Experimental gastroesophageal reflux in the Australian brush-tailed possum.

It has been suggested that the lower esophageal sphincter (LES) plays an important role in preventing gastroesophageal reflux. This study was designed to determine if abolition of the LES alone is sufficient to induce gastroesophageal reflux and esophagitis. Studies were performed in the Australian brush-tailed possum (Trichosurus vulpecula) which has a lower esophagus resembling that of man. Esophageal manometry, esophagoscopy, and contrast radiography of the lower esophagus and stomach were performed before and after surgery in a group of animals undergoing cardioplasty and in a group of sham operated control animals. In the animals undergoing cardioplasty, LES pressure fell from a preoperative level of 12.6 +/- 1.3 mm Hg to 0 mm Hg. This was followed by the development of gastroesophageal reflux and esophagitis. Sham operation did not alter LES pressure or result in either gastroesophageal reflux or esophagitis. In 4 of 5 animals undergoing cardioplasty, LES activity returned after 10 weeks, and this time gastroesophageal reflux ceased and esophagitis healed. It is concluded that abolition of the LES alone can induce gastroesophageal reflux and esophagitis.