压(Mean arterial pressure,MAP)、采取血样和监测中心静脉压(Central venous pressure,CVP)。开胸前接AH-Ⅱ型呼吸机,开胸后,三组均模拟Williams等建立CPB肺损伤模型,C组制模作损伤对照,N1组于体外循环开始前静脉注射NAC150mg/kg,余50mg/kg静脉维持泵入至实验结束,N2组于体外循环开始后复温前应用NAC,用法、用量同N1组,停机时三组动物均以机器收血回输及1:1000肾上腺素0.1mL/kg、多巴胺10?g/kg/min静脉泵入辅助循环至实验结束。三组均于体外循环前(T0)、体外循环中30min(T1)、停机后15 min(T2)、30min(T3)、60min(T4)各时间点取肺组织标本,免疫组化染色分析肺组织转化生长因子-β1(Transforming Growth Factor-Beta1,TGF—β1)的表达并光镜学观察病理变化;肺组织匀浆离心取上清液测丙二醛(Malondialdehyde,MDA)含量;电镜下观察Ⅱ型肺泡上皮细胞(TypeⅡaveolar epithelial, AEC-Ⅱ)超微结构的变化。同时于T0、T2时间点抽取动脉血样监测呼吸指数(Respiratory index,RI)。【结果】1、RI:T0时三组动物无明显差异(P>0.05);T2时C组(4.57±0.69)明显高于N1组(0.81±0.04)和N2组(1.70±0.06)(P<0.05),N2组高于N1组(P<0.05)。2、肺组织MDA含量:组间比较:T0时肺组织匀浆MDA的含量无明显差异(P>0.05),其余时间点,N1组、N2组MDA的含量均较C组低,差异有显著性意义(P<0.05),其中T3时变化明显,差异有非常显著性意义(P<0.01);N1组与N2组间MDA的含量差异无显著性意义{P(Sig.=0.057)>0.05}。组内比较:三组CPB后MDA的含量较CPB前增高,差异有显著性意义(P<0.05), CPB后各时间点MDA的含量无明显差异。3、光镜下肺组织病理改变:C组见肺组织结构紊乱,大量的炎性细胞浸润,肺泡毛细血管扩张、充血,肺泡壁明显充血,肺泡隔增宽,甚至肺泡腔内出现大量的红细胞,局灶性肺不张;N1组与N2组肺组织结构均清晰,见少量的炎性细胞浸润,肺泡毛细血管无扩张、充血,未见周围水肿液,肺泡结构未见明显破坏,肺组织损伤均较C组明显减轻。4、肺组织TGF-β1的表达:T0时偶见TGF-β1表达(P>0.05);随心肺转流时间的延长,TGF-β1表达均增强,但N1组弱于N2组、C组(P<0.05)且病理显示肺损伤明显减轻;除T1时T组与C组表达相近外(P>0.05),N2组弱于C组(P<0.05),病理显示肺损伤也明显减轻。5、Ⅱ型肺泡上皮细胞(TypeⅡaveolar epithelial,AEC-Ⅱ)超微结构:C组可见AEC-Ⅱ板层体明显排空,损伤严重,N1组偶见板层体排空,损伤明显减轻,N2组少见板层体排空,损伤也明显减轻。【结论】CPB期间多种途径产生大量的氧自由基(Oxygen free radical,OFR),肺组织TGF-β1表达明显增强,导致肺组织损伤,通过加入一定量的抗氧化剂NAC,可减轻肺组织的氧化损伤,下调TGF-β1的表达,改善RI,减轻AEC-Ⅱ损伤.对体外循环相关肺损伤有明显的保护作用。更多还原

【Abstract】 Object To study the protective effect of N-acetylcysteine on injury of lungs associated with Cardiopulmonary Bypass (CPB)in dogs. Methods Twenty-four adult hybrid healthy dogs,each weighting 15±0.2kg,were randomly divided into three groups: sham group(group C,n=8),prevention group(group N1,n=8),treartment group(group N2,n=8).All the dogs were anesthesitized with 2.5%sodium pentobarbital(25mg/kg).The trachea was intubated with a cuffed endotracheal tube(Inner diameter: 9.5mm).A femoral artery catheter was placed for mean arterial pressure(MAP) monitoring and blood sampling.A femoral vein catheter was placed for central venous pressure(CVP) monitoring and transfusion.The animals were placed on a AH-Ⅱventilator(Hongrunda tech company,Beijing) in the volume control mode before a median sternotomy.Injury model of lungs was established through CPB in dogs.NAC was adminstrated intravenously before CPB in group N1 and in the middle of CPB in group N2.The usage and dose in group N1 and N2were the same:150mg/kg,intravenous injection;50 mg/kg,intravenous infusion to the end of the experiment.While in groupC,physiological salt solution was adminstrated intravenously to compare the injury.All animals received an intravenous dose of 0.1 mL/kg of 1:1000 epinephrine and blood collected from Sarns5000,while were started on a dopamine drip at 10 ?g/kg/min at the time of separation from bypass.Lung specimens were obtained before CPB(T0)、at 30min following CPB(T1)、15min after CPB(T2)、30 min after CPB(T3)、60 min after CPB(T4)in all groups.The expression of TGF-β1 in lung tissue was detected by the immunohistochemical staining at above-mentioned time points.Malondialdehyde(MDA) in lung homogenate was also examined at above-mentioned time points.Specimens of lung tissue were observed forthe pathological change of lung structure with optical microscope,and the Ultrastructural change of TypeⅡalveolar epithelial(AEC-Ⅱ)were observed by electron microscope.Blood samples were collected from femoral artery for the monitoring of Respiratory index(RI)at T0,T2.更多还原