Modulation of salivation and heartburn in response to the site of acid infusion in the human oesophagus.

BACKGROUND: The pathogenesis of gastro-oesophageal reflux disease includes increased acid reflux, reduced salivation and impaired peristalsis. This may depend upon the height of acid wave and magnitude of oesophageal mucosal exposure. Interestingly, the effect of site of acid infusion upon salivary secretion and heartburn has not been examined in any detail. AIM: To examine whether acid infusion in the upper oesophagus may cause increased salivation and heartburn as compared with acid infusion in the lower oesophagus. METHODS: Twelve healthy male subjects (mean age 30) received infusions of HCl, citric acid and acetic acid at 10 and 20 cm above the lower oesophageal sphincter (LES) for fixed time periods. Parotid saliva collected periodically and heartburn severity scored using standardized scale. Standard statistical methods (paired t-tests, analysis of variance) were used to determine the significance of results. RESULTS: Acid infusion in the upper oesophagus increased parotid flow rate as compared with that in the lower oesophagus (P < 0.05). Likewise, there was a significantly increased heartburn score at 20 cm as well as 10 cm above LES (P < 0.05) as compared with that in the stomach. CONCLUSION: These data suggest a significant increase in salivation and heartburn in response to acid infusion in the upper vs. lower part of the oesophagus.