电针“内关”穴对心肌缺血再灌注大鼠心肌组织一氧化氮、一氧化氮合酶和细胞内钙的影响

Influence of Electroacupuncture on Myocardial NO and NOS and Intracellular Ca^(2+) Contents in Myocardial Ischemia-reperfusion Injury Rats

目的:观察电针"内关"穴对实验性心肌缺血再灌注损伤大鼠心肌细胞内钙超载及内源性保护物质一氧化氮(NO)、一氧化氮合酶(NOS)的影响,为针刺防治心血管疾病及经脉脏腑相关理论提供实验依据。方法:50只Wistar雄性大鼠随机分为假手术组、缺血再灌注模型组、电针内关组、电针列缺组、电针合谷组。采用冠脉结扎法建立心肌缺血再灌注模型,各电针组于冠脉结扎前后各电针20 min(30 Hz/100 Hz,2～4 mA)。硝酸还原酶比色法检测各组心肌组织NO、NOS的含量,在Fluo-3/AM染色后于激光共聚焦显微镜下检测心肌细胞内Ca2+荧光强度。结果:与假手术组比较,模型组心肌组织NOS含量明显降低(P<0.05),心肌细胞内Ca2+荧光强度明显升高(P<0.01);电针心包经"内关"穴组与模型组比较,心肌组织NO、NOS含量明显升高(P<0.05),心肌细胞内Ca2+荧光强度明显降低(P<0.01);电针肺经"列缺"穴及电针大肠经"合谷"穴与模型组比较,各指标的差异无统计学意义(P>0.05)。结论:电针心包经"内关"穴可上调心肌内源性保护物质的水平,降低Ca2+超载,且这种效应存在经脉(穴)与脏腑间的相对特异性联系。

Objective To observe the effect of electroacupuncture （EA） on contents of myocardial nitric oxide （NO）, nitric oxide synthase （NOS）, and intracellular Ca^2＋ levels in experimental myocardial ischemia-reperfusion injury （MI/RI） rats, so as to provide some evidence for acupuncture treatment of cardiovascular disorders and for the correlation between the acupoints and the internal organs. Methods Fifty male Wistar rats were randomly divided into sham-operation （sham）, model, Neiguan （PC 6）, Lieque （LU 7）, and Hegu （LI 4） groups （n = 10/group）. MI/RI model was established by occlusion of the descending anterior branch of the left coronary artery for 40 min and reperfusion for 60 min. EA （30 Hz/100 Hz, 2- 4 mA） was applied to the bilateral PC 6, LU 7 and LI 4 for 20 min. The myocardial tissue of the ischemic area was taken, homogenated and centrifuged, separated for assaying NO and NOS activity by using spectrophotometer and their contents with nitrate reductase colorimetric assay. Another part of the myocardium tissue was processed to be cell suspension （added with Fluo-3/AM dye） for assaying intracellular free[Ca^2＋ ]i concentration under the laser confocal microscope. Results Compared with sham group, myocardial NO and NOS contents of model group decreased mildly and significantly （P〈0.05）, while myocardial fluorescence intensity （content） of intraceliular Ca^2＋ increased evidently （P〈0.01）. In comparison with model group, the contents of myocardial NO and NOS were upregulated considerably in PC 6 group （P〈0.05）, and intracellular Ca^2＋ content in PC 6 group reduced significantly （P〈0.01）. No significant differences were found between LU 7 and model groups and between LI 4 and model groups in the abovementioned 3 indexes （P〉0.05）. Conclusion EA of PC 6 can upregulate myocardial NO and NOS contents and downregulate myocardial intracellular Ca^2＋ level in MI/RI rats, which may contribute to its effect in relieving myocardial injury. Neiguan （PC 6） and the heart have a relatively specific correlation.