The initiation of the heart beat

Peng Sheng Chen*, Boyoung Joung, Tetsuji Shinohara, Mithilesh Das, Zhenhui Chen, Shien-Fong Lin

*此作品的通信作者

研究成果: Review article同行評審

37 引文 斯高帕斯(Scopus)

摘要

During a normal lifetime, the heart may beat over 2 billion times, but the mechanisms by which the heart beats are initiated remain a subject of intense investigation. Since the discovery of a pacemaker current (If ) in 1978, multiple studies have shown that rhythmic changes in membrane voltage (the "membrane voltage clock") underlie the mechanisms of automaticity. The If is a depolarization current activated during hyperpolarization. Therefore, when the cardiac cells recover, the If is activated and slowly depolarizes the cell membrane, leading to the onset of action potential. Recent studies, however, suggest that increased intracellular Ca (Cai) induced by spontaneous rhythmic sarcoplasmic reticulum Ca release (the "calcium clock") is also jointly responsible for the initiation of the heart beat. Elevated Cai activates another ionic current (the sodium-calcium exchanger current or INCX), leading to spontaneous phase 4 depolarization. Under normal conditions, both clocks are needed to initiate the heart beat. Malfunction of the clocks is associated with sinus node dysfunction in heart failure and atrial fibrillation. More studies are needed to determine how both clocks work together to initiate heart beat under normal and disease conditions.

原文English
頁(從 - 到)221-225
頁數5
期刊Circulation Journal
74
發行號2
DOIs
出版狀態Published - 1 2月 2010

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