Objective To observe the effect of electroacupuncture(EA)stimulation of"Neiguan"(PC 6)-"Jianshi"(PC 7)on ischemic myocardial injury in myocardial ischemic(MI)rats

so as to explore its mechanism underlying improvement of MI.Methods A total of 48 male Wistar rats were randomly divided into normal

MI model

PC 6-PC 7

Sanyinjiao-Diji(SP 6-SP 8)groups(n=8in each group for physiological experiments

n=4in each group for immunoflorescence stain).The MI model was established by occlusion of the anterior descending branch of the left coronary artery.Electrocardiogram(ECG)of the neckthoracic lead was recorded and the heart rate variability(HRV)analyzed by using aphysiological signal collecting system(MP 150)and PowerLab software.EA(2Hz/15 Hz

0.5mA)was applied to bilateral PC 6-PC 7or SP 6-SP 8for 30 min every time

on the 1

2

3day after modeling.Serum creatine kinase-MB isoenzyme(CK-MB)and lactate dehydrogenase-1(LDH 1)and endothelin(ET)contents were assayed by ELISA.The expression of choline acetyltransferase(ChAT)and vesicular acetylcholine transporter(VAChT)and c-fos proteins in the nucleus ambiguus(NA)region of the medulla oblongata was detected by immunofluorescence stain.Results Compared with the normal group

the ECG J-point height(1h)

serum CK-MB

LDH 1and ET contents(1dand 3d)

HR(1hand 1d)and LF/HF levels of HRV(1h

1dand 3d)and the number of c-fos positive neurons(3d)in the NA region were significantly increased in the model group(P<0.01

P<0.05)

while HF levels(1h

1dand 3d)and ECG J-point height(1dand 3d)were considerably decreased after MI.After EA intervention

the ECG J-point height 3dafter MI was close to zero in both PC 6-PC 7and SP 6-SP 8groups

being better than that(negative value)of the model group

and serum CKMB

LDH 1and ET contents(1d

3d)of both EA groups

and HR(1d)and LF/HF(3d)of the PC 6-PC 7group were obviously down-regulated(P<0.01

P<0.05)

and the decreased HF 3dpost-MI and the increased number of c-fos positive neurons were significantly up-regulated in the PC 6-PC 7group(P<0.01).No significant differences were found between the two EA groups in raising J-point height and in down-regulating serum CK-MB

LDH 1and ET contents(P>0.05).Compared with the model group

no significant changes were found in HR 1dpost-MI of the SP 6-SP 8group

3dpost-MI of both EA groups

in HF3dpost-MI of the SP 6-SP 8group

in LF/HF 1dpost-MI of both EA groups and 3dpost-MI of the SP 6-SP 8group

in the number of c-fos positive neurons of the SP 6-SP 8group

and ChAT and VAChT positive neurons of both EA groups(P>0.05).Conclusion EA intervention may improve ischemic myocardial injury in MI rats

probably by activating neurons in the NA region

and enhancing the cardiac parasympathetic tension

and balancing cardiac sympathetic/parasympathetic nerve activities

but the effect of cholinergic neurons of NA needs being studied further.