左西孟旦对犬体外循环的肺保护作用

The lung protective effect of levosimendan during cardiopulmonary bypass in canine model

目的观察左西孟旦（Ls）对犬体外循环后肺组织的湿／干重比（W／D）、丙二醛（MDA）及超氧化物歧化酶（SOD）的含量及肺组织的影响，探讨LS对犬体外循环的肺保护作用。方法实验用杂种犬32只，随机分为4组，常规开胸建立体外循环，主动脉阻断1h，开放心脏复跳2h。对照组（C组）主动脉阻断后无特殊处理；实验1组（P组）在主动脉阻断后，以冷氧合血进行肺动脉灌注；实验2组（LSIV组）左西孟旦（65斗g／kg）于开胸前静脉注射，余操作同C组；实验3组（LSP组）主动脉阻断后，含左西孟旦（65μg／k）的冷氧合血肺动脉灌注。实验结束后，立即取出实验犬的右肺，处理后观察肺组织的病理改变，并测定肺组织W／D，肺组织中MDA及SOD含量。结果与C组相比，其他组W／D降低，差异有统计学意义；与C组相比，其他组MDA含量明显减少，SOD活性明显降低，差异有统计学意义（P〈0．05）；与P组及LSIV组相比，LSP组MDA含量降低、SOD活性明显增高，差异有统计学意义（P〈0．05）；P组和LSIV组之间比较，无明显差异（P〉0．05）。通过光镜和电镜观察，应用LS后，肺组织的损伤减轻。结论通过犬动物实验模型，静脉应用Ls及肺动脉灌注Ls，肺组织W／D降低，MDA含量明显减少，SOD活性增高，Ls对肺组织具有保护作用。

Objective To explore lung protection effect of levosimendan（LS） during cardiopulmonary bypass in canine model by ratio between dry and wet （W/D） lung tissue, concentrations of malonaldehyde （MDA） and superexide dismutase （SOD） and alterations of histology. Methods A total of 32 canines were divided into 4 groups at random with the procedure of myocardial blocking for 1 hour and then recovering for 2 hours. Animals in 4 groups were handled as following ： No any spe- cial treatment after myocardial blocking in control group（ group C ）. Lung perfusion was performaned with cold oxygenated blood after myocardial blocking in experiment 1 group（ group P）. LS（65 μg/kg） was injected intravenously before thoracotomy in ex- periment 2 group（ group LSIV） and remaining procedure was same to the control one. Combined with LS （65 μg/kg） , lung perfusion was performaned with cold oxygenated blood after myocardial blocking in experiment 3 group（ group LSP）. Right lung tissue of canines was taken immediately after the study for observing pathological alterations and measuring the concentrations of MDA and SOD through corresponding procedure. Results Compared with group C, the ratios of W/D and the concentrations of MDA were lower significantly, while those of SOD were higher significantly（P 〈0.05）. Compared with group P and LSIV, the concentration of MDA was lower significantly, while that of SOD was higher significantly（ P 〈0.05 ）. There was no signifi- cant difference between group P and LSIV（ P 〉 0.05 ）. Less impairment of lung tissue was found after LS intervention by light and electric microscope. Conclusion LS plays an important role in protecting lung tissue, based on founding in canine mod- el, with decreasing ration of W/D and concentration of MDA and increasing that of SOD by both intravenous injection and lung perfusion.