缺血后适应对老龄大鼠心肌缺血再灌注损伤的保护作用

目的：研究缺血后适应能否减轻老龄大鼠急性心肌缺血再灌注损伤，比较缺血后适应的心脏保护作用在成年和老龄大鼠之间有无差别。方法32只雄性F344大鼠分为成年（6～8月龄）和老龄（20～22月龄）组，每组再分为缺血再灌注（I/R）组（缺血30min，再灌注2h，8只）和缺血后适应（IPost）组（缺血30min，给予4轮10s再通/10s缺血后再灌注2h，8只），监测平均动脉压（MAP）、心率收缩压乘积（RPP）等血流动力学参数和心电图，测定心肌梗死面积，再灌注2h后检测血清肌酸激酶（CK）和乳酸脱氢酶（LDH）浓度。结果再灌注2h时，成年IPost组MAP和RPP均高于I/R组（P＜0.05），而老龄IPost组与I/R组间差异无统计学意义（P＞0.05）。再灌注初30min内，成年IPost组和I/R组心律失常评分分别为1分和3.5分，两者间差异有统计学意义（P＜0.05）；老龄IPost组和I/R组心律失常评分分别为2分和3分，两者间差异无统计学意义（P＞0.05）。成年和老龄IPost组心肌梗死面积较I/R组分别减少52%和44%（均P＜0.05）。成年和老龄IPost组CK和LDH浓度较I/R组均有明显降低（P＜0.05）。结论缺血后适应能缩小老龄大鼠心肌梗死面积、减少心肌酶释放，且其程度与成年大鼠相似；同时缺血后适应能改善成年大鼠心肌顿抑、减少再灌注心律失常，但此作用在老龄大鼠未观察到。

Ischemic post-conditioning protects aged rat hearts against ischemia/reperfusion injury

ObjectiveTo investigate whether ischemic post-conditioning（IPost）can ameliorate acute myocardial ischemia/reperfusion（I/R）injury in senescent rats and to compare the cardioprotective effects of ischemic post-conditioning between aged and adult rats.MethodsA total of 32 male F344 rats were divided into adult （6 to 8 months）groupand aged （18 to 20 months） group. Afterthe rats weresubjected to 30min ischemia by ligating the left anterior descending coronary artery（LAD）,theirhearts from each group were further randomized to receive standard, abrupt reperfusion （I/R group）, or were post-conditioned with4 cycles of 10s ischemia interspersed by 10s reperfusion immediately at the end of the ischemia （IPost group）. Hemodynamic changes, such asmean arterial pressure （MAP） andrate-pressure product （RPP）, and electrocardiogram （ECG） were recorded. Infarct size was measured by Evans blue and triphenyltetrazolium chloride （TTC） staining. At 120min of reperfusion, serum levels of creatine kinase （CK） and lactate dehydrogenase （LDH） were assayed.ResultsAfter 2 hoursreperfusion, MAP andRPP were significantly higher in IPost group thanin the corresponding I/R groupfor adult rats （P〈0.05）. However, no significance was achieved in aged rats （P〉0.05）. During the first 30min reperfusion, in adult rats, the arrhythmia scores were 1.0 and 3.5 respectively for the IPost group and I/R group with significant difference （P〈0.05）. However, in aged rats, the arrhythmia scores were 2.0 and 3.0 for the IPost group and I/R group, but without significant difference （P〉0.05）.Post obviously decreasedtheinfarctsize in the IPost group than in corresponding I/R group in both adult （by 52%） and aged cohorts （by 44%;P〈0.05 for both）. The serum levels of CK and LDH were markedly lower in IPost group than in I/R group from both adult and aged rats （P〈0.05 for both）.ConclusionIPost, as same powerful as to adult rats, reduces infarct size and decreases the release of