Zhang Guo-Gang, Shi Rui-Zheng, Jiang De-Jian, Chen Yue-Rong, Tang Zheng-Yan, Bai Yong-Ping, Xiao Hong-Bo, Li Yuan-Jian
Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, 410008, China.
Life Sci. 2008 Mar 26;82(13-14):699-707. doi: 10.1016/j.lfs.2008.01.002. Epub 2008 Jan 18.
Previous studies have shown that nitroglycerin (GTN) tolerance is closely related to an oxidative stress-induced decrease in activity of mitochondrial isoforms of aldehyde dehydrogenase (ALDH-2), and prolonged GTN treatment causes endothelial dysfunction. Asymmetric dimethylarginine (ADMA), a major endogenous NO synthase (NOS) inhibitor, could inhibit NO production and induce oxidative stress in endothelial cells. ADMA and its major hydrolase dimethylarginine dimethylaminohydrolase (DDAH) have recently been thought of as a novel regulatory system of endothelium function. The aim of the present study was to determine whether the DDAH/ADMA pathway is involved in the development of GTN tolerance in endothelial cells. Tolerance, reflected by the decrease in cyclic GMP (cGMP) production, was induced by exposure of human umbilical vein endothelial cells (HUVECs) to GTN (10 microM) for 16 h. While the treatment increased reactive oxygen species (ROS) production/malondialdehyde (MDA) concentration and decreased ALDH-2 activity as well as cGMP production, it markedly increased the level of ADMA in culture medium and decreased DDAH activity in endothelial cells. Exogenous ADMA significantly enhanced ROS production/MDA concentration and inhibited ALDH-2 activity, and overexpression of DDAH2 could significantly suppress GTN-induced oxidative stress and inhibition of ALDH-2 activity, which is also attenuated by L-arginine. Therefore, our results suggest for the first time that the endothelial DDAH/ADMA pathway plays an important role in the development/maintenance of GTN tolerance.
先前的研究表明，硝酸甘油（GTN）耐受性与氧化应激诱导的线粒体醛脱氢酶（ALDH-2）亚型活性降低密切相关，长期使用GTN治疗会导致内皮功能障碍。不对称二甲基精氨酸（ADMA）是一种主要的内源性一氧化氮合酶（NOS）抑制剂，可抑制一氧化氮生成并在内皮细胞中诱导氧化应激。ADMA及其主要水解酶二甲基精氨酸二甲胺水解酶（DDAH）最近被认为是内皮功能的一种新型调节系统。本研究的目的是确定DDAH/ADMA途径是否参与内皮细胞中GTN耐受性的形成。通过将人脐静脉内皮细胞（HUVECs）暴露于GTN（10 microM）16小时来诱导耐受性，以环磷酸鸟苷（cGMP）生成减少来反映。该处理增加了活性氧（ROS）生成/丙二醛（MDA）浓度，降低了ALDH-2活性以及cGMP生成，同时显著增加了培养基中ADMA的水平，并降低了内皮细胞中的DDAH活性。外源性ADMA显著增强了ROS生成/MDA浓度并抑制了ALDH-2活性，DDAH2的过表达可显著抑制GTN诱导的氧化应激和对ALDH-2活性的抑制，L-精氨酸也可减轻这种抑制。因此，我们的结果首次表明内皮DDAH/ADMA途径在GTN耐受性的形成/维持中起重要作用。
