Effects of electroacupuncture on gastric migrating myoelectrical complex in dogs

The aim of this study was to investigate the characteristics of the gastric slow wave during different phases of the migrating myoelectrical complex (MMC) and the effect of electroacupuncture on the MMC. The experiment was performed in eight hound dogs implanted with one pair of bipolar serosal electrodes 2 cm proximal to the pylorus. Gastric myoelectrical activity was recorded for three complete cycles of the MMC in two sessions, one with electroacupuncture at points ST36 and PC6 and the other at sham points. The acupuncture was performed for 30 min in phase I of the second cycle of the MMC. Spectral analysis was performed to compute the frequency and power (amplitude) of the gastric slow wave, whereas blind visual analysis was applied to compute the appearance of spike potentials and the length of each phase of the MMC. It was found that there was a significant difference in the frequency and power of the gastric slow wave during different phases of the MMC (P < 0.05). Phase I was characterized with the highest frequency and lowest power of the gastric slow wave, whereas phase III exhibited the highest power in the slow wave. It was also found that in comparison with the sham points, electroacupuncture at the acupoints increased the number of spike bursts. This increase was not significant during the MMC cycle with electroacupuncture (34.4 ± 4.1 vs 27.5 ± 2.5%, P > 0.05) but became significant during the cycle after electroacupuncture (39.8 ± 3.3% vs 27.5 ± 2.5%, P < 0.0005). Similarly, during the MMC cycle after electroacupuncture at the acupoints, there was a significant decrease in the length of phase I (14.8 ± 2.2 vs 46.9 ± 6.1 min, P < 0.003) and a significant increase in the length of phase II (75.6 ± 9.9 vs 30.6 ± 4.1 min, P < 0.003) and phase III (25.8 ± 0.6 vs 22.1 ± 0.7 min, P < 0.003). A similar increase was observed during the MMC cycle with electroacupuncture but was not statistically significant. In conclusion, the gastric slow wave has the highest power during phase III of the MMC, indicating that the antral contraction is characterized not only by the appearance of spikes, but also by the increased power of the slow wave. Electroacupuncture at acupoints of ST36 and PC6 enhances the gastric MMC by reducing the length of phase I and increasing the length of phases II and III.