纳洛酮对兔心肌缺血-再灌注损伤的影响

Effects of Naloxone on Injury in Rabbits During Myocardial Ischemia-reperfusion

目的探讨纳洛酮对心肌缺血再灌注损伤时心肌超微结构改变的干预和对血浆β-内啡肽(β-EP)及内皮素-1(ET-1)的影响。方法新西兰兔20只,随机分成两组,缺血再灌注组、纳洛酮治疗组,每组10只。制作心肌缺血模型和缺血再灌注损伤模型,并抽取不同时间点的静脉血,采用放射免疫法分别测定β-EP及ET-1的含量;缺血后6h取缺血部位的心肌标本,用电镜观察心肌超微结构的变化。结果缺血再灌注后各时段β-EP含量明显高于缺血前(P<0.05或P<0.01);纳洛酮治疗组β-EP在缺血后各时间点与缺血前比较均无显著性差异(P>0.05)。缺血再灌注损伤后0.5～1hET-1含量明显高于结扎前(P<0.05或P<0.01);纳洛酮治疗组除结扎后0.5h高于结扎前外,其余各时间段与结扎前比较均无显著性差异(P>0.05)。超微结构改变:缺血再灌注组,大部分心肌纤维呈收缩状态,大部分肌原纤维局灶性溶解、断裂,核周水肿;纳洛酮治疗组,肌原纤维结构较清晰,排列整齐,未见明显断裂,肌原纤维收缩状态缓解,线粒体水肿减轻,胞质轻度水肿。结论纳洛酮可有效降低心肌缺血再灌注损伤时血浆β-EP水平;从而减轻β-EP对血管和心肌组织的损伤作用;可有效防止心肌缺血再灌注损伤时ET-1的合成和分泌,降低不可逆损伤。对心肌超微结构的损伤性改变有明显减轻。

Objective To study the effects of naloxone on β - endorphin （β - EP） in plasma and on myocardial uhrastrucmre during myocardial ischemia - reperfusion （I/R） injury in rabbits. Methods The myocardial ischemia models and myocardial ischemia - reperfusion injury models in rabbits, by ligating the left anterior descending branch of coronary artery, were used to investigate the changes of β- EP and ET - 1 in plasma during I/R injury, and after treatment with naloxone, an antagonist of opiate receptor. 20 New Zealand rabbits were randomly assignedto 2 groups （each 10 rabbits in naloxone treatment and ischemia- reperfusion group） . The bloods were taken at different times in each group. The concentrations of β - EP and ET - 1 were detected with radioimmunology method. The changes of myocardial ultrastructure in samples of myocardial ischemia, were observed through electron microscope. Rseults The levels of β - EP were significantly improved after I/R injury compared with those before ischemia （ P 〈 0.05 or P 〈 0.01 ）, but in the naloxone treatment group the levels of β - EP showed no significant change in any time （ P 〉 0.05） . For ischemia- reperfusion group, most of cardiac muscles were in the contracting state, the myofibril dissolved and broke locally. The edema was found on the circumference of nucleus. For naloxone treatment group, the structure of myofibril was clear and its arrangement was in good order, and no obvious breakage was found. The contracting of myofibril, the edema of mitochondria and kytoplasm were moderating. Conclusion Naloxone may effectively control the levels of β - EP and the synthesis and secreting of ET - 1 after myocardial ischemia and during I/R injury; and reduce the injury to the myocardial uhrastructure and decrease the injury to blood vessel and myocardium.