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ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells.
Hear Res. 2006 Jan; 211(1-2):26-32.HR

Abstract

Ion channels, such as the epithelial sodium channel (ENaC), are essential for maintaining a fluid-free middle ear cavity by controlling periciliary fluid. Deviations from the normal volume or compositions of periciliary fluid are probably responsible for otitis media with effusion. To elucidate the physiologic roles of the ENaC and cystic fibrosis transmembrane conductance regulator (CFTR) in the middle ear mucosa, we compared the electrophysiological activity and protein expressions of ENaC and CFTR in normal human middle ear epithelial (NHMEE) cells with those in normal human nasal epithelial (NHNE) cells. We also evaluated the role of ENaC and CFTR in fluid transport by NHMEE cells. Short-circuit current (Isc) was measured in cell monolayers by modified Ussing chambers. Immunoblotting was performed for ENaC and CFTR. In addition, transepithelial fluid transport was measured after loading 100 microl of fluid onto the luminal cell surface. The amiloride-sensitive Isc in NHMEE cells was much larger than in NHNE cells, whereas the forskolin-induced Isc, presumably mediated by CFTR, was significantly smaller in NHMEE cells. ENaC subunits alpha, beta, and gamma were all detected in NHMEE cells, and their expressions were stronger than those in NHNE cells. In comparison, CFTR was also detected in the middle ear mucosa, but at a lower expression level than in NHNE cells. NHMEE cells showed more amiloride-sensitive fluid absorption than NHNE cells. In contrast, fluid absorption was less sensitive to forskolin/IBMX in NHMEE cells than in NHNE cells. The ATP induced Cl- efflux and the amplitude of ATP-induced current in NHMEE cells was much larger than in NHNE cells. In the present study, we have demonstrated an enhanced amiloride-sensitive Isc and fluid absorption in NHMEE cells, where the role of CFTR is limited. Our data also suggest that the ATP-induced Cl- channel could be an alternative Cl- channel to CFTR in NHMEE cells.

Authors+Show Affiliations

Department of Otorhinolaryngology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu Seoul, 120-752, Republic of Korea.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16226002

Citation

Choi, Jae Young, et al. "ENaC- and CFTR-dependent Ion and Fluid Transport in Human Middle Ear Epithelial Cells." Hearing Research, vol. 211, no. 1-2, 2006, pp. 26-32.
Choi JY, Son EJ, Kim JL, et al. ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells. Hear Res. 2006;211(1-2):26-32.
Choi, J. Y., Son, E. J., Kim, J. L., Lee, J. H., Park, H. Y., Kim, S. H., Song, M. H., & Yoon, J. H. (2006). ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells. Hearing Research, 211(1-2), 26-32.
Choi JY, et al. ENaC- and CFTR-dependent Ion and Fluid Transport in Human Middle Ear Epithelial Cells. Hear Res. 2006;211(1-2):26-32. PubMed PMID: 16226002.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells. AU - Choi,Jae Young, AU - Son,Eun Jin, AU - Kim,Jung Lim, AU - Lee,Joo-Hyeung, AU - Park,Hun Yi, AU - Kim,Sung Huhn, AU - Song,Mee Hyun, AU - Yoon,Joo-Heon, Y1 - 2005/10/12/ PY - 2005/07/06/received PY - 2005/08/24/accepted PY - 2005/10/18/pubmed PY - 2006/3/28/medline PY - 2005/10/18/entrez SP - 26 EP - 32 JF - Hearing research JO - Hear. Res. VL - 211 IS - 1-2 N2 - Ion channels, such as the epithelial sodium channel (ENaC), are essential for maintaining a fluid-free middle ear cavity by controlling periciliary fluid. Deviations from the normal volume or compositions of periciliary fluid are probably responsible for otitis media with effusion. To elucidate the physiologic roles of the ENaC and cystic fibrosis transmembrane conductance regulator (CFTR) in the middle ear mucosa, we compared the electrophysiological activity and protein expressions of ENaC and CFTR in normal human middle ear epithelial (NHMEE) cells with those in normal human nasal epithelial (NHNE) cells. We also evaluated the role of ENaC and CFTR in fluid transport by NHMEE cells. Short-circuit current (Isc) was measured in cell monolayers by modified Ussing chambers. Immunoblotting was performed for ENaC and CFTR. In addition, transepithelial fluid transport was measured after loading 100 microl of fluid onto the luminal cell surface. The amiloride-sensitive Isc in NHMEE cells was much larger than in NHNE cells, whereas the forskolin-induced Isc, presumably mediated by CFTR, was significantly smaller in NHMEE cells. ENaC subunits alpha, beta, and gamma were all detected in NHMEE cells, and their expressions were stronger than those in NHNE cells. In comparison, CFTR was also detected in the middle ear mucosa, but at a lower expression level than in NHNE cells. NHMEE cells showed more amiloride-sensitive fluid absorption than NHNE cells. In contrast, fluid absorption was less sensitive to forskolin/IBMX in NHMEE cells than in NHNE cells. The ATP induced Cl- efflux and the amplitude of ATP-induced current in NHMEE cells was much larger than in NHNE cells. In the present study, we have demonstrated an enhanced amiloride-sensitive Isc and fluid absorption in NHMEE cells, where the role of CFTR is limited. Our data also suggest that the ATP-induced Cl- channel could be an alternative Cl- channel to CFTR in NHMEE cells. SN - 0378-5955 UR - https://www.unboundmedicine.com/medline/citation/16226002/ENaC__and_CFTR_dependent_ion_and_fluid_transport_in_human_middle_ear_epithelial_cells_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0378-5955(05)00249-2 DB - PRIME DP - Unbound Medicine ER -