腺苷A2a受体激动剂后处理对兔缺血再灌注心肌的保护作用

Effects of A2a adenosine receptors agonist postconditioning on acute myocardial ischemia reperfusion injury

目的观察三磷酸腺苷（ATP）、腺苷A2a受体激动剂CGS-21680及缺血后处理对兔缺血再灌注心肌的影响，并探讨后处理与腺苷受体亚型的关系及其保护机制。方法健康新西兰大耳白兔48只，随机分成4组：缺血再灌注组（IR组）、缺血后处理组（IPO组）、ATP后处理组（ATP组）和CGS．21680后处理组（CGS-21680组），每组12只。建立兔急性心肌缺血再灌注模型，实验终点测定血清肌酸激酶同工酶（CK—MB）、丙二醛（MDA）水平及超氧化物歧化酶（SOD）活力；采用Evans蓝和四氮唑蓝（NBT）双重染色测定心肌梗死面积。光镜下观察心肌组织病理形态变化。结果IR组心肌损伤较重，有心肌断裂、坏死，间质肿胀、出血及中性粒细胞浸润，IPO组、ATP组及CGS-21680组心肌组织损伤明显轻于IR组。与IR组比较，IPO组、ATP组和CGS-21680组血清MDA生成量减少[（3．68±0．60）U／ml、（3．75±0．82）U／ml和（4．05±0．86）U／ml比（5．05±0．65）U／ml，均为P〈0．05]，CK—MB活性降低[（231．83±16．22）U／L、（225．83±9．22）U／L和（238．33±22．26）U／L比（343．42±21．55）U／L，均为P〈0．01]，心肌梗死面积降低（13．86％±2．77％、14．22％±2．24％和14．57％±1．66％比30．49％±1．57％，均为P〈0．01）以及SOD活力升高[（238．08±38．22）nmol／ml、（261．75±40．27）nmol／ml和（294．78±23．38）nmol／ml比（149．98±42．42）nmol／ml，均为P〈0．05]；而CGS-21680组、IPO组和ATP组组间比较，差异无统计学意义。结论ATP和CGS-21680后处理可减轻心肌缺血再灌注损伤，保护强度与机械性缺血后处理相似，且后处理对再灌注心肌的保护与腺苷A2a受体的激活有关，其机制可能与清除氧自由基，抑制脂质过氧化反应从而提高机体的抗氧化能力有关。

Objective To observe the effects of adenosine triphosphate （ATP） and A2a adenosine receptors agonist CGS-21680 pharmacological and ischemic postconditioning on acute myocardial ischemia reperfusion （IR） injury, to investigate the relationship between posteonditioning and adenosine receptors subtypes and to explore the protective mechanism. Methods A total of 48 New Zealand white male rabbits were randomly divided into 4 groups （ n = 12 each） , the IR group as controls, the ischemic postconditioning （IPO） group, the ATP postconditioning group and the CGS-21680 postconditioning group. The model of acute myocardial ischemia reperfusion was established. Serum creatine kinase-MB （CK-MB）, malondialdehyde （MDA） and superoxide dismutase （SOD） of every group were determined at the end of reperfusion, lschemic and infarct areas were measured by Evans blue and nitroblue tetrazolium （NBT） staining. Light microscope was used to observe tissue changes of myocardium. Results The myocardial injury was most severe in the IR group compared with other groups. Compared with the IR group, the histopathological changes of the myocardium were relieved significantly in the IPO group, the ATP group and the CGS-21680 group. Compared with the IR group, the generation of MDA was decreased in the IPO group, the ATP group and the CGS-21680 group [ （ 3.68 ± 0. 60） U/ml, （3.75 ± 0. 82 ） U/ml and （4. 05 ± 0. 86） U/ml vs. （5.05 ± 0. 65 ） U/ml, all P 〈 0. 05 ], the activity of CK-MB was lowered [ （231.83 ± 16. 22） U/L, （225.83 ±9. 22） U/L and （238.33 ±22.26） U/L vs. （343.42 ±21.55） U/L, all P 〈 0.01 ], and the myocardial infarct size was decreased [ （ 13.86 ± 2. 77） %, （ 14. 22 ± 2. 24） % and （ 14. 57 ± 1.66） % vs. （30. 49 ± 1.57 ） %, all P 〈 0. 01 ], while the activity of SOD was increased significantly [ （238.08 ± 38.22 ） nmol/ ml, （261.75 ± 40. 27 ） nmol/ml and （294. 78 ± 23.38） nmol/ml vs. （ 149.98 ± 42. 42） nmol/ml, all P 〈 0. 05 ]. However, there were no significant differences among the IPO group, the ATP group and the CGS-21680 group. Conclusions ATP postconditioning and adenosine receptor agonists CGS-21680 postconditioning may reduce myocardial ischemia reperfusion injury, which are as effective as mechanical ischemic postconditioning. Moreover, the protective effect of postconditioning is associated with A2a adenosine receptors activation. Its potential mechanism might be related to increasing resistance to oxidation stress via attenuating the generation of oxygen free radical and inhibiting lipid peroxidation.