Gap Junction-associated Na+ Influx Is Involved in the Mediation of Ca2+ Transients in Neonatal Rat Ventricular Myocytes
Gap Junction-associated Na+ Influx Is Involved in the Mediation of Ca2+ Transients in Neonatal Rat Ventricular Myocytes
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间隙连接相关的 Na 内流参与新生大鼠心室肌细胞 Ca2 瞬变的介导
DOI：
10.1097/fjc.0000000000000241
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发表时间：
2015-07-01
影响因子：
3
通讯作者：
Luo, Dali
中科院分区：
文献类型：
--
作者：
Yan, Xinxin;Zeng, Zheng;Luo, Dali
摘要：缝隙连接（GJ）偶联参与了新生大鼠心室肌细胞（NRVM）自发性钙瞬变的调控，但其机制尚不完全清楚。在这项研究中，我们研究了Na+内流介导的Cx43相关的GJ调制自发NRVM兴奋。通过共聚焦显微镜分别使用CoroNa绿色和Fluo-4荧光探针评估细胞内Na+和Ca 2+浓度（[Na+]i和[Ca 2 +]i）。通过测量光漂白后的荧光恢复来评价GJ功能。结果表明，GJ解偶联剂或腺病毒介导的Cx43基因敲低均能显著降低NRVM细胞内[Na+]i和自发性Ca 2+振荡，而腺病毒介导的Cx43过表达则能提高细胞内[Na+]i和自发性Ca 2+振荡。Na+通道阻滞剂（河豚毒素）、GJ解偶联剂（Gap 27）或Cx43短发夹RNA腺病毒都不能完全抑制Ca 2+瞬变，但它们的联合使用可以。此外，在无Na+培养的NRVMs中，Ca 2+瞬变消失，但在无Ca 2+培养液中则不然，其中剩余的瞬变可被Gap 27进一步消除。总的来说，我们的研究结果表明，Cx43相关的GJ功能参与调节Na+流入心肌细胞，这有助于，至少部分，触发自发兴奋和调节心肌细胞自律性。
Abstract: Gap junction (GJ) coupling is involved in the regulation of spontaneous Ca2+ transients in neonatal rat ventricular myocytes (NRVMs); however, the underlying mechanism(s) remains incompletely clear. In this study, we investigated Na+ influx mediated by Cx43-associated GJ modulating the spontaneous NRVM excitation. Intracellular Na+ and Ca2+ concentrations ([Na+]i and [Ca2+]i) were assessed using CoroNa Green and Fluo-4 fluorescent probes, respectively, by confocal microscopy. GJ function was evaluated by measuring fluorescence recovery after photobleaching. The results showed that [Na+]i and spontaneous Ca2+ oscillating were significantly decreased by the treatment of NRVMs with GJ uncouplers or adenovirus-mediated Cx43 gene knockdown using short hairpin RNA, while both of the intracellular cation levels were increased by adenovirus-mediated Cx43 overexpression. Neither Na+ channel blocker (tetrodotoxin) nor the GJ uncoupler (Gap27) or Cx43-short hairpin RNA adenovirus could completely suppress the Ca2+ transients, but their combination usage could. In addition, Ca2+ transients disappeared in NRVMs incubated in Na+-free, but not in Ca2+-free medium, in which the remained transients could be further abolished by Gap27. Collectively, our findings suggest that Cx43-associated GJ function is involved in the regulation of Na+ influx into cardiomyocytes, which contributes, at least in part, to triggering spontaneous excitation and regulation of cardiomyocyte automaticity.