title: Salivary bicarbonate as a major factor in the prevention of upper esophageal mucosal injury in gastroesophageal reflux disease.
abstract: BACKGROUND
  It has been previously demonstrated that the exposure of the lower esophageal mucosa to acid and pepsin results in significant increase in salivary protective factors secretion, mediated by the esophago-salivary reflex. The impact of the upper esophageal mucosal exposure to acid and pepsin on salivary secretory response remains unknown.
  
  
  OBJECTIVE
  To investigate the rate of salivary protective factors secretion during the upper esophageal mucosal exposure to acid and pepsin and to compare with the corresponding results recorded during the lower esophageal mucosal exposure, in the same group of asymptomatic volunteers.
  
  
  METHODS
  The study was conducted in 10 asymptomatic volunteers. Salivary samples were collected during the esophageal mucosal exposure to saline, followed by acid/pepsin and the final saline, using the esophageal perfusion catheter. Salivary bicarbonate and non-bicarbonate buffers were analyzed using TitraLab. Salivary mucin and protein were quantified through PAS and Lowry methodologies, respectively, whereas PE2 using radioimmunoassay. Statistical analysis was performed using Σ-Stat software.
  
  
  RESULTS
  The rate of salivary bicarbonate secretion was significantly higher (3.1-fold) during the upper versus the lower esophageal mucosal exposure to acid and pepsin (87.5 ± 14.4 vs. 28.0 ± 7.70 μEq/min, p < 0.05). The volumes of saliva, pH, salivary protein, mucin and PE2 were similar in both esophageal perfusions.
  
  
  CONCLUSIONS
  Threefold stronger secretion of salivary bicarbonate could be a major factor protecting the upper esophageal mucosa. This phenomenon may represent an ultimate defense mechanism potentially preventing further complications within the upper esophageal mucosa; however, it needs to be confirmed in patients of gastroesophageal reflux disease.
authors.affiliation: 2nd Department of General Surgery, Medical University of Lublin, Lublin, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Skoczylas
authors.forename: Harathi
authors.initials: H
authors.lastname: Yandrapu
authors.forename: Cezary
authors.initials: C
authors.lastname: Poplawski
authors.forename: Mazen
authors.initials: M
authors.lastname: Asadi
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Wallner
authors.forename: Jerzy
authors.initials: J
authors.lastname: Sarosiek
mesh_terms: D000328:Adult; D001639:Bicarbonates / Q000737:chemistry*; D004947:Esophagus / Q000473:pathology*; D005260:Female; D005744:Gastric Acid; D005764:Gastroesophageal Reflux / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010434:Pepsin A; D012463:Saliva / Q000737:chemistry*
chemical_list: D001639:Bicarbonates; D010434:Pepsin A