Effect of esophageal distention on pressure and electromyographic activity of the pharyngoesophageal sphincter, with identification of the esophagopharyngeal reflex.

PURPOSE

My purpose was to study the effect of balloon-produced esophageal distention on the pharyngoesophageal sphincter to shed light on the mechanism by which esophagopharyngeal reflux is prevented.

METHOD

Nine dogs (mean weight 15.7 +/- 4.3 kg) were used for the study. A balloon-tipped catheter was introduced into the esophagus and a manometric catheter into the pharyngoesophageal sphincter. The pressure response of the pharyngoesophageal sphincter to esophageal distention was recorded. The response was also tested while the esophagus and the pharyngoesophageal sphincter were anesthetized, each separately. In six of nine dogs the electromyographic response of the pharyngoesophageal sphincter to esophageal distention was studied before and after the esophagus was anesthetized.

RESULTS

Lower and midesophageal distention produced no pressure changes in the pharyngoesophageal sphincter (p = 0.082). Upper esophageal distention effected an elevation in pharyngoesophageal sphincter pressure (p = 0.024), which showed no further rise when the distending volume was increased. The anesthetized pharyngoesophageal sphincter did not respond to esophageal distention. Likewise, the pharyngoesophageal sphincter did not respond to distention of the anesthetized upper esophagus. Esophageal distention produced increased electromyographic activity of the pharyngoesophageal sphincter, but no activity was recorded in response to distention of the anesthetized esophagus.

CONCLUSION

This study has demonstrated contraction of the pharyngoesophageal sphincter on distention of the upper esophagus. This response seems to prevent esophagopharyngeal reflux and choking and is postulated to be evoked by means of an "esophagopharyngeal reflex."