title: Bicarbonate availability for vocal fold epithelial defense to acidic challenge.
abstract: OBJECTIVE
  Bicarbonate is critical for acid-base tissue homeostasis. In this study we investigated the role of bicarbonate ion transport in vocal fold epithelial defense to acid challenges. Acidic insults to the larynx are common in gastric reflux, carcinogenesis and metastasis, and acute inflammation.
  
  
  METHODS
  Ion transport was measured in viable porcine vocal fold epithelium. First, 18 vocal folds were exposed to either the carbonic anhydrase antagonist acetazolamide or to vehicle. Second, 32 vocal folds were exposed to either a control buffer or a bicarbonate-free buffer on their luminal or basolateral surface or both. Third, 32 vocal folds were challenged with acid in the presence of bicarbonate-free or control buffer.
  
  
  RESULTS
  The vocal fold transepithelial resistance was greater than 300 Ω*cm(2), suggesting robust barrier integrity. Ion transport did not change after exposure to acetazolamide (p > 0.05). Exposure to bicarbonate-free buffer did not compromise vocal fold ion transport (p > 0.05). Ion transport increased after acid challenge. This increase approached statistical significance and was the greatest for the control buffer and for the bicarbonate-free buffer applied to the basolateral surface.
  
  
  CONCLUSIONS
  Bicarbonate secretion may contribute to vocal fold defense against acid challenge. Our data offer a potential novel role for bicarbonate as a therapeutic agent to reduce pH abnormalities in the larynx and prevent associated pathological changes.
authors.affiliation: Department of Comparative Pathobiology, College of Veterinary Medicine (Durkes), Purdue University, West Lafayette, Indiana.
authors.forename: Abigail
authors.initials: A
authors.lastname: Durkes
authors.forename: M Preeti
authors.initials: MP
authors.lastname: Sivasankar
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology*; D006706:Homeostasis / Q000187:drug effects; D006851:Hydrochloric Acid / Q000494:pharmacology*; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D007820:Laryngeal Mucosa / Q000187:drug effects / Q000378:metabolism*; D013552:Swine; D014827:Vocal Cords / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001639:Bicarbonates; D002257:Carbonic Anhydrase Inhibitors; D000086:Acetazolamide; D006851:Hydrochloric Acid
keywords: bicarbonate; ion transport; laryngopharyngeal reflux; vocal fold