速度の高い中央シナプスでのトランスミッター放出率の細胞内カルシウム依存性
1Abteilung Membranbiophysik, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany. rschneg@gwdg.de
Nature
|September 6, 2000
まとめ
急速な神経伝達物質の放出は,カルシウムに依存しています. この研究は,低細胞内カルシウムレベル (10マイクロM) が,中枢神経系シナプスにおける迅速な膀融合と放出を誘発することを明らかにしています.
科学分野:
- 神経科学は神経科学である.
- 細胞生物学 細胞生物学
- バイオフィジックス 生物物理学
背景:
- シナプス胞の融合と神経伝達物質の放出は,ニューロン信号伝達に極めて重要です.
- 急速な神経伝達物質の放出は,局所的な高細胞内カルシウム濃度 ([Ca2+]i > 100 μM) を要求すると考えられている.
- シナプス放出部位における局所的な[Ca2+]iの実験的な推定は欠けている.
研究 の 目的:
- 快速な神経伝達物質の放出に必要な局所的な細胞内カルシウム濃度 ([Ca2+]i) を実験的に決定する.
- カルシウム結合と膀融合の動態を調査する.
- カルシウムに対する急速なシナプス伝達の感受性を理解するために.
主な方法:
- 大きなシナプス端末 (Heldのカリックス) でカルシウムイオンの脱出.
- 制御された[Ca2+]iステップの後の神経伝達物質の放出率の運動分析.
- 膀プール枯渇の測定. 膀プール枯渇の測定. 膀プール枯渇の測定.
主要な成果:
- [Ca2+]iが10マイクロMにステップのように上昇すると,高速送信機が放出されます.
- 利用可能な膀の約80%が3ヶ月未満で枯渇しました.
- 25マイクロMまでの一時的な[Ca2+]i上昇は,単一のアクションポテンシャル中の放出を説明することができます.
- カルシウムセンサーは,通常の放出確率で飽和していない.
結論:
- 急速な神経伝達物質の放出は,これまで考えられていたよりも低い[Ca2+]iによって引き起こされる可能性があります.
- 高い協力性とカルシウムセンサーの不飽和は,シナプス伝送の感度を高めます.
- 短期間で局所的なカルシウム信号は,迅速なシナプス伝送に十分である.
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