Objective: To explore the effect of electroacupuncture(EA) of acupoints of the Pericardium Meridian of Hand-Jueyin on changes of mitochondria in myocardial ischemia/reperfusion(MI/R) injury rats so as to explore the protective mechanism of acupuncture on ischemic myocardiocytes. Methods: Fifty male Wistar rats anesthetized by 10% urethane(1 g/kg) were evenly randomized into control

model

EA-"Neiguan"(PC 6)

EA-"Ximen"(PC 5)

EA-"Zhigou"(TE 6) groups.Under artificial respiration

MI/R model was established by occlusion of the left descending anterior branch(DAB) of the coronary artery for 40 min

followed by reperfusion for 60 min.EA(30-100 Hz in frequency

20-30 V in strength

dense-sparse waves) was applied to the above mentioned acupoints for 20 min

two times altogether.Then

the myocardial sample(below the ligation site of DAB) of the left cardiac ventricle was taken for observing the morphological changes of mitochondria under transmission electron microscope. Results: Before occlusion of DAB

ECG-ST_Ⅱ values of the 5 groups had no significant differences(P>0.05)

while after occlusion of the coronary artery

ECG-ST_Ⅱ of model and 3 EA groups increased considerably.Compared with model group

ST values of EA-"Neiguan"(PC 6) and EA-"Ximen"(PC 5) groups were significantly lower from 20 min to 40 min after occlusion

and 30 min after reperfusion(P<0.05)

showing that EA could remarkably reduce MI/R induced myocardial injury.Correspondingly

in model group

mitochondrial swelling

reduction in the number of the mitochondrial cristsae

and broken cristae with disordered arrangement and vacuous changes were found

and in EA-"Zhigou"(TE 6) group

these pathological changes were similar.But in EA-"Neiguan"(PC 6) group

and EA-"Ximen"(PC 5) group

the situations were much better. Conclusion: EA stimulation of acupoints of the Pericardium Meridian can improve ischemic ECG and reduce MI/R induced structural injury of myocardial mitochondria in rats

which may contribute to its protective effect on the ischemic myocardial cells.