N-arachidonoyl glycine suppresses Na+/Ca2+exchanger-mediated Ca2+entry into endothelial cells and activates BKCa channels independently of GPCRs
N-arachidonoyl glycine suppresses Na+/Ca2+exchanger-mediated Ca2+entry into endothelial cells and activates BKCa channels independently of GPCRs
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DOI：
10.1111/bph.12180
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发表时间：
2013-06-01
影响因子：
7.3
通讯作者：
Graier, Wolfgang F.
中科院分区：
文献类型：
--
作者：
Bondarenko, Alexander I.;Drachuk, Konstantin;Graier, Wolfgang F.
背景与目的N-花生四烯酸甘氨酸（NAGly）是一种具有血管舒张作用的脂族氨基酸。我们的目的是探讨NAGly对未受刺激和激动剂刺激的内皮细胞的作用机制。结合血管反应性研究NAGly对内皮电信号传导的影响。关键结果在EA.hy926细胞中，持续超极化组胺被抑制的非选择性Na+/Ca 2+交换（NCX）抑制剂苄普地尔和反向模式NCX的抑制剂，KB-R7943。在细胞透析Cs+为基础的Na+的溶液中，具有典型特征的NCX的外向整流电流增加组胺暴露后，进一步增加外部Na+撤退和抑制苄普地尔。NAGly（0.330M）以URB 597和鸟苷5-O-（2-硫代二磷酸）（GDPS）不敏感的方式抑制NCX电流、Na+清除引起的[Ca ~（2+）]i升高和组胺引起的超极化。在大鼠主动脉，NAGly对抗ACh引起的内皮超极化和舒张反应。在未受刺激的EA.hy926细胞中，NAGly以GDPS不敏感、paxilline敏感的方式增强归因于大电导Ca 2+激活的K+（BKCa）通道的全细胞电流，并产生持续的超极化。在无细胞的由内而外的贴片中，NAGly刺激单个BKCa通道活性。结论和影响我们的数据表明，NCX是一个Ca 2+进入途径在内皮细胞和NAGly是一个有效的G-蛋白不依赖的调节器的内皮细胞的电信号，并具有双重作用的内皮细胞的电反应。在激动剂预刺激的细胞中，NAGly通过抑制NCX介导的Ca 2+进入来对抗超极化和舒张，而在未刺激的细胞中，它通过受体非依赖性激活BKCa通道来促进超极化。
Background and Purpose N-arachidonoyl glycine (NAGly) is a lipoamino acid with vasorelaxant properties. We aimed to explore the mechanisms of NAGly's action on unstimulated and agonist-stimulated endothelial cells. Experimental Approach The effects of NAGly on endothelial electrical signalling were studied in combination with vascular reactivity. Key Results In EA.hy926 cells, the sustained hyperpolarization to histamine was inhibited by the non-selective Na+/Ca2+ exchanger (NCX) inhibitor bepridil and by an inhibitor of reversed mode NCX, KB-R7943. In cells dialysed with Cs+-based Na+-containing solution, the outwardly rectifying current with typical characteristics of NCX was augmented following histamine exposure, further increased upon external Na+ withdrawal and inhibited by bepridil. NAGly (0.330M) suppressed NCX currents in a URB597- and guanosine 5-O-(2-thiodiphosphate) (GDPS)-insensitive manner, [Ca2+]i elevation evoked by Na+ removal and the hyperpolarization to histamine. In rat aorta, NAGly opposed the endothelial hyperpolarization and relaxation response to ACh. In unstimulated EA.hy926 cells, NAGly potentiated the whole-cell current attributable to large-conductance Ca2+-activated K+ (BKCa) channels in a GDPS-insensitive, paxilline-sensitive manner and produced a sustained hyperpolarization. In cell-free inside-out patches, NAGly stimulated single BKCa channel activity. Conclusion and Implications Our data showed that NCX is a Ca2+ entry pathway in endothelial cells and that NAGly is a potent G-protein-independent modulator of endothelial electrical signalling and has a dual effect on endothelial electrical responses. In agonist pre-stimulated cells, NAGly opposes hyperpolarization and relaxation via inhibition of NCX-mediated Ca2+ entry, while in unstimulated cells, it promotes hyperpolarization via receptor-independent activation of BKCa channels.