Objective To observe the effect of electroacupuncture(EA)stimulation of the Heart Meridian on electrical activities of neck sympathetic and vagal nerves in acute myocardial ischemia(AMI)rats.Methods Thirty SD rats were randomly divided into 3groups

sham operation(sham)

model and EA(n=10rats in each group).The left anterior descending branch(LADB)of the coronary artery was occluded to make an acute myocardial ischemia(AMI)model.For rats of the sham group

a surgical suture was simply threaded beneath the LADB without ligation.EA stimulation(2Hz

1mA)was applied to bilateral"Shenmen"(HT 7)

"Tongli"(HT 5)and the middle-point between HT 7and HT 5for 20 min.The electrical activities of the left cervical sympathetic and vagal nerves were recorded using a bipolar platinum wire electrodes and a BIOPAC MPl 50 system

and the electrocardiogram(ECG)of the standard limb lead II was recorded simultaneously.The AMI severity was evaluated by using J-spot height of ECG.Results After AMI

the heart rate(HR)

J-spot of ECG

and the discharge frequency of the cervical sympathetic nerve were significantly increased in the model group compared with the sham group(P<0.01)

while the discharge frequency of vagal nerve was obviously decreased(P<0.01).Following EA stimulation

the increased levels of HR

J-spot height and discharge frequency of sympathetic nerve

and the decreased discharge frequency of vagus were significantly suppressed at time-points of 1

3

5and 15 min after EA(P<0.01).In addition

the ratio of discharge frequencies of vagal/sympathetic nerves was notably down-regulated after AMI(P<0.01).After EA stimulation

the ratios of vagal/sympathetic discharge at the time-points of 1

3

5and 15 min following EA were significantly increased(P<0.01).Conclusion EA stimulation of the Heart Meridian may improve AMI by inhibiting sympathetic discharges and elevating vagal discharges in AMI rats

i.e.

coordinating activities of the autonomic nerve systems.