ラット網膜ニューロンにおける電位駆動型Na^+電流の slow-inactivation と活動電位発火  [in Japanese] Slow-inactivation of voltage-gated Na^+ current and spike firing in rat retinal neurons  [in Japanese]

Search this Article

Author(s)

    • 原部 翔 HARABE Sho
    • 熊本大学大学院自然科学研究科人間環境情報講座 Department of Human and Environmental Informatics, Graduate school of Science and Technology, Kumamoto University
    • 本村 珠美 MOTOMURA Tamami
    • 熊本大学大学院自然科学研究科人間環境情報講座 Department of Human and Environmental Informatics, Graduate school of Science and Technology, Kumamoto University
    • 林田 祐樹 [他] HAYASHIDA Yuki
    • 熊本大学大学院自然科学研究科人間環境情報講座 Department of Human and Environmental Informatics, Graduate school of Science and Technology, Kumamoto University
    • 村山 伸樹 MURAYAMA Nobuki
    • 熊本大学大学院自然科学研究科人間環境情報講座 Department of Human and Environmental Informatics, Graduate school of Science and Technology, Kumamoto University

Abstract

脊椎動物網膜の出力段に位置する神経節細胞は,神経回路の演算結果を電気的スパイク列に符号化しその情報を脳へと伝達する.近年,このスパイク発生を担う電位駆動型Na^+チャネルが,数msecから数百msecの範囲の時定数をもって不活性化を起こし,スパイク列の順応的出力に寄与することが示された.但し現在までに,秒を超える時間尺度の不活性化について生理学実験による解析が成された報告例は無い.そこで本研究では,ラット網膜より機械的に急性単離した神経節細胞を試料とし,穿孔パッチホールセル記録法を用いた膜電位固定実験よって,電位駆動型Na^+電流における緩徐な不活性化(slow-inactivation)の状態遷移過程を解析した.その結果,数秒の時定数をもつ不活性化状態への進行とそこからの回復の遷移過程が存在することが示された.また電流固定下の膜電位計測の結果から,不活性化状態遷移によるNa^+電流の増減が,活動電位の発火闘値に影響を与えることが示された.複数の時間尺度をもつNa^+チャネルの不活性化は,網膜神経節細胞における履歴依存的スパイク発生に寄与すると考えられる.

Ganglion cells located at the output of vertebrate retina encode the computational results of the neural circuit into electrical spike trains, to send the information to the brain. Recent studies have shown that voltage-gated Na^+ channels, which are responsible for the spike generation, exhibit inactivation with the time constants in the range between a few milliseconds and several hundred milliseconds, thereby contributing to the adaptive output of spikes. However, the slower inactivation in the time scale over seconds has not been previously analyzed in the physiological experiment. In this study, therefore, we made analyses on the transition process of the slow-inactivation of voltage-gated Na^+ current in the ganglion cells acutely dissociated from rat retinas, by means of voltage-clamp experiments with perforated-patch whole-cell mode. The results indicated that there exist the transition processes of entry into, and recovery from, inactivation with the time constants of several seconds as well as a few milliseconds. Voltage measurements under current-clamp showed that the threshold for action potential firing can be affected by the change of Na^+ current due to the inactivation. The multiple time scales of Na^+ channel inactivation are thought to contribute to history-dependent spike firings in retinal ganglion cells.

Journal

  • IEICE technical report

    IEICE technical report 110(399), 9-12, 2011-01-20

    The Institute of Electronics, Information and Communication Engineers

References:  8

Codes

  • NII Article ID (NAID)
    110008676324
  • NII NACSIS-CAT ID (NCID)
    AN1001320X
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    09135685
  • NDL Article ID
    10970511
  • NDL Source Classification
    ZN33(科学技術--電気工学・電気機械工業--電子工学・電気通信)
  • NDL Call No.
    Z16-940
  • Data Source
    CJP  NDL  NII-ELS 
Page Top