Location and function of the epithelial Na channel in the cochlea
Location and function of the epithelial Na channel in the cochlea
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DOI：
10.1152/ajprenal.2001.280.2.f214
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发表时间：
2001-02-01
影响因子：
4.2
通讯作者：
Ferrary, E
中科院分区：
文献类型：
--
作者：
Couloigner, V;Fay, M;Ferrary, E
在耳蜗中，内淋巴是富钾贫钠的流体。本研究的目的是检查上皮Na通道（ENaC）在该器官中的存在并评估其作用。用RT-PCR和Western blot检测大鼠耳蜗中ENaC α、β和γ亚基mRNA和蛋白的表达。α-ENaC亚基mRNA通过原位杂交定位于上皮（血管纹、螺旋突起、螺旋利姆布斯）和非上皮结构（螺旋韧带、螺旋神经节）中。α-ENaC阳性组织的β-亚基mRNA（螺旋神经节除外）或γ-亚基mRNA（螺旋利姆布斯、螺旋韧带和螺旋神经节）也呈阳性，但β-和γ-亚基的信号弱于α-亚基。在体内，耳蜗内电位记录在常氧和缺氧条件下的豚鼠后，内淋巴灌注ENaC抑制剂（阿米洛利，苯扎米尔）溶解在富钾或富钠的解决方案。ENaC抑制剂改变耳蜗内电位时，钠丰富，但不富钾的解决方案灌注。总之，ENaC亚基在上皮和非上皮耳蜗结构中表达。其功能之一可能是维持内淋巴低浓度的Na。
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.