Location and function of the epithelial Na channel in the cochlea

被引:50
作者
Couloigner, V
Fay, M
Djelidi, S
Farman, N
Escoubet, B
Runembert, I
Sterkers, O
Friedlander, G
Ferrary, E
机构
[1] Fac Xavier Bichat, UFR Xavier Bichat, INSERM, U426, F-75870 Paris 18, France
[2] Fac Xavier Bichat, INSERM, U478, F-75870 Paris, France
[3] AP HP, Hop Beaujon, Dept Otorhinolaryngol, F-92118 Clichy, France
关键词
endolymph; stria vascularis; in situ hybridization; endocochlear potential; hypoxia;
D O I
10.1152/ajprenal.2001.280.2.F214
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
In the cochlea, endolymph is a K-rich and Na-poor fluid. The purpose of the present study was to check the presence and to assess the role of epithelial Na channel (ENaC) in this organ. alpha-, beta-, and gamma -ENaC subunit mRNA, and proteins were detected in rat cochlea by RT-PCR and Western blot. alpha -ENaC subunit mRNA was localized by in situ hybridization in both epithelial (stria vascularis, spiral prominence, spiral limbus) and nonepithelial structures (spiral ligament, spiral ganglion). The alpha -ENaC-positive tissues were also positive for beta -subunit mRNA (except spiral ganglion) or for gamma -subunit mRNA (spiral limbus, spiral ligament, and spiral ganglion), but the signals of beta- and gamma -subunits were weaker than those observed for alpha -subunit. In vivo, the endocochlear potential was recorded in guinea pigs under normoxic and hypoxic conditions after endolymphatic perfusion of ENaC inhibitors (amiloride, benzamil) dissolved either in K-rich or Na-rich solutions. ENaC inhibitors altered the endocochlear potential when Na-rich but not when K-rich solutions were perfused. In conclusion, ENaC subunits are expressed in epithelial and nonepithelial cochlear structures. One of its functions is probably to maintain the low concentration of Na in endolymph.
引用
收藏
页码:F214 / F222
页数:9
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