Molecular Insights into the Local Anesthetic Receptor within Voltage-Gated Sodium Channels Using Hydroxylated Analogs of Mexiletine.
Molecular Insights into the Local Anesthetic Receptor within Voltage-Gated Sodium Channels Using Hydroxylated Analogs of Mexiletine.
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DOI：
10.3389/fphar.2012.00017
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发表时间：
2012
影响因子：
5.6
通讯作者：
Camerino DC
中科院分区：
文献类型：
--
作者：
Desaphy JF;Dipalma A;Costanza T;Carbonara R;Dinardo MM;Catalano A;Carocci A;Lentini G;Franchini C;Camerino DC
我们之前的研究表明，β-肾上腺素受体调节剂克伦特罗和普萘洛尔直接阻断电压门控的钠通道，而沙丁胺醇和纳多洛尔则没有（Desaphy等人），这表明在药物的芳香部分上存在两个羟基，是阻碍钠通道阻断的分子必要条件。为了验证这一假设，我们通过在钠通道阻滞剂的芳基部分添加一个或两个羟基合成了五种新的美西汀类似物，并在HEK293细胞中表达的hNav1.4通道上测试了这些化合物。在0.1 Hz（强音区）和10 Hz（使用依赖区）刺激频率下，施加保持电位为- 120 mV的- 30 mV的25 ms长去极化脉冲，构建浓度-响应关系。半最大抑制浓度（IC50）与药物亲脂性呈线性相关：药物亲脂性越低，阻滞程度越小。同样的化合物也在F1586C和Y1593C hNav1.4通道突变体上进行了测试，以进一步了解美西汀与钠通道孔内受体的分子相互作用。特别是用非芳香族半胱氨酸残基取代Phe1586和Tyr1593可能有助于理解π -π或π -阳离子相互作用在美西汀结合中的作用。补药阻滞的改变提示美西汀的芳基部分可能在封闭的钠通道中直接或间接与Phe1586相互作用产生低亲和力的结合阻滞，这种相互作用依赖于药物芳尾的静电电位。使用依赖性阻滞的改变表明，在芳基部分添加羟基可能通过两个药效团之间的协同作用改变药物胺端与Phe1586的高亲和力结合，这种作用主要与药物亲脂性有关。Tyr1593的突变进一步破坏了这种协同性。总之，这些结果证实了我们之前的假设，表明美西汀的芳基部分羟基的存在大大减少了钠通道阻塞，并为局部麻醉剂与其受体的密切相互作用提供了分子见解。
We previously showed that the β-adrenoceptor modulators, clenbuterol and propranolol, directly blocked voltage-gated sodium channels, whereas salbutamol and nadolol did not (Desaphy et al.,), suggesting the presence of two hydroxyl groups on the aromatic moiety of the drugs as a molecular requisite for impeding sodium channel block. To verify such an hypothesis, we synthesized five new mexiletine analogs by adding one or two hydroxyl groups to the aryloxy moiety of the sodium channel blocker and tested these compounds on hNav1.4 channels expressed in HEK293 cells. Concentration–response relationships were constructed using 25-ms-long depolarizing pulses at −30 mV applied from an holding potential of −120 mV at 0.1 Hz (tonic block) and 10 Hz (use-dependent block) stimulation frequencies. The half-maximum inhibitory concentrations (IC50) were linearly correlated to drug lipophilicity: the less lipophilic the drug, minor was the block. The same compounds were also tested on F1586C and Y1593C hNav1.4 channel mutants, to gain further information on the molecular interactions of mexiletine with its receptor within the sodium channel pore. In particular, replacement of Phe1586 and Tyr1593 by non-aromatic cysteine residues may help in the understanding of the role of π–π or π–cation interactions in mexiletine binding. Alteration of tonic block suggests that the aryloxy moiety of mexiletine may interact either directly or indirectly with Phe1586 in the closed sodium channel to produce low-affinity binding block, and that this interaction depends on the electrostatic potential of the drug aromatic tail. Alteration of use-dependent block suggests that addition of hydroxyl groups to the aryloxy moiety may modify high-affinity binding of the drug amine terminal to Phe1586 through cooperativity between the two pharmacophores, this effect being mainly related to drug lipophilicity. Mutation of Tyr1593 further impaired such cooperativity. In conclusion, these results confirm our former hypothesis by showing that the presence of hydroxyl groups to the aryloxy moiety of mexiletine greatly reduced sodium channel block, and provide molecular insights into the intimate interaction of local anesthetics with their receptor.
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影响因子：
--
作者：
Cavalluzzi, Maria Maddalena;Catalano, Alessia;Tortorella, Vincenzo
通讯作者：
Tortorella, Vincenzo
影响因子：
7.3
作者：
Franchini, C;Carocci, A;De Luca, A
通讯作者：
De Luca, A
影响因子：
2
作者：
Catalano, A;Carocci, A;Camerino, DC
通讯作者：
Camerino, DC
影响因子：
7.3
作者：
Desaphy, JF;Camerino, DC;De Luca, A
通讯作者：
De Luca, A
影响因子：
56.9
作者：
HIDALGO, P;MACKINNON, R
通讯作者：
MACKINNON, R