摘要
目的本研究旨在探讨酰胺类局部麻醉药罗哌卡因对外源表达的大鼠脑型(rNav1.2)和心肌型(rNav1.5)电压门控钠通道电流的药理调制作用。方法运用双电极和膜片钳全细胞记录技术记录全细胞电流。结果罗哌卡因能以浓度和频率依赖的方式抑制rNav1.2和rNav1.5亚型通道的峰钠电流,其中Nav1.5亚型通道对罗哌卡因的敏感性相对较高。此外,罗哌卡因能使rNav1.2和rNav1.5亚型通道的稳态失活曲线向超极化方向显著偏移,但对激活曲线没有影响。通过重复高频去极化刺激,罗哌卡因能以使用依赖性的方式抑制rNav1.2和rNav1.5亚型通道的电流。结论结果提示罗哌卡因的药理机制体现在对钠通道亚型失活态的调制上。该结果有助于进一步理解罗哌卡因对脑型和心肌型电压门控钠通道的药理调制作用。
Objective The present study was aimed to investigate the pharmacological modulatory effects of ropivacaine,an amide-type local anesthetic,on rat Nav1.2（rNav1.2）and rNav1.5,the two Na＋channel isoforms heterologously expressed in Xenopus oocytes and in HEK293t cell line,respectively.Methods Two-electrode voltage-clamp（TEVC）and whole-cell patchclamp recordings were employed to record the whole-cell currents.Results Ropivacaine induced tonic inhibition of peak Na＋ currents of both subtypes in a dose-and frequency-dependent manner.rNav1.5 appeared to be more sensitive to ropivacaine.In addition,for both Na＋channel subtypes,the steady-state inactivation curves,but not the activation curves,were significantly shifted to the hyperpolarizing direction by ropivacaine.Use-dependent blockade of both rNav1.2 and rNav1.5 channels was induced by ropivacaine through a high frequency of depolarization,suggesting that ropivacaine could preferentially bind to the 2 inactivated Na＋channel isoforms.Conclusion The results will be helpful in understanding the pharmacological modulation by ropivacaine on Nav1.2 subtype in the central nervous system,and on Nav1.5 subtype abundantly expressed in the heart.
基金
supported by the National Basic Research Development Program of China(No. 2006CB500801,2010CB529806)
the National Natural Science Foundation of China(No.30900422)
the Natural Science Foundation of Shanghai Municipality,China(No.08JC1409500)
State Key Laboratory of Medical Neurobiology,Fudan University(No.09-02)
National Laboratory of Biomacro-molecules,Institute of Biophysics,Chinese Academy of Sciences(No.O5SY021097)
