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Contribution of the Paracellular Pathway to the Electrophysiological Asymmetry of Vocal Fold Epithelium
Author(s) -
Zhang Qianru,
Fisher Kimberly
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a351-c
Subject(s) - paracellular transport , tight junction , occludin , electrophysiology , barrier function , epithelium , chemistry , transcellular , biology , inner ear , biophysics , anatomy , permeability (electromagnetism) , endocrinology , microbiology and biotechnology , medicine , biochemistry , neuroscience , genetics , membrane
Wet stratified squamous epithelium of the vocal fold possesses electrophysiological asymmetry (lumen‐negative) to support ionically‐driven vectorial water fluxes. We studied the role of paracellular pathway in the maintenance of this bioelectrical asymmetry by demonstrating the tight junction (TJ) ‐ related barrier function of vocal fold epithelia. Cryosections of fresh ovine vocal fold mucosae (N=5) were used for the immunostaining of occludin and ZO‐1 proteins, markers of the TJ. An Ussing chamber system, and voltage/current clamp were used to measure the transepithelial electrical resistance (TER) with and without luminal histamine (N=46). Permeability of paracellular pathway to the protein tracer, horseradish peroxidase (HRP), was measured spectrophotometrically (N=35), and penetration was confirmed by detection of HRP activity within the epithelium. We detected positive immunoreactions of occludin and ZO‐1 proteins with distinct patterns of distribution in all epithelia. Baseline TER of 410±173.9 Ω·cm 2 was reduced by 94% (p<0.001) with high‐dose histamine (2 hr, 0.1M) but not low dose (10μM, 1mM) or sham control. Histamine (but not sham) increased permeability (1mM, p<0.044, n=12; 0.1M, p<0.001, n=11) to HRP in a dose‐ and time‐dependent manner. These results suggest that TJ‐related barrier function in the paracellular pathway contributes to maintenance of the electrophysiological gradient in this epithelium. Interference with the TJ‐related barrier function may provide a novel direction for the understanding of physiological as well as pathological mechanisms of vocal fold hydration. NIDCD K23DC00168 (KF)