Objective: To observe the influence of electroacupuncture (EA) of different acupoints on changes of mean arterial pressure (MAP), heart rate (HR) and heart rate variability (HRV) in colorectal distension (CRD) rats, so as to analyze the specificity of actions of acupoints in relieving visceral pain and regulating activities of the autonomic nerve system.
Methods: Forty-five Wistar rats were randomized into control, Zusanli (ST 36), non-acupoint, Neiguan (PC 6) and Taichong (LR 3) groups (n = 9/group). Under anesthesia, CRD was given to the rats by using an aerostat for 5 min. EA (2 Hz/15 Hz, 2 mA) was applied to bilateral ST 36, non-acupoint (1.0 cm lateral to ST 36), PC 6 and LR 3 for 15 min, respectively. Electrocardiogram of the cervico-chest lead was recorded by using a bioelectric amplifier, and MAP recorded by using a pressure transducer and an amplifier. Low frequency and high frequency of HRV were analyzed by Chart 5.0.
Results: Following CRD, the HR, MAP, LF and LF/HF levels increased significantly in all the 5 groups (P < 0.05), while HF had no apparent changes (P > 0.05). Compared with the control group, 5 min and 15 min after EA ,and 10 min after ceasing EA, MAP values of ST 36 and PC 6 groups were decreased obviously (P < 0.05). The HR values of ST 36 and PC 6 groups at 15 min after EA and 10 min after ceasing EA were decreased markedly in comparison with those of each of the other groups during CRD (P < 0.05). The LF levels of both ST 36 and PC 6 groups at 5 min after EA, and those of ST 36, PC 6 and LR 3 at 15 min after EA were significantly lower than those of control group (P < 0.05). LF/HF levels of ST 36 and PC 6 at 10 min after ceasing EA were obviously lower than those of control group (P < 0.05). No significant differences were found among ST 36, non-acupoint, PC 6 and LR 3 groups in HR, LF and LF/HF (P > 0.05).
Conclusion: EA of ST 36 and PC 6 can suppress CRD-induced increase of MAP, HR and LF/HF, suggesting beneficial effects of EA in relieving visceral pain and mediating autonomic nerve system. The aforementioned effects of EA of LR 3 and non-acupoint are not obvious.