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Roles of water on the functions of ion channels

Research Project

Project/Area Number 12670053
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field General physiology
Research InstitutionOkazaki Research Institutes

Principal Investigator

KUKITA Fumio  Okazaki Research Institutes National Institutes for Physiological Sciences, Research Associate, 生理学研究所, 助手 (40113427)

Project Period (FY) 2000 – 2001
Project Status Completed (Fiscal Year 2001)
Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
Keywordsion channel / fluctuation in proteins / water / voltage-sensor / structure / squid giant axion / viscosity / osmotic pressure / 蛋白質のゆらぎ
Research Abstract

Ion channels has been generally thought to work in the lipid environment and then be regulated by the physical properties of lipid. However, they are controlled by the physical properties of aqueous solutions facing the ion channels but not by those of lipids. The rate of opening of Squid K^+ channels are controlled by the solution viscosity as that of Squid Na^+ channels. In a concentrated nonelectrolyte solutions, the time course of opening of Na^+ channels and K^+ channels was slowed mainly by way of a viscosity-dependent slowing of voltage-sensor movement.
Ion channels are pertinently designed to have an aqueous pore for ions to permeate thought the hydrophobic lipid bilayer. Therefore, a decrease in a water activity in the environment of channel pore has been thought to depress a channel pore opening. This is observed in the sodium channel but is not in all ionic channels, depending on the pore interior structure. Although opening of K^+ channel was also slowed by viscosity, a part of channels opened at the instant of a depolarizing voltage jump from -180 mV, as if pore is free from the control of voltage-sensor. The channel in this open state can close very slowly with the time constant larger by 50-fold on returning to -180 mV. These data suggested that volume of pore interior decreased when the channel was open. Even if the volume decreases, the wavy surface of pore interior might be smooth and narrow constrictions might disappear for ions to pass smoothly. Osmotic effects on the channel pore might suggest a pore interior structure which dose not parallel the conductance itself.

Report

(3 results)
  • 2001 Annual Research Report   Final Research Report Summary
  • 2000 Annual Research Report

Research Products

(13 results)

All Other

All Publications (13 results)

  • [Publications] Kukita, F.: "Solvent effects on squid sodium channel are attributable to movements of a flexible protein structure in gating currents and to hydration in a pore"J.Physiol.(Lond). 522. 357-373 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Nakanishi, K., Kukita, F.: "Intracelluar [Cl-] modulates synchronous electrical activity in rat neocortical neurons in culture by way of GABAergic inputs"Brain Research. 863. 192-204 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] 久木田文夫: "膜電位依存性イオンチャネルの開機構に対する水の効果"生物物理. 40(3). 185-190 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Nakanishi, K., Kukita, F., Asai, K., Kato, T.: "Recurrent subthreshold electrical activities of rat neocortical neurons progress during long-term culture"Neurosci.Lett.. 304. 85-88 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Kukita, F.: "Solvent effects on squid sodium channel are Attributable to movements of a flexible protein structure in gating currents and to hydration in a pore"J. Physiol. (Lond). 522. 357-373 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Nakanishi, K., Kukita, F.: "Intracelluar [Cl-] modulates synchronous electrical activity in rat neocortical neurons in culture by way of GABA ergic inputs"Brain Research. 863. 192-204 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Nakanishi, K., Kukita, F., Asai, K., Kato, T.: "Recurrent subthreshold electrical activities of rat neocortical neurons progress during long-term culture"Neurosci. Lett.. 304. 85-88 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Kukita, F.: "Roles of water in a gating of voltage-gated ion channels"Biophysics (Japanese). 40(3). 185-190 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] 久木田文夫: "膜電位依存性イオンチャネルの開機構に対する水の効果"生物物理. 40(3). 185-190 (2000)

    • Related Report
      2001 Annual Research Report
  • [Publications] Kukita, F.: "K^+channel opened by a water activity decrease"Jpn J Physiol. 51S. S183 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Kukita,F.: "Solvent effects on squid sodium channel are attributable to movements of a flexible protein structure in gating currents and to hydration in a pore."J.Physiol.(Lond). 522. 357-373 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Nakanishi,K.,Kukita,F.: "Intracelluar [Cl-] modulates synchronous electrical activity in rat neocortical neurons in culture by way of GABAergic inputs. "Brain Research.. 863. 192-204 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] 久木田文夫: "膜電位依存性イオンチャネルの開機構に対する水の効果"生物物理. 40(3). 185-190 (2000)

    • Related Report
      2000 Annual Research Report

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Published: 2000-03-31   Modified: 2016-04-21  

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