title: Mechanisms of acid damage to oesophageal epithelium: role of the paracellular pathway.
abstract: The mechanisms of acid damage to oesophageal epithelium are incompletely understood. In particular, it is unclear whether luminal acid enters and damages the oesophageal epithelium by traversing the paracellular and/or transcellular route. The present paper describes studies of the role of serosal bicarbonate ions (HCO3-) in oesophageal protection against acid damage, the results of which have direct implications regarding the route of H+ entry. The results indicate that HCO3- protects by buffering H+ within the intercellular compartment of the extracellular space, and that this protection can be mimicked almost completely by replacement of serosal HCO3- with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethane sulphonic acid), a buffer that cannot permeate cells. These findings support the hypothesis that luminal acid damages oesophageal epithelium primarily by H+ diffusion through the paracellular pathway.
authors.affiliation: Department of Medicine, University of North Carolina School of Medicine, Chapel Hill.
authors.forename: R C
authors.initials: RC
authors.lastname: Orlando
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000137:Acid-Base Imbalance / Q000473:pathology*; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000473:pathology; D004947:Esophagus / Q000187:drug effects / Q000473:pathology*; D006851:Hydrochloric Acid / Q000037:antagonists & inhibitors / Q000633:toxicity; D066298:In Vitro Techniques; D011817:Rabbits
chemical_list: D001639:Bicarbonates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000086:Acetazolamide; D006851:Hydrochloric Acid