Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Eur J Pharmacol. 2015 Jul 5;758:164-70. doi: 10.1016/j.ejphar.2015.03.061. Epub 2015 Apr 3.
The effect of two positive modulators, RE1 and EX15, on the voltage-gated K(+) channel Kv3.1 was investigated using the whole-cell patch-clamp technique on HEK293 cells expressing Kv3.1a. RE1 and EX15 increased the Kv3.1 currents in a concentration-dependent manner with an EC50 value of 4.5 and 1.3µM, respectively. However, high compound concentrations caused an inhibition of the Kv3.1 current. The compound-induced activation of Kv3.1 channels showed a profound hyperpolarized shift in activation kinetics. 30µM RE1 shifted V1/2 from 5.63±0.31mV to -9.71±1.00mV and 10µM EX15 induced a shift from 10.77±0.32mV to -15.11±1.57mV. The activation time constant (Tauact) was reduced for both RE1 and EX15, with RE1 being the fastest activator. The deactivation time constant (Taudeact) was also markedly reduced for both RE1 and EX15, with EX15 inducing the most prominent effect. Furthermore, subjected to depolarizing pulses at 30Hz, both compounds were showing a use-dependent effect resulting in a reduction of the compound-mediated effect. However, during these conditions, RE1- and EX15-modified current amplitudes still exceeded the control condition amplitudes by up to 200%. In summary, the present study introduces the first detailed biophysical characterization of two new Kv3.1 channel modifying compounds with different modulating properties.
采用在表达 Kv3.1a 的 HEK293 细胞上进行全细胞膜片钳技术，研究了两种正调节剂 RE1 和 EX15 对电压门控 K(+) 通道 Kv3.1 的影响。RE1 和 EX15 以浓度依赖性方式增加 Kv3.1 电流，EC50 值分别为 4.5 和 1.3µM。然而，高化合物浓度会导致 Kv3.1 电流抑制。化合物诱导的 Kv3.1 通道激活表现出显著的超极化激活动力学偏移。30µM RE1 将 V1/2 从 5.63±0.31mV 移至 -9.71±1.00mV，而 10µM EX15 诱导从 10.77±0.32mV 移至 -15.11±1.57mV。RE1 和 EX15 均缩短了激活时间常数 (Tauact)，其中 RE1 是最快的激活剂。RE1 和 EX15 也明显缩短了失活时间常数 (Taudeact)，其中 EX15 诱导的效果最为显著。此外，在 30Hz 的去极化脉冲下，两种化合物均表现出使用依赖性效应，导致化合物介导的效应降低。然而，在这些条件下，RE1 和 EX15 修饰的电流幅度仍然比对照条件高 200%。总之，本研究介绍了两种具有不同调节特性的新型 Kv3.1 通道修饰化合物的首次详细的生物物理特性。
