犬肺缺血预处理对体外循环心肌的影响

Impact of lung ischemic preconditioning on myocardium in canine cardiopulmonary bypass

目的探讨肺缺血预处理对体外循环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,然后同对照组行体外循环,两组体外循环均持续1h。于体外循环前、再灌注120min后采集心肌标本,测定心肌含水量、MDA、SOD活性及病理改变。结果体外循环后心肌含水量和MDA实验组低于对照组;心肌SOD活性实验组高于对照组;实验组心肌标本炎症水肿程度明显较对照组轻。结论犬肺缺血预处理对体外循环心肌缺血再灌注损伤有保护作用,其机制可能是减轻了心肌缺血再灌注损伤。

Objactive To explore the mechanism of protection effect of lung ischemic preconditioning on myocardium in canine cardiopulmonary bypass （CPB）. Methods 12 adult mongrel canines （12-15 kg） were randomly divided into two groups, 6 for Control （Group C）, in which the CPB was established by abdominal aorta and right atrium cannulation, experimental group was treated with ischemic preconditioning, in which left lung hilus were clumped for two cycles of five minutes followed five minutes released before cross-clamping of the aorta in 6 canines （Group IP）. CPB was controlled running for 1 hour in both groups. The myocardial tissue were sampled at the time of pre- CPB and 120 minutes after reperfusion to test myocardial water content （MWC）, maleic dialdehyde（MDA ）and superoxid dismutase（SOD）. Myocardial biopsies were obtained before and after CPB in beth groups for microscope pathological examination. Results After reperfusion, the MWC and MDA of myocardium in Group IP was significantly lower than that in Group C; SOD activity of myocardium in Group IP was significantly higher than Group C; pathological examination of myocardial tissue revealed that there were more obvious intraalveolar hemorrhage, leukocyte adherence and interstitial edema in Control group compared with group IP. Conclusion The study indicates that lung ischemic preconditioning may have protective effect on myocardium after CPB. The possible mechanism was that ischemic preconditioning reduced the production of ischemia-reperfusion injury.