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Expression of an inwardly rectifying K+ channel, Kir5.1, in specific types of fibrocytes in the cochlear lateral wall suggests its functional importance in the establishment of endocochlear potential.
Eur J Neurosci. 2004 Jan; 19(1):76-84.EJ

Abstract

Cochlear endolymph contains 150 mm K+ and has a highly positive potential of approximately +80 mV. The specialized ionic composition and high potential in endolymph are essential for hearing and maintained by circulation of K+ from perilymph to endolymph through the cochlear lateral wall. Various types of K+ channel such as Kir4.1 and KCNQ1/KCNE1 are expressed in stria vascularis of the lateral wall and play essential roles in K+ circulation. In this study, we examined a distribution of another K+ channel, Kir5.1, and found it specifically expressed in the spiral ligament of the cochlear lateral wall. Specific immunoreactivity for Kir5.1 was detected in type II, IV and V fibrocytes of the ligament and spiral limbus, all of which are directly involved in K+ circulation. Kir5.1 was not found in either type I or III fibrocytes. Although Kir5.1 assembles with Kir4.1 to form a functional Kir channel in renal epithelia and retinal Müller cells, double-immunolabelling revealed that they were expressed in distinct regions in the cochlea lateral wall, i.e. Kir4.1 only in stria vascularis vs. Kir5.1 in spiral ligament. During development, the expression of Kir5.1 subunits started significantly later than Kir4.1 and was correlated with the 'rapid' phase of the elevation of endocochlear potential (EP). Kir5.1 and Kir4.1 channel-subunits may therefore play distinct functional roles in K+ circulation in the cochlear lateral wall.

Authors+Show Affiliations

Department of Pharmacology II, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

14750965

Citation

Hibino, Hiroshi, et al. "Expression of an Inwardly Rectifying K+ Channel, Kir5.1, in Specific Types of Fibrocytes in the Cochlear Lateral Wall Suggests Its Functional Importance in the Establishment of Endocochlear Potential." The European Journal of Neuroscience, vol. 19, no. 1, 2004, pp. 76-84.
Hibino H, Higashi-Shingai K, Fujita A, et al. Expression of an inwardly rectifying K+ channel, Kir5.1, in specific types of fibrocytes in the cochlear lateral wall suggests its functional importance in the establishment of endocochlear potential. Eur J Neurosci. 2004;19(1):76-84.
Hibino, H., Higashi-Shingai, K., Fujita, A., Iwai, K., Ishii, M., & Kurachi, Y. (2004). Expression of an inwardly rectifying K+ channel, Kir5.1, in specific types of fibrocytes in the cochlear lateral wall suggests its functional importance in the establishment of endocochlear potential. The European Journal of Neuroscience, 19(1), 76-84.
Hibino H, et al. Expression of an Inwardly Rectifying K+ Channel, Kir5.1, in Specific Types of Fibrocytes in the Cochlear Lateral Wall Suggests Its Functional Importance in the Establishment of Endocochlear Potential. Eur J Neurosci. 2004;19(1):76-84. PubMed PMID: 14750965.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Expression of an inwardly rectifying K+ channel, Kir5.1, in specific types of fibrocytes in the cochlear lateral wall suggests its functional importance in the establishment of endocochlear potential. AU - Hibino,Hiroshi, AU - Higashi-Shingai,Kayoko, AU - Fujita,Akikazu, AU - Iwai,Kaori, AU - Ishii,Masaru, AU - Kurachi,Yoshihisa, PY - 2004/1/31/pubmed PY - 2004/6/21/medline PY - 2004/1/31/entrez SP - 76 EP - 84 JF - The European journal of neuroscience JO - Eur. J. Neurosci. VL - 19 IS - 1 N2 - Cochlear endolymph contains 150 mm K+ and has a highly positive potential of approximately +80 mV. The specialized ionic composition and high potential in endolymph are essential for hearing and maintained by circulation of K+ from perilymph to endolymph through the cochlear lateral wall. Various types of K+ channel such as Kir4.1 and KCNQ1/KCNE1 are expressed in stria vascularis of the lateral wall and play essential roles in K+ circulation. In this study, we examined a distribution of another K+ channel, Kir5.1, and found it specifically expressed in the spiral ligament of the cochlear lateral wall. Specific immunoreactivity for Kir5.1 was detected in type II, IV and V fibrocytes of the ligament and spiral limbus, all of which are directly involved in K+ circulation. Kir5.1 was not found in either type I or III fibrocytes. Although Kir5.1 assembles with Kir4.1 to form a functional Kir channel in renal epithelia and retinal Müller cells, double-immunolabelling revealed that they were expressed in distinct regions in the cochlea lateral wall, i.e. Kir4.1 only in stria vascularis vs. Kir5.1 in spiral ligament. During development, the expression of Kir5.1 subunits started significantly later than Kir4.1 and was correlated with the 'rapid' phase of the elevation of endocochlear potential (EP). Kir5.1 and Kir4.1 channel-subunits may therefore play distinct functional roles in K+ circulation in the cochlear lateral wall. SN - 0953-816X UR - https://www.unboundmedicine.com/medline/citation/14750965/Expression_of_an_inwardly_rectifying_K+_channel_Kir5_1_in_specific_types_of_fibrocytes_in_the_cochlear_lateral_wall_suggests_its_functional_importance_in_the_establishment_of_endocochlear_potential_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0953-816X&date=2004&volume=19&issue=1&spage=76 DB - PRIME DP - Unbound Medicine ER -