β-肾上腺素受体介导电针改善游泳疲劳诱发的急性心肌缺血效应的初步研究

Involvement of β-adrenoceptors in Cardioprotective Effect of Electroacupuncture Intervention in Mice with Swimming Fatigue-induced Myocardial Ischemia

目的:观察电针"内关"穴对游泳疲劳诱发的小鼠急性心肌缺血性损伤的改善效应,并探讨β-肾上腺素受体在其中的作用。方法:野生型成年雄性C 57BL/6及同品系的β1/β2-AR双敲小鼠各16只,分别将两种小鼠随机分为对照组和电针组,每组8只。采用无负重游泳疲劳方式造成急性心肌缺血模型。电针组均采用电针"内关"穴干预(2Hz,0.5mA)30min,每日1次,共7d。观察比较7d后各组标准Ⅱ导联心电图ST段幅值、心率(HR)和心律失常评分的变化。结果:与基础值比较,C 57BL/6小鼠游泳疲劳后可诱发急性心肌缺血发生,表现为:ST段幅值显著升高(P<0.01),心率降低(P<0.05),心律失常评分增加(P<0.05);与对照组比较,电针组ST段幅值明显下降(P<0.01),心律失常评分明显降低(P<0.05)。与基础值比较,β1/β2-AR敲除小鼠游泳疲劳后亦可诱发急性心肌缺血发生,而与对照组比较,电针组ST段幅值、HR以及心律失常评分都没有明显的改善(P>0.05)。结论:电针"内关"穴具有改善游泳疲劳诱发的急性心肌缺血的作用,β-肾上腺素受体参与介导了该针刺效应。

Objective To observe the cardioprotective effect of electroacupuncture （EA） stimulation at ＂Neiguan＂ （PC 6） in mice with myocardial ischemia （MI） and to explore the involvement of cardiac beta-adrenergic receptors （β-AR） in the cardioprotective effect of EA intervention. Methods Adult male C 57 BL/6 mice of wild type and β1/β2-AR double-knockout（ β1/β2-AR-/- ） mice were randomly and respectively divided into control group and EA group, with 8 mice in each group. These mice were subject to procedures of basic control, fatigue swimming and fatigue swimming＋ EA. The model was established by fa- tigue swimming for inducing acute MI. EA （2 Hz, 0.5 mA） was applied to bilateral ＂Neiguan＂ （PC 6） for 30 min, once daily for 7 days in both EA groups. The ST-segment of electrocardiogram （ECG） of standard limb lead Ⅱ , heart rate were recorded by using a biophysical amplifier and the arrhythmia score was assessed according to Curtis and Walker＇s methods （ 1988）. Results Self- comparison showed that, compared with the baseline, the amplitude of ECG-STⅡ segment was obviously increased in swimming fatigue C 57 BL/6 mice （P〈0.01） and further obviously increased in β1/β2-AR-/- mice （ P,〈0. 01 ）, suggesting an acute MI in C 57 BL/6 mice and a worsened MI in β11/β2-AR-/- mice. Simultaneously, the heart rate was markedly decreased （P〈0. 05）, and the score of arrhythmia obviously increased in both C 57 BL/6 and β1/β2-AR-/- mice （P〈0.05）. Compared with the mode- ling procedures, ECG-STⅡ amplitude and arrhythmia score were significantly decreased in C 57 BL/6 mice of the EA group （P〈0.01, P〈0. 05）, rather than in the β1/β2-AR-/- mice of the EA group （P〉0.05）. In addition, heart rate levels of bothC 57 BL/6 mice and β1/β2-AR-/- mice had no significant differences between control and EA groups （P〈0.05）. Conclusion EA at ＂Neiguan＂ （PC 6） can protect the heart from swimming fatigue-induced MI in C 57 BL/6 mice not in β1/β2-AR-/- mice, sug- gesting an involvement of β1/β2-AR in the protective effect of EA.