AJP - Gastrointestinal and Liver Physiology, Vol 256, Issue 1 198-G205, Copyright © 1989 by American Physiological Society
Evidence for inhibition of opossum LES through intrinsic gastric nerves
K. Schulze-Delrieu, W. H. Percy, J. Ren, S. S. Shirazi and K. Von Derau
Gastroenterological Research Laboratories, Veterans Administration Medical Center, Iowa City, Iowa 52240.
We have studied the mechanical responses of the isolated opossum
gastroesophageal junction to a variety of stimuli. Lower esophageal
sphincter (LES) relaxations were readily produced by gastric stretch and by
electrical stimulation of the intramural gastric nerves. Gastric
stimulation also led in 60% of stimuli to a contraction of circular muscle
(the off response) in the distal esophagus, but in less than 15% of stimuli
to a contraction of longitudinal esophageal muscle (the duration response).
Mechanical or electrical stimulation of the esophagus led to a mechanical
response of the stomach (relaxation, contraction, or both) in 76% of
stimuli. The LES relaxation produced by esophageal stimulation was not as
long as that produced by gastric stimulation. Direct electrical stimulation
of the esophageal or gastric muscle produced a ring contraction that spread
readily across the gastroesophageal junction but did not produce a
relaxation of the LES or a contraction of the longitudinal esophageal
muscle. Thus intramural nervous pathways can coordinate the mechanical
activity of the esophagus, LES, and stomach. LES relaxations may occur as
part of intrinsic reflexes that mediate gastric accommodation to volume.
