内耳蝸牛血管条における細胞外空間のK+濃度・電位と蝸牛内高電位の関連の解析
書誌事項
- タイトル別名
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- Endocohlear potential is controlled by the extracellular K+-dynamics via K+-transport apparatuses in cochlear stria vascularis of inner ear.
説明
A cochlear extracellular fluid, endolymph, has 150 mM K+ and positive potential of ∼+80 mV called "endocochlear potential (EP)". EP is essential for hearing. K+-transport via an epithelial tissue "stria vasclularis" in the lateral wall is crucial for maintaining the high K+ and EP. Stria vascularis comprises marginal (MCs) and intermediate (ICs) cells. The extracellular space sandwiched by the two is referred as "intrastrial space (IS)" and harbors low K+ of ∼2 mM and high potential of ∼+90 mV. This unique property is proposed to be an origin of EP and achieved by cooperation of Na+,K+,2Cl−-cotransporter (NKCC) and Na+,K+-ATPase at the basolateral membrane of MCs and K+ channel at the apical site of ICs. However, the mechanism for its establishment is unknown. We thus measured the potential and K+ concentration ([K+]) of IS with a double-barreled electrode while applying furosemide, a NKCC-blocker, and anoxia, which dysfunctions Na+,K+-ATPase. Strial perfusion of furosemide largely declined the potential and increased [K+] in IS as well as reduced EP. Anoxia caused the same effect. The amplitude of change in IS-potential and EP paralleled that in K+ equilibrium potential toward IS. Hence, low [K+] in IS maintained by NKCC and Na+,K+-ATPase in MCs may promote [K+] diffusion via K+ channel in ICs, which forms IS potential and EP. [J Physiol Sci. 2007;57 Suppl:S108]
収録刊行物
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- 日本生理学会大会発表要旨集
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日本生理学会大会発表要旨集 2007 (0), 108-108, 2007
一般社団法人 日本生理学会
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