Gap junctions in the rabbit sinoatrial node
Gap junctions in the rabbit sinoatrial node
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DOI：
10.1152/ajpheart.2001.280.5.h2103
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发表时间：
2001-05-01
影响因子：
4.8
通讯作者：
Jongsma, HJ
中科院分区：
文献类型：
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作者：
Verheule, S;van Kempen, MJA;Jongsma, HJ
与起搏的细胞基础相比，窦房结中介导同步化和传导的电相互作用知之甚少。因此，我们采取了免疫组织化学和电生理学相结合的方法来表征结节区域的缝隙连接。我们报道了兔窦房结中央的起搏器肌细胞表达缝隙连接蛋白(Cx)40和Cx46。在结节周围，表达Cx43的起搏器肌细胞链与表达Cx40和Cx46的链混合在一起。采用穿孔贴片方法，在双电压钳下记录单个起搏器心肌细胞缝隙连接的生物物理特性。宏观结电导在0.6~25 ns之间，平均值为7.5 ns。结点电导对跨结点电势差没有明显的敏感性。起搏器心肌细胞对的单通道记录显示在133、202和241ps处有大量的单通道电导。有了这些单通道电导，观测到的平均宏观结电导为7.5 ns，只需要30-60个开隙结通道。
In comparison to the cellular basis of pacemaking, the electrical interactions mediating synchronization and conduction in the sinoatrial node are poorly understood. Therefore, we have taken a combined immunohistochemical and electrophysiological approach to characterize gap junctions in the nodal area. We report that the pacemaker myocytes in the center of the rabbit sinoatrial node express the gap junction proteins connexin (Cx) 40 and Cx46. In the periphery of the node, strands of pacemaker myocytes expressing Cx43 intermingle with strands expressing Cx40 and Cx46. Biophysical properties of gap junctions in isolated pairs of pacemaker myocytes were recorded under dual voltage clamp with the use of the perforated-patch method. Macroscopic junctional conductance ranged between 0.6 and 25 nS with a mean value of 7.5 nS. The junctional conductance did not show a pronounced sensitivity to the transjunctional potential difference. Single-channel recordings from pairs of pacemaker myocytes revealed populations of single-channel conductances at 133, 202, and 241 pS. With these single-channel conductances, the observed average macroscopic junctional conductance, 7.5 nS, would require only 30-60 open gap junction channels.