A Preliminary Study on the Cardioprotection of Acupuncture Pretreatment in Rats with Ischemia and Reperfusion: Involvement of Cardiac β-Adrenoceptors

The purpose of this study was to determine the cardioprotective effects of the repetitive pretreatment of acupuncture in rats with myocardial ischemia and reperfusion (MIR). Experimental MIR was produced by ligating and reperfusing the left anterior descending coronary artery in the rats. The elevated ST segments of electrocardiogram (ECG), cardiac arrhythmias, and ratio of infarct size/risk zone were compared among the normal control (NC), ischemia and reperfusion (IR), electro-acupuncture (EA), electro-acupuncture plus propranolol (EAP), and EA at nonacupoint (EAN) groups. Before the experiment, EA was applied at bilateral Neiguan acupoints (PC6) in the forelimbs in EA and EAP groups for 30 min once a day for 3 consecutive days. In the EAN group, the same EA treatment was administered at bilateral nonacupoints in the hind limbs. In the EAP group, propranolol, a nonspecific antagonist of β-adrenoceptors, was administered intraperitoneally 15 min before each EA pretreatment. The results showed that the elevated ST segment of ECG, cardiac arrhythmia score, and ratio of infarct size/risk zone were significantly attenuated in the EA group when compared with those in the IR group (P < 0.05), indicating a cardioprotection of EA pretreatment. When propranolol was given before each EA pretreatment in the EAP group, the cardioprotective effect of EA pretreatment was abolished, showing an involvement of β-adrenoceptors in mediating the effect of EA pretreatment. There was no significant cardioprotective effect observed in the EAN group. The results suggest that pretreatment may be a better way to apply acupuncture in the prevention and treatment of coronary heart disease.