MULTIPLE BINDING-SITES FOR LOCAL-ANESTHETICS IN MEMBRANES - CHARACTERIZATION OF THE SITES AND THEIR EQUILIBRIA BY DEUTERIUM NMR OF SPECIFICALLY DEUTERATED PROCAINE AND TETRACAINE
MULTIPLE BINDING-SITES FOR LOCAL-ANESTHETICS IN MEMBRANES - CHARACTERIZATION OF THE SITES AND THEIR EQUILIBRIA BY DEUTERIUM NMR OF SPECIFICALLY DEUTERATED PROCAINE AND TETRACAINE
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DOI：
10.1139/o80-134
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发表时间：
1980-01-01
期刊：
影响因子：
--
通讯作者：
SMITH, ICP
中科院分区：
文献类型：
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作者：
BOULANGER, Y;SCHREIER, S;SMITH, ICP
通过2 H NMR直接观察到与模型膜结合的麻醉剂。具体氘代局部麻醉剂，普鲁卡因和丁卡因，合成，并确定其分配系数（水：磷脂酰胆碱）和pKa值。这些麻醉剂与卵磷脂的层状分散体的相互作用进行了研究，通过2 H NMR，并通过电子自旋共振（ESR）的自旋标记的磷脂在低（5.5）和高（9.5）pH值。ESR实验表明，丁卡因插入在膜，它平衡水和磷脂双层的多层系统之间。核磁共振结果是一致的模型，其中麻醉剂是游离在水中，弱结合到膜，并强烈绑定到it.A快速交换之间存在的第2个第1网站，但交换是缓慢的第3网站。普鲁卡因仅在高pH下观察到3型结合，而丁卡因在低pH和高pH下均发现3型结合。的带电和不带电形式的丁卡因的分配系数的计算表明，这两个网站，2和3，被占领的带电形式在低pH值，和不带电的形式在高pH值。分配系数为弱结合的物种估计从分析的依赖性的线宽上的脂质与水的比例。NMR数据表明，强结合的带电和不带电物种的结合位点是不同的，前者可能更接近膜-水界面。强结合物种的分子序参数的估计表明，它是位于其长分子轴近似平行的指示剂的脂肪酰基链的排序。在低pH值下观察到丁卡因的脂质有序性的小幅增加，如磷脂酰胆碱的氘代N-甲基基团的2 H NMR所证明的;在高pH值下发生相反的情况。
Anesthetics bound to model membranes were observed directly by 2H NMR. The specifically deuterated local anesthetics, procaine and tetracaine, were synthesized, and their partition coefficients (water:phosphatidylcholine) and pKa values determined. The interaction of these anesthetics with lamellar dispersions of egg phosphatidylcholine was studied by 2H NMR, and by electron spin resonance (ESR) of a spin-labeled phospholipid at low (5.5) and high (9.5) pH. The ESR experiments suggest that tetracaine intercalates in the membrane, and that it equilibrates between water and the phospholipid bilayers of the multilamellar system. The NMR results are consistent with a model in which the anesthetic is free in water, weakly-bound to the membrane, and strongly-bound to it. A fast exchange exists between the 2 1st sites, but exchange is slow with the 3rd site. Binding of type 3 is observed only at high pH for procaine, whereas it is found both at low and high pH for tetracaine. Calculations of the partition coefficients for the charged and uncharged forms of tetracaine indicate that both sites, 2 and 3, are occupied by the charged form at low pH, and by the uncharged form at high pH. The partition coefficient for the weakly-bound species was estimated from an analysis of the dependence of line width on the lipid to water ratio. The NMR data suggest that the binding sites for the strongly-bound charged and uncharged species are different, the former probably being closer to the membrane-water interface. Estimates of molecular order parameters for the strongly-bound species indicate that it is located with its long molecular axis approximately parallel to the director for ordering of the fatty acyl chains. A small increase in lipid ordering by tetracaine is observed at low pH, as evidenced by 2H NMR of the deuterated N-methyl groups of phosphatidylcholine; the reverse occurs at high pH.