Department of Physiology & Biophysics, Rush University Medical Center, 1750 W. Harrison Street, Chicago, IL, 60612, USA.
Department of Internal Medicine/Cardiology, Rush University Medical Center, Chicago, IL, 60612, USA.
Pflugers Arch. 2021 Mar;473(3):317-329. doi: 10.1007/s00424-020-02506-x. Epub 2021 Jan 5.
In cardiac muscle, the process of excitation-contraction coupling (ECC) describes the chain of events that links action potential induced myocyte membrane depolarization, surface membrane ion channel activation, triggering of Ca induced Ca release from the sarcoplasmic reticulum (SR) Ca store to activation of the contractile machinery that is ultimately responsible for the pump function of the heart. Here we review similarities and differences of structural and functional attributes of ECC between atrial and ventricular tissue. We explore a novel "fire-diffuse-uptake-fire" paradigm of atrial ECC and Ca release that assigns a novel role to the SR SERCA pump and involves a concerted "tandem" activation of the ryanodine receptor Ca release channel by cytosolic and luminal Ca. We discuss the contribution of the inositol 1,4,5-trisphosphate (IP) receptor Ca release channel as an auxiliary pathway to Ca signaling, and we review IP receptor-induced Ca release involvement in beat-to-beat ECC, nuclear Ca signaling, and arrhythmogenesis. Finally, we explore the topic of electromechanical and Ca alternans and its ramifications for atrial arrhythmia.
在心肌中，兴奋-收缩偶联（ECC）的过程描述了将动作电位引起的心肌细胞膜去极化、表面膜离子通道激活、触发肌浆网（SR）Ca 储存中 Ca 释放引发收缩机制激活的一连串事件，最终负责心脏的泵功能。在这里，我们回顾了心房和心室组织之间 ECC 和 Ca 释放的结构和功能属性的相似之处和差异。我们探索了心房 ECC 和 Ca 释放的新型“火扩散吸收火”范例，该范例赋予了 SR SERCA 泵的新作用，并涉及细胞浆和腔 Ca 协同“串联”激活 Ryanodine 受体 Ca 释放通道。我们讨论了肌醇 1,4,5-三磷酸（IP）受体 Ca 释放通道作为 Ca 信号辅助途径的贡献，我们回顾了 IP 受体诱导的 Ca 释放在心脏跳动 ECC、核 Ca 信号和心律失常发生中的作用。最后，我们探讨了机电和 Ca 交替的主题及其对心房性心律失常的影响。
