低能激光照射对大鼠梗死心肌组织中超氧化物歧化酶和丙二醛的影响

Effect of low level laser irradiation on superoxide dismutase activity and malondialdehyde content in infarcted myocardial tissue of rats

目的探讨低能激光照射（LLLI）对大鼠梗死心肌组织中超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量的影响和意义。方法SD大鼠120只分为3组：假手术组、对照组、治疗组。通过结扎左冠状动脉前降支制备心肌梗死模型。3周后进行LILI，处理后各时间点采用黄嘌呤氧化酶法和硫代巴比妥酸（TBA）法分别检测SOD活性和MDA含量，并做组织病理学观察。结果LLLI后1h至48h，SOD活性明显高于对照组，48h时达最高[（0．94±0．47）U／mg蛋白比（0．92±0．25）U／mg蛋白，P〈0．05]；MDA含量显著低于对照组，48h达最低[（0．48±0．20）nmol／mg蛋白比（0．52±O．25）nmol／mg蛋白，P〈0．05]；72h和1周时对照组和治疗组差异无统计学意义（P〉0．05）。结论LI上I可以显著增加大鼠梗死心肌组织中SOD活性，降低MDA含量，有较好的心肌保护作用。

Objective To investigate effect of low level laser irradiation （LLLI） on superoxide dismutase （SOD） activity and malondialdehyde （MDA） content in infarcted myocardial tissue of rats. Methods Myocardial infarction （MI） was created by the left anterior descending （LAD） coronary artery ligation in 90 rats. The surviving rats were divided randomly into sham operated, control and laser groups. Thirty rats received a thoracotomy without coronary ligation as sham operated group. Three weeks after MI, all the rats received a thoraeotomy. The rats in laser group were exposed to a diode laser （635 nm, 6 mW, 150 s, 0. 96 J/cm2 ）. In the control and sham operated grouPs, laser irradiation was not applied. At differ- ent time points after second thoraeotomy, 4-6 rats from each group were sacrificed and the infarcted myocar- dial tissues were analyzed to determine SOD activity and MDA content at each time point. The MI was de- termined from histological sections stained with hematoxylin and eosin （HE）. Results From 1 h to 48 h after LLLI, the myocardial SOD activity was higher in laser group than in control group, and reached the peak at 48 h [ （0. 94 ± 0. 47 ） U/mg protein vs （0. 92 ± 0. 25 ） U/mg protein, P 〈 0. 05 ], and myocardial MDA content was decreased in laser group as compared with control group and touched the bottom at 48 h [ （0. 48±0. 20） nmol/mg protein vs. （0. 52 ±0. 25） nmol/mg protein,P 〈0. 05]. There was no statisti- cally significant difference in the SOD activity and MDA content between laser group and control group at 72 h and 1 week after LLLI. Conclusion LLLI increases SOD activity and decreases MDA content in in- farcted myocardial tissue after MI, and has a better cardioprotective effect.