Pyloric relaxation regulated via intramural neural pathway of the antrum

Current information about pyloric relaxation is not sufficient. For this re ason, our study aimed at measuring pyloric relaxation correctly and determi ning the role of the intrinsic and extrinsic neural pathway in pyloric rela xation. Five groups of dogs were used: five dogs had an intact gastrointest inal tract (control group); five dogs had transection and reanastomosis of the antrum 3 cm proximal to the pylorus (antral transection group); five do gs had extrinsic pyloric denervation (denervation group); five dogs had tra nsection and reanastomosis of the antrum with extrinsic pyloric ring denerv ation (transection with denervation group); and five dogs had truncal vagot omy (vagotomy group). Gastropyloroduodenal motility was recorded by a strai n-gauge force transducer in conscious dogs. In the control and denervation, groups, pyloric relaxation was observed only during phase III of the interd igestive migrating motor complex. In the antral transection, transection wi th denervation, and vagotomy groups, pyloric relaxation was not observed in either the interdigestive or the postprandial state. The frequency of pylo ric contractions increased in these groups in comparison with the control g roup. In conclusion, the results suggest that pyloric relaxation occurred d uring phase III to expel undigested particles from the stomach and that des cending antral intramural pathways play an important role in the control of pyloric relaxation.