再灌注损伤抢救激酶对小鼠缺血后适应心肌再灌注损伤中的减轻作用

Effects of ischemia postconditioning on ischemia-reperfusion injury and reperfusion injury salvage kinase signal transduction pathways in isolated mouse hearts

目的研究缺血后适应（IPC）对离体小鼠心肌缺血再灌注（I／R）损伤的作用及其影响因素，探讨再灌注损伤抢救激酶在IPC心肌保护中的作用。方法建立Langendorff小鼠心肌I／R模型，全心缺血30min后分为6组[（1）对照组，（2）3次IPC组（采取缺血108及再灌注108的3次IPC周期），（3）6次IPC组（采取缺血108及再灌注108的6次IPC周期），（4）延迟IPC组（恢复再灌注1min后进行IPC），（5）IPC＋PD98059组，（6）I／R＋PD98059组]，随后再灌注2h；观察IPC对心脏血流动力学、心肌酶的释放、心肌超氧化物歧化酶活性和丙二醛的含量、梗死心肌范围的影响以及与细胞外信号调节激酶（ERKI／2）、磷脂酰肌醇3激酶．蛋白激酶B表达水平的关系。结果与对照组比较，3次[PC组和6次IPC组小鼠心脏血流动力学显著改善，心肌酶释放减少，心肌丙二醛减少、超氧化物歧化酶活性增加，心肌梗死范围减小。6次与3次IPC周期的保护作用相似。而IPC作用在恢复再灌注1min后消失。3次IPC组和6次IPC组心肌的ERKI／2磷酸化水平显著增高，蛋白激酶B磷酸化水平无明显变化。PD98059显著抑制IPC所致的ERKI／2的磷酸化，并能消除IPC对心肌的保护作用。结论IPC能有效地减轻离体小鼠心肌缺血再灌注损伤，增加IPC的周期数并没有扩大保护作用，延迟IPC没有产生类似的保护作用。ERKI／2细胞信号途径参与介导IPC对离体心脏缺血再灌注心肌的保护作用。

Objective To explore the effects of iscbemia postconditioning （IPC） on ischemia- reperfusion （I/R） injury and associated reperfusion injury salvage kinase （RISK） signal transduction pathways changes in isolated mouse hearts. Methods Langendorff perfused C57/BL mouse hearts were divided to 6 groups： （ 1 ） control： 30 min global isehemia and 2 h reperfusion （I/R） ; （ 2 ） IPC with 3 episodes, IPC with 3 episodes of 10 s of ischemia and 10 s reperfusion after 30 min isehemia and before 2 h reperfusion; （3） IPC with 6 episodes, IPC with six episodes of 10 s of ischemia and 10 s reperfusion after 30 min isehemia and before 2 h reperfusion; （4） delayed IPC, IPC with 3 episodes of 10 s of ischemia and 10 s reperfusion after 30 min ischemia and at one minute after reperfusion; （5） IPC ＋ ERK1/2 inhibitor PD98059 （ 10 -5 mol/L for 15 min） ; （6） I/R ＋ ERK1/2 inhibitor PD98059 （ 10 -5 mol/L for 15 min）. The effects of IPC on hemodynamies, coronary artery flow, ereatine kinase （ CK ） and lactate dehydrogenase （LDH） release, myocardial SOD, MDA, phospho-protein kinase （ P-ERK1/2 ） and phospho-protein kinase B（P-Akt） as well as myocardial infarction size were measured. Results IPC with 3 episodes and IPC with 6 episodes significantly and equally improved myocardial function, increased myocardial SOD, reduced CK and LDH release and myocardial infarction size compared with IR group （all P 〈 0. 01 ） while these parameters were similar between I/R hearts and delayed IPC hearts. IPC significantly increased myocardial ERK1/2 phosphorylation, PD98059 inhibited the phosphorylation of ERK1/2 and abolished the eardioproteetive effects induced by IPC. Conclusions IPC obviously attenuated I/R injury in isolated mouse hearts, the cardioprotection of IPC was not enhanced because of increasing of IPC episodes and disappeared in delayed IPC. The cardioprotective effects of IPC were mediated through ERK1/2-MAPK signal transduction pathway.