金属硫蛋白参与心肌缺血预处理的延迟保护作用

Metallothionein involuement in the delayed protection after ischemic or anoxic preconditioning in myocardium or cultured cardiomyocytes

探讨金属硫蛋白（ＭＴ）参与心肌缺血预处理延迟保护作用的可能性。方法在原位兔心脏缺血预处理和培养乳兔心肌细胞缺氧预处理的模型上，检测预处理后即刻，１２小时和２４小时ＭＴ含量的变化，观察预处理后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以及用丝裂素蛋白激酶抑制剂ＰＤ０９８０５９抑制预处理后ＭＴ含量增高对预处理后延迟保护作用的影响。结果ＭＴ含量在预处理后１２小时（心肌细胞）和２４小时（心肌细胞和心肌组织）显著增高，与未预处理的损伤的心肌组织或心肌细胞相比较，预处理后２４小时其心肌梗塞范围缩小，血浆乳酸脱氢酶活性升高程度减轻，心肌细胞存活率增高，细胞丙二醛含量和乳酸脱氢酶释放均降低。用ＰＤ０９８０５９抑制ＭＴ生成时，则消除了预处理后的延迟保护作用，上述心肌损伤指标接近缺血－再灌注组或缺氧－复氧组（Ｐ＞０．０５）。结论预处理后２４小时心肌或心肌细胞对再次缺血－再灌注或缺氧－复氧的损伤有保护作用。ＭＴ参入心肌或心肌细胞预处理后的延迟保护作用。

Objective To stady whetter metallothionein (MT) is an OH scanvenger and plays a protective role in cardiac ischemic/reperfusion injury. MT involves in the delayed protection 24 hr after preconditioning (PC). Methods MT contents in myocardium or cultured cardiomyocytes are assayed at the 0 hr, 12hr, and 24 hr after PC on the model of rabbit heart in situ or that of 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 mitogen activated protein kinase in the models before PC and different time intervals after PC. Results The MT contents were increased significantly at 12 hr(1406 2±112 2vs 129 9±10 4pmol/mg Pr., P <0 01, in cardiomyocytes )and 24hr (1032.7±199.1vs 129.9±10.4pmol/mg Pr., P <0.01, in cardiomyocytes; 62.1±12.6vs 27.2±3.7pmol/mg Pr., P <0.01, in myocardium) after PC compared with those in normal group. The infarct sizes (13.2 ±3.6% vs 32.3±5.7%, P <0.05) and the rise of LDH release in plasma (1944±256vs 2826±239IU/L, P <0.05) were greatly decreased in preconditioned myocardium after a long time ischemia reperfusion 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±15.0nmol/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. All the delayed protection at 24 hr after PC were completely disappeared with the inhibition of 作者单位:100034 北京医科大学第一医院(陈 魁、张钧华、陈 ? ⒄耪窀铡⑼衾鲛?,北京医科大学心血管基础研究所(叶 赤、刘秀华、庞永政、唐朝枢) MT′s production with PD 098059 ( P >0.05). Conclusion The myocardium or cardiomyocytes at 24 hr after PC are offered more capacity to tolerate the I/R damage, and MT involves in the delayed protection.