title: Role for ion transport in porcine vocal fold epithelial defense to acid challenge.
abstract: OBJECTIVE
  The vocal fold epithelium is routinely exposed to gastric contents, including acid and pepsin, during laryngopharyngeal reflux events. The epithelium may possess intrinsic defenses to reflux. The first objective of the current study was to examine whether vocal fold epithelial ion transport is one potential mechanism of defense to gastric contents. The second objective was to determine whether ion transport in response to gastric contents is associated with the secretion of bicarbonate.
  
  
  METHODS
  Prospective design in excised porcine larynges.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Porcine vocal folds (N = 56) were exposed on the luminal surface to acid, pepsin, or sham challenges. Ion transport at baseline and following challenge exposure was measured using electrophysiological techniques. To examine specific ion transport mechanisms, vocal folds were pretreated with either a sodium channel blocker or bicarbonate channel blocker.
  
  
  RESULTS
  Within 60 seconds of acid but not pepsin exposure, there was a significant increase in ion transport. This rapid increase in ion transport was transient and related to bicarbonate secretion.
  
  
  CONCLUSIONS
  The current data suggest that porcine vocal folds immediately increase bicarbonate secretion following exposure to acid. Bicarbonate secretion may act to neutralize acid. These findings contribute to the identification of the mechanisms underlying vocal fold defense to reflux and offer implications for the development of treatments for reflux-induced vocal fold injury.
authors.affiliation: Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Erickson-Levendoski
authors.forename: M Preeti
authors.initials: MP
authors.lastname: Sivasankar
mesh_terms: D000818:Animals; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism*; D006851:Hydrochloric Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D017136:Ion Transport; D010434:Pepsin A / Q000494:pharmacology; D011446:Prospective Studies; D013464:Sulfuric Acids / Q000494:pharmacology; D013552:Swine; D014827:Vocal Cords / Q000187:drug effects / Q000378:metabolism*
chemical_list: D013464:Sulfuric Acids; D010434:Pepsin A; C033158:sulfuric acid; D006851:Hydrochloric Acid
references.citation: Laryngoscope. 2009 Mar;119(3):602-7
references.pmid: 19177504
references.citation: J Clin Pathol. 2005 Dec;58(12):1265-70
references.pmid: 16311345
references.citation: Otolaryngol Head Neck Surg. 2011 Nov;145(5):783-8
references.pmid: 21753033
references.citation: Laryngoscope. 2003 Nov;113(11):1927-30
references.pmid: 14603049
references.citation: J Gastrointest Surg. 2001 Mar-Apr;5(2):183-90; discussion 190-1
references.pmid: 11331482
references.citation: Inflammopharmacology. 2005;13(1-3):179-90
references.pmid: 16259737
references.citation: Ann Otol Rhinol Laryngol. 2003 Jun;112(6):481-91
references.pmid: 12834114
references.citation: Laryngoscope. 2004 Dec;114(12):2129-34
references.pmid: 15564833
references.citation: Aliment Pharmacol Ther. 2011 Apr;33 Suppl 1:1-71
references.pmid: 21366630
references.citation: J Food Sci. 2008 Sep;73(7):R99-105
references.pmid: 18803726
references.citation: Laryngoscope. 2008 Aug;118(8):1511-7
references.pmid: 18596479
references.citation: Laryngoscope. 2010 Aug;120(8):1569-75
references.pmid: 20564752
references.citation: Laryngoscope. 1991 Apr;101(4 Pt 2 Suppl 53):1-78
references.pmid: 1895864
references.citation: Annu Rev Physiol. 2005;67:377-409
references.pmid: 15709963
references.citation: Otolaryngol Head Neck Surg. 2010 Jan;142(1):79-84
references.pmid: 20096227
references.citation: J Voice. 2009 Nov;23(6):658-65
references.pmid: 19111440
references.citation: Ann Otol Rhinol Laryngol. 2001 Dec;110(12):1099-108
references.pmid: 11768697
references.citation: J Clin Invest. 2001 Dec;108(12):1807-16
references.pmid: 11748264
references.citation: Am J Physiol Gastrointest Liver Physiol. 2006 Sep;291(3):G464-71
references.pmid: 16710054
references.citation: Otolaryngol Head Neck Surg. 2005 Nov;133(5):718-24
references.pmid: 16274799
references.citation: Otolaryngol Head Neck Surg. 2000 Oct;123(4):385-8
references.pmid: 11020172
references.citation: J Physiol Pharmacol. 2008 Sep;59(3):525-42
references.pmid: 18953095
references.citation: Am J Vet Res. 2002 May;63(5):744-9
references.pmid: 12013478
references.citation: Eur Arch Otorhinolaryngol. 2009 Jun;266(6):795-801
references.pmid: 19340444