シナプス端末におけるエクソサイトーシスの速度のカルシウム依存性
R Heidelberger1, C Heinemann, E Neher
1Abteilung Membranbiophysik, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.
Nature
|October 6, 1994
まとめ
この研究では,細胞内カルシウムと神経伝達物質の放出との関係を定量化しています. 神経末端におけるカルシウム濃度の急速な増加は,神経細胞のコミュニケーションに不可欠なシナプス胞の融合の高速性を明らかにした.
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:
- 神経伝達物質の放出は,神経細胞のコミュニケーションに不可欠です.
- カルシウム濃度とエクソサイトーシス率の正確な関係は,完全に理解されていません.
研究 の 目的:
- 前シナプス細胞内カルシウムイオン濃度 ([Ca2+]i) とエクソサイトーシスの速度との関係を定量的に決定する.
- 神経伝達物質の最大分泌率を決定する.
主な方法:
- 檻に閉じ込められたカルシウムのフラッシュ光分解を用いて,シナプス端末で[Ca2+]iを迅速かつ均等に上昇させました.
- エクソサイトーシスの指数として測定された膜容量.
- カルシウム指標染料を用いて[Ca2+]iをモニターした.
主要な成果:
- [Ca2+]iでエクソサイトーシス速度は急激に増加し,少なくとも4つのカルシウムイオンが結合して融合を活性化することを示唆しています.
- カルシウムの半飽和濃度は194マイクロMでした.
- エクソサイトーシスの最大速度の常数は2,000〜3,000s-1.
- シナプス胞は,[Ca2+]iが100マイクロMを超えるとマイクロ秒以内に高い確率でエクソサイトーゼを行うことができます.
結論:
- この研究は,カルシウム依存性エクソサイトーシスの運動学に関する定量的な洞察を提供します.
- これらの発見は,神経細胞の急速な信号伝達能力を説明します.
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