Role of pylorus in the control of the canine migrating motor complex

The cyclic myoelectric activity of the gastroduodenal area and the antral mucosal ionic permeability, measured by the transmural potential difference, were simultaneously evaluated in the dog. These parameters were recorded before and after section of the omental attachments to the pyloric area, section of the terminal antrum, and excision of a 2-cm segment at the pylorus. None of the surgical procedures modified the duration of the postprandial disruption of the migrating motor complexes, whereas the potential difference was increased. In fasted dogs resection of the omentum increased the migrating motor complex intervals and the duration of the phase of regular spiking activity; however, the regular spiking activities still occurred in a sequential manner. Transection of the terminal antrum was associated with a decrease in duration of the regular spiking activity phases that started simultaneously on the antrum and duodenum, without changes in the migrating motor complex intervals, and prevented the occurrence of the increase in potential difference associated with feeding. After pylorectomy, the migrating motor complex intervals were reduced by 46% on both antrum and duodenum. Our observation that only pylorectomy was able to consistently increase the frequency of migrating motor complexes suggests a pyloric inhibition of the normal pacing of the cyclic motor events at both antral and duodenal levels.