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首页> 外文期刊>Neurochemistry International: The International Journal for the Rapid Publication of Critical Reviews, Preliminary and Original Research Communications in Neurochemistry >Enhancement of inward Ca(2+) currents in bovine chromaffin cells by green tea polyphenol extracts.
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Enhancement of inward Ca(2+) currents in bovine chromaffin cells by green tea polyphenol extracts.

机译：绿茶多酚提取物增强牛嗜铬细胞内Ca（2+）电流。

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摘要

Green tea contains four major polyphenol compounds: they are (-)-epigallocatechin-3-gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG), and (-)-epicatechin (EC). Although all four polyphenol compounds are known to affect tumor suppression, little is known about whether they alter membrane properties. In this study, we examined the effects of ECG and EGCG on ionic currents and secretion. Membrane capacitance changes were used to monitor secretion in bovine chromaffin cells. ECG had the ability to reversibly enhance the inward Ca(2+) current by 21%, and inhibited the peak sodium current by 34%. EGCG had no effect on Ca(2+) current even though it differs from ECG by just a hydroxyl group. The EC(50) of ECG in enhancing Ca(2+) current was 7.6 microM. The maximum enhancement of Ca(2+) current was observed at 0 mV and the maximum current was shifted approximately 10 mV in the hyperpolarizing direction. When cells were stimulated by trains of depolarizations, the exocytosis elicited was enhanced by ECG treatment and the largest enhancement of secretion was observed in later stimulations. EGCG, although it had no significant effect on Ca(2+) current, enhanced exocytosis and slowed endocytosis. These results suggest that green tea polyphenol compounds modulate stimulus-secretion coupling in bovine chromaffin cells.
机译：绿茶包含四种主要的多酚化合物：它们是（-）-表没食子儿茶素-3-没食子酸酯（EGCG），（-）-表没食子儿茶素（EGC），（-）-表没食子儿茶素3-没食子酸酯（ECG）和（-）-表儿茶素（EC）。尽管已知所有四种多酚化合物均会影响肿瘤抑制，但对于它们是否会改变膜的性质知之甚少。在这项研究中，我们检查了ECG和EGCG对离子电流和分泌的影响。膜电容变化用于监测牛嗜铬细胞的分泌。心电图有能力可逆地增加21％的内向Ca（2+）电流，而将峰值钠电流抑制了34％。 EGCG对Ca（2+）电流没有影响，即使它与ECG的区别仅在于羟基。 ECG在增强Ca（2+）电流中的EC（50）为7.6 microM。在0 mV处观察到Ca（2+）电流的最大增强，并且最大电流在超极化方向上偏移了大约10 mV。当细胞受到去极化的刺激时，引起的胞吐作用通过ECG处理得到增强，并且在随后的刺激中观察到最大的分泌增强。 EGCG，尽管它对Ca（2+）电流没有明显影响，增强了胞吐作用并减慢了内吞作用。这些结果表明，绿茶多酚化合物调节牛嗜铬细胞中的刺激-分泌偶联。

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