EFFECT OF TOPICAL ESOPHAGEAL ACIDIFICATION ON HUMAN SALIVARY AND ESOPHAGEAL ALKALI SECRETION

Recent human studies suggest that oesophageal HCO3- secretion, in conj unction with salivary HCO3- secretion and secondary oesophageal. peris talsis, is important for the protection of oesophageal mucosa from ref luxed gastric contents. This study evaluated simultaneously the respon siveness of oesophageal and salivary HCO3- secretion to oesophageal ac idification in eight healthy subjects. A 10 cm segment of oesophagus w as perfused at a constant rate of 5 ml/min with a specially designed t ube assembly. Saline was used initially, and then 10 mM and 100 mM HCl . The perfusates contained H-3-polyethylene glycol (PEG) as a concentr ation marker to determine volumes. Corrections were applied for a smal l degree of contamination by swallowed saliva and refluxed gastric alk ali. Oesophageal perfusion with 10 mM HCl did not cause symptoms (naus ea and heartburn), but tripled the oesophageal HCO3- output from a bas eline of 51 mu mol/10 cm/10 min (p=0.021), while doubling the rate of salivary HCO3- secretion from a median basal value of 140 mu mol/10 mi n (p=0.021). Oesophageal perfusion with 100 mM HCl was associated with symptoms of nausea and heartburn in all subjects. The median oesophag eal HCO3- output increased 32 fold to 1659 mu mol/10 cm/10 min (interq uartile range 569 to 3373; p=0.036), and salivary HCO3- secretion appr oximately tripled from basal values (p=0.036). In conclusion, oesophag eal acidification stimulates both salivary and oesophageal HCO3- secre tion, responses which may be protective to the oesophageal epithelium.