NNC 55-0396 [(1<i>S</i>,2<i>S</i>)-2-(2-(<i>N</i>-[(3-Benzimidazol-2-yl)propyl]-<i>N</i>-methylamino)ethyl)-6-fluoro-1,2,3,4-tetrahydro-1-isopropyl-2-naphtyl cyclopropanecarboxylate dihydrochloride]: A New Selective Inhibitor of T-Type Calcium Channels
作者:Luping Huang、Brian M. Keyser、Tina M. Tagmose、J. Bondo Hansen、James T. Taylor、Hean Zhuang、Min Zhang、David S. Ragsdale、Ming Li
DOI:10.1124/jpet.103.060814
日期:2004.4
Mibefradil is a Ca2+ channel antagonist that inhibits both T-type and high-voltage-activated Ca2+ channels. We previously showed that block of high-voltage-activated channels by mibefradil occurs through the production of an active metabolite by intracellular hydrolysis. In the present study, we modified the structure of mibefradil to develop a nonhydrolyzable analog, (1 S , 2 S )-2-(2-( N -[(3-benzimidazol-2-yl)propyl]- N -methylamino)ethyl)-6-fluoro-1,2,3,4-tetrahydro-1-isopropyl-2-naphtyl cyclopropanecarboxylate dihydrochloride (NNC 55-0396), that exerts a selective inhibitory effect on T-type channels. The acute IC50 of NNC 55-0396 to block recombinant α1G T-type channels in human embryonic kidney 293 cells was ∼7 μM, whereas 100 μM NNC 55-0396 had no detectable effect on high-voltage-activated channels in INS-1 cells. NNC 55-0396 did not affect the voltage-dependent activation of T-type Ca2+ currents but changed the slope of the steady-state inactivation curve. Block of T-type Ca2+ current was partially relieved by membrane hyperpolarization and enhanced at a high-stimulus frequency. Washing NNC 55-0396 out of the recording chamber did not reverse the T-type Ca2+ current activity, suggesting that the compound dissolves in or passes through the plasma membrane to exert its effect; however, intracellular perfusion of the compound did not block T-type Ca2+ currents, arguing against a cytoplasmic route of action. After incubating cells from an insulin-secreting cell line (INS-1) with NNC 55-0396 for 20 min, mass spectrometry did not detect the mibefradil metabolite that causes L-type Ca2+ channel inhibition. We conclude that NNC 55-0396, by virtue of its modified structure, does not produce the metabolite that causes inhibition of L-type Ca2+ channels, thus rendering it more selective to T-type Ca2+ channels.
米贝地尔是一种 Ca2+ 通道拮抗剂,能抑制 T 型和高压激活的 Ca2+ 通道。我们以前的研究表明,米贝地尔对高电压激活通道的阻断是通过细胞内水解产生活性代谢产物来实现的。在本研究中,我们修改了米贝拉地尔的结构,开发出一种不可水解的类似物,即 (1 S , 2 S )-2-(2-( N -[(3- 苯并咪唑-2-基)丙基]- N -甲基氨基)乙基)-6-氟-1、2,3,4- 四氢-1-异丙基-2-萘基环丙烷羧酸二盐酸盐(NNC 55-0396),它对 T 型通道具有选择性抑制作用。在人胚肾 293 细胞中,NNC 55-0396 阻断重组 α1G T 型通道的急性 IC50 为 7 μM,而在 INS-1 细胞中,100 μM 的 NNC 55-0396 对高电压激活通道没有检测到影响。NNC 55-0396 不影响 T 型 Ca2+ 电流的电压依赖性激活,但改变了稳态失活曲线的斜率。膜超极化可部分缓解对 T 型 Ca2+ 电流的阻滞,并在高刺激频率下增强阻滞。将 NNC 55-0396 从记录室中冲洗出来并不能逆转 T 型 Ca2+ 电流的活性,这表明该化合物溶解在质膜中或通过质膜产生作用;然而,在细胞内灌注该化合物并不能阻断 T 型 Ca2+ 电流,这证明该化合物的作用途径不是细胞质。用 NNC 55-0396 与胰岛素分泌细胞系(INS-1)的细胞培养 20 分钟后,质谱分析仪没有检测到导致 L 型 Ca2+ 通道抑制的米贝拉地尔代谢物。我们的结论是,NNC 55-0396 由于其结构的改变,不会产生导致 L 型 Ca2+ 通道抑制的代谢物,从而使其对 T 型 Ca2+ 通道更具选择性。