Mode and determination of the initial contraction stage in the mouse embryo heart
Mode and determination of the initial contraction stage in the mouse embryo heart
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DOI：
10.1007/s00429-005-0065-x
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发表时间：
2006-03-01
期刊：
影响因子：
--
通讯作者：
Shibata, Y
中科院分区：
文献类型：
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作者：
Nishii, K;Shibata, Y
发育中的哺乳动物心脏在心肌从内脏中胚层分化后不久就开始自发收缩。然而，在小鼠中还没有统计学描述心跳开始的精确时间和模式。我们分析了从体节前期到第10.5天（E10.5）的视频记录心脏区域的收缩活动模式。第一个迹象是在3体节期（E8.25）检测到的，当一些心肌细胞在心管两侧构成小的收缩群时。在休眠的3体节期心脏中检测到基础[Ca-1（2+）]水平的波动，表明在可见收缩之前开始了电活动。在3-体节期出现弱而不规则的收缩后，早在4-体节期收缩几乎协调一致。在E9.25的20体节期左右，通过房室管的单向血流建立，与内膜垫的发育相关。我们认为，不仅是内膜垫，而且协调的收缩是必不可少的单向流动，因为诱导心动过缓，由于短期暴露在室温下引起反流在E10.5时，否则高度有组织的流动观察。这些发现补充和扩展了早期对功能性心脏发育的观察，为哺乳动物心脏发生的基础研究提供了参考。
The developing mammalian heart initiates spontaneous contractions shortly after the myocardium differentiates from the splanchnic mesoderm. The precise timing and mode of the onset of heartbeat, however, have not been statistically described in mice. We analyzed the patterns of contractive activity in video-recorded heart regions ranging from the pre-somite stage to day 10.5 (E10.5). The first sign was detected at the 3-somite stage (E8.25), when a few cardiac myocytes constituted small contracting groups on both sides of the heart tube. Fluctuations of the basal [Ca-i(2+)] level were detected in dormant 3-somite-stage hearts, indicating the initiation of electrical activity before visible contractions. After weak and irregular contractions at the 3-somite stage, the contractions were almost coordinated as early as the 4-somite stage. Unidirectional blood flow through the atrioventricular canal was established around the 20-somite stage at E9.25, correlated with the development of the endocardial cushion. We propose that not only the endocardial cushion but also coordinated contractions are essential for unidirectional flow, because induced bradycardia due to short exposure at room temperature caused regurgitation at E10.5 when otherwise highly organized flow was observed. These findings complement and extend earlier observations on functional heart development, providing a reference for fundamental research on mammalian cardiogenesis.