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Figure

Figure 5: Schematic model of cochlear potassium circulation and the formation of the endocochlear potential. (a) K+ ions that escape from the hair cells are taken up by Deiters cells. K+ is subsequently transported via the epithelial gap junction network to the type II and type IV fibrocytes of the spiral ligament. The epithelial gap junction network consists of supporting cells, epithelial cells and the outer sulcus cells. K+ is then taken up by the type II and type IV fibrocytes and transported to the stria vascularis via the connective tissue gap junction network. The connective tissue gap junction network consists of fibrocytes, basal cells and intermediate cells. K+ is eventually released via the stria vascularis into the endolymph of the scala media. The diagram also shows the K+ concentration ([K+]) and the potential of the various cochlear fluids. (b) The figure shows the ion transport system of the stria vascularis and the spiral ligament, which are the crucial components for cochlear potassium circulation and the formation of the endocochlear potential. As in (a), the K+ concentration ([K+]) and the potential of the various cochlear fluids is shown. Abbreviations: NKCC1 (Na+ K+ 2Cl- cotransporter), TJ (tight junctions) (Figure modified after Hibino & Kurachi [53]).