Modulation of esophageal contractions by distensionin Vitro

Publisher Website
Google Scholar
Abstract
Stimulation of the intrinsic nerves of the esophageal body leads to a twitch of the circular muscle after the end of the stimulation (the esophageal off-response), and the twitch spreads in the distal direction because of a latency gradient in the onset of the off-response between the proximal and the distal esophagus. We investigated the possibility that local input can modulate the basic off-response through intrinsic mechanisms and make it resemble more closely the sequential ring contractions that move boluses in the esophagus of intact animals (esophageal peristalsis). The esophagus up to the aortic arch and down to the gastroesophageal junction was removed from opossums and suspended in an organ bath containing 2 liters of Krebs solution at 36° C. The mechanical activity of the esophagus was recorded by force transducers on the serosal surface of the esophagus 2, 4, and 6 cm above the LES. The intramural nerves of the proximal esophagus were stimulated by electrical pulses with and without distension of the esophagus by inflation of a luminal balloon. Balloon distension increased the latency of the off-response in the distal esophagus, thereby reducing the velocity at which the circular muscle contraction spread through the esophagus. In addition, balloon distension increased the amplitude and the duration of the esophageal circular muscle contraction (both off- and on-responses), and decreased the amplitude of the longitudinal muscle contraction (duration response) and LES response (relaxation response). Similar changes in the esophageal contraction responses were produced by radial stretch of an open preparation of the esophagus from which the mucosa had been removed. The present results demonstrate that intramural mechanisms can modulate the contraction pattern of the isolated esophageal smooth muscle. The observed changes make it likely that radial stretch is an important factor in turning the intrinsic off-response of the esophageal smooth muscle into the sequential ring contraction observed with esophageal bolus transport in the intact animal.