Electrical activity of the canine esophagus and gastroesophageal sphincter: its relation to intraluminal pressure and movement of material.

Abstract

Myogenic electrical activity of the sphincter and adjacent esophagus and stomach was detected by the chronic implantation of bipolar silver/silver chloride electrodes. Action potentials occurred in the esophagus following deglutition and were synchronous with the peristaltic contractions detected from within the lumen. Continuous phasic activity was present in the gastroesophageal sphincter and the adjacent gastric fundus. Reduction of the continuous phasic electrical activity occurred in the sphincter with relaxation. Reduction of it also occurred in the fundus with distention of the esophagus or stomach and during anesthesia. With swallowing, sphincteric action potentials, related to sphincteric contraction, followed the inhibition of phasic activity in the orad segment of the sphincter, while only inhibition of phasic activity and its return occurred in the caudad segment. Esophageal distention caused inhibition of action potentials in the esophagus distal to the distention as well as inhibition of the sphincteric continuous phasic activity. The inhibition continued until the distention was terminated. After subhilar bilateral vagotomy, intraluminal pressures and myogenic action potentials were simultaneous and of lesser magnitude in the vagotomized segment of the esophagus. The motor action of the gastroesophageal sphincter was not altered by vagotomy but the incidence of response to swallowing was reduced by about 50%.