Aminoglycoside block of P2X2 receptors heterologously expressed in Xenopus laevis oocytes
Aminoglycoside block of P2X2 receptors heterologously expressed in Xenopus laevis oocytes
复制标题
DOI：
10.1007/s11302-010-9204-9
复制
发表时间：
2010-12-01
影响因子：
3.5
通讯作者：
Hausmann, Ralf
中科院分区：
文献类型：
--
作者：
Bongartz, Eva-Verena;Rettinger, Juergen;Hausmann, Ralf
氨基糖苷类是聚阳离子抗生素，已被证明可以阻断多种阳离子通道。采用双电极电压钳技术研究了外源性氨基糖苷类药物对非洲爪蟾卵母细胞P2 X2受体电流的抑制作用。所有测试的氨基糖苷类抑制ATP诱发的反应，效力范围从71 μ M至2 mM（IC 50值）。效价大小依次为链霉素>庆大霉素>新霉素>巴龙霉素>卡那霉素。P2 X受体电流的抑制是独立的ATP浓度用于激活，这是兼容的非竞争性机制。抑制是电压依赖性的，并减少在更积极的膜电位。为了检查电流阻断是否依赖于受体构象，分析了氨基糖苷类对非脱敏性P2 X2-X1受体嵌合体的作用。这些测量的结果表明，抑制是由一个开放的孔块，锁定P2 X受体嵌合体在一个开放的非导电状态，从激动剂解离缓慢。我们还证明，P2 X2-X1嵌合体可以作为一种工具，直接测试是否拮抗剂的竞争性或不。
Aminoglycosides are polycationic antibiotics that have been shown to block a variety of cation channels. The inhibitory effect of externally applied aminoglycosides on P2X2 receptor currents was examined after heterologous expression in Xenopus laevis oocytes using the two-electrode voltage-clamp technique. All of the aminoglycosides tested inhibited the ATP-evoked responses with potencies ranging from 71 mu M to 2 mM (IC50 values). The ranked order of potency was streptomycin>gentamicin>neomycin>paromomycin> kanamycin. The inhibition of P2X receptor currents was independent of the ATP concentration used for the activation, which is compatible with a noncompetitive mechanism. The inhibition was voltage-dependent and was reduced at more positive membrane potentials. To examine whether the current block was dependent on the receptor conformation, the aminoglycoside effect on a non-desensitizing P2X2-X1 receptor chimera was analyzed. The results from these measurements suggest that inhibition is caused by an open pore block that locks the P2X receptor chimera in an open nonconducting state from which the agonist dissociation is slow. We also demonstrate that the P2X2-X1 chimera can serve as a tool to directly test whether an antagonist acts competitively or not.