Activation of Slo2.1 channels by niflumic acid.
Activation of Slo2.1 channels by niflumic acid.
复制标题
DOI：
10.1085/jgp.200910316
复制
发表时间：
2010-03
期刊：
影响因子：
--
通讯作者：
Sanguinetti MC
中科院分区：
文献类型：
--
作者：
Dai L;Garg V;Sanguinetti MC
Slo2.1通道在高[Na+]i激活时传导向外整流的K+电流。在这里，我们表明，门控这些通道也可以激活fenamates，如尼氟灭酸（NFA），即使在细胞内Na+的情况下。在注射<10 ng cRNA的爪蟾卵母细胞中，异源表达的人Slo2.1电流可以忽略不计，但通过细胞外应用NFA（EC 50 = 2.1 mM）或氟灭酸（EC 50 = 1.4 mM）迅速激活。1 mM NFA激活的Slo2.1通道表现出弱的电压依赖性。在高[K+]e时，电导-电压（G-V）关系的V1/2为+95 mV，有效价态z为0.48 e。较高浓度的NFA使V1/2向更负的电位偏移（EC 50 = 2.1 mM），并增加G/Gmax的最小值（EC 50 = 2.4 mM）;在6 mM NFA下，Slo2.1通道激活是电压无关的。相反，当[K+]e从1升高到300 mM（EC 50 = 21.2 mM）时，G-V关系的V1/2向更正的电位移动。在反转电位下测量的斜率电导表现出相同的[K+]e依赖性（EC 50 = 23.5 mM）。电导也是[Na+]e依赖性的。当Na+被胆碱或甘露醇取代时，钾电流减少，但不受Rb+或Li+取代的影响。S1-S4结构域中带电残基的中和并没有明显改变Slo2.1激活的电压依赖性。因此，Slo2.1通道激活的弱电压依赖性与S1-S4段中的带电残基无关。相反，位于相邻S4-S5接头的R190突变为中性（Ala或Gln）或酸性（Glu）残基诱导组成型通道活性，其被高[K+]e降低。总的来说，这些发现表明Slo2.1通道门控由[K+]e和[Na+]e调节，并且NFA将通道激活与跨膜电压和细胞内Na+的调节解偶联。
Slo2.1 channels conduct an outwardly rectifying K+ current when activated by high [Na+]i. Here, we show that gating of these channels can also be activated by fenamates such as niflumic acid (NFA), even in the absence of intracellular Na+. In Xenopus oocytes injected with <10 ng cRNA, heterologously expressed human Slo2.1 current was negligible, but rapidly activated by extracellular application of NFA (EC50 = 2.1 mM) or flufenamic acid (EC50 = 1.4 mM). Slo2.1 channels activated by 1 mM NFA exhibited weak voltage dependence. In high [K+]e, the conductance–voltage (G-V) relationship had a V1/2 of +95 mV and an effective valence, z, of 0.48 e. Higher concentrations of NFA shifted V1/2 to more negative potentials (EC50 = 2.1 mM) and increased the minimum value of G/Gmax (EC50 = 2.4 mM); at 6 mM NFA, Slo2.1 channel activation was voltage independent. In contrast, V1/2 of the G-V relationship was shifted to more positive potentials when [K+]e was elevated from 1 to 300 mM (EC50 = 21.2 mM). The slope conductance measured at the reversal potential exhibited the same [K+]e dependency (EC50 = 23.5 mM). Conductance was also [Na+]e dependent. Outward currents were reduced when Na+ was replaced with choline or mannitol, but unaffected by substitution with Rb+ or Li+. Neutralization of charged residues in the S1–S4 domains did not appreciably alter the voltage dependence of Slo2.1 activation. Thus, the weak voltage dependence of Slo2.1 channel activation is independent of charged residues in the S1–S4 segments. In contrast, mutation of R190 located in the adjacent S4–S5 linker to a neutral (Ala or Gln) or acidic (Glu) residue induced constitutive channel activity that was reduced by high [K+]e. Collectively, these findings indicate that Slo2.1 channel gating is modulated by [K+]e and [Na+]e, and that NFA uncouples channel activation from its modulation by transmembrane voltage and intracellular Na+.
登录
查看更多内容
影响因子：
16.2
作者：
Aggarwal, SK;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
56.9
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
通讯作者：
MacKinnon, R
DOI：
10.1085/jgp.27.1.37
发表时间：
1943-09-20
期刊：
The Journal of general physiology
影响因子：
--
作者：
Goldman DE
通讯作者：
Goldman DE
DOI：
10.1073/pnas.0709809105
发表时间：
2008-03-04
影响因子：
11.1
作者：
Contreras, Jorge E.;Srikumar, Deepa;Holmgren, Miguel
通讯作者：
Holmgren, Miguel
DOI：
10.1085/jgp.95.5.961
发表时间：
1990-05
期刊：
The Journal of general physiology
影响因子：
--
作者：
Haimann C;Bernheim L;Bertrand D;Bader CR
通讯作者：
Bader CR