Watanabe T, Pakala R, Koba S, Katagiri T, Benedict C R
Department of Internal Medicine, Division of Cardiology, University of Texas-Houston Health Science Center, Houston, TX 77030, USA.
Circulation. 2001 Mar 13;103(10):1440-5. doi: 10.1161/01.cir.103.10.1440.
Mild oxidation of LDL enhances its atherogenic potential and induces a synergistic interaction with serotonin (5HT) on vascular smooth muscle cell (VSMC) proliferation. Because of its complex chemical nature, the mitogenic components of mildly oxidized LDL (moxLDL) remain unclear.
We examined both the effects of lysophosphatidylcholine (LPC) and hydrogen peroxide (H(2)O(2)), a donor of reactive oxygen species, as major components of moxLDL and their interactions with 5HT on VSMC proliferation. Growth-arrested VSMCs were incubated with different concentrations of moxLDL, LPC, H(2)O(2), or LPC with H(2)O(2) in the absence or presence of 5HT. DNA synthesis in VSMCs was examined by [(3)H]thymidine incorporation. MoxLDL, LPC, H(2)O(2), and 5HT stimulated DNA synthesis in a dose-dependent manner. MoxLDL had a maximal stimulatory effect at a concentration of 5 microg/mL (211%), LPC at 15 micromol/L (156%), H(2)O(2) at 5 micromol/L (179%), and 5HT at 50 micromol/L (205%). Added together, moxLDL (50 ng/mL) and 5HT (50 micromol/L) synergistically increased DNA synthesis (443%). Coincubation of LPC (1 micromol/L) with H(2)O(2) (0.5 micromol/L) and 5HT (5 micromol/L) resulted in a synergistic increase in DNA synthesis (439%), which was nearly equal to that of moxLDL with 5HT (443%). The combined effects of LPC, H(2)O(2), and 5HT on DNA synthesis were completely reversed by the combined use of an antioxidant, N:-acetylcysteine (400 micromol/L) or butylated hydroxytoluene (20 micromol/L), with a 5HT(2) receptor antagonist, LY281067 (10 microg/mL).
Our results suggest that both LPC and reactive oxygen species may contribute to the mitogenic effect of moxLDL on VSMCs and its synergistic effect with 5HT.
低密度脂蛋白（LDL）的轻度氧化增强了其致动脉粥样硬化的潜能，并在血管平滑肌细胞（VSMC）增殖方面诱导了与5-羟色胺（5HT）的协同相互作用。由于其复杂的化学性质，轻度氧化的LDL（moxLDL）的促有丝分裂成分仍不清楚。
我们研究了溶血磷脂酰胆碱（LPC）和活性氧供体过氧化氢（H₂O₂）作为moxLDL的主要成分的作用，以及它们与5HT对VSMC增殖的相互作用。将生长停滞的VSMC与不同浓度的moxLDL、LPC、H₂O₂或LPC与H₂O₂在不存在或存在5HT的情况下孵育。通过[³H]胸腺嘧啶掺入法检测VSMC中的DNA合成。MoxLDL、LPC、H₂O₂和5HT以剂量依赖方式刺激DNA合成。MoxLDL在浓度为5μg/mL时具有最大刺激作用（211%），LPC在15μmol/L时（156%），H₂O₂在5μmol/L时（179%），5HT在50μmol/L时（205%）。moxLDL（50ng/mL）和5HT（50μmol/L）共同作用时，协同增加DNA合成（443%）。LPC（1μmol/L）与H₂O₂（0.5μmol/L）和5HT（5μmol/L）共同孵育导致DNA合成协同增加（439%），这几乎与moxLDL和5HT共同作用时（443%）相同。LPC、H₂O₂和5HT对DNA合成的联合作用通过联合使用抗氧化剂N-乙酰半胱氨酸（400μmol/L）或丁基羟基甲苯（20μmol/L）与5HT₂受体拮抗剂LY281067（10μg/mL）而完全逆转。
我们的结果表明，LPC和活性氧可能都对moxLDL对VSMC的促有丝分裂作用及其与5HT的协同作用有贡献。
