褪黑素对在体大鼠心肌缺血再灌注损伤的作用

目的　探讨外源性褪黑素(MLT)对在体大鼠心肌急性缺血再灌注损伤的保护作用。方法　36只大鼠随机分为对照组、缺血再灌注(I/R)组及缺血再灌注+褪黑素(I/R+MLT)组,I/R组及I/R+MLT组在体大鼠心脏左冠状动脉前降支完全阻断10min,再灌15min,术中监测记录心电及血流动力学的变化,随后测定局部受损心肌中MDA(丙二醛)的含量和SOD(超氧化物歧化酶)的活性并用电镜检查心肌结构。结果心脏血流动力学指标I/R+MLT组好于I/R组(P<0 .01);I/R组MDA的含量明显高于对照组及I/R+MLT组(P<0.01 ),SOD活性明显低于对照组及I/R+MLT组(P<0 .01),I/R+MLT组MDA含量及SOD活性与对照组无明显差异(P>0 .05);电镜下I/R组心肌细胞结构损伤明显,而I/RMLT组心肌细胞结构基本正常。结论　褪黑素对在体大鼠心肌急性缺血再灌注损伤具有保护作用,其作用与抗氧化损伤有关。

The protective effects of melatonin on acute ischemia/reperfusion induced myocardium damage in rats in vivo

Aim To investigate the protective effects of MLT(melatonin) on acute ischemia-reperfusion induced myocardium damage in rats in vivo. Methods 36 anesthetized rats were separated randomly into 3 groups: ① Control group (n=12), without LAD (left anterior descending coronary artery) ligation and MLT; ② I/R(ischemia reperfusion) group(n=12), LAD was ligated for 10 min and reperfused for 15 min without MLT; ③ I/R+MLT group(n=12): MLT(10 mg·kg~(-1)) was in jected via peritonium 10 minutes before LAD ligation and reperfusion. ECG and haemodynamics were continuously monitored and recorded throughout the whole process, MDA(malondialdehyde, lipid peroxidation product, an index of myocardium damage) and SOD( superoxide dismutase ) activity were tested in the injuried myocardium. The hearts tissue of each group was also examinated by electron microscopy.Result The levels of MDA were significantly higher while the SOD activities were lower in I/R group compared with I/R+MLT and control group(P<0.01), but there was not significant difference between I/R+MLT and control groups(P>0.05). The haemodynamics indices of contractile and diastolic functions were also better in I/R+MLT group than inI/R group(P<0.01). The myocardial subcellular structure was seriously damaged in I/R group, and was normal in I/R+MLT group.Conclusion These results suggest that melatonin protects myocardium against reperfusion injury in vivo, via its properties as membrane stabilizer and oxygen free radical scavenger and improving the activities of related antioxidative enzymes.