Resurgent-like currents in mouse vas deferens myocytes are mediated by NaV1.6 voltage-gated sodium channels.
Resurgent-like currents in mouse vas deferens myocytes are mediated by NaV1.6 voltage-gated sodium channels.
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小鼠输精管肌细胞中的复苏样电流由 NaV1.6 电压门控钠通道介导。
DOI：
10.1007/s00424-012-1153-4
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Cunnane TC
中科院分区：
文献类型：
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作者：
Teramoto N;Zhu HL;Yotsu-Yamashita M;Inai T;Cunnane TC
利用NaV1.6-null小鼠（NaV1.6 −/−），缺乏Scn 8aNa+通道基因的表达，以及它们的野生型同窝出生小鼠（NaV1.6 +/+），进行膜片钳实验，以研究从小鼠输精管分散的单个平滑肌细胞中复活样电流的分子特性。在从NaV1.6+/+而不是NaV1.6 −/−输精管获得的分散的平滑肌细胞中，NaV1.6免疫反应性清晰可见。在从保持电位−70 mV去极化至+30 mV（使Na+电流最大程度失活）后，复极化至−60 mV至+20 mV之间的电压在NaV1.6+/+而非NaV1.6−/−输精管肌细胞中引发河豚毒素（TTX）敏感性内向电流。在NaV1.6+/+输精管肌细胞中，类复活电流在电流-电压关系中的峰值约为−20 mV。在施加去极化矩形脉冲至比+20 mV更正的电位后，当膜电位复极化至-20 mV时，复苏样电流的峰值幅度保持在恒定水平。4，9-脱水河豚毒素（4，9-anhydroTTX）是一种选择性的NaV1.6阻断毒素，通过LC-FLD技术从TTX类似物的粗混合物中纯化，可逆地抑制复活样电流。电压门控性Na+通道激活剂β-Pompilidotoxin在NaV1.6+/+而非NaV1.6−/−小鼠输精管肌细胞中诱发持续的复活样电流。这些结果强烈地表明，主要是由于NaV1.6通道活性而产生的复活样电流。
Patch-clamp experiments were performed to investigate the molecular properties of resurgent-like currents in single smooth muscle cells dispersed from mouse vas deferens, utilizing both NaV1.6-null mice (NaV1.6−/−), lacking the expression of theScn8aNa+channel gene, and their wild-type littermates (NaV1.6+/+). NaV1.6 immunoreactivity was clearly visible in dispersed smooth muscle cells obtained from NaV1.6+/+, but not NaV1.6−/−, vas deferens. Following a depolarization to +30 mV from a holding potential of −70 mV (to produce maximal inactivation of the Na+current), repolarization to voltages between −60 and +20 mV elicited a tetrodotoxin (TTX)-sensitive inward current in NaV1.6+/+, but not NaV1.6−/−, vas deferens myocytes. The resurgent-like current in NaV1.6+/+vas deferens myocytes peaked at approximately −20 mV in the current–voltage relationship. The peak amplitude of the resurgent-like current remained at a constant level when the membrane potential was repolarized to −20 mV following the application of depolarizing rectangular pulses to more positive potentials than +20 mV. 4,9-Anhydrotetrodotoxin (4,9-anhydroTTX), a selective NaV1.6 blocking toxin, purified from a crude mixture of TTX analogues by LC-FLD techniques, reversibly suppressed the resurgent-like currents. β-Pompilidotoxin, a voltage-gated Na+channel activator, evoked sustained resurgent-like currents in NaV1.6+/+but not NaV1.6−/−murine vas deferens myocytes. These results strongly indicate that, primarily, resurgent-like currents are generated as a result of NaV1.6 channel activity.