Effect of intraesophageal bile and acid (HCl) perfusion on the action of the lower esophageal sphincter.

We examined the effect of acid and bile on the lower esophageal high pressure zone (LEHPZ) in a combined manometric, pH testing and morphologic study in 12 cats. LEHPZ pressures and swallowing waves (SW) were simultaneously recorded before, during and after perfusion of the esophagus with control fluid, acid (0.1 n HCl) natural bile and a mixture of acid and bile. Endoscopy was performed and biopsies taken before and after the experiments. Bile caused a rise of LEHPZ and SW pressure and mild esophagitis. Acid and bile acid mixture produced a marked progressive decline of LEHPZ and SW pressure (p less than 0.001), incomplete relaxation and severe discoordination of esophageal motility. Continuous pH measurements showed diminished or no clearance and reflux. All acid perfused cats developed necrotic esophagitis and strictures within 4 weeks. LEHPZ pressures returned to almost normal values after this recovering period but peristalsis was still completely discoordinated. Swallowing waves were of exaggerated magnitude and length. From our findings it is evident that bile and acid change LEHPZ competence. Bile and acid seem to have a different effect on motor function of the LEHPZ and esophageal peristalsis.