Barium-induced electro-mechanical uncoupling in myocardial cells.
Barium-induced electro-mechanical uncoupling in myocardial cells.
复制标题
钡诱导心肌细胞机电解偶联。
DOI：
10.1016/0300-9629(84)90534-6
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Cole,JJ
中科院分区：
文献类型：
--
作者：
McCann,FV;Chen,LS;Cole,JJ
成蛾的心脏需要细胞外钙来维持电生成和张力发育。在这项研究中，我们询问自律性、驱动电发生和张力发育的过程是否需要特定的钙，或者二价阳离子Ba2+是否可以取代钙来支持这些活性。等摩尔量的Ba2+替代钙离子引起明显的超极化(25 MV)，抑制了自发跳动的半离体心动细胞的起搏器活动和张力发展。在Ba2+生理盐水浴和动作电位(由外界刺激产生)的刺激下，心肌细胞的动作电位幅度显著增加，2相(平台)延长，潜伏期延长，30min后，未观察到机械活动。当重新注入钙时，这些变化是完全可逆的。我们认为，Ba2+替代钙离子是蛾心肌细胞中一种有效的机电解偶联剂。虽然Ba2+可以支持电发生，但它不能取代从肌浆库中释放钙以影响张力发育所需的“触发器”-钙离子。
The heart of the adult moth Hyalophora cecropia requires extracellular calcium to maintain electrogenesis as well as tension development. In this study we ask whether the processes of autorhythmicity, driven electrogenesis and tension development require calcium specifically or whether the divalent cation Ba2+ can be substituted for calcium to support these activities. Ba2+ substituted for Ca2+ in equimolar amounts caused a marked (25 mV) hyperpolarization, suppression both of pacemaker activity and of tension development in spontaneously beating semi-isolated heart cells. Heart cells bathed in Ba2+ saline and paced by action potentials (produced by external stimuli) of greatly increased amplitude, prolonged phase 2 (plateau) and increased latency, and after 30 min, no mechanical activity was observed. These changes were completely reversible when calcium was reintroduced. We conclude that Ba2+ substitution for Ca2+ is an effective electromechanical uncoupler in moth heart cells. Although Ba2+ can support electrogenesis, it cannot replace'trigger'-Ca2+ needed to release calcium from sarcoplasmic stores to effect tension development.