d'Uscio L V, Baker T A, Mantilla C B, Smith L, Weiler D, Sieck G C, Katusic Z S
Departments of Anesthesiology and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
Arterioscler Thromb Vasc Biol. 2001 Jun;21(6):1017-22. doi: 10.1161/01.atv.21.6.1017.
Endothelium-dependent relaxations mediated by NO are impaired in a mouse model of human atherosclerosis. Our objective was to characterize the mechanisms underlying endothelial dysfunction in aortas of apolipoprotein E (apoE)-deficient mice, treated for 26 to 29 weeks with a lipid-rich Western-type diet. Aortic rings from apoE-deficient mice showed impaired endothelium-dependent relaxations to acetylcholine (10(-)(9) to 10(-)(5) mol/L) and Ca(2+) ionophore (10(-)(9) to 10(-)(6) mol/L) and endothelium-independent relaxations to diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-)(10) to 10(-)(5) mol/L) compared with aortic rings from C57BL/6J mice (P<0.05). By use of confocal microscopy of an oxidative fluorescent probe (dihydroethidium), increased superoxide anion (O(2)(-)) production was demonstrated throughout the aortic wall but mainly in smooth muscle cells of apoE-deficient mice. CuZn-superoxide dismutase (SOD) and Mn-SOD protein expressions were unaltered in the aorta exposed to hypercholesterolemia. A cell-permeable SOD mimetic, Mn(III) tetra(4-benzoic acid) porphyrin chloride (10(-)(5) mol/L), reduced O(2)(-) production and partially normalized relaxations to acetylcholine and DEA-NONOate in apoE-deficient mice (P<0.05). [(14)C]L-Citrulline assay showed a decrease of Ca(2+)-dependent NOS activity in aortas from apoE-deficient mice compared with C57BL/6J mice (P<0.05), whereas NO synthase protein expression was unchanged. In addition, cGMP levels were significantly reduced in the aortas of apoE-deficient mice (P<0.05). Our results demonstrate that in apoE-deficient mice on a Western-type fat diet, impairment of endothelial function is caused by increased production of O(2)(-) and reduced endothelial NO synthase enzyme activity. Thus, chemical inactivation of NO with O(2)(-) and reduced biosynthesis of NO are key mechanisms responsible for endothelial dysfunction in aortas of atherosclerotic apoE-deficient mice.
在人类动脉粥样硬化的小鼠模型中，由一氧化氮（NO）介导的内皮依赖性舒张功能受损。我们的目的是确定载脂蛋白E（apoE）缺陷小鼠主动脉内皮功能障碍的潜在机制，这些小鼠用富含脂质的西式饮食治疗26至29周。与C57BL/6J小鼠的主动脉环相比，apoE缺陷小鼠的主动脉环对乙酰胆碱（10⁻⁹至10⁻⁵mol/L）和钙离子载体（10⁻⁹至10⁻⁶mol/L）的内皮依赖性舒张功能受损，对二乙铵（Z）-1-（N，N-二乙氨基）重氮-1，2-二醇盐（DEA-NONOate，10⁻¹⁰至10⁻⁵mol/L）的非内皮依赖性舒张功能也受损（P<0.05）。通过使用氧化荧光探针（二氢乙锭）的共聚焦显微镜检查，在整个主动脉壁中均显示超氧阴离子（O₂⁻）产生增加，但主要在apoE缺陷小鼠的平滑肌细胞中。暴露于高胆固醇血症的主动脉中铜锌超氧化物歧化酶（SOD）和锰超氧化物歧化酶的蛋白表达未改变。一种细胞可渗透的SOD模拟物，氯化锰（III）四（4-苯甲酸）卟啉（10⁻⁵mol/L），减少了O₂⁻的产生，并使apoE缺陷小鼠对乙酰胆碱和DEA-NONOate的舒张功能部分恢复正常（P<0.05）。[¹⁴C]L-瓜氨酸测定显示，与C57BL/6J小鼠相比，apoE缺陷小鼠主动脉中钙依赖性一氧化氮合酶活性降低（P<0.05），而一氧化氮合酶蛋白表达未改变。此外，apoE缺陷小鼠主动脉中的环鸟苷酸（cGMP）水平显著降低（P<0.05）。我们的结果表明，在西式高脂肪饮食的apoE缺陷小鼠中，内皮功能障碍是由O₂⁻产生增加和内皮型一氧化氮合酶活性降低引起的。因此，O₂⁻对NO的化学失活和NO生物合成减少是动脉粥样硬化apoE缺陷小鼠主动脉内皮功能障碍的关键机制。
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