title: Tetramethylpyrazine Protects against Hydrogen Peroxide-Provoked Endothelial Dysfunction in Isolated Rat Aortic Rings: Implications for Antioxidant Therapy of Vascular Diseases.
abstract: Background and Objectives. Oxidative stress can initiate endothelial dysfunction and atherosclerosis. This study evaluated whether tetramethylpyrazine (TMP), the predominant active ingredient in Rhizoma Ligustici Wallichii (chuanxiong), prevents endothelial dysfunction in a rat model of oxidative stress. Methods. Isolated rat aortic rings were pretreated with various drugs before the induction of endothelial dysfunction by hydrogen peroxide (H2O2). Changes in isometric tension were then measured in acetylcholine- (ACh-) relaxed rings. Endothelial nitric oxide synthase (eNOS) expression was evaluated in the rings by Western blotting, and superoxide anion (O2 (∙-)) content was assessed in primary rat aortic endothelial cells by dihydroethidium- (DHE-) mediated fluorescence microscopy. Results. ACh-induced endothelium-dependent relaxation (EDR) was disrupted by H2O2 in endothelium-intact aortic rings. H2O2-impaired relaxation was ameliorated by acute pretreatment with low concentrations of TMP, as well as by pretreatment with catalase and the NADPH oxidase inhibitors, apocynin and diphenyleneiodonium (DPI). TMP, apocynin, and DPI also reduced O2 (∙-) accumulation in endothelial cells,but TMP failed to alter eNOS expression in aortic rings incubated with H2O2. Conclusions. TMP safeguards against oxidative stress-induced endothelial dysfunction, suggesting that the agent might find therapeutic utility in the management of vascular diseases. However, TMP's role in inhibiting NADPH oxidase and its vascular-protective mechanism of action requires further investigation.
authors.affiliation: Guangdong Provincial Hospital of Chinese Medicine, No. 111 Dade Road, Guangzhou 510120, China ; Second College of Clinical Medicine, Guangzhou University of Chinese Medicine, No. 12 Jichang Road, Guangzhou 510405, China ; School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Xiaojia
authors.identifier: 0000-0001-6624-5244
authors.initials: X
authors.lastname: Ni
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Siu Ling
authors.identifier: 0000-0002-2294-3187
authors.initials: SL
authors.lastname: Wong
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Chi Ming
authors.identifier: 0000-0002-3048-8890
authors.initials: CM
authors.lastname: Wong
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Chi Wai
authors.initials: CW
authors.lastname: Lau
authors.affiliation: Guangdong Provincial Hospital of Chinese Medicine, No. 111 Dade Road, Guangzhou 510120, China.
authors.forename: Xiaogeng
authors.initials: X
authors.lastname: Shi
authors.affiliation: Guangdong Provincial Hospital of Chinese Medicine, No. 111 Dade Road, Guangzhou 510120, China.
authors.forename: Yefeng
authors.initials: Y
authors.lastname: Cai
authors.affiliation: School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong.
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang