利多卡因对爪蟾卵母细胞Nav1．8钠离子通道的影响  

The effects of lidocaine on Nav1.8 sodium channel on Xenopus laevis oocyte

作　　者：王英伟[1] 谭弘[1] 卞金俊[2] 丁玉强[3] 

机构地区：[1]上海交通大学医学院附属新华医院麻醉科,200092 [2]第二军医大学附属长海医院麻醉科 [3]中国科学院上海神经科学研究所

出　　处：《中华麻醉学杂志》2007年第7期613-616,共4页Chinese Journal of Anesthesiology

基　　金：国家自然科学基金资助项目（30300330）;上海市科委青年科技启明星课题资助项目（05QMX1431）

摘　　要：目的探讨利多卡因对爪蟾卵母细胞Nav1．8钠通道的影响。方法取成年雄性SD大鼠的背根神经节100mg，以TRIzol试剂提取总RNA，直接进行逆转录反应。以大鼠背根神经节的cDNA为模板，采用PCR技术合成Nav1．8亚基的mRNA。取出雌性爪蟾卵母细胞，用微量注射器将制备好的Nav1．8钠通道亚基的mRNA注射到爪蟾卵母细胞的胞质中，在18％下，置于ND96溶液中孵育3～4d，使用双电极电压钳记录Nav1．8钠离子通道电流。将利多卡因用ND96溶液稀释并制备以下5个浓度：25、50、100、500、800μmol／L。ND96溶液的灌流速率为2～3ml／min。记录时，钳制电压为-100mv，命令电压为-90～60mV，间隔电压梯度为10mv，实验室温度为22—24℃。当连续记录到3个稳定的钠电流后，分别加入以上浓度的利多卡因进行实验，每个爪蟾卵母细胞只记录一种浓度。结果在不同的命令电压下，可记录到Nav1．8钠电流。利多卡因对Nav1．8钠电流的幅度有明显地抑制作用，随着其浓度的增加，抑制程度也逐渐增强。当利多卡因浓度为800μmol／L时，Nav1．8钠电流抑制近90％。不同命令电压下利多卡因的平均IC50为186μmol／L。在不同去极化电压下，同一浓度的利多卡因对Nav1．8钠电流抑制程度的差异无统计学意义（P〉0．05）。利多卡因对Nav1．8钠通道的V1/2和失活时间常数无影响（P〉0．05）。结论利多卡因可抑制Nav1．8钠通道，减少钠离子内流，但对通道的电压门控特性无明显影响。Objective To investigate the molecular mechanism of local anesthetics by assessing the effects of lidocaine on Nav1.8 sodium channel. Methods Dorsal root ganglion （DRG） 100 mg was obtained from adult nude SD rats. Nav 1.8 sodium channel was made from mRNA of DRG by PCR. Xenopus laevis oocytes were obtained and kept in ND96 solution （NaCl 96 mmol/L , KCl 2.0 mmol/L ,CaCl, 1.8 mmol/L , MgCl2 1.0 mmol/ L and HEPES 5.0 mmol/L, pH 7.4）. The mRNA of Nav1.8 subunit was prepared and injected into Xenopus laevis oocytes by micro-injection. Ooeytes were stored at 18℃ and used in experiments 3-4 days after injection. Whole cell inward sodium currents were recorded with the two micro-electrode voltage clamp method. During recording, currents were obtained under holding potential of - 100 mV to test potential of 60 mV in 10 mV increments.Results Nav 1.8 sodium currents were evoked by applying a series of depolarizing voltages. Lidoeaine produced significant inhibition of Nav 1.8 sodium channel in a concentration-dependent manner. The average amplitude of Nav 1.8 sodium currents was decreased by about 90 percent when lidocaine 800 μmol/L was applied. There was no significant difference in the degree of inhibition of Nav1.8 sodium currents by the same concentration of lidocaine at different command potential. Lidocaine had no significant effects on V1/2 or time constant of inactivation. Conclusion Lidocaine produces distinct inhibition of Nav1.8 currents but has no effect on inactivation of the channel.

关 键 词：利多卡因 钠通道 卵母细胞 

分 类 号：R686[医药卫生—骨科学]