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ENaC- and CFTR-dependent ion and fluid transport in human middle ear epithelial cells

Authors
 Jae Young Choi  ;  Eun Jin Son  ;  Jung Lim Kim  ;  Joo-Hyeung Lee  ;  Hun Yi Park  ;  Sung Huhn Kim  ;  Mee Hyun Song  ;  Joo-Heon Yoon 
Citation
 HEARING RESEARCH, Vol.211(1-2) : 26-32, 2006 
Journal Title
HEARING RESEARCH
ISSN
 0378-5955 
Issue Date
2006
MeSH
1-Methyl-3-isobutylxanthine/pharmacology ; 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid/pharmacology ; Adenosine Triphosphate/pharmacology ; Amiloride/pharmacology ; Cells, Cultured ; Chloride Channels/metabolism ; Colforsin/pharmacology ; Cystic Fibrosis Transmembrane Conductance Regulator/metabolism* ; Ear, Middle/cytology ; Ear, Middle/drug effects ; Ear, Middle/metabolism* ; Epithelial Cells/drug effects ; Epithelial Cells/metabolism ; Epithelial Sodium Channels ; Humans ; Ion Transport/drug effects ; Nasal Mucosa/cytology ; Nasal Mucosa/drug effects ; Nasal Mucosa/metabolism ; Sodium Channels/metabolism* ; Water-Electrolyte Balance/drug effects
Keywords
Ion channel ; Fluid transport ; Sodium ; Chloride
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 μl 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 α, β, and γ 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.
Full Text
http://www.sciencedirect.com/science/article/pii/S0378595505002492
DOI
10.1016/j.heares.2005.08.007
Appears in Collections:
1. College of Medicine (의과대학) > Dept. of Otorhinolaryngology (이비인후과학교실) > 1. Journal Papers
Yonsei Authors
Yoon, Joo Heon(윤주헌)
Choi, Jae Young(최재영) ORCID logo https://orcid.org/0000-0001-9493-3458
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/110387
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