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Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs.
J Physiol Sci. 2007 Oct; 57(5):287-98.JP

Abstract

Using immunohistochemical and electrophysiological methods, we investigated the role of L-type Ca(2+) channels in the regulation of the endocochlear potential (EP) of the endolymphatic surface cells (ESC) of the guinea pig stria vascularis. The following findings were made: (1) Administration of 30 microg/ml nifedipine via a vertebral artery significantly suppressed the transient asphyxia-induced decrease in the EP (TAID) and the transient asphyxia-induced increase in the Ca(2+), referred to as TAIICa, concentration in the endolymph ([Ca](e)). (2) The endolymphatic administration of 1 microg/ml nifedipine significantly inhibited the TAID as well as the TAIICa. The endolymphatic administration of nifedipine (0.001-10 microg/ml) inhibited the TAID in a dose-dependent manner. (3) The endolymphatic administration of (+)-Bay K8644, an L-type Ca(2+) channel closer, significantly inhibited the TAID, whereas (-)-Bay K8644, an L-type Ca(2+) channel opener, caused a large decrease in the EP from approximately +75 mV to approximately +20 mV at 10 min after the endolymphatic administration. (4) By means of immunohistochemistry, a positive staining reaction with L-type Ca(2+) channels was detected in the marginal cells of the stria vascularis. (5) Under the high [Ca](e) condition, we examined the mechanism of the TAIICa and hypothesized that the TAIICa might have been caused by the decrease in the EP through a shunt pathway in the ESC. (6) The administration of nifedipine to the endolymph significantly inhibited the Ba(2+)-induced decrease in the EP. These findings support the view that L-type Ca(2+) channels in the marginal cells regulate the EP, but not directly the TAIICa.

Authors+Show Affiliations

Department of Otolaryngology, Osaka Medical College, Takatsuki, Osaka, 569-8686, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo 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

17963592

Citation

Inui, Takaki, et al. "Physiological Role of L-type Ca2+ Channels in Marginal Cells in the Stria Vascularis of Guinea Pigs." The Journal of Physiological Sciences : JPS, vol. 57, no. 5, 2007, pp. 287-98.
Inui T, Mori Y, Watanabe M, et al. Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs. J Physiol Sci. 2007;57(5):287-98.
Inui, T., Mori, Y., Watanabe, M., Takamaki, A., Yamaji, J., Sohma, Y., Yoshida, R., Takenaka, H., & Kubota, T. (2007). Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs. The Journal of Physiological Sciences : JPS, 57(5), 287-98.
Inui T, et al. Physiological Role of L-type Ca2+ Channels in Marginal Cells in the Stria Vascularis of Guinea Pigs. J Physiol Sci. 2007;57(5):287-98. PubMed PMID: 17963592.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs. AU - Inui,Takaki, AU - Mori,Yoshiaki, AU - Watanabe,Masahito, AU - Takamaki,Atsuko, AU - Yamaji,Junko, AU - Sohma,Yoshiro, AU - Yoshida,Ryotaro, AU - Takenaka,Hiroshi, AU - Kubota,Takahiro, Y1 - 2007/10/29/ PY - 2007/06/27/received PY - 2007/10/25/accepted PY - 2007/10/30/pubmed PY - 2008/8/13/medline PY - 2007/10/30/entrez SP - 287 EP - 98 JF - The journal of physiological sciences : JPS JO - J Physiol Sci VL - 57 IS - 5 N2 - Using immunohistochemical and electrophysiological methods, we investigated the role of L-type Ca(2+) channels in the regulation of the endocochlear potential (EP) of the endolymphatic surface cells (ESC) of the guinea pig stria vascularis. The following findings were made: (1) Administration of 30 microg/ml nifedipine via a vertebral artery significantly suppressed the transient asphyxia-induced decrease in the EP (TAID) and the transient asphyxia-induced increase in the Ca(2+), referred to as TAIICa, concentration in the endolymph ([Ca](e)). (2) The endolymphatic administration of 1 microg/ml nifedipine significantly inhibited the TAID as well as the TAIICa. The endolymphatic administration of nifedipine (0.001-10 microg/ml) inhibited the TAID in a dose-dependent manner. (3) The endolymphatic administration of (+)-Bay K8644, an L-type Ca(2+) channel closer, significantly inhibited the TAID, whereas (-)-Bay K8644, an L-type Ca(2+) channel opener, caused a large decrease in the EP from approximately +75 mV to approximately +20 mV at 10 min after the endolymphatic administration. (4) By means of immunohistochemistry, a positive staining reaction with L-type Ca(2+) channels was detected in the marginal cells of the stria vascularis. (5) Under the high [Ca](e) condition, we examined the mechanism of the TAIICa and hypothesized that the TAIICa might have been caused by the decrease in the EP through a shunt pathway in the ESC. (6) The administration of nifedipine to the endolymph significantly inhibited the Ba(2+)-induced decrease in the EP. These findings support the view that L-type Ca(2+) channels in the marginal cells regulate the EP, but not directly the TAIICa. SN - 1880-6546 UR - https://www.unboundmedicine.com/medline/citation/17963592/Physiological_role_of_L_type_Ca2+_channels_in_marginal_cells_in_the_stria_vascularis_of_guinea_pigs_ L2 - http://joi.jlc.jst.go.jp/JST.JSTAGE/physiolsci/RP006807?from=PubMed DB - PRIME DP - Unbound Medicine ER -