Objective To observe the effect of electroacupuncture(EA) on contents of myocardial nitric oxide(NO)

nitric oxide synthase(NOS)

and intracellular Ca2+ levels in experimental myocardial ischemia-reperfusion injury(MI/RI) rats

so as to provide some evidence for acupuncture treatment of cardiovascular disorders and for the correlation between the acupoints and the internal organs.Methods Fifty male Wistar rats were randomly divided into sham-operation(sham)

model

Neiguan(PC 6)

Lieque(LU 7)

and Hegu(LI 4) groups(n=10/group).MI/RI model was established by occlusion of the descending anterior branch of the left coronary artery for 40 min and reperfusion for 60 min.EA(30 Hz/100 Hz

2-4 mA) was applied to the bilateral PC 6

LU 7 and LI 4 for 20 min.The myocardial tissue of the ischemic area was taken

homogenated and centrifuged

separated for assaying NO and NOS activity by using spectrophotometer and their contents with nitrate reductase colorimetric assay.Another part of the myocardium tissue was processed to be cell suspension(added with Fluo-3/AM dye) for assaying intracellular freei concentration under the laser confocal microscope.Results Compared with sham group

myocardial NO and NOS contents of model group decreased mildly and significantly(P<0.05)

while myocardial fluorescence intensity(content) of intracellular Ca2+ increased evidently(P<0.01).In comparison with model group

the contents of myocardial NO and NOS were upregulated considerably in PC 6 group(P<0.05)

and intracellular Ca2+ content in PC 6 group reduced significantly(P<0.01).No significant differences were found between LU 7 and model groups and between LI 4 and model groups in the abovementioned 3 indexes(P>0.05).Conclusion EA of PC 6 can upregulate myocardial NO and NOS contents and downregulate myocardial intracellular Ca2+ level in MI/RI rats

which may contribute to its effect in relieving myocardial injury.Neiguan(PC 6) and the heart have a relatively specific correlation.