I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg 194223, Russia.
Institute of Experimental Medicine, RAMS, St. Petersburg 197376, Russia.
Int J Mol Sci. 2019 Apr 6;20(7):1713. doi: 10.3390/ijms20071713.
Acid-sensing ion channel 3 (ASIC3) is an important member of the acid-sensing ion channels family, which is widely expressed in the peripheral nervous system and contributes to pain sensation. ASICs are targeted by various drugs and toxins. However, mechanisms and structural determinants of ligands' action on ASIC3 are not completely understood. In the present work we studied ASIC3 modulation by a series of "hydrophobic monoamines" and their guanidine analogs, which were previously characterized to affect other ASIC channels via multiple mechanisms. Electrophysiological analysis of action via whole-cell patch clamp method was performed using rat ASIC3 expressed in Chinese hamster ovary (CHO) cells. We found that the compounds studied inhibited ASIC3 activation by inducing acidic shift of proton sensitivity and slowed channel desensitization, which was accompanied by a decrease of the equilibrium desensitization level. The total effect of the drugs on the sustained ASIC3-mediated currents was the sum of these opposite effects. It is demonstrated that drugs' action on activation and desensitization differed in their structural requirements, kinetics of action, and concentration and state dependencies. Taken together, these findings suggest that effects on activation and desensitization are independent and are likely mediated by drugs binding to distinct sites in ASIC3.
酸敏离子通道 3（ASIC3）是酸敏离子通道家族的重要成员，广泛表达于外周神经系统，参与痛觉感受。ASIC 是多种药物和毒素的作用靶点。然而，配体作用于 ASIC3 的机制和结构决定因素尚未完全阐明。在本工作中，我们研究了一系列“疏水性单胺”及其胍基类似物对 ASIC3 的调制作用，这些化合物先前被证实通过多种机制影响其他 ASIC 通道。通过全细胞膜片钳方法在表达于中国仓鼠卵巢（CHO）细胞的大鼠 ASIC3 上进行了通过电生理分析。我们发现，所研究的化合物通过诱导质子敏感性的酸性偏移和减缓通道脱敏来抑制 ASIC3 的激活，同时伴有平衡脱敏水平的降低。药物对持续 ASIC3 介导电流的总作用是这些相反作用的总和。研究表明，药物对激活和脱敏的作用在结构要求、作用动力学以及浓度和状态依赖性方面存在差异。综上所述，这些发现表明，激活和脱敏作用是独立的，可能是由药物结合到 ASIC3 中的不同位点介导的。
