不同强度电针"内关"及"足三里"对心肌缺血后自主神经及心功能的调控效应OA

Objective To screen the optimal stimulation intensity of electroacupuncture(EA)at"Neiguan"(PC6)and"Zusanli"(ST36)for regulating autonomic nerve activity and cardiac function in rats with myocardial ischemia(MI),so as to explore the potential underlying mechanism.Methods Forty male Sprague-Dawley(SD)rats were randomly divided into a control group and a model group,with 20 rats in each group.The MI model was established by ligating the left anterior descending coronary artery(LAD).Rats in the control group underwent thoracotomy without LAD ligation.Lead Ⅱ electrocardiogram(ECG)was used to monitor ST segment elevation;Masson staining was performed to measure the cardiac collagen volume fraction(CVF);Doppler echocardiography was applied to assess ejection fraction(EF)and fractional shortening(FS),respectively for model evaluation.At the 7th day after MI induction,EA with different intensities(0.5,1.5,3 mA)was administered at left PC6 and ST36 for 1 min in both the control and model groups.In vivo neuroelectrophysiological recording was used to detect the discharge frequency of the left cervical sympathetic nerve(SN)and cervical vagus nerve(VN).ECG was employed to record heart rate(HR)and heart rate variability(HRV),and the Millar pressure-volume conductance catheter system was used to measure stroke volume(SV),stroke work(SW),and cardiac output(CO),so as to screen the optimal stimulation intensity for each acupoint.Autonomic denervation was performed in the model group(n=10).Before and after denervation,EA with the optimal intensity was delivered at left PC6 and ST36,and the above indicators were measured repeatedly to verify whether the autonomic nervous system is involved in the regulatory effect of EA on cardiac function in MI rats.Results After LAD ligation,ECG showed a significant elevation of the ST segment(P<0.000 1),accompanied by marked decreases in EF and FS(P<0.000 1)and an increase in CVF(P<0.01),indicating successful establishment of the MI model.The basal discharge frequency of SN in the model group was significantly higher than that in the control group(P<0.05).In the control group,1.5 mA EA at PC6 resulted in an increased HR(P<0.01).In the model group,1.5 mA EA at PC6 led to increases in the discharge frequency of SN and VN,HRV,as well as SV,SW and CO(P<0.01,P<0.05,P<0.001).1.5 mA EA at ST36 increased the discharge frequency of VN in the model group(P<0.05).In the control group,3 mA EA at ST36 induced an elevation of HR(P<0.05);in the model group,the same intervention increased the discharge frequency of SN,along with SV,SW and CO(P<0.05,P<0.01).After autonomic denervation,the regulatory effects of EA at the above acupoints with optimal intensities on cardiac function were abolished.Conclusion The optimal intensity of EA at PC6 for improving cardiac function is 1.5 mA,while that at ST36 is 3 mA.The EA-induced regulatory effects depend on the integrity of the autonomic nervous system.