Zhigulin Arseniy S, Tikhonov Denis B, Barygin Oleg I
I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia.
I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia.
Eur J Pharmacol. 2023 Jan 5;938:175394. doi: 10.1016/j.ejphar.2022.175394. Epub 2022 Nov 17.
Acid-sensing ion channels (ASICs) are blocked by many cationic compounds. Mechanisms of action, which may include pore block, modulation of activation and desensitization, need systematic analysis to allow predictable design of new potent and selective drugs. In this work, we studied the action of the serine protease inhibitors nafamostat, sepimostat, gabexate and camostat, on native ASICs in rat giant striatal interneurons and recombinant ASIC1a and ASIC2a channels, and compared it to that of well-known small molecule ASIC blocker diminazene. All these compounds have positively charged amidine and/or guanidine groups in their structure. Nafamostat, sepimostat and diminazene inhibited pH 6.5-induced currents in rat striatal interneurons at -80 mV holding voltage with IC values of 0.78 ± 0.12 μM, 2.4 ± 0.3 μM and 0.40 ± 0.09 μM, respectively, whereas camostat and gabexate were practically ineffective. The inhibition by nafamostat, sepimostat and diminazene was voltage-dependent evidencing binding in the channel pore. They were not trapped in the closed channels, suggesting "foot-in-the-door" mechanism of action. The inhibitory activity of nafamostat, sepimostat and diminazene was similar in experiments on native ASICs and recombinant ASIC1a channels, while all of them were drastically less active against ASIC2a channels. According to our molecular modeling, three active compounds bind in the channel pore between Glu 433 and Ala 444 in a similar way. In view of the relative safety of nafamostat for clinical use in humans, it can be considered as a potential candidate for the treatment of pathophysiological conditions linked to ASICs disfunction, including inflammatory pain and ischemic stroke.
酸敏感离子通道（ASICs）可被多种阳离子化合物阻断。其作用机制可能包括孔道阻断、对激活和脱敏的调节，需要进行系统分析，以便可预测地设计出新的强效和选择性药物。在这项研究中，我们研究了丝氨酸蛋白酶抑制剂那法莫司他、西莫司他、加贝酯和卡莫司他对大鼠大纹状体中间神经元中的天然ASICs以及重组ASIC1a和ASIC2a通道的作用，并将其与著名的小分子ASIC阻断剂二脒那嗪的作用进行比较。所有这些化合物在其结构中都带有带正电荷的脒基和/或胍基。那法莫司他、西莫司他和二脒那嗪在-80 mV的钳制电压下抑制大鼠纹状体中间神经元中pH 6.5诱导的电流，IC值分别为0.78±0.12 μM、2.4±0.3 μM和0.40±0.09 μM，而卡莫司他和加贝酯实际上无效。那法莫司他、西莫司他和二脒那嗪的抑制作用具有电压依赖性，表明其在通道孔中结合。它们不会被困在关闭的通道中，提示其“脚在门内”的作用机制。那法莫司他、西莫司他和二脒那嗪在天然ASICs和重组ASIC1a通道实验中的抑制活性相似，而它们对ASIC2a通道的活性都显著降低。根据我们的分子模拟，三种活性化合物以相似的方式结合在通道孔中Glu 433和Ala 444之间。鉴于那法莫司他在人类临床使用中的相对安全性，它可被视为治疗与ASIC功能障碍相关的病理生理状况（包括炎性疼痛和缺血性中风）的潜在候选药物。
