BLOCK OF HUMAN VOLTAGE-SENSITIVE NA+ CURRENTS IN DIFFERENTIATED SH-SY5Y CELLS BY LIFARIZINE
BLOCK OF HUMAN VOLTAGE-SENSITIVE NA+ CURRENTS IN DIFFERENTIATED SH-SY5Y CELLS BY LIFARIZINE
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DOI：
10.1111/j.1476-5381.1994.tb17032.x
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发表时间：
1994-10-01
影响因子：
7.3
通讯作者：
SEABROOK, GR
中科院分区：
文献类型：
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作者：
BROWN, NA;KEMP, JA;SEABROOK, GR
1应用全细胞膜片钳技术研究利法利嗪（RS-87476）对人神经母细胞瘤细胞（SH-SY 5 Y）电压型Na+通道电流的阻断作用.分化的SH-SY 5 Y细胞的Na ~+电导（24.0 +/- 2.4 nS，n = 11）被10 ms去极化至-37 +/- 2 mV的半最大激活，并被持续时间为200 ms的预去极化脉冲至-86 +/- 3 mV的半最大失活（n = 11）。3在低刺激频率下通过细胞外应用河豚毒素（EC（50）= 4 +/- 1 nM，n = 12）或利法利嗪（EC（50）= 783 +/- 67 nM，n = 9），以浓度依赖性方式完全阻断（0.1至0.33 Hz）电压依赖性钠电流。利伐利嗪阻滞起效时间（tau = 91 +/- 14 s，10 μ M）比河豚毒素慢得多（tau = 16 +/- 3 s，100 nM）。4利法利嗪（1 μ M）降低了每个细胞中的峰值钠电导率（从26.4 +/- 2.0 nS到15.1 +/- 2.7 nS，n = 4），而不改变钠电流激活或失活的宏观动力学（V1/2分别=-35 +/- 1 mV和-87 +/- 4 mV，n = 4）。同样，利法利嗪（1 μ M）也不影响宏观钠电流的反转电位（对照组+ 14 +/- 5 mV，1 μ M利伐利嗪组+ 16 +/- 2 mV; n = 4）或再激活时间常数（tau = 14.0 +/- 4.4 ms）。5河豚毒素（30 nM）阻断钠通道开放状态不能阻止随后应用利法利嗪（3 μ M）引起的抑制。与此相反，利法利嗪引起的抑郁症在用局部麻醉剂，木质素（10 mM）预处理细胞后很容易逆转。6这些数据表明，利法利嗪是人类电压敏感性钠电流的使用和电压依赖性拮抗剂。利法利嗪阻滞的缓慢动力学和药理学表明，这种药物进入通道比河豚毒素更受限制，可能涉及通道的变构位点或状态，也受局部麻醉剂的调节。
1 The ability of lifarizine (RS-87476) to block human voltage Na+ channel currents was studied by use of whole cell patch clamp recording from differentiated neuroblastoma cells (SH-SY5Y).2. The Na+ conductance in differentiated SH-SY5Y cells (24.0 +/- 2.4 nS, n = 11) was half-maximally activated by 10 ms depolarizations to - 37 +/- 2 mV and was half-maximally inactivated by predepolarizing pulses of 200 ms duration to - 86 +/- 3 mV (n = 11).3 At low stimulus frequencies (0.1 to 0.33 Hz) voltage-dependent sodium currents were completely blocked, in a concentration-dependent manner, by extracellular application of either tetrodotoxin (EC(50) = 4 +/- 1 nM, n = 12) or by lifarizine (EC(50) = 783 +/- 67 nM, n = 9). The onset of block by lifarizine (tau = 91 +/- 14 s at 10 mu M) was considerably slower than that of tetrodotoxin (tau = 16 +/- 3 s at 100 nM).4 Lifarizine (1 mu M) reduced the peak sodium conductance in each cell (from 26.4 +/- 2.0 nS to 15.1 +/- 2.7 nS, n = 4) without changing the macroscopic kinetics of sodium current activation or inactivation (V1/2 = - 35 +/- 1 mV and - 87 +/- 4 mV respectively, n = 4). Similarly, lifarizine (1 mu M) did not affect the reversal potential of the macroscopic sodium current (+ 14 +/- 5 mV in control and + 16 +/- 2 mV in 1 mu M lifarizine; n = 4) or reactivation time-constant (tau = 14.0 +/- 4.4 ms).5 Block of the sodium channel open state by tetrodotoxin (30 nM) did not prevent the inhibition caused by a subsequent application of lifarizine (3 mu M). In contrast the depression caused by lifarizine was readily reversible after pretreatment of cells with the local anaesthetic, lignocaine (10 mM).6 These data demonstrate that lifarizine is a use- and voltage-dependent antagonist of human voltage-sensitive sodium currents. The slow kinetics and pharmacology of the block by lifarizine indicate that access of this drug to the channel is more restricted than that of tetrodotoxin and may involve an allosteric site or state of the channel that is also regulated by local anaesthetics.