心臓のカリウム電流表現のフィードバック改造:リポラライゼーション・リザーブを制御するための新しい潜在的なメカニズム
Ling Xiao1, Jiening Xiao, Xiaobin Luo
1Department of Medicine, Montreal Heart Institute and Université de Montréal, Quebec, Canada.
Circulation
|August 20, 2008
まとめ
心筋細胞における急速遅延補正器カリウム電流 (I(Kr)) の持続的抑制は,転写後の調節を通じて遅延補正器カリウム電流 (I(Ks)) を増加させた. これは,マイクロRNAの変化が心臓のリポラライゼーション・リザーブに影響を及ぼすことを示唆している.
科学分野:
- 心血管生理学 心血管の生理学
- 分子心臓病学 分子心臓病学
- イオンチャネル生物学
背景:
- 個々のK(+) 流の阻害は,他のK(+) 流の補償的な増加につながり,アクションポテンシャル持続時間 (再極化準備) を維持します.
- 持続的なK (((+) チャンネル阻害がイオン電流表現 (再構成) に与える影響は,ほとんど未知のままである.
- 本研究では,慢性的なK (((+) 電流阻害が心臓のイオン電流表現に及ぼす影響を調査しています.
研究 の 目的:
- 急速遅延補正器K ((+)) 流 (I ((Kr)) の持続的阻害が他の心臓イオン流の改造を誘導するかどうかを決定する.
- イオン電流表現の観測された変化の背後にあるメカニズムを解明する.
- これらの変化がリポラライゼーション準備金に与える影響を評価する.
主な方法:
- 大人の犬の左心室内心筋細胞を培養し,選択的I ((Kr)) 阻害剤であるドフェチリドを投与または投与せずに24時間ペースさせました.
- アクションポテンシャル期間と再極化準備金も評価された.
- イオン電流密度 (I(Kr),I(Ks),I(to),I(K1),I(CaL)),mRNA,およびKvLQT1/minKのタンパク質発現,およびマイクロRNAレベル (miR-133a/b) を定量化しました.
主要な成果:
- 継続的なI(Kr) 封鎖は,アクションポテンシャル期間を短縮し,リポラライゼーション・リザーブを増加させた.
- 遅い遅延補正器K ((+)) の電流密度 (I ((Ks)) の有意な増加が観察され,他の測定電流の変化はありませんでした.
- KvLQT1/minKタンパク質のレベルはmRNAの変化なしに増加し,転写後の調節を示唆し,潜在的にmiR-133a/b発現の減少を含む.
結論:
- 持続的なI(Kr) 減少は,トランスクリプション後のメカニズムを通じた補償的なI(Ks) アップレギュレーションにつながり,おそらくマイクロRNA媒介の調節が含まれます.
- これらの発見は,イオンチャネル発現におけるフィードバック制御システムを強調し,心臓のリポラライゼーション準備を調節します.
- このイオンチャネル発現の改造は,心臓の電気生理学と心律変異 (arrhythmogenesis) に影響を及ぼす可能性があります.
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