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1994 Fiscal Year Final Research Report Summary

Control of single K^+channels closed by light in the extra-ocular photoreceptor cells.

Research Project

Project/Area Number 05680582
Research Category

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

Allocation TypeSingle-year Grants
Research Field Biophysics
Research InstitutionKagoshima University

Principal Investigator

GOTOW Tsukasa  Kagoshima Univ., Fac.of Med., Assoc. Prof., 医学部, 助教授 (60136851)

Co-Investigator(Kenkyū-buntansha) KIJIMA Hiromasa  Nagoya Univ., Fac.of Sci., Prof., 理学部, 教授 (30012397)
Project Period (FY) 1993 – 1994
KeywordsInvertebrate visual cell / Mollusc, Onchidium photoreceptor cell / Properties of K^+-channel / K^+-channel closed by light / cGMP-gated K^+-channel / Second messengers of photoreceptor potential / Single-channel recordings
Research Abstract

Now, a second messenger involved in phototransduction of invertebrate photoreceptors remains unclear. Then, the molecular mechanism mediating the depolarizing receptor potential of the extra-ocular photoreceptor cells, A-P-1 and Es-1 was examined. A-P-1 and Es-1, the photoresponsive neurons located within the mollusc, Onchidium ganglia are thought to be a primitive visual cell. Previous studies have shown that light depolarizes A-P-1 or Es-1 by suppressing the dark K^+ currents which are controlled by an internal messenger, cGMP.
In cell-attached patch recordings of A-P-1 or Es-1, single-channels which are active in the dark and closed by light (the light-sensitive channels)could be shown in the presence of external Ca^<2+> and Mg^<2+>. The reversal potential and its shift for the single-channel currents, measured with different K^+-filled patch pipettes showed that the light-sensitive channels were K^+-selective. The single-channel conductance was about 71 pS with 200 mM K^+ and about 100 pS with 450 mM K^+ in the pipettes, as determined from the slope of I-V relationship. Application of cGMP to excised inside-out patches activated (opened) a channel, equivalent to the light-sensitive channel recorded from the same membrane in the intact cell. Channel activation was dependent on the concentration of cGMP,and half-maximal activation occured between 20 and 100 muM cGMP.However, no channel activity was observed with application of cAMP of Ca^<2+> to the same patches in concentrations as high as 2 mM.Thus, we succeeded in clearing a new class of K^+ channel which is closed by light and is opened by cGMP in the Onchidium photoreceptor cells. Further, we are currently trying to clear immunocytochemical localization and chromatographic properties of photopigments in A-P-1 and Es-1.

  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] 後藤司(Gotow,T.): "Properties of single K^+channels closed by light in the Onchidium extra-ocular photoreceptor cell." The Japanese Journal of Physiology. 44(1). S206-S206 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 後藤司(T.Gotow): "Color information processing in Onchidium extra-ocular photoreceptor cells." Zoological Science. 11. 100-100 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 後藤司(T.Gotow): "Single K^+channels closed by light and opened by cyclic GMP in molluscan extra-ocular photoreceptor cell." Brain Research. 662. 268-272 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 三村芳弘(Y.Mimura): "Mechanisms of hyperpolarization induced by two cytokines,h TNFα and hIL-1α in neurons of the mollusc,Onchidium." Brain Research. 653. 112-118 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 後藤司: "イソアワモチ眼外光受容細胞における単一K^+チャネルの特性," 生物物理. 33. S68-S68 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 後藤司(Gotow,T.): "Single K^+channels closed by light and opened by cGMP of Onchidium photoreceptor cells." Zoological Science. 10. 117-117 (1993)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Tsukasa Gotow: "Single K^+ channels closed by light and opened by cyclic GMP in mollusca extra-ocular photoreceptor cells." Brain Research. 662. 268-272 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshihiro Mimura: "Mechanisms of hyperpolarization induced by two cytokines, hTNFalpha and hIL-1alpha in neurons of the mollusc, Onchidium." Brain Research. 653. 112-118 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshito Sonoda: "Electrical myotonia of rabbit skeletal muscles by HMG-CoA Reductase inhibitors." Muscle & Nerve. 17. 891-897 (1994)

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

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Published: 1996-04-15  

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