金属硫蛋白介导腺苷A1受体激动剂延迟预处理对兔心肌的保护作用

Metallothionein mediates cardioprotection induced by delayed preconditioning with adenosine A1 receptor agonist in rabbits

目的:探讨腺苷A1受体激动剂——2-氯环戊腺苷(2-chloro-N6-cyclopentyladenosine,CCPA)延迟预处理对兔心肌缺血再灌注损伤的延迟相保护机制。方法:30只健康新西兰雄性大白兔随机均分成3组:假手术组(C组)、缺血再灌注组(I/R组)和CCPA组(P组)。C组仅行左冠脉套线而不阻断160min;I/R组行左冠脉阻断40min,再灌注120min;P组在静注CCPA0.1mg/kg24h后处理同I/R组。再灌注结束后观察心肌细胞超微结构和心肌梗死面积的变化,测超氧化物歧化酶(superoxide dismutase,SOD)活性和丙二醛(malondialdhyde,MDA)含量,免疫印记法测心肌金属硫蛋白(metallothionein,MT)表达。结果:与I/R组比,P组血清中SOD的活性增高,MDA的含量降低(P<0.05),MT表达增高(P<0.05),心肌梗死面积减少(P<0.05)。结论:CCPA预处理对缺血再灌注心肌的延迟相保护作用与促进心肌MT表达有关。

Objective To investigate the protective effect of adenosine A1 receptor （2-chloro-N6-cyclopentyladenosine, CCPA） delayed preconditioning on myocardial ischemia sion injury and the potential mechanism in rabbits. Methods Thirty New Zealand male white were randomly assigned to 3 groups： a control group, an I/R group, and a CCPA group. agonist reperfurabbits CCPA group was given CCPA 0. 1 mg/kg before the myocardial ischemia. Twenty-four hours later I/R group and CCPA group underwent 40 min of coronary occlusion followed reperfusion for 2 h. At the end of the reperfusion, blood samples were taken from the arterial line for determining the plasma level of malondialdhyde and superoxide dismutase activity. The infarct size and area at risk were de- fined by Evans and TTC staining. The heart was harvested and levels of metallothionein （MT） were determined by Western blot, and uhrastructures were observed under the electron microscope. Results The MT level of CCPA group was significantly higher than that of the I/R group （ P 〈 0.05 ）. CCPA significantly reduced the infarct size （ 22. 1% ± 3.8 % in the CCPA group ） of the left ven-tricular area at risk as compared with the control （41.8% ±4.3% in the I/R group,P 〈0.05）. The injury of I/R group was worse than that of the CCPA group under the light microscope. CCPA group had higher superoxide dismutase and lower malondialdhyde than those of the I/R group. Conclusion CCPA can increase the level of metallothionein during ischemia-reperfusion, which may be part of the molecular mechanism of CCPA delayed preconditioning on cardioprotection.