Influence of vagal cooling on esophageal function

Experiments were performed on adult opossums to determine the effect of decreased vagal activity on the esophageal peristalsis and lower esophageal sphincter (LES) relaxation associated with pharyngeal stimulation (PS) and esophageal balloon distension (ED). The cervical vagi were exposed and cooled (individually and bilaterally) to 3 degrees C using Dry Ice and alcohol-chilled saline. Unilateral vagal cooling had no effect on the esophageal peristalsis or LES relaxation associated with PS or ED. Similarly, bilateral vagal cooling did not alter the peristalsis and sphincter relaxation induced by ED. Bilateral vagal cooling, on the other hand, significantly decreased the incidence of peristalsis and the sphincter relaxation associated with PS. Studies were also performed to examine the effect of unilateral and bilateral vagotomy of esophageal function. Neither right nor left cervical vagotomy affected esophageal peristalsis or LES relaxation, regardless of the model of stimulation. Bilateral vagotomy, however, diminished the esophageal response to PS but was without effect on the peristalsis and LES relaxation produced in response to ED. From the studies we condlude: 1) the vagus nerve is of primary importance in regulating the esophageal response to PS, and 2) local neuromuscular factors within the esophageal wall appear sufficient to initiate and maintain an esophageal response to distension.