Dose-dependent activation of Ca2+-activated K+ channels by ethanol contributes to improved endothelial cell functions
Dose-dependent activation of Ca2+-activated K+ channels by ethanol contributes to improved endothelial cell functions
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DOI：
10.1097/01.alc.0000130811.92457.0d
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发表时间：
2004-07-01
影响因子：
3.2
通讯作者：
Wiecha, J
中科院分区：
文献类型：
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作者：
Kuhlmann, CRW;Li, F;Wiecha, J
背景：定期适量摄入酒精 (EtOH) 似乎可以预防冠状动脉疾病和缺血性中风，但大量摄入乙醇则风险增加。 EtOH 对内皮细胞功能的影响可能与这些不同的影响有关。钾通道在内皮细胞功能的调节中发挥重要作用。因此，我们研究了 Ca2+ 激活的 K+ 通道 (BKCa) 是否受 EtOH 调节。此外，我们还检测了EtOH诱导的内皮一氧化氮（NO）形成和细胞增殖的变化是否是由于BKCa激活所致。方法：采用膜片钳技术研究培养的人脐静脉内皮细胞（HUVEC）中的BKCa活性。使用荧光染料 4,5-二氨基荧光素分析 NO 的形成。通过使用细胞计数和测量 [H-3] 胸苷掺入来检查内皮增殖。结果：EtOH 剂量依赖性 (10-150 mmol/L) 调节 BKCa 活性，在浓度为 50 mmol/L 时开放状态概率增加最高 (n = 13;p < 0.05)。由内而外的记录显示，这种效应是由于直接 BKCa 激活所致，而百日咳毒素预孵育后细胞附着记录中的开放状态概率没有改变。 EtOH（10 和 50 mmol/L）引起 NO 水平显着升高，这种升高可被高选择性 BKCa 抑制剂伊贝里奥毒素（100 nmol/l；n = 30；p < 0.05）阻断。较高浓度的 EtOH（100 和 150 mmol/L）显着减少 NO 合成（n = 30；p < 0.05）。两种方法均显示 HUVEC 增殖显着增加，而这种增殖受到伊比利亚毒素的抑制（n = 30；p < 0.05）。在150 mmol/L浓度下，EtOH引起内皮增殖显着减少。结论：EtOH直接激活HUVEC中的BKCa，导致内皮增殖和NO产生增加。这些结果表明低剂量的乙醇可能对内皮功能产生有益作用，而较高浓度则必须被认为是有害的。
Background: Regular moderate alcohol (EtOH) intake seems to protect against both coronary artery disease and ischemic stroke, whereas the risk increases with heavy EtOH consumption. Effects of EtOH on endothelial cell function may be relevant to these disparate effects. Potassium channels play an important role in the regulation of endothelial cell functions. Therefore, we investigated whether Ca2+-activated K+ channels (BKCa) are modulated by EtOH. Furthermore, we examined whether EtOH-induced changes of endothelial nitric oxide (NO) formation and cell proliferation are due to BKCa activation.Methods: The patch-clamp technique was used to investigate BKCa activity in cultured human umbilical vein endothelial cells (HUVEC). NO formation was analyzed by using the fluorescence dye 4,5-diaminofluorescein. Endothelial proliferation was examined by using cell counts and measuring [H-3]thymidine incorporation.Results: EtOH dose-dependently (10-150 mmol/liter) modulated BKCa-activity, with the highest increase of open-state probability at a concentration of 50 mmol/liter (n = 13;p < 0.05). Inside-out recordings revealed that this effect was due to direct BKCa activation, whereas open-state probability was not changed in cell-attached recordings after pertussis toxin preincubation. EtOH (10 and 50 mmol/liter) caused a significant increase of NO levels, which was blocked by the highly selective BKCa inhibitor iberiotoxin (100 nmol/l; n = 30; p < 0.05). Higher concentrations of EtOH (100 and 150 mmol/liter) significantly reduced NO synthesis (n = 30; p < 0.05). Both methods revealed a significant increase of HUVEC proliferation, which was inhibited by iberiotoxin (n = 30; p < 0.05). At a concentration of 150 mmol/liter, EtOH caused a significant reduction of endothelial proliferation.Conclusions: EtOH directly activates BKCa in HUVEC, leading to an increase of endothelial proliferation and production of NO. These results indicate a possible beneficial effect of low-dose EtOH on endothelial function, whereas higher concentrations must be considered as harmful.