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1993 Fiscal Year Final Research Report Summary

Synaptic mechanisms in the outerplexiform layr of the vertebrate retina

Research Project

Project/Area Number 04640670
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 動物発生・生理学
Research InstitutionDepartment of Physiology, Keio University School of Medicine

Principal Investigator

TAKAHASHI Kyoh-Ichi  Department of Physiology, Keio University School of Medicine Research Associate, 医学部, 助手 (70138121)

Project Period (FY) 1992 – 1993
KeywordsVertebrate / Retina / Synaptic mechanism / Outerplexiform layr / Ligand-gated receptor / Ion channel / Calcium channel / Glutamate
Research Abstract

For elucidating the synaptic mechanisms in the outerplexiform layr of the vertebrate retina, the physiological and biophysical properties of photoreceptors, bipolar cells and horizontal cells should be investigated. In an attempt to pursue this purpose, I studied on ligand-gated receptors and ion channels in cone-driven horizontal cells dissociated from the retina of the catfish (Ictalurus punctatus) with a conventional intracellular technique and a whole-cell patch-clamp technique.
1. The horizontal cell responded to an application of L-glutamate(Glu, 100mM) with depolarization. The Glu-induced depolarization was suppressed by an application of 2-amino-4-phosphonobutyric acid(APB 10 - 100 muM), which is known to be an agonist for a Glu receptor of ON-type bipolar cells. This suppression was modified by a change of intracellular proton concentration(pH).
2. Glu(1 - 100 muM) caused an intracellular acidification in a concentration-dependent manner, although the mechanism by which the cell was acidified remained to be solved. The acidification evoked by Glu inhibited an HVA calcium channel current. EC_<50> for pH inhibition of HVA current was pH 7.1 and the Hill coefficient was approximately 2.
From the above results, it is tempting to suggest that intracellular protons as a second messenger play an important role on regulation of ligand-gated receptors and ion channels. To confirm function of the intracellular protons, a further analysis will be needed.

  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] TAKAHASHI,Kyoh-Ichi: "APB suppresses synaptic input to retinal horizontal cells in fish:A direct action on horizontal cells modulated by intracellular pH" Journal of Neurophysiology. 67. 1633-1642 (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] TAKAHASHI,Kyoh-Ichi: "Modulation of a sustained calcium current by intracellular pH in horizontal cells of fish retina" Journal of General Physiology. 101. 695-714 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] DIXON,Donald B.: "L-glutamate suppresses HVA calcium current in catfish horizontal cells by raising intracellular proton concentration" Neuron. 11. 267-277 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] MURAKAMI,Motohiko: "Modulation of gap junctions between horizontal cells by second messenger" Progress in Retinal and Eye Research. in press.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] TAKAHASHI,Kyoh-Ichi and COPENHAGEN,David R.: "APB suppresses synaptic input to retinal horizontal cells in fish : A direct action on horizontal cells modulated by intracellular pH" Journal of Neurophysiology. 67. 1633-1642 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] TAKAHASHI,Kyoh-Ichi, DIXON, Donald B.and COPENHAGEN,David R.: "Modulation of a sustained calcium current by intracellular pH in horizontal cells of fish retina" Journal of General Physiology. 101. 695-714 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] DIXON, Donald B., TAKAHASHI, Kyoh-Ichi and COPENHAGEN,David R.: "L-glutamate suppresses HVA calcium current in catfish horizontal cells by raising intracellular proton concentration" Neuron. 11. 267-277 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] MURAKAMI, Motohiko, MIYACHI, Ei-Ichi and TAKAHASHI, Kyoh-Ichi: "Modulation of gap junctions between horizontal cells by second messenger" Progress in Retinal and Eye Research. (in press).

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1995-03-27  

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