缺血预适应对高血脂动脉硬化兔心肌的影响

Effect of myocardial ischemic preconditioning on myocardium in hyperlipemia rabbits

目的研究缺血预适应(IP)对高血脂动脉硬化兔心肌的影响。方法用高胆固醇饲料喂养家兔,血总胆固醇≥15mmol/L,29只高血脂兔分为三组,采用结扎/开放左冠状动脉前降支(LDADC)的方法,给予不同时间和强度的缺血预处理:无缺血预处理组(HR1);缺血预处理组(HR2);多次及延长缺血预处理组(HR3),24只正常血脂兔也分为三组(NR1,NR2,NR3),实验方法与上述各组相同。缺血预处理后阻断冠状动脉30min,再灌注30min,给予程序电刺激,测定心室颤动阈(VFT)。心肌切片氯化硝基四氮唑蓝染色(NBT),判断心肌梗死面积(IS)。结果IP对正常兔心肌有保护作用:NR2、NR3组与NR1组相比,IS缩小,(P<0.01);VFT增高(P<0.05);对高血脂兔无作用(P>0.05)。增加缺血次数,延长缺血时间,对正常血脂兔,保护作用无改变(P>0.05);但加重高血脂兔后续缺血的损害:IS增加(P<0.01);VFT降低(P<0.05)。结论缺血预处理的保护作用与心肌的状态有关。对高血脂、动脉硬化兔心肌,缺血预处理的保护作用可能消失。

Objective To investigate the effect of myocardial ischemic preconditioning(IP)on myocardium in hyperlipemia rabbits. Methods The hyperlipemia rabbits were established by feeding high cholesterol diet three months.The rabbits showing blood cholesterol ≥15mmol/L were considered to have hyperlipemia. After continually feeding one month, twenty nine rabbits were divided three groups , each group received the different strength or duration of stimulation in ischemic preconditioning by ligating and opening left anterior descending branch of coronary artery(LADCA): no ischemic preconditioning group(HR_1); preconditioning group(HR_2); stronger and longer preconditioning group(HR_3). Twenty four normal rabbits were divided three groups too (NR_1,NR_2,NR_3), each group received same operation and stimulation as hyperlipemia groups. Ventricalar fibrillation threshold (VFT) was examined by means of electrical stimulation programm. Infarct size(IS)was estimated by NBT staining. Results The protective effect of ischemic preconditioning was evident in NR_2,NR_3 groups :The IS was decreased significantly (P<0.01). VFT was higher significantly in HR_2,HR_3 groups compared with HR_1 group(P<0.05). No protective effect took place in hyperlipemia groups(P>0.05). As the ischemic preconditioning became stronger and longer, serious lesion could be seen in HR_3 group:IS was increase(P< 0.01);VFT was lower(P<0.05). Conclusion The protective effect of ischemic preconditioning is relative with the state of myocardium and disappeared in hyperlipemia rabbits.