Inhibition of cardiac L-type calcium channels by epoxyeicosatrienoic acids
Inhibition of cardiac L-type calcium channels by epoxyeicosatrienoic acids
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DOI：
10.1124/mol.55.2.288
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发表时间：
1999-02-01
影响因子：
3.6
通讯作者：
Rosenberg, RL
中科院分区：
文献类型：
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作者：
Chen, JY;Capdevila, JH;Rosenberg, RL
环氧二十碳三烯酸（Epoxyeicosatrienoicacids，EEA）是细胞色素P-450单加氧酶代谢花生四烯酸的产物，具有调节离子通道活性的作用。我们研究了Escherichia coli对心脏L型Ca 2+通道的影响，这些通道在调节心脏收缩力、控制心率和介导正常结细胞和缺血心肌的慢传导中起重要作用。我们的实验方法是将猪L型钙通道重组成平面脂质双层，在那里我们可以控制通道的水和脂质环境以及改变通道特性的调节途径。我们发现，20至125 nM的雌二醇抑制重建的L-型Ca 2+通道的开放概率，加速通道的失活，并降低开放通道的单位电流幅度。当11，12-EET被酯化到磷脂酰胆碱的sn-2位，限制在平面脂双层的疏水相时，重构的通道同样被抑制，表明EET通过脂相直接与Ca 2+通道相互作用。EET的抑制作用持续存在的微囊藻毒素，蛋白磷酸酶1和2A的抑制剂，这表明，去磷酸化的机制，通过这些类花生酸下调通道活性，这种抑制可能是一个重要的保护机制，在设置的心脏缺血，花生四烯酸水平显着增加和EET已被证明表现出预处理样的效果。
Epoxyeicosatrienoic acids (EETs), products of the cytochrome P-450 monooxygenase metabolism of arachidonic acid, can regulate the activity of ion channels. We examined the effects of EETs on cardiac L-type Ca2+ channels that play important roles in regulating cardiac contractility, controlling heart rate, and mediating slow conduction in normal nodal cells and ischemic myocardium. Our experimental approach was to reconstitute porcine L-type Ca2+ channels into planar lipid bilayers where we could control the aqueous and lipid environments of the channels and the regulatory pathways that change channel properties. We found that 20 to 125 nM EETs inhibited the open probability of reconstituted L-type Ca2+ channels, accelerated the inactivation of the channels, and reduced the unitary current amplitude of open channels. There was no selectivity among different EET regioisomers or stereoisomers, When 11,12-EET was esterified to the sn-2 position of phosphatidylcholine, restricting it to the hydrophobic phase of the planar lipid bilayer, the reconstituted channels were similarly inhibited, suggesting that the EET interacts directly with Ca2+ channels through the lipid phase. The inhibitory effects of EET persisted in the presence of microcystin, an inhibitor of protein phosphatases 1 and 2A, suggesting that dephosphorylation was not the mechanism through which these eicosanoids down-regulate channel activity, This inhibition may be an important protective mechanism in the setting of cardiac ischemia where arachidonic acid levels are dramatically increased and EETs have been shown to manifest preconditioning-like effects.