In situ Ca2+ dynamics of Purkinje fibers and its interconnection with subjacent ventricular myocytes
In situ Ca2+ dynamics of Purkinje fibers and its interconnection with subjacent ventricular myocytes
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DOI：
10.1016/j.yjmcc.2005.01.004
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发表时间：
2005-04-01
影响因子：
5
通讯作者：
Takamatsu, T
中科院分区：
文献类型：
--
作者：
Hamamoto, T;Tanaka, H;Takamatsu, T
浦肯野纤维在向心室的脉冲传播中起着重要作用，其功能损伤可能导致心律失常。然而，人们对浦肯野纤维网络与心脏内底层心室心肌之间互连的精确时空模式知之甚少。为了解决这个问题，我们使用多针孔型快速扫描共聚焦显微镜同时观察 Langendorff 灌注大鼠心脏中浦肯野纤维和下方心室肌细胞的细胞内 Ca2+ 动态。在室温下记录心电图时，可以在右心室间隔的心内膜下区域观察到荧光强度的时空变化。用 Fluo3、碘化乙酰硫胆碱 (ATCHI) 或 di-4-ANEPPS 对心脏进行染色，揭示了浦肯野纤维的特征结构。在窦性心律（约 60 bpm）或心房起搏（高达 3 Hz）期间，每根浦肯野纤维几乎与心室兴奋同时表现出时空同步 Ca2+ 瞬变。单个纤维中的 Ca2+ 瞬变仍然在浦肯野纤维网络内同步，不仅在高 K+ (8 mM) 灌注引起的浦肯野至心室 (P-V) 传导延迟下，而且在 10-mM K+ 灌注产生的单向、顺向 P-V 阻滞下。虽然在局部浦肯野网络受损纤维中发现了自发的异步细胞内 Ca2+ 波，但周围纤维仍然表现出与心室兴奋同步的 Ca2+ 瞬变。总之，这些结果首次证明了浦肯野纤维网络中细胞内 Ca2+ 动力学的原位。即使在 P-V 传导干扰或出现 Ca2+ 波的情况下，同步 Ca2+ 瞬变仍保留，这意味着浦肯野纤维作为专门传导系统的合胞作用，而 P-V 交界处的单向阻滞表明折返性心律失常的基础。 (c) 2005 Elsevier Ltd. 保留所有权利。
Purkinje fibers play essential roles in impulse propagation to the ventricles, and their functional impairment can become arrhythmogenic. However, little is known about precise spatiotemporal pattern(s) of interconnection between Purkinje-fiber network and the underlying ventricular myocardium within the heart. To address this issue, we simultaneously visualized intracellular Ca2+ dynamics at Purkinje fibers and subjacent ventricular myocytes in Langendorff-perfused rat hearts using multi-pinhole type, rapid-scanning confocal microscopy. Under recording of electrocardiogram at room temperature spatiotemporal changes in fluo3-fluorescence intensity were visualized on the subendocardial region of the right-ventricular septum. Staining of the heart with either fluo3, acetylthiocholine iodide (ATCHI), or di-4-ANEPPS revealed characteristic structures of Purkinje fibers. During sinus rhythm (about 60 bpm) or atrial pacing (up to 3 Hz) each Purkinje-fiber exhibited spatiotemporally synchronous Ca2+ transients nearly Simultaneously to ventricular excitation. Ca2+ transients in individual fibers were still synchronized within the Purkinje-fiber network not only under high-K+ (8 mM) perfusion-induced Purkinje-to-ventricular (P-V) conduction delay, but also under unidirectional, orthodromic P-V block produced by 10-mM K+ perfusion. While spontaneous, asynchronous intracellular Ca2+ waves were identified in injured fibers of Purkinje network locally, surrounding fibers still exhibited Ca2+ transients synchronously to ventricular excitation. In summary, these results are the first demonstration of intracellular Ca2+ dynamics in the Purkinje-fiber network in situ. The synchronous Ca2+ transients, preserved even under P-V conduction disturbances or under emergence of Ca2+ waves, imply a syncytial role of Purkinje fibers as a specialized conduction system, whereas unidirectional block at P-V junctions indicates a substrate for reentrant arrhythmias. (c) 2005 Elsevier Ltd. All rights reserved.