超速起搏预处理对急性心肌梗死的延迟保护

目的　探讨超速心室起搏 (ventricularoverdrivepacing,VOP)预处理对急性心肌梗死的延迟保护作用 (delayedprotection ,DP)及可能机制。方法　 2 0只兔随机分为 4组 :(1)对照组 ,将电极导管送至右心室旷置 70min ,2 4h后结扎、冠状动脉左前降支造成缺血再灌注模型。 (2 )起搏组 ,缺血再灌注前 2 4h予VOP。 (3)放线菌素组 ,缺血再灌注前 2 4h静注放线菌素D阻滞热休克蛋白 (HSP)转录。 (4 )起搏 放线菌素组 ,延迟缺血再灌注前 2 4h予VOP并静脉注射放线菌素D ,缺血再灌注前后测定血流动力学变化 ,以TTC染色测量各组心肌梗死面积百分比 ,免疫组化染色间检测HSP70抗原 ,并观察心肌缺血再灌注后的组织学改变。结果　与对照组比较 ,起搏组心肌梗死面积减少 34 35 % (P <0 0 0 1) ,左心收缩和舒张功能均改善 ;心肌超微结构损伤减轻。其余组与对照组比较 ,在各项指标上差别无显著意义。HSP70免疫组化染色仅在起搏组心肌标本呈阳性。结论　多次VOP预处理对急性梗死心肌有明显的延迟保护作用 ,此作用与HSP70的表达密切相关。

Delayed cardioprotection induced by ventricular overdrive pacing precondition in acute myocardial infarction

Objection To investigate delayed cardioprotection induced by ventricular overdrive pacing in acute myocardial infarction and its possible mechanism.Methods 20 Newzealand rabbits were randomly divided into 4 groups: (1) control group: catheter was left in the right ventricle for 70 min and these rabbits under wentdelay ischemia and reperfusion by ligating left anterior descending branch of coronary artery after 24h. (2)pacing group: preconditioning for 60min 24h before ischemia and reperfusion. (3)Actinomycin group: treatment as control group followed by 8-PT injection. (4) Pacing Actinomycin group: treatment as ischemia pacing group followed by actinomycin D injection. During period of ischemia and reperfusion,the hemodynamic changes were monitored. Infarction area was measured by TTC. The myocardial biopsy samples were examined under electromicroscope. Heat shock protein (HSP70) was tested by immunohistochemistry.Results Myocardial infarction area in pacing group decreased 34.35%,compared with control group, P<0.001.Left ventricular function in pacing group was improved and myocadial ultrastructure of pacing group was less damaged than control group.Differences of myocardial infarction area, left ventricular function , damage of ultrastructure between Pacing Actinomycin group were not significantly different in Actinomycin group and control group. HSP70 was only positive in pacing group.Conclusion Preconditioning with VOP can exert delayed myocardial protection in acute myocardial infarction. Expression of HSP70 has close relationship with delayed protectoion.