Wenzel Philip, Schuhmacher Swenja, Kienhöfer Joachim, Müller Johanna, Hortmann Marcus, Oelze Matthias, Schulz Eberhard, Treiber Nicolai, Kawamoto Toshihiro, Scharffetter-Kochanek Karin, Münzel Thomas, Bürkle Alexander, Bachschmid Markus Michael, Daiber Andreas
Second Medical Clinic, Department of Cardiology, Johannes Gutenberg University, Mainz, Germany.
Cardiovasc Res. 2008 Nov 1;80(2):280-9. doi: 10.1093/cvr/cvn182. Epub 2008 Jul 2.
Imbalance between pro- and antioxidant species (e.g. during aging) plays a crucial role for vascular function and is associated with oxidative gene regulation and modification. Vascular aging is associated with progressive deterioration of vascular homeostasis leading to reduced relaxation, hypertrophy, and a higher risk of thrombotic events. These effects can be explained by a reduction in free bioavailable nitric oxide that is inactivated by an age-dependent increase in superoxide formation. In the present study, mitochondria as a source of reactive oxygen species (ROS) and the contribution of manganese superoxide dismutase (MnSOD, SOD-2) and aldehyde dehydrogenase (ALDH-2) were investigated.
Age-dependent effects on vascular function were determined in aortas of C57/Bl6 wild-type (WT), ALDH-2(-/-), MnSOD(+/+), and MnSOD(+/-) mice by isometric tension measurements in organ chambers. Mitochondrial ROS formation was measured by luminol (L-012)-enhanced chemiluminescence and 2-hydroxyethidium formation with an HPLC-based assay in isolated heart mitochondria. ROS-mediated mitochondrial DNA (mtDNA) damage was detected by a novel and modified version of the fluorescent-detection alkaline DNA unwinding (FADU) assay. Endothelial dysfunction was observed in aged C57/Bl6 WT mice in parallel to increased mitochondrial ROS formation and oxidative mtDNA damage. In contrast, middle-aged ALDH-2(-/-) mice showed a marked vascular dysfunction that was similar in old ALDH-2(-/-) mice suggesting that ALDH-2 exerts age-dependent vasoprotective effects. Aged MnSOD(+/-) mice showed the most pronounced phenotype such as severely impaired vasorelaxation, highest levels of mitochondrial ROS formation and mtDNA damage.
The correlation between mtROS formation and acetylcholine-dependent relaxation revealed that mitochondrial radical formation significantly contributes to age-dependent endothelial dysfunction.
促氧化剂和抗氧化剂之间的失衡（如在衰老过程中）对血管功能起着关键作用，并与氧化基因调控及修饰相关。血管衰老与血管稳态的渐进性恶化相关，导致舒张功能降低、肥大以及血栓形成事件风险增加。这些效应可通过游离生物可利用一氧化氮的减少来解释，一氧化氮会因超氧化物生成的年龄依赖性增加而失活。在本研究中，对作为活性氧（ROS）来源的线粒体以及锰超氧化物歧化酶（MnSOD，SOD - 2）和醛脱氢酶（ALDH - 2）的作用进行了研究。
通过器官浴槽中的等长张力测量，测定C57/Bl6野生型（WT）、ALDH - 2（ - / - ）、MnSOD（ + / + ）和MnSOD（ + / - ）小鼠主动脉中年龄依赖性对血管功能的影响。通过鲁米诺（L - 012）增强的化学发光以及在分离的心脏线粒体中基于高效液相色谱法测定2 - 羟基乙锭的形成来测量线粒体ROS生成。通过一种新颖且改良的荧光检测碱性DNA解旋（FADU）试验检测ROS介导的线粒体DNA（mtDNA）损伤。在老年C57/Bl6 WT小鼠中观察到内皮功能障碍，同时线粒体ROS生成增加和mtDNA氧化损伤。相反，中年ALDH - 2（ - / - ）小鼠表现出明显的血管功能障碍，老年ALDH - 2（ - / - ）小鼠中也是如此，这表明ALDH - 2发挥年龄依赖性血管保护作用。老年MnSOD（ + / - ）小鼠表现出最显著的表型，如血管舒张严重受损、线粒体ROS生成和mtDNA损伤水平最高。
mtROS生成与乙酰胆碱依赖性舒张之间的相关性表明，线粒体自由基形成显著促成了年龄依赖性内皮功能障碍。
