Local Anesthetics Depolarize Mitochondrial Membrane Potential by Intracellular Alkalization in Rat Dorsal Root Ganglion Neurons
Local Anesthetics Depolarize Mitochondrial Membrane Potential by Intracellular Alkalization in Rat Dorsal Root Ganglion Neurons
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DOI：
10.1213/ane.0b013e3181e9f03b
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发表时间：
2010-08
影响因子：
5.7
通讯作者：
S. Onizuka;Ryuji Tamura;N. Hosokawa;Y. Kawasaki;I. Tsuneyoshi
中科院分区：
文献类型：
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作者：
S. Onizuka;Ryuji Tamura;N. Hosokawa;Y. Kawasaki;I. Tsuneyoshi
背景：虽然已有文献报道局部麻醉药，尤其是利多卡因具有细胞毒性，但其作用机制尚不清楚。线粒体膜电位（m）的去极化是线粒体衰竭的标志之一，其受质子电化学梯度（H+）调节。因此，细胞内pH（[pH]in）和线粒体pH（[pH]m）是改变m的重要因素。然而，局麻药对[pH]in和[pH]m的影响尚不清楚。为了研究线粒体对局部麻醉剂的反应，我们同时测量了[pH]m和[pH]in，沿着m。方法：用JC-1和HPTS比率荧光探针同时测定大鼠背根神经节神经元内的m和[pH]。羧基-SNARF-1荧光探针用于测量[pH]m。评价了利多卡因、甲哌卡因、布比卡因、普鲁卡因、QX-314（一种荷电形式的利多卡因）和氯化铵（NH 4Cl）。结果：利多卡因、甲哌卡因、布比卡因和普鲁卡因均使m去极化，并使[pH]升高，呈剂量依赖性。值得注意的是，在利多卡因、甲哌卡因、布比卡因、普鲁卡因和氯化铵灌注中观察到m和[pH]之间的关系。相比之下，QX-314没有改变m或[pH]。在低pH盐水（pH 6）和弱酸存在下，利多卡因不能增加[pH]或去乙酰化。利多卡因、甲哌卡因、布比卡因、普鲁卡因和氯化铵也可增加[pH]m。结论：这些结果表明，不带电荷的（碱）形式的局部麻醉药诱导m去极化。原因之一是细胞内和线粒体碱化。
BACKGROUND: Although it has been reported that local anesthetics, especially lidocaine, are cytotoxic, the mechanism is unclear. Depolarization of the mitochondrial membrane potential (&Dgr;&PSgr;m), one of the markers of mitochondrial failure, is regulated by the proton electrochemical gradient (&Dgr; H+). Therefore, intracellular pH ([pH]in) and mitochondrial pH ([pH]m) are important factors for modifying &Dgr;&PSgr;m. However, the effects of local anesthetics on [pH]in and [pH]m are unclear. To investigate mitochondrial responses to local anesthetics, we simultaneously measured [pH]m and [pH]in, along with &Dgr;&PSgr;m. METHODS: The ratiometric fluorescent probe JC-1 and HPTS were used for the simultaneous measurements of &Dgr;&PSgr;m with [pH]in in rat dorsal root ganglion neurons. A carboxy-SNARF-1 fluorescent probe was used to measure [pH]m. Lidocaine, mepivacaine, bupivacaine, procaine, QX-314, a charged form of lidocaine, and ammonium chloride (NH4Cl) were evaluated. RESULTS: &Dgr;&PSgr;m was depolarized and [pH]in was increased by lidocaine, mepivacaine, bupivacaine, and procaine in a dose-dependent manner. Significantly, a relationship between &Dgr;&PSgr;m and [pH]in was observed for lidocaine, mepivacaine, bupivacaine, procaine, and NH4Cl perfusion. In contrast, QX-314 did not change &Dgr;&PSgr;m or [pH]in. In low-pH saline (pH6) and in the presence of a weak acid, lidocaine failed to increase [pH]in or depolarize &Dgr;&PSgr;m. The [pH]m was also increased by lidocaine, mepivacaine, bupivacaine, procaine, and NH4Cl. CONCLUSION: These results demonstrate that uncharged (base) forms of local anesthetics induce &Dgr;&PSgr;m depolarization. One of the causes is intracellular and mitochondrial alkalization.