17β-estradiol potentiates the cardiac cystic fibrosis transmembrane conductance regulator chloride current in guinea-pig ventricular myocytes
17β-estradiol potentiates the cardiac cystic fibrosis transmembrane conductance regulator chloride current in guinea-pig ventricular myocytes
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DOI：
10.2170/physiolsci.r2131
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发表时间：
2006-02-01
影响因子：
2.3
通讯作者：
Figtree, G. A.
中科院分区：
文献类型：
--
作者：
Goodstadt, L.;Powell, T.;Figtree, G. A.
在心脏中存在充分表征的膜氯离子电流（I-CI，I-cAMP），其可以被β-肾上腺素能激动剂激活，并且是由于上皮囊性纤维化跨膜传导调节因子（CFTR）的心脏同种型的表达。我们研究了17 β-雌二醇（E2）是否调节单个心室肌细胞中的I-CI/cAMP。在全细胞紧密密封电压钳条件下，通过将细胞暴露于20 nM异丙肾上腺素来诱发I-CI、I-cAMP。在加入30 μ mE 2时，在接近0 mV的电位下测量的膜斜率电导比单独异丙肾上腺素诱导的膜斜率电导增加2.46 ± 0.16（p < 0.001）。E2的作用是浓度依赖性的，并通过Hill图描述，EC 50为8.2 μ m，Hill系数为1.63。与牛血清白蛋白（E2-BSA）结合的膜不透性E2的应用增强了异丙肾上腺素诱发的I-CI/cAMP，其程度与游离E2的同等水平大致相同。通过使用BSA-FITC标记的E2用共聚焦显微镜观察细胞表面结合。这种结合被非标记、非偶联E2、特异性E2拮抗剂ICI 182，780以及E2 coBSA与特异性抗E2抗体（E2885）孵育抑制。ICI 182，780（100 μ m）显着降低了10 μ m E2诱发的I-CI、I-cAMP的增加至1.46 +/- 0.10（p < 0.02）。用NOS抑制剂N-ω-硝基精氨酸（L-NNA，1 mm）预孵育心肌细胞，30 μ M E2使I-CI、I-cAMP的增强作用降低到1.93 +/- 0.06（p < 0.02），10 μ M E2使I-CI、I-cAMP的增强作用降低到1.32 +/- 0.05（p < 0.002）。E_2还增加0.5 μ M毛喉素浴用引起的I-CI、I-cAMP。这些实验表明，在我们的实验条件下，E2显着增加I-CI，I-cAMP在心室肌细胞的机制涉及的贡献由NOS，但只能部分占通过结合到经典的质膜雌激素受体网站。E2对I-CI、I-cAMP的这种增强作用可能在E2对心律失常和心肌肥厚发生率的临床作用中起重要作用。
There is a well-characterized membrane chloride current (I-CI,I-cAMP) in the heart that can be activated by beta-adrenergic agonists and is due to expression of the cardiac isoform of the epithelial cystic fibrosis transmembrane conductance regulator (CFTR). We have investigated whether 17 beta-estradiol (E2) modulates I-CI/cAMP in single ventricular myocytes. Under whole-cell tight-seal voltage-clamp conditions, I-CI,I-cAMP was evoked by exposing cells to 20 nM isoprenaline. On the addition of 30 mu m E2, membrane slope conductance, measured at potentials near 0 mV, increased over that induced by isoprenaline alone by 2.46 +/- 0.16 (p < 0.001). The effects of E2 were concentration-dependent and described by a Hill Plot with an EC50 of 8.2 mu m and a Hill coefficient of 1.63. The application of membrane-impermeant E2 conjugated to bovine serum albumin (E2-BSA) potentiated isoprenaline-evoked I-CI/cAMP by approximately the same degree as that for the equivalent level of free E2. Cell surface binding was observed with confocal microscopy by using BSA-FITC tagged E2. This binding was inhibited by nonlabeled, nonconjugate E2, the specific E2 antagonist ICI 182,780, and incubation of E2coBSA with a specific anti-E2 antibody (E2885). ICI 182,780 (100 mu m) significantly reduced the increase in I-CI,I-cAMP evoked by 10 mu m E2 to 1.46 +/- 0.10 (p < 0.02). The preincubation of myocytes with the NOS inhibitor N-omega-nitro-arginine (L-NNA, 1 mm) reduced the potentiation of I-CI,I-cAMP by 30 mu m E2, to 1.93 +/- 0.06 (p < 0.02), and for 10 mu M E2, to 1.32 +/- 0.05 (p < 0.002). E2 also increased I-CI,I-cAMP evoked by bath application of 0.5 mu M Forskolin. These experiments demonstrate that, under our experimental conditions, E2 dramatically increases I-CI,I-cAMP in ventricular myocytes by mechanisms involving a contribution by NOS, but that can be only partially accounted for through binding to classical plasma membrane estrogen receptor sites. This potentiation of I-CI,I-cAMP by E2 may play a significant role in the observed clinical actions of E2 on the incidence of cardiac arrhythmias and hypertrophy.