Tertiapin-Q blocks recombinant and native large conductance K+ channels in a use-dependent manner
Tertiapin-Q blocks recombinant and native large conductance K+ channels in a use-dependent manner
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DOI：
10.1124/jpet.105.085928
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发表时间：
2005-09-01
影响因子：
3.5
通讯作者：
Bellingham, MC
中科院分区：
文献类型：
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作者：
Kanjhan, R;Coulson, EJ;Bellingham, MC
Tertiapin是一种来源于蜜蜂毒液的短肽，据报道可特异性阻断内向整流钾通道，包括G蛋白偶联内向整流钾通道（GIRK）1 + GIRK 4异多聚体和ROMK 1同源多聚体。在本研究中，检测了特硫平的稳定且功能相似的衍生物特硫平-Q对重组人电压依赖性Ca 2+激活的大电导K+通道（BK或MaxiK; α-亚基或hSlo 1同源多聚体）和小鼠内向整流GIRK 1 + GIRK 2（即，Kir3.1和Kir3.2）异源多聚体K+通道在非洲爪蟾卵母细胞和培养的新生小鼠背根神经节（DRG）神经元中表达。在双电极电压钳位卵母细胞中，tertiapin-Q（1-100 nM）以使用和浓度依赖性方式抑制BK型K+通道。我们还证实了抑制重组GIRK 1 + GIRK 2异多聚体tertiapin-Q，这对内源性去极化和超极化激活电流敏感的细胞外二价阳离子（Ca 2+，Mg 2+，Zn 2+，Ba 2+）在去卵泡卵母细胞没有影响。在电压钳位DRG神经元，tertiapin-Q电压和使用依赖性抑制外向整流K+电流，但Cs+阻断超极化激活内向电流，包括I-H不敏感tertiapin-Q，巴氯芬，钡，锌，这表明在新生儿的功能GIRK通道的情况下。在电流钳条件下，tertiapin-Q阻断动作电位后超极化（AHP），并增加动作电位持续时间在DRG神经元。总之，这些结果表明，特硫平-Q的阻断作用不是特异性的Kir通道，重组BK通道和天然神经元AHP电流的阻断是使用依赖性的。特硫平-Q在纳摩尔范围内通过不同机制抑制特定类型的Kir和电压依赖性Ca 2+激活的K+通道可能对疼痛生理学和治疗有影响。
Tertiapin, a short peptide from honey bee venom, has been reported to specifically block the inwardly rectifying K+ (Kir) channels, including G protein-coupled inwardly rectifying potassium channel (GIRK) 1 + GIRK4 heteromultimers and ROMK1 homomultimers. In the present study, the effects of a stable and functionally similar derivative of tertiapin, tertiapin-Q, were examined on recombinant human voltage-dependent Ca2+-activated large conductance K+ channel (BK or MaxiK; alpha-subunit or hSlo1 homomultimers) and mouse inwardly rectifying GIRK1 + GIRK2 (i.e., Kir3.1 and Kir3.2) heteromultimeric K+ channels expressed in Xenopus oocytes and in cultured newborn mouse dorsal root ganglion (DRG) neurons. In two-electrode voltage-clamped oocytes, tertiapin-Q (1-100 nM) inhibited BK-type K+ channels in a use- and concentration-dependent manner. We also confirmed the inhibition of recombinant GIRK1 + GIRK2 heteromultimers by tertiapin-Q, which had no effect on endogenous depolarization- and hyperpolarization-activated currents sensitive to extracellular divalent cations (Ca2+, Mg2+, Zn2+, and Ba2+) in defolliculated oocytes. In voltage-clamped DRG neurons, tertiapin-Q voltage- and use-dependently inhibited outwardly rectifying K+ currents, but Cs+-blocked hyperpolarization-activated inward currents including I-H were insensitive to tertiapin-Q, baclofen, barium, and zinc, suggesting absence of functional GIRK channels in the newborn. Under current-clamp conditions, tertiapin-Q blocked the action potential after hyperpolarization (AHP) and increased action potential duration in DRG neurons. Taken together, these results demonstrate that the blocking actions of tertiapin-Q are not specific to Kir channels and that the blockade of recombinant BK channels and native neuronal AHP currents is use-dependent. Inhibition of specific types of Kir and voltage-dependent Ca2+-activated K+ channels by tertiapin-Q at nanomolar range via different mechanisms may have implications in pain physiology and therapy.