Measurement of bicarbonate output from the intact human oesophagus

• Published in: Gut Vol. 34; no. 7; pp. 872 - 880
• Main Authors: Brown, C M, Snowdon, C F, Slee, B, Sandle, L N, Rees, W D
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Society of Gastroenterology 01.07.1993; BMJ; BMJ Publishing Group LTD
• Subjects: Adolescent; Adult; Bicarbonates - metabolism; Biological and medical sciences; Biopsy, Needle; Digestive system; Esophagus - metabolism; Female; Gastric Juice - chemistry; Gastroesophageal Reflux - metabolism; Humans; Hydrogen-Ion Concentration; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Mucous Membrane - metabolism; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Saliva - chemistry; Human; Measurement; Prevention; Secretion; Mucosa; Lesion; Technique; Experimental study; Hydrogencarbonates; Esophagus
• ISSN: 0017-5749; 1468-3288; 1458-3288
• DOI: 10.1136/gut.34.7.872

Injury of the oesophageal mucosa can result from exposure to refluxed gastric acid and pepsin. Competence of the lower oesophageal sphincter and peristaltic activity serve to reduce contract time between luminal acid and oesophageal mucosa, but intraluminal neutralisation of residual acid by bicarbonate may also be important in preventing oesophageal mucosal injury. Whereas swallowed saliva contains bicarbonate, recent experiments have also demonstrated alkali secretion from the mammalian oesophagus. Bicarbonate secretion from the human oesophagus was therefore examined with an intubation technique and perfusion of the oesophagus with a non-absorbable marker. Saliva, gastric, and oesophageal aspirates were collected and bicarbonate concentrations determined by measurements of pH and pCO2 or by back titration. In 32 normal subjects (17 women, 15 men) median basal oesophageal bicarbonate secretion determined by a pH/pCO2 method was 416 (range 139-1050) mumol/hour/10 cm. In a subgroup of 15 experiments median oesophageal bicarbonate output was 489 (range 157-1033) mumol/hour/10 cm (pH/pCO2 method) compared with a median alkali output of 563 (range 135-799) mumol/hour/10 cm as determined by back titration. The difference was not significant. Salivary contamination of the oesophagus accounted for 25% of all bicarbonate measured within the oesophagus and refluxed gastric bicarbonate accounted for 2.5%. Bicarbonate secretion from the normal human oesophagus may, in combination with swallowed salivary bicarbonate, play a part in preventing oesophageal mucosal damage due to refluxed gastric acid and pepsin.