title: Hypertonic challenge to porcine vocal folds: effects on epithelial barrier function.
abstract: OBJECTIVE
  Dehydration challenges can increase the chemical composition of surface fluid overlying vocal fold epithelia (hypertonic surface fluid). The vocal fold epithelium is posited to act as a barrier, shielding the lamina propria from perturbations in the airway lumen. However, the effects of hypertonic surface fluid on the barrier functions of vocal fold epithelia have not been quantified. We, therefore, sought to investigate whether hypertonic surface fluid compromises epithelial barrier function. We examined the effects of hypertonic surface fluid on vocal fold epithelial resistance, paracellular pathway morphology, and tight junction protein integrity.
  
  
  METHODS
  Ex vivo, between group design.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  Porcine vocal folds (n = 24) were exposed to hypertonic or isotonic challenge and examined by electrophysiology, transmission electron microscopy, and Western blot analyses.
  
  
  RESULTS
  Hypertonic, but not isotonic, challenge significantly reduced transepithelial resistance. This decrease in resistance was observed immediately after the challenge and was consistent with the appearance of dilated paracellular pathway morphology. However, hypertonic challenge did not alter protein levels of occludin, zona occludens-1, E-cadherin, or beta-catenin.
  
  
  CONCLUSIONS
  Hypertonic surface fluid alters epithelial barrier function in the vocal folds. Specifically, exposure to hypertonic challenges increases epithelial permeability. Given the important role of the vocal fold epithelium in shielding the underlying mucosa from inhaled pathogens and pollutants, our data provide the impetus for future studies on pharmacological treatments aimed at restoring the hydration level and chemical composition of vocal fold surface fluid.
authors.affiliation: Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, IN, USA. msivasankar@purdue.edu
authors.forename: Mahalakshmi
authors.initials: M
authors.lastname: Sivasankar
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Erickson
authors.forename: Mark
authors.initials: M
authors.lastname: Rosenblatt
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Branski
mesh_terms: D000818:Animals; D006982:Hypertonic Solutions / Q000494:pharmacology*; D007820:Laryngeal Mucosa / Q000187:drug effects* / Q000378:metabolism*; D010539:Permeability; D013552:Swine; D014827:Vocal Cords / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D006982:Hypertonic Solutions