Block of human heart hH1 sodium channels by the enantiomers of bupivacaine
Block of human heart hH1 sodium channels by the enantiomers of bupivacaine
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DOI：
10.1097/00000542-200010000-00026
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发表时间：
2000-10-01
期刊：
影响因子：
8.8
通讯作者：
Wang, GK
中科院分区：
文献类型：
--
作者：
Nau, C;Wang, SY;Wang, GK
背景资料：据报道，S（-）-布比卡因与R（+）-布比卡因相比具有较低的心脏毒性，但具有相似的局部麻醉效力。迄今为止，尚未研究布比卡因在人心脏（hH 1）Na+通道中的结合位点。作者研究了布比卡因对映异构体与hH 1 Na+通道的相互作用，评估了pupecaine相关残基对结合的贡献，并比较了与另一种亚型，大鼠骨骼肌（mu 1）Na+通道的内在亲和力。方法：人心脏和mu 1 Na+通道α亚基在HEK 293 t细胞中瞬时表达，并在全细胞电压钳条件下进行研究。使用定点突变，作者通过引入带正电荷的赖氨酸（K）或带负电荷的天冬氨酸（D），在hH 1-F1760、hH 1-N1765、hH 1-Y1767和hH 1-N406位点产生点突变，并研究了它们对布比卡因对映体状态依赖性阻滞的影响。失活的hH 1 Na+通道显示出弱的立体选择性，立体效能比（+/-）为1.5。在突变hH 1-F1760 K和hH 1-N1765 K中，失活通道的布比卡因亲和力降低了20- 40倍，在突变hH 1-N406 K中降低了7倍，在突变hH 1-Y176 TK和hH 1-Y1767 D中降低了2 - 3倍。失活突变通道从阻断中恢复的变化超过了失活通道亲和力的变化。失活的hH 1 Na+通道表现出略高的内在亲和力比mu 1 Na+ channels.Conclusions：布比卡因的立体选择性和内在亲和力之间的差异山和mu 1 Na+通道是小，最有可能的轻微的临床相关性。位置hH 1-F1760、hH 1-N1765和hH 1-N406中的氨基酸残基可能有助于布比卡因对映体在hH 1 Na+通道中的结合，而hH 1-Y1767的作用尚不清楚。
Background: S(-)-bupivacaine reportedly exhibits lower cardiotoxicity but similar local anesthetic potency compared with R(+)-bupivacaine, The bupivacaine binding site in human heart (hH1) Na+ channels has nor been studied to date. The authors investigated the interaction of bupivacaine enantiomers with hH1 Na+ channels, assessed the contribution of putatively relevant residues to binding, and compared the intrinsic affinities to another isoform, the rat skeletal muscle (mu 1) Na+ channel.Methods: Human heart and mu 1 Na+ channel alpha subunits were transiently expressed in HEK293t cells and investigated during whole cell voltage-clamp conditions. Using site-directed mutagenesis, the authors created point mutations at positions hH1-F1760, hH1-N1765, hH1-Y1767, and hH1-N406 by introducing the positively charged lysine (K) or the negatively charged aspartic acid (D) and studied their influence on state-dependent block by bupivacaine enantiomers.Results: Inactivated hH1 Na+ channels displayed a weak stereoselectivity with a stereopotency ratio (+/-) of 1.5. In mutations hH1-F1760K and hH1-N1765K, bupivacaine affinity of inactivated channels was reduced by similar to 20- to 40-fold, in mutation hH1-N406K by similar to sevenfold, and In mutations hH1-Y176TK and hH1-Y1767D by similar to twofold to threefold. Changes In recovery of inactivated mutant channels from block paralleled those of inactivated channel affinity. Inactivated hH1 Na+ channels exhibited a slightly higher intrinsic affinity than mu 1 Na+ channels.Conclusions: Differences in bupivacaine stereoselectivity and intrinsic affinity between hill and mu 1 Na+ channels are small and most likely of minor clinical relevance. Amino acid residues in positions hH1-F1760, hH1-N1765, and hH1-N406 may contribute to binding of bupivacaine enantiomers in hH1 Na+ channels, whereas the role of hH1-Y1767 remains unclear.