犬肺缺血预处理对体外循环肺和心肌保护的实验研究

Experimental study on protection effect of lungischemic preconditioning for lung and myocardiuin canine cardio pulmonary bypass

目的探讨肺缺血预处理对体外循环肺和心肌的保护作用及机制。方法12只健康杂种犬,体重12～15Kg,随机分为实验组和对照组,每组6只。对照组为单纯体外循环(CPB)组,实验组为缺血预处理组,在主动脉阻断前行左肺门阻断5min,再灌注5min,重复一次,然后同对照组行CPB。两组采用相同的心肌保护(冷晶体停跳液)。两组CPB均持续1h,于CPB前、再灌注120min后采集左下肺和心肌标本测定肺湿干重和心肌含水量、肺和心肌MDA、SOD活性以及肺和心肌病理改变。结果①CPB后实验组肺湿干重低于对照组(P<0.05),分别为3.4867±0.6776和5.3067±0.3034;肺组织MDA实验组低于对照组(P<0.05),分别为(5.3517±1.0769)nmol/mgprot和(7.4002±1.1569)nmol/mgprot;肺组织SOD活性实验组高于对照组(P<0.05),分别为(127.4512±18.8801)U/mgpro和(103.6103±9.5299)U/mgprot。②CPB后心肌含水量实验组低于体外循环前(P<0.05),分别为64.6173±4.1682和77.3333±3.0807;心肌MDA实验组低于对照组(P<0.05),分别为(5.3233±1.5304)nmol/mgprot和(7.5517±1.0236)nmol/mgprot;心肌SOD活性实验组高于对照组(P<0.05),分别为(166.0104±6.3458)U/mgprot和(140.4514±13.9413)U/mgprot;③组织学检查:CPB前两组肺和心肌病理检查组织结构正常。CPB后实验组肺和心肌标本可见轻度的中性粒细胞和淋巴细胞积聚、毛细血管淤血和轻度水肿,而对照组肺标本可见明显的中性粒细胞和淋巴细胞积聚、毛细血管淤血和间质明显水肿,对照组心肌组织可见明显的淋巴细胞积聚,心肌间质水肿明显,心肌组织损伤较重。结论犬肺缺血预处理对CPB肺和心肌缺血再灌注损伤有保护作用,其机制可能是减轻了肺和心肌缺血再灌注损伤。

Objectives To explore the protection effect and mechanism of lung ischemic preconditioning on lung and myocardium in canine cardiopulmonary bypass （CPB）. Methods 12 adult mongrel canines （12-15 kg） were randomly divided into two groups, 6 for control group （group C ）, in which the CPB was established by abdominal aorta and right atrium cannulafion, experimental group was treated with ischemic preconditioning, in which left lung hilus were clamped for two cycles of five minutes followed five minutes released before crossclamping of the aorta in six canines（croup IP）. The technique of myocardium protection and cardiac arrest was the same in beth groups（cold crystalline cardioplegia）. CPB was controlled running for 1 hour in beth groups. The lung and myocardial tissue were sampled at the time of pre- CPB and 120 minutes after reperfusion to test the wet/dry ratio of lung tissue and myocardial water content （MWC）, maleic dialdehyde （MDA）and superoxid dismutase （SOD） of beth tissue. Lung and myocardial biopsies were obtained before and after CPB in beth groups for microscope pathological examination. Results （1）After reperfusion, the wet/dry ratio of lung tissue in group IP was significantly lower than that in group C （3.4867±0.6776 vs 5.3067±0.3034,P〈0.05）. The MDA of lung tissue in group IP was significantly lower than that in group C[（5.3517±1.0769）nmol/mgprot vs （7.4002±1.1569）nmol/mgprot,P〈0.05 ）. SOD activity of lung tissue in group IP was significantly higher than group C[ （127.4512±18.88）U/ mgprot vs （103.6103±9.5299）U/mgprot,P〈0.05）. （2）After reperfusion, the MWC of myocardium in group IP was significantly lower than that in group C （64.6173±4.1682 vs 77.3333±3.0807,P〈0.05 ）. The MDA of myocardium in group IP was significantly lower than that in group C [ （ 5.3233 ± 1.5304 ）nmol/mgprot vs （7.5517 ± 1.0236 ）nmol/ mgprot,P〈0.05）;SOD activity of myocardium in group IP was significantly higher than group C [（166.0104± 6.3458）U/mgprotvs （140.4514±13.9413）U/mgprot,P〈0.05）. （3） pathological examination of lung and myocardial tissue revealed that in control group there were more obvious intraalveolar hemorrhage, leukocyte adherence and interstitial edema compared with group IP. Conclusion The study indicates that lung isehemie preconditioning may have protective effect on lung and myocardium after CPB. The possible mechanism was that isehemie preconditioning reduced the production of ischemia-reperfusion injury.