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 pe rformed in eight hound dogs implanted with one pair of bipolar serosal elec trodes 2 cm proximal to the pylorus. Gastric myoelectrical activity was rec orded for three complete cycles of the MMC in two sessions, one with electr oacupuncture at points ST36 and PC6 and the other at sham points. The acupu ncture 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 (amplitu de) 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 freque ncy 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 pow er in the dow wave. It was also found that in comparison with the sham poin ts, electroacupuncture at the acupoints increased the number of spike burst s. This increase was not significant during the MMC cycle with electroacupu ncture (34.4 +/- 4.1 vs 27.5 +/- 2.5%, P > 0.05) but became significant dur ing 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 a cupoints, 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 le ngth of phase II (75.6 +/- 9.9 vs 30.6 +/- 4.1 min, P < 0.003) and phase II I (25.8 +/- 0.6 vs 22.1 +/- 0.7 min, P < 0.003). A similar increase was obs erved during the MMC cycle with electroacupuncture but was not statisticall y significant. In conclusion, the gastric slow wave has the highest power d uring phase III of the MMC, indicating that the antral contraction is chara cterized not only by the appearance of spikes, but also by the increased po wer of the slow wave. Electroacupuncture at acupoints of ST36 and PC6 enhan ces the gastric MMC by reducing the length of phase I and increasing the le ngth of phases II and III.