title: Human esophageal secretion: mucosal response to luminal acid and pepsin.
abstract: OBJECTIVE
  Although esophageal histology in humans reveals numerous submucosal mucous glands, their secretion has never been explored. Therefore, we have studied the chemical composition and physical characteristics of esophageal secretion under the impact of luminal saline, acid, and acid/pepsin solutions.
  
  
  METHODS
  The esophageal lumen in 21 healthy volunteers was continuously perfused with saline, HCI, or HCI/pepsin. Perfusates were assayed for mucin, protein, and viscosity. In addition, analysis of amino acid and sugar composition of purified esophageal mucin was performed.
  
  
  RESULTS
  Esophageal perfusion with saline resulted in luminal release of mucin at the rate of 0.23 +/- 0.03 mg.cm-2 x min-1. Acid/pepsin solution significantly enhanced luminal release of mucin (0.32 +/- 0.03 mg.cm-2 x min-1; P < 0.01). HCI/pepsin solution also significantly increased the luminal output of protein (P < 0.01) and significantly impaired the viscosity of the esophageal perfusate (P < 0.05). Threonine, serine, and proline were the major amino acids within the esophageal mucin, whereas galactose was the predominant carbohydrate.
  
  
  CONCLUSIONS
  Luminally released esophageal mucin, shown for the first time in humans, contributes significantly to maintaining the high viscosity of esophageal secretions. Significant increase in the luminal release of mucin under the impact of acid and pepsin, with subsequent decline of the perfusate viscosity, may indicate that mucin is the major target for gastric acid and pepsin, absorbing the deleterious impact of the gastroesophageal refluxate.
authors.affiliation: University of Virginia Health Sciences Center, Charlottesville.
authors.forename: Z
authors.initials: Z
authors.lastname: Namiot
authors.forename: J
authors.initials: J
authors.lastname: Sarosiek
authors.forename: R M
authors.initials: RM
authors.lastname: Rourk
authors.forename: D P
authors.initials: DP
authors.lastname: Hetzel
authors.forename: R W
authors.initials: RW
authors.lastname: McCallum
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000032:analysis; D002241:Carbohydrates / Q000032:analysis; D004947:Esophagus / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology*; D008297:Male; D009077:Mucins / Q000737:chemistry / Q000378:metabolism*; D009092:Mucous Membrane / Q000187:drug effects / Q000378:metabolism; D010434:Pepsin A / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D014783:Viscosity
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D009077:Mucins; D011506:Proteins; D010434:Pepsin A; D006851:Hydrochloric Acid