The pressures in the esophagus and gastro-esophageal sphincter in 22 healthy unanesthetized dogs were studied by the use of three small open tipped tubes with internal diameter of 1.4 mm. The tubes were introduced and manipulated without anesthesia through the previously made esophageal fistula. To record the resting pressure, an open tipped tube was withdrawn slowly from the stomach back to the esophagus. The swallowing action was induced by an injection of water into the esophagus.
The resting pressure in the esophagus was less than that in the f undus of the stomach.A band of elevated pressure was recorded at the gastro-esophageal junctional area in thedogs while at rest. The mean maximal pressure in this area was 9.5 cm H2O and themean width was 2.6 cm H2O.
As for the changes in pressure during swallowing, the peristaltic waves were seen to sweep downward in the esophagus. In the gastro-esophageal junctional area, the negative wave (relaxation) occurred 4 seconds after the onset of water injection inducing swallowing, lasting about 3 seconds, and was followed by the positive wave (contraction) lasting 3.3 seconds.
