Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs

Takaki Inui, Yoshiaki Mori, Masahito Watanabe, Atsuko Takamaki, Junko Yamaji, Yoshiro Sohma, Ryotaro Yoshida, Hiroshi Takenaka, Takahiro Kubota

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Using immunohistochemical and electrophysiological methods, we investigated the role of L-type Ca2+ 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 μg/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 Ca2+, referred to as TAIICa, concentration in the endolymph ([Ca]e).(2) The endolymphatic administration of 1 μg/ml nifedipine significantly inhibited the TAID as well as the TAIICa. The endolymphatic administration of nifedipine (0.001-10 μg/ml) inhibited the TAID in a dose-dependent manner. (3) The endolymphatic administration of (+)-Bay K8644, an L-type Ca2+ channel closer, significantly inhibited the TAID, whereas (-)-Bay K8644, an L-type Ca 2+ channel opener, caused a large decrease in the EP from ∼+75 mV to ∼+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 Ba2+-induced decrease in the EP. These findings support the view that L-type Ca2+ channels in the marginal cells regulate the EP, but not directly the TAIICa.

Original languageEnglish
Pages (from-to)287-298
Number of pages12
JournalJournal of Physiological Sciences
Volume57
Issue number5
DOIs
Publication statusPublished - 2007 Oct
Externally publishedYes

Fingerprint

Stria Vascularis
Asphyxia
Nifedipine
Guinea Pigs
Endolymph
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Vertebral Artery
Immunohistochemistry
Staining and Labeling

Keywords

  • Asphyxia
  • Ca-selective microelectrode
  • Endocochlear potential
  • L-type Ca channel
  • Nifedipine

ASJC Scopus subject areas

  • Physiology

Cite this

Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs. / Inui, Takaki; Mori, Yoshiaki; Watanabe, Masahito; Takamaki, Atsuko; Yamaji, Junko; Sohma, Yoshiro; Yoshida, Ryotaro; Takenaka, Hiroshi; Kubota, Takahiro.

In: Journal of Physiological Sciences, Vol. 57, No. 5, 10.2007, p. 287-298.

Research output: Contribution to journalArticle

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', Journal of Physiological Sciences, vol. 57, no. 5, pp. 287-298. https://doi.org/10.2170/physiolsci.RP006807
Inui, Takaki ; Mori, Yoshiaki ; Watanabe, Masahito ; Takamaki, Atsuko ; Yamaji, Junko ; Sohma, Yoshiro ; Yoshida, Ryotaro ; Takenaka, Hiroshi ; Kubota, Takahiro. / Physiological role of L-type Ca2+ channels in marginal cells in the stria vascularis of guinea pigs. In: Journal of Physiological Sciences. 2007 ; Vol. 57, No. 5. pp. 287-298.
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AU - Yamaji, Junko

AU - Sohma, Yoshiro

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AU - Takenaka, Hiroshi

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