Identification of diaphragmatic crural component of gastroesophageal barrier in the rat.

Manometric assessment of the diaphragmatic contribution to the human gastroesophageal barrier is difficult because it overlaps with that of the lower esophageal sphincter. Our aim was to investigate the barrier components in the rat in which the gastroesophageal junction is widely separated from the hiatus. Rats under anesthesia (N = 119) and after muscle relaxation (N = 14) underwent stationary and pull-through perfusion manometry. Inspiratory transdiaphragmatic pressure gradient was 5.79 +/- 1.69 mm Hg and lower esophageal sphincter pressure was 14.76 +/- 8.63 mm Hg. A 13.78 +/- 3.13-mm intraabdominal segment of the esophagus was interposed cranially between the sphincter and a group of phasic oscillations with frequency identical to the respiratory rate and pressure of 13.81 +/- 6.54 mm Hg, which disappeared after muscle relaxation. Both components of the gastroesophageal barrier in the rat are widely separated by a long intraabdominal esophagus. This arrangement allows investigation of the behavior of both components under challenging conditions.