Department of Neurosurgery, College of Medicine and Institute of Health Sciences, Gyeongsang National University, Jinju 52727, South Korea.
Department of Physiology and Institute of Health Sciences, College of Medicine, Gyeongsang National University, Jinju 52727, South Korea.
Int J Mol Sci. 2018 Jul 4;19(7):1961. doi: 10.3390/ijms19071961.
Tandem pore domain weak inward rectifier potassium channel (TWIK)-related spinal cord K⁺ (TRESK; K18.1) channel is the only member of the two-pore domain K⁺ (K) channel family that is activated by an increase in intracellular Ca concentration ([Ca]) and linked to migraines. This study was performed to identify the effect of verapamil, which is an L-type Ca channel blocker and a prophylaxis for migraines, on the TRESK channel in trigeminal ganglion (TG) neurons, as well as in a heterologous system. Single-channel and whole-cell currents were recorded in TG neurons and HEK-293 cells transfected with mTRESK using patch-clamping techniques. In TG neurons, changes in [Ca] were measured using the fluo-3-AM Ca indicator. Verapamil, nifedipine, and NiCl₂ inhibited the whole-cell currents in HEK-293 cells overexpressing mTRESK with IC values of 5.2, 54.3, and >100 μM, respectively. The inhibitory effect of verapamil on TRESK channel was also observed in excised patches. In TG neurons, verapamil (10 μM) inhibited TRESK channel activity by approximately 76%. The TRESK channel activity was not dependent on the presence of extracellular Ca. In addition, the inhibitory effect of verapamil on the TRESK channel remained despite the absence of extracellular Ca. These findings show that verapamil inhibits the TRESK current independently of the blockade of Ca influx in TG neurons. Verapamil will be able to exert its pharmacological effects by modulating TRESK, as well as Ca influx, in TG neurons in vitro. We suggest that verapamil could be used as an inhibitor for identifying TRESK channel in TG neurons.
串联孔域弱内向整流钾通道（TWIK）相关的脊髓 K⁺（TRESK；K18.1）通道是双孔域 K⁺（K）通道家族中唯一的一种，其活性受细胞内 Ca 浓度增加（[Ca]）的调节，并与偏头痛有关。本研究旨在确定维拉帕米（一种 L 型钙通道阻滞剂，偏头痛的预防药物）对三叉神经节（TG）神经元中的 TRESK 通道的影响，以及在异源系统中的影响。使用膜片钳技术在 TG 神经元和转染 mTRESK 的 HEK-293 细胞中记录单通道和全细胞电流。使用 fluo-3-AM Ca 指示剂测量 TG 神经元中的 [Ca]变化。维拉帕米、硝苯地平、和 NiCl₂分别对过表达 mTRESK 的 HEK-293 细胞的全细胞电流的抑制作用的 IC 值分别为 5.2、54.3 和>100 μM。在分离的膜片上也观察到维拉帕米对 TRESK 通道的抑制作用。在 TG 神经元中，维拉帕米（10 μM）抑制 TRESK 通道活性约 76%。TRESK 通道活性不依赖于细胞外 Ca 的存在。此外，即使不存在细胞外 Ca，维拉帕米对 TRESK 通道的抑制作用仍然存在。这些发现表明，维拉帕米抑制 TRESK 电流与 TG 神经元中 Ca 内流的阻断无关。维拉帕米能够通过调节 TG 神经元中的 TRESK 通道和 Ca 内流来发挥其药理学作用。我们建议维拉帕米可以作为鉴定 TG 神经元中 TRESK 通道的抑制剂。
