Oesophageal peristalsis in normal subjects. Influence of pH and volume during imitated gastro-oesophageal reflux.

Acid gastro-oesphageal reflux in normal human subjects is followed by oesphageal peristalsis. The aim of the present study was to investigate the influence of pH and volume during imitated reflux on oesophageal peristalsis. Fluid volumes of 2.5, 5, 10, and 15 ml (pH 1.0, 4.0, or 7.0) were instilled randomly in the lower end of the oesophagus in eight healthy subjects. Further, repeated instillations were carried out in one subject. Oesophageal pressures were measured 5, 10, and 15 cm oral to the gastro-oesophageal sphincter and in the pharynx, and pH 5 cm oral to the sphincter. Peristalsis confined to the oesophagus was found to be related to the volume of the instilled fluid, whereas pharynx-mediated peristalsis seemed to be related to the acidity of the fluid. It is concluded that peristalsis after imitated gastro-oesophageal reflux is influenced by both the volume and the acidity of the instilled fluid. Volume seems to initiate a local clearing mechanism, whereas low pH initiates pharynx-mediated peristalsis.