心臓のサルコプラズマ網膜から,ナトリウム電流が誘発したカルシウム放出
1Department of Physiology, University of Nevada School of Medicine, Reno 89557-0046.
Science (New York, N.Y.)
|April 20, 1990
まとめ
心臓の細胞におけるナトリウムとカルシウムの交換は,直接的なカルシウムチャネルへの侵入とは無関係に,内部貯蔵物からカルシウムの放出を誘発する. このメカニズムは,心筋収縮と薬物効果に影響を及ぼします.
科学分野:
- 心臓病学 心臓病学
- 細胞生理学 細胞生理学
- 分子生物学は分子生物学である.
背景:
- 心臓の機能は,筋細胞内の正確なカルシウム処理に依存しています.
- ナトリウム・カルシウム交換 (NCX) は,細胞内カルシウムの重要な調節因子である.
- サルコプラズマ網膜のカルシウム放出を誘発するNCXの正確な役割は,完全に理解されていません.
研究 の 目的:
- 心臓のサルコプラズマ網膜からカルシウムの放出におけるサルコレマのナトリウム・カルシウム交換の役割を調査する.
- 心筋細胞におけるナトリウム電流によるカルシウム放出のメカニズムを解明する.
主な方法:
- 使用した,電圧圧縮された,分離された心筋細胞.
- 電圧に依存するカルシウムチャネル活動がない場合のカルシウム放出を調査した.
- カルシウムの放出がナトリウム摂取と細胞外カルシウム濃度の依存度を評価した.
主要な成果:
- 膜脱極化により,リヤノジンに敏感な貯蔵物からカルシウムの放出が誘発され,カルシウムチャネルへの入り口がなかった.
- このカルシウム放出は,テトロドトキシンに敏感なナトリウムチャネル経由でナトリウムが入り込むことに依存していた.
- また,カルシウムの放出は細胞外カルシウムに依存しており,これは,ナトリウムとカルシウムの交換を含むカルシウム誘発のトリガー放出を示唆している.
結論:
- ナトリウムとカルシウムの交換は,サルコプラズマ網膜からカルシウムの放出を誘発することができます.
- このメカニズムは,心臓のグリコシドのイノトロピー効果に寄与する可能性があります.
- また,心臓のナトリウムチャネルと相互作用する抗リズム薬の効果も説明できるかもしれません.
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