丝裂素活化蛋白激酶参与缺血预适应的延迟保护作用

Mitogen activated protein kinase involvement in the delayed protection after ischemic or anoxic preconditioning in myocardium or cultured cardiomyocytes

为探讨丝裂素活化蛋白激酶（ｍｉｔｏｇｅｎ－ａｃｔｉｖａｔｅｄｐｒｏｔｅｉｎｋｉｎａｓｅ，ＭＡＰＫ）参与心肌缺血预适应的延迟保护作用。我们在原位兔心脏缺血预适应和培养乳兔心肌细胞缺氧预适应的模型上，检测预适应后即刻、１２小时和２４小时ＭＡＰＫ活性变化，观察预适应后２４小时对再次长时间缺血／再灌注或缺氧／复氧损伤的保护作用（心肌梗塞范围、细胞存活率、ＬＤＨ释放和细胞ＭＤＡ含量），以及用特异的ＭＡＰＫ系统抑制剂ＰＤ０９８０５９抑制预适应后ＭＡＰＫ活性的增高对预适应后延迟保护作用的影响。结果提示：ＭＡＰＫ活性在预适应后即刻增高１０倍以上（Ｐ＜０．０１），在１２小时和２４小时降至或接近正常对照水平。与未预适应的心肌组织或心肌细胞遭受缺血／再灌注或缺氧／复氧的损伤相比较，预适应后２４小时其心梗范围缩小，血浆ＬＤＨ活性升高程度减轻，心肌细胞存活率增高，细胞ＭＤＡ含量和ＬＤＨ释放均降低（均Ｐ＜０．０１）。用ＰＤ０９８０５９抑制ＭＡＰＫ活性增高时，则消除了预适应后的延迟保护作用，上述心肌损伤指标接近单纯缺血／再灌注组或缺氧／复氧组（Ｐ＞０．０５）。结论：（１）预适应后２４小时心肌或心肌细胞对再次缺血／再灌注或缺氧／复氧的损伤?

Mitogen activated protein kinase (MAPK) is involved in the delayed protection (DP) of preconditioning (PC). MAPK activities in myocardium or cultured cardiomyocytes were assayed at the 0h, 12h, and 24h after PC on the model of rabbit heart in situ or the cultured cardiomyocytes. The myocardial infarct size, LDH release, cell viability, and the content of cellular MDA were measured with or without the intervention of PD 098059, the inhibitor of MAPK, in the models before PC and different time intervals after PC. Results showed that the MAPK activities were increased significantly immediately after PC ( P <0.01) and decreased to control level at 12h and 24h after PC ( P >0.05) compared with those in normal group. The infarct sizes and the rise of plasma LDH level were greatly decreased in preconditioned myocardium after a long time ischemia/reperfusion (I/R) than those in the unpreconditioned. Compared with the cardiomyocytes unconditioned, the number of viable cell (71.0±1.6 vs 48.2±2.2%, P <0.01) was greatly increased, the cellular MDA contents (33.5±12.8 vs 103.5± 15.0 nmol/mg Pr., P <0.01) and the LDH release (850.0±139.1 vs 1552.0±102.6 IU/L, P <0.01) were dramatically decreased in preconditioned ones. The inhibition of MT′s production with PD 098059 completely removed all the delayed protection at 24h after PC. Conclusion: The myocardium or cardiomyocytes at 24h after PC are offered more capacity to tolerate the I/R damage, and MAPK is involved in the delayed protection.