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1990 Fiscal Year Final Research Report Summary

Mechanisms of Transmitter Release : Ca-Dependent Release and Ca-Independent Release.

Research Project

Project/Area Number 63480111
Research Category

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

Allocation TypeSingle-year Grants
Research Field Neurophysiology and muscle physiology
Research InstitutionThe University of Tokyo (1989-1990)
Okazaki National Research Institutes (1988)

Principal Investigator

TACHIBANA Masao  The Univ. of Tokyo, Dept. of Psychol, Associate Prof., 文学部, 助教授 (60132734)

Project Period (FY) 1988 – 1990
KeywordsRetina / Neuron / Glia / Synapse / Chemical transmitter / Glutamic acid / Ca ions / Ca current
Research Abstract

The purpose of this project was to investigate how chemical transmitters are released from retinal cells. Cells were isolated from the vertebrate retinae and voltage-clamped using a patch pipette in the whole-cell clamp configuration. The following results were obtained.
1. The Ca current of mouse bipolar cells was of T type. The activation threshold was low and the current was not blocked by dihydropyridines. On the other hand, the Ca current of goldfish bipolar cells was of L type ; activation threshold was high, and the current was sensitive to dihydropyridines. In both species, Ca current was induced at the synaptic terminal as well as at the cell body. This observation suggests that the Ca current may play a key role in the transmitter release.
2. Since glutamate is a leading candidate for the transmitter of bipolar cells, release of glutamate was examined by using bipolar cells isolated from the goldfish retina. Solitary catfish horizontal cells were used as a glutamate probe. It was demonstrated that gultamate (or closely related substance) was released from bipolar cells when the Ca current of synaptic terminal was activated by depolarization.
3. Uptake mechanisms of transmitter were investigated electrophysiologically. Application of glutamate induced an inward current in salamander Muller cells (retinal glia). This current was due to the activation of electrogenic glutamate uptake carriers ; one molecule of glutamate was cotransported with three Na ions. The carrier showed a strong voltage-dependence and Ca ions were not required for its activation. Efflux of glutamate was observed but it was not electrogenic. This carrier seems to contribute to the Ca-independent release of transmitters.
4. Turtle photoreceptors responded to glutamate with depolarization. Some response properties were similar to those of the glutamate carrier of salamander Muller cells. This suggests that turtle photoreceptors may have glutamate carriers.

  • Research Products

    (17 results)

All Other

All Publications (17 results)

  • [Publications] M.Tachibana: "LーGlutamateーinduced depolarization in solitary photoreceptors:A process that may contribute to the interaction between photoreceptors in situ." Proc.Natl.Acad.Sci.USA. 85. 5315-5319 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Tachibana: "Glutamateーinduced depolarization in retinal photoreceptors:Carrierーmediated uptake or channel activity?" Biomed.Res.Suppl.2. 53-54 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Tachibana: "Differences in glutamateーinduced response properties between photoreceptors and horizontal cells." Neurosci.Res.Suppl.8. S59-S67 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Kaneko: "Transient calcium current of retinal bipolar cells of the mouse." J.Physiol.(London). 410. 613-629 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Kaneko: "Membrane currents of retinal bipolar cells:goldfish vs.mouse." NATO ASI Series. H31. 413-424 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 立花 政夫: "視細胞から水平細胞・双極装細胞へのシナプス伝達" 蛋白質 核酸 酵素. 34. 642-651 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Kaneko: "Transient calcium current of retinal bipolar cells of the mouse." Neurosci. Res.Suppl.10. S67-S76 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] E.A.Schwartz: "Electrophysiology of glutamate and sodium coーtransport in a glial cell of the salamander retina." J.Physiol.(London). 426. 43-80 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Tachibana: "Release of endogenous excitatory amino acids from ONーtype bipolar cells isolated from the goldfish retina." J.Neurosci.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M. Tachibana and A. Kaneko: "L-Glutamate-induced depolarization in solitary photoreceptors : Aprocess that may contribute to the interaction between photoreceptors in situ." Proc. Natl. Acad. Sci. USA,. 85,. 5315-5319 (1988)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Tachibana and A. Kaneko: "Glutamate-induced depolarization in retinal photoreceptors : Carrier-mediated uptake or channel activity?" Biomed. Res.,. Supple. 2,. 53-54, (1988)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M, Tachibana and A. Kaneko: "Differences in glutamate-induced response properties between photoreceptors and horizontal cells." Neurosci. Res.,. Suppl. 8,. 59-67, (1988)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Kaneko, L. H. Pinto and M. Tachibana: "Transient calcium current of retinal bipolar cells of the mouse." J. Physiol. (London),. 410,. 613-629, (1989)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Keneko, M. Tachibana and L. H. Pinto: "Membrane currents of retinal bipolar cells : goldfish vs. mouse." NATO ASI Series,. Vol. H31, Neurobiology of the Inner Retina. Edited by R. Weiler and N. N. Osborne, Springerverlag, Berlin Heidelberg,. 413-424 (1989)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Kaneko, M. Tachibana and L. H. Pinto: "Transient calcium current of retinal bipolar cels of the mouse." Neurosci. Res.,. Suppl. 10,. S67-S76, (1989)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] E. A. Schwartz and M. Tachibana: "Electrophysiology of glutamate and sodium cotransport in a glial cell of the salamander retina." J. Physiol. (London),. 426,. 43-80, (1990)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Tachibana and T. Okada: "Release of endogenous excitatory amino acids from ON-type bipolar cells isolated from the goldfish retina." J. Neurosci.,.

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

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Published: 1993-08-12  

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