Quinine blocks specific gap junction channel subtypes
Quinine blocks specific gap junction channel subtypes
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DOI：
10.1073/pnas.191206198
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发表时间：
2001-09-11
影响因子：
11.1
通讯作者：
Spray, DC
中科院分区：
文献类型：
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作者：
Srinivas, M;Hopperstad, MG;Spray, DC
我们证明抗疟药奎宁特异性地降低转染的哺乳动物细胞中某些连接蛋白（Cx）形成的缝隙连接电流，但不影响其他类型的缝隙连接。奎宁以可逆的和浓度依赖性的方式阻断Cx 36和Cx 50连接电流，其半最大阻断浓度分别为32和73 μ M;两种连接蛋白被奎宁阻断的希尔系数约为2。与此相反，奎宁并没有实质上阻止缝隙连接通道形成的Cx 26，Cx 32，Cx40，和Cx43，只有中度影响Cx45连接。为了确定奎宁（pKa = 8.7）的结合位点的位置，我们研究了奎宁在各种外部和内部pH值的影响和奎宁的永久带电的季衍生物的影响。我们的研究结果表明，奎宁的结合位点是细胞内，可能在孔内。单通道研究表明，暴露于奎宁诱导开放和完全关闭状态之间的缓慢转换，降低了通道的开放概率。因此，奎宁提供了一种潜在有用的方法来阻断某些类型的间隙连接通道，包括由Cx 36形成的神经元之间的通道。此外，从其他类型的膜通道中排除的奎宁衍生物可以提供具有连接蛋白特异性以及连接蛋白选择性阻断活性的分子。
We demonstrate that the antimalarial drug quinine specifically reduces currents through gap junctions formed by some connexins (Cx) in transfected mammalian cells, but does not affect other gap junction types, Quinine blocked Cx36 and Cx50 junctional currents in a reversible and concentration-dependent manner with half maximal blocking concentrations of 32 and 73 muM, respectively; Hill coefficients for block by quinine were about 2 for both connexins. In contrast, quinine did not substantially block gap junction channels formed by Cx26, Cx32, Cx40, and Cx43, and only moderately affected Cx45 junctions. To determine the location of the binding site of quinine (pKa = 8.7), we investigated the effect of quinine at various external and internal pH values and the effect of a permanently charged quaternary derivative of quinine. Our results indicate that the binding site for quinine is intracellular, possibly within the pore. Single-channel studies indicated that exposure to quinine induced slow transitions between open and fully closed states that decreased open probability of the channel. Quinine thus offers a potentially useful method to block certain types of gap junction channels, including those between neurons that are formed by Cx36. Moreover, quinine derivatives that are excluded from other types of membrane channels may provide molecules with connexin-specific as well as connexin-selective blocking activity.