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NKCCs in the fibrocytes of the spiral ligament are silent on the unidirectional K⁺ transport that controls the electrochemical properties in the mammalian cochlea.
Pflugers Arch. 2015 Jul; 467(7):1577-1589.PA

Abstract

Unidirectional K(+) transport across the lateral cochlear wall contributes to the endocochlear potential (EP) of +80 mV in the endolymph, a property essential for hearing. The wall comprises two epithelial layers, the syncytium and the marginal cells. The basolateral surface of the former and the apical membranes of the latter face the perilymph and the endolymph, respectively. Intrastrial space (IS), an extracellular compartment between the two layers, exhibits low [K(+)] and a potential similar to the EP. This IS potential (ISP) dominates the EP and represents a K(+) diffusion potential elicited by a large K(+) gradient across the syncytial apical surface. The K(+) gradient depends on the unidirectional K(+) transport driven by Na(+),K(+)-ATPases on the basolateral surface of each layer and the concomitant Na(+),K(+),2Cl(-)-cotransporters (NKCCs) in the marginal cell layer. The NKCCs coexpressed with the Na(+),K(+)-ATPases in the syncytial layer also seem to participate in the K(+) transport. To test this hypothesis, we examined the electrochemical properties of the lateral wall with electrodes measuring [K(+)] and potential. Blocking NKCCs by perilymphatic perfusion of bumetanide suppressed the ISP. Unexpectedly and unlike the inhibition of the syncytial Na(+),K(+)-ATPases, the perfusion barely altered the electrochemical properties of the syncytium but markedly augmented [K(+)] of the IS. Consequently, the K(+) gradient decreased and the ISP declined. These observations resembled those when the marginal cells' Na(+),K(+)-ATPases or NKCCs were blocked with vascularly applied inhibitors. It is plausible that NKCCs in the marginal cells are affected by the perilymphatically perfused bumetanide, and these transporters, but not those in the syncytium, mediate the unidirectional K(+) transport.

Authors+Show Affiliations

Department of Molecular Physiology, School of Medicine, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan. Center for Transdisciplinary Research, Niigata University, Niigata, Japan. Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.Department of Molecular Physiology, School of Medicine, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan. Center for Transdisciplinary Research, Niigata University, Niigata, Japan.Department of Molecular Physiology, School of Medicine, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan. Center for Transdisciplinary Research, Niigata University, Niigata, Japan.Department of Molecular Physiology, School of Medicine, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan. Center for Transdisciplinary Research, Niigata University, Niigata, Japan. Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Suita, Japan.Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Suita, Japan. Department of Otorhinolaryngology-Head and Neck Surgery, Nara Medical University, Kashihara, Japan.Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Suita, Japan.Department of Medical Informatics, Niigata University Medical and Dental Hospital, Niigata, Japan.Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.Division of Molecular and Cellular Pharmacology, Department of Pharmacology, Graduate School of Medicine, and The Center for Advanced Medical Engineering and Informatics, Osaka University, Suita, Japan.Department of Molecular Physiology, School of Medicine, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata, Niigata, 951-8510, Japan. hibinoh@med.niigata-u.ac.jp. Center for Transdisciplinary Research, Niigata University, Niigata, Japan. hibinoh@med.niigata-u.ac.jp.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25143138

Citation

Yoshida, Takamasa, et al. "NKCCs in the Fibrocytes of the Spiral Ligament Are Silent On the Unidirectional K⁺ Transport That Controls the Electrochemical Properties in the Mammalian Cochlea." Pflugers Archiv : European Journal of Physiology, vol. 467, no. 7, 2015, pp. 1577-1589.
Yoshida T, Nin F, Ogata G, et al. NKCCs in the fibrocytes of the spiral ligament are silent on the unidirectional K⁺ transport that controls the electrochemical properties in the mammalian cochlea. Pflugers Arch. 2015;467(7):1577-1589.
Yoshida, T., Nin, F., Ogata, G., Uetsuka, S., Kitahara, T., Inohara, H., Akazawa, K., Komune, S., Kurachi, Y., & Hibino, H. (2015). NKCCs in the fibrocytes of the spiral ligament are silent on the unidirectional K⁺ transport that controls the electrochemical properties in the mammalian cochlea. Pflugers Archiv : European Journal of Physiology, 467(7), 1577-1589. https://doi.org/10.1007/s00424-014-1597-9
Yoshida T, et al. NKCCs in the Fibrocytes of the Spiral Ligament Are Silent On the Unidirectional K⁺ Transport That Controls the Electrochemical Properties in the Mammalian Cochlea. Pflugers Arch. 2015;467(7):1577-1589. PubMed PMID: 25143138.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - NKCCs in the fibrocytes of the spiral ligament are silent on the unidirectional K⁺ transport that controls the electrochemical properties in the mammalian cochlea. AU - Yoshida,Takamasa, AU - Nin,Fumiaki, AU - Ogata,Genki, AU - Uetsuka,Satoru, AU - Kitahara,Tadashi, AU - Inohara,Hidenori, AU - Akazawa,Kohei, AU - Komune,Shizuo, AU - Kurachi,Yoshihisa, AU - Hibino,Hiroshi, Y1 - 2014/08/22/ PY - 2014/05/09/received PY - 2014/08/07/accepted PY - 2014/07/08/revised PY - 2014/8/22/entrez PY - 2014/8/22/pubmed PY - 2016/3/5/medline SP - 1577 EP - 1589 JF - Pflugers Archiv : European journal of physiology JO - Pflugers Arch. VL - 467 IS - 7 N2 - Unidirectional K(+) transport across the lateral cochlear wall contributes to the endocochlear potential (EP) of +80 mV in the endolymph, a property essential for hearing. The wall comprises two epithelial layers, the syncytium and the marginal cells. The basolateral surface of the former and the apical membranes of the latter face the perilymph and the endolymph, respectively. Intrastrial space (IS), an extracellular compartment between the two layers, exhibits low [K(+)] and a potential similar to the EP. This IS potential (ISP) dominates the EP and represents a K(+) diffusion potential elicited by a large K(+) gradient across the syncytial apical surface. The K(+) gradient depends on the unidirectional K(+) transport driven by Na(+),K(+)-ATPases on the basolateral surface of each layer and the concomitant Na(+),K(+),2Cl(-)-cotransporters (NKCCs) in the marginal cell layer. The NKCCs coexpressed with the Na(+),K(+)-ATPases in the syncytial layer also seem to participate in the K(+) transport. To test this hypothesis, we examined the electrochemical properties of the lateral wall with electrodes measuring [K(+)] and potential. Blocking NKCCs by perilymphatic perfusion of bumetanide suppressed the ISP. Unexpectedly and unlike the inhibition of the syncytial Na(+),K(+)-ATPases, the perfusion barely altered the electrochemical properties of the syncytium but markedly augmented [K(+)] of the IS. Consequently, the K(+) gradient decreased and the ISP declined. These observations resembled those when the marginal cells' Na(+),K(+)-ATPases or NKCCs were blocked with vascularly applied inhibitors. It is plausible that NKCCs in the marginal cells are affected by the perilymphatically perfused bumetanide, and these transporters, but not those in the syncytium, mediate the unidirectional K(+) transport. SN - 1432-2013 UR - https://www.unboundmedicine.com/medline/citation/25143138/NKCCs_in_the_fibrocytes_of_the_spiral_ligament_are_silent_on_the_unidirectional_K⁺_transport_that_controls_the_electrochemical_properties_in_the_mammalian_cochlea_ L2 - https://dx.doi.org/10.1007/s00424-014-1597-9 DB - PRIME DP - Unbound Medicine ER -