Local Anesthetics Inhibit Transient Receptor Potential Vanilloid Subtype 3 Channel Function in Xenopus Oocytes
Local Anesthetics Inhibit Transient Receptor Potential Vanilloid Subtype 3 Channel Function in Xenopus Oocytes
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DOI：
10.1213/ane.0000000000005546
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发表时间：
2021-06-01
影响因子：
5.7
通讯作者：
Horishita, Takafumi
中科院分区：
文献类型：
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作者：
Horishita, Reiko;Ogata, Yuichi;Horishita, Takafumi
背景：瞬时受体电位香草样亚型3(TRPV3)通道被无害的温度和几种化学刺激激活。它被认为参与了病理性疼痛的发展，因此被认为是治疗疼痛的潜在靶点。局部麻醉剂已被用于急性和慢性疼痛的患者。虽然阻断电压门控钠通道是局麻药发挥作用的主要机制，但仅靠这一机制是不能解释的，特别是在慢性疼痛等病理状态下。事实上，局部麻醉剂对涉及疼痛通路的多个靶点的影响已有报道。局部麻醉药的作用机制之一是调节瞬时受体电位通道(如TRPV1和TRPA1)的功能。方法：在非洲爪哇卵母细胞中表达TRPV3，并用双电极电压钳技术研究局麻药对2-氨基乙氧基二苯基硼酸酯(2APB)诱发电流的影响。结果：临床使用的局麻药以浓度依赖的方式抑制TRPV3通道的激活电流，半数抑制浓度(IC50值)分别为2.5(利多卡因)、1.4(甲哌卡因)、0.28(罗比卡因)和0.17(布比卡因)mmol/L。相反，这些局麻药也在较高浓度时直接诱导电流，尽管与2APB诱导的电流相比，这些电流相当小。我们发现利多卡因对TRPV3的抑制是非竞争性的，不依赖于细胞内的信号转导。2细胞外N-(2，6-二甲基苯基氨基甲酰甲基)三乙基溴化铵(QX-314)可降低APB诱发的TRPV3电流，而细胞内的QX-314或苯佐卡因对此无明显影响。此外，利多卡因对TRPV3的抑制作用呈剂量依赖性阻断。最后，根据对共表达TRPV3和钠通道的卵母细胞的检查，QX-314似乎轻微地渗透到激活的TRPV3通道孔中。这些结果表明，局麻药可通过其荷电形式与通道孔的细胞外相互作用来抑制TRPV3通道的功能。结论：当TRPV3在非洲爪哇卵母细胞中表达时，局麻药在药物相关浓度下抑制TRPV32APB诱发的电流。这些效应似乎是通过带电形式的麻醉剂与TRPV3通道孔之间的细胞外相互作用而发生的。这些结果有助于阐明局麻药的作用机制。
BACKGROUND:The transient receptor potential vanilloid subtype 3 (TRPV3) channel is activated by innocuous temperature and several chemical stimuli. It is proposed to be involved in pathological pain development and is therefore considered a potential target for treating pain. Local anesthetics have been used for patients with both acute and chronic pain. Although blockage of the voltage-gated sodium channel is the primary mechanism by which local anesthetics exert their effects, they cannot be explained by this mechanism alone, especially in pathologic states such as chronic pain. Indeed, the effects of local anesthetics on multiple targets involved in the pain pathway have been reported. It has also been suggested that modulating the function of transient receptor potential (TRP) channels (eg, TRPV1 and transient receptor potential ankyrin 1 [TRPA1]) is one of the mechanisms of action of local anesthetics. However, the effects of local anesthetics on TRPV3 have not been reported.METHODS:We expressed TRPV3 in Xenopus oocytes and investigated the effects of local anesthetics on 2-aminoethoxydiphenyl borate (2APB)-induced currents using 2-electrode voltage-clamp techniques.RESULTS:Clinically used local anesthetics inhibited the 2APB-activated currents from the TRPV3 channel in a concentration-dependent manner at pharmacologically relevant concentrations with half maximal inhibitory concentration (IC50) values of 2.5 (lidocaine), 1.4 (mepivacaine), 0.28 (ropivacaine), and 0.17 (bupivacaine) mmol/L, respectively. Conversely, these local anesthetics also directly induced currents at higher concentrations, although these currents were quite small compared to the 2APB-induced currents. We found that the inhibition of TRPV3 by lidocaine is noncompetitive and independent of intracellular signaling cascades. 2APB-induced TRPV3 currents were reduced by extracellular N-(2,6-dimethylphenylcarbamoylmethyl) triethylammonium bromide (QX-314) but not by intracellular QX-314 nor benzocaine. Moreover, lidocaine showed a use-dependent block in TRPV3 inhibition. Finally, QX-314 appeared to slightly permeate the activated TRPV3 channel pore based on examination of oocytes coexpressing TRPV3 and a sodium channel. These results suggest that local anesthetics could inhibit TRPV3 channel function by extracellular interactions of their charged forms with the channel pore.CONCLUSIONS:Local anesthetics inhibited TRPV3 2APB-induced currents at pharmacologically relevant concentrations when TRPV3 was expressed in Xenopus oocytes. These effects seem to occur via an extracellular interaction between the charged form of the anesthetic with the TRPV3 channel pore. These results help to elucidate the mechanisms of action of local anesthetics.