[Influence of electroacupuncture on myocardial NO and NOS and intracellular Ca2+ contents in myocardial ischemia-reperfusion injury rats].

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 free [Ca2+]i 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 above mentioned 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.