Sullivan L M, Hönemann C W, Arledge J A, Durieux M E
Department of Anesthesiology, University of Virginia Health System Charlottesville, 22906-0010, USA.
Anesth Analg. 1999 May;88(5):1117-24. doi: 10.1097/00000539-199905000-00029.
We investigated the mechanism of benzocaine (permanently uncharged) and QX314 (permanently charged) inhibition of lysophosphatidic acid (LPA) signaling. To determine their site of action, we studied effects of these drugs, alone and in combination, on LPA-induced Ca2+-dependent Cl currents (I(Cl(Ca))) in Xenopus oocytes. After 10 min exposure to benzocaine, QX314 (10(-6)-10(-2) M), or both, we measured effects on I(Cl(Ca)) induced by LPA (with and without protein kinase [PKC] activation/inhibition) and on I(Cl(Ca)) induced by the intracellular injection of IP3 and GTPgammaS. LPA application to oocytes resulted in I(Cl(Ca)) (50% effective concentration approximately 10(-8) M). Both anesthetics inhibited LPA signaling concentration-dependently (50% inhibitory concentration [IC50] benzocaine 0.9 mM, QX314 0.66 mM). The combination acted synergistically (IC50 benzocaine 0.097 mM/QX314 0.048 mM). Intracellular signaling pathways were not affected. This study shows that benzocaine and QX314 inhibit LPA signaling and act synergistically, which is most easily explained by the existence of two different binding sites. Lack of inhibition of IP3 or GTPgammaS-induced I(Cl(Ca)) identifies the receptor as a target. Activation of PKC can be excluded as a potential mechanism.
Lysophosphatidic acid may play a role in wound healing, and its signaling is inhibited by local anesthetics. We identified the membrane receptor as the local anesthetic site of action and showed that charged (QX314) and uncharged (benzocaine) local anesthetics inhibit lysophosphatidic acid signaling synergistically, which can be explained by the presence of different binding sites.
我们研究了苯佐卡因（永久不带电荷）和QX314（永久带电荷）对溶血磷脂酸（LPA）信号传导的抑制机制。为了确定它们的作用位点，我们研究了这些药物单独及联合使用对非洲爪蟾卵母细胞中LPA诱导的Ca2+依赖性Cl电流（I(Cl(Ca))）的影响。在暴露于苯佐卡因、QX314（10^(-6)-10^(-2) M）或两者10分钟后，我们测量了对LPA诱导的I(Cl(Ca))（有和没有蛋白激酶[PKC]激活/抑制）以及细胞内注射IP3和GTPγS诱导的I(Cl(Ca))的影响。向卵母细胞施加LPA导致I(Cl(Ca))（50%有效浓度约为10^(-8) M）。两种麻醉剂均浓度依赖性地抑制LPA信号传导（50%抑制浓度[IC50]：苯佐卡因为0.9 mM，QX314为0.66 mM）。联合使用具有协同作用（IC50：苯佐卡因为[0.097 mM/QX314为0.048 mM]）。细胞内信号通路未受影响。本研究表明，苯佐卡因和QX314抑制LPA信号传导并具有协同作用，这最容易通过存在两个不同的结合位点来解释。对IP3或GTPγS诱导的I(Cl(Ca))缺乏抑制作用表明该受体是作用靶点。可以排除PKC激活作为潜在机制。
溶血磷脂酸可能在伤口愈合中起作用，其信号传导受到局部麻醉剂的抑制。我们确定膜受体为局部麻醉剂的作用位点，并表明带电荷（QX314）和不带电荷（苯佐卡因）的局部麻醉剂协同抑制溶血磷脂酸信号传导，这可以通过存在不同的结合位点来解释。
