Objective: To observe changes of vagal electrical activity after electroacupuncture(EA) at "Zusanli"(ST 36).Methods: Thirty male SD rats(220±20 g) were evenly and randomly divided into control group

EA group

and non-acupoint group.After anesthesia(20% urethane

1 g/kg

i.p.)

the rat's bilateral cervical vagus nerves were isolated and ligated on the middle part;then

two pairs of bipolar platinum electrodes were respectively placed at the cephalic and caudal ends of the ligated site for recording the discharges of the afferent and efferent fibers of the vagus nerve(covered with mineral oil).The electrical signals from the electrodes were amplified

filtered(100-1000 Hz)

and fed to a computer for recording and analysis.EA(3 Hz

2-4 V) was applied to bilateral "Zusanli"(ST 36) and non-acupoints(about 5 mm beside ST 36) for 30 min separately.Results: Both afferent and efferent vagal activity of control group and non-acupoint group had no apparent changes(P>0.05) during the experimental course.In EA group

about 7.5 min after EA of "Zusanli"(ST 36)

both the frequency and the peak values of the efferent vagal electrical activity increased significantly in comparison with pre-stimulation(P<0.01).However

this situation did not happen in the afferent vagal activity.Conclusion: EA of "Zusanli"(ST 36) can increase the efferent activity of the vagal nerve

but does not influence the afferent activity.