title: Unbuffered highly acidic gastric juice exists at the gastroesophageal junction after a meal.
abstract: OBJECTIVE
  Gastroesophageal reflux typically occurs after meals. During dual gastric and esophageal pH monitoring, we observed that postprandial refluxate was often more acidic than the gastric contents. This study aimed to investigate this phenomenon.
  
  
  METHODS
  Dual gastric and esophageal pH tracings were analyzed from 40 dyspeptic patients. Dual pH electrode pull-through studies were performed in healthy volunteers to document regional variation in intragastric pH under both fasting and postprandial conditions. The squamocolumnar junction was identified using radio-opaque endoscopic clips. We also examined in vitro partitioning of gastric juice added to a homogenized fatty meal.
  
  
  RESULTS
  The dual pH traces confirmed that esophageal refluxate was frequently more acidic than the body of the stomach after meals but not during fasting. The pull-through studies showed a pocket of acid at the gastroesophageal junction that escaped the buffering effect of meals, remaining highly acidic (median pH 1.6) compared with the body of the stomach (pH 4.7; P < 0.001). This proximal acid pocket extended from the cardia across the squamocolumnar junction 1.8 cm into the distal esophagus. The in vitro studies showed that acidic gastric juice could partition on top of a homogenized fatty meal.
  
  
  CONCLUSIONS
  After eating, highly acidic unbuffered gastric juice is present at the gastroesophageal squamocolumnar junction and is likely to contribute to the high prevalence of disease at this site.
authors.affiliation: Department of Medicine and Therapeutics, Gardiner Institute, Western Infirmary, Glasgow, Scotland, UK.
authors.forename: J
authors.initials: J
authors.lastname: Fletcher
authors.forename: A
authors.initials: A
authors.lastname: Wirz
authors.forename: J
authors.initials: J
authors.lastname: Young
authors.forename: R
authors.initials: R
authors.lastname: Vallance
authors.forename: K E
authors.initials: KE
authors.lastname: McColl
mesh_terms: D000328:Adult; D000368:Aged; D002021:Buffers; D004415:Dyspepsia / Q000503:physiopathology; D004947:Esophagus / Q000502:physiology*; D005215:Fasting; D005260:Female; D005750:Gastric Juice / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period / Q000502:physiology; D012016:Reference Values; D013270:Stomach / Q000502:physiology*
chemical_list: D002021:Buffers