title: Sensitization of esophageal mucosa by prior acid infusion: effect of decreasing intervals between infusions.
abstract: OBJECTIVE
  To determine the effect of decreasing time intervals between acid exposures on the sensitivity of the esophageal mucosa.
  
  
  METHODS
  Ten healthy subjects with no history of gastroesophageal reflux disease who were symptomatic during a modified Bernstein acid infusion test were recruited for the study. Hydrochloric acid solutions of pH 3, 2, and 1 were sequentially tested. The weakest pH solution that was perceived by the patient was used for the study. The same duration of acid infusions (9 ml/min for 5 min) were made but with decreasing time intervals between each subsequent acid infusion (30-0 min). Esophageal sensation during each of the infusions, the amount of distilled water required to raise intraesophageal pH > 4, and the duration of residual heartburn after pH > 4 were recorded.
  
  
  RESULTS
  Seven of the 10 subjects (70%) were Bernstein-positive to pH 3, two to pH 2, and only one to pH 1 solution. The median time to initial heartburn was significantly reduced only between the initial infusion and the first subsequent acid exposure 30 min later (165 vs 51.5 s, p < 0.009). Subsequent reductions in the time interval between infusions did not significantly reduce the perception threshold. The water required to clear the esophagus to pH > 4 and time required for the residual esophageal sensation to disappear were not significantly altered throughout the study.
  
  
  CONCLUSIONS
  These data suggest that some episodes of reflux may be felt sooner and perhaps more severely despite similar levels of acid burden in the esophagus when sensitization by a prior reflux episode occurs.
authors.affiliation: Department of Medicine, Graduate Hospital, Philadelphia, Pennsylvania, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Siddiqui
authors.forename: B T
authors.initials: BT
authors.lastname: Johnston
authors.forename: L P
authors.initials: LP
authors.lastname: Leite
authors.forename: D A
authors.initials: DA
authors.lastname: Katzka
authors.forename: D O
authors.initials: DO
authors.lastname: Castell
mesh_terms: D000328:Adult; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D004947:Esophagus / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005744:Gastric Acid; D005764:Gastroesophageal Reflux / Q000175:diagnosis / Q000503:physiopathology*; D006356:Heartburn / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009092:Mucous Membrane / Q000187:drug effects / Q000502:physiology; D017288:Pain Threshold / Q000502:physiology*; D013997:Time Factors