Department of Dental Basic Education, Asahi University School of Dentistry, Mizuho, Japan.
Basic Clin Pharmacol Toxicol. 2012 Nov;111(5):303-8. doi: 10.1111/j.1742-7843.2012.00909.x. Epub 2012 Jun 29.
While myocardial ischaemia enhances the cardiotoxicity of local anaesthetics, the pharmacological background remains unclear. Cardiolipin (CL) localized in mitochondrial membranes is possibly the site of cardiotoxic action of local anaesthetics and peroxynitrite is produced by cardiac ischaemia and reperfusion. We verified the hypothetic mechanism that local anaesthetics may interact with CL-containing biomembranes to change the membrane biophysical property and their membrane interactions may be increased by peroxynitrite. Biomimetic membranes were prepared with different phospholipids and cholesterol of varying compositions. The membrane preparations were reacted with peroxynitrite of pathologically relevant concentrations and local anaesthetics (bupivacaine and lidocaine) of a cardiotoxic concentration separately or in combination. Changes in membrane fluidity were determined by measuring fluorescence polarization. Peroxynitrite decreased the fluidity of biomimetic membranes at 0.1-10 μM with the relative potency being CL>1-stearoyl-2-arachidonoylphosphatidylcholine>1,2-dipalmitoylphosphatidylcholine-constituting membranes, indicating the lipid peroxidation-induced membrane rigidification determined by the unsaturation degree of membrane lipids. When treated with 0.1-10 μM peroxynitrite, biomimetic membranes were more rigid with elevating the CL content from 0% to 30 mol%, suggesting that CL is a primary target of peroxynitrite. Bupivacaine and lidocaine fluidized at 200 μM biomimetic membranes containing 10 mol% CL and their effects were increased by pre-treating the membranes with 0.1 and 1 μM peroxynitrite. Cardiotoxic bupivacaine and lidocaine increasingly interact with CL-containing mitochondria model membranes which are relatively rigidified by peroxynitrite. Such an increasing membrane interaction may be, at least in part, responsible for the local anaesthetic cardiotoxicity enhanced by myocardial ischaemia.
虽然心肌缺血会增强局部麻醉剂的心脏毒性，但其中的药理学机制仍不清楚。位于线粒体膜中的心磷脂（CL）可能是局部麻醉剂心脏毒性作用的靶位，而过氧化亚硝阴离子是由心肌缺血和再灌注产生的。我们验证了一种假设机制，即局部麻醉剂可能与含有 CL 的生物膜相互作用，改变膜的生物物理性质，而过氧化亚硝阴离子可能会增加它们与膜的相互作用。用不同组成的磷脂和胆固醇制备仿生膜。将膜制剂分别与病理相关浓度的过氧亚硝酸盐和具有心脏毒性浓度的局部麻醉剂（布比卡因和利多卡因）反应，或者联合反应。通过测量荧光偏振来测定膜流动性的变化。过氧亚硝酸盐以 0.1-10 μM 的浓度降低仿生膜的流动性，相对效力为 CL>1-硬脂酰-2-花生四烯酰磷脂酰胆碱>1,2-二棕榈酰基磷脂酰胆碱构成的膜，表明脂质过氧化诱导的膜刚性由膜脂的不饱和度决定。用 0.1-10 μM 过氧亚硝酸盐处理时，随着 CL 含量从 0%增加到 30 mol%，仿生膜变得更加刚性，表明 CL 是过氧亚硝酸盐的主要靶位。200 μM 含 10 mol% CL 的仿生膜中，布比卡因和利多卡因在 200 μM 时使膜流动化，并且用 0.1 和 1 μM 过氧亚硝酸盐预处理膜后，其作用增强。具有心脏毒性的布比卡因和利多卡因与过氧亚硝酸盐使相对刚性化的含 CL 的线粒体模型膜的相互作用增加。这种膜相互作用的增加可能至少部分解释了心肌缺血增强的局部麻醉剂心脏毒性。
