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Evidence-Based Complementary and Alternative Medicine
Volume 2014 (2014), Article ID 627181, 10 pages
http://dx.doi.org/10.1155/2014/627181
Research Article

Tetramethylpyrazine Protects against Hydrogen Peroxide-Provoked Endothelial Dysfunction in Isolated Rat Aortic Rings: Implications for Antioxidant Therapy of Vascular Diseases

1Guangdong Provincial Hospital of Chinese Medicine, No. 111 Dade Road, Guangzhou 510120, China
2Second College of Clinical Medicine, Guangzhou University of Chinese Medicine, No. 12 Jichang Road, Guangzhou 510405, China
3School of Biomedical Sciences, Chinese University of Hong Kong, Shatin, NT, Hong Kong

Received 24 February 2014; Revised 30 July 2014; Accepted 7 August 2014; Published 2 September 2014

Academic Editor: I-Min Liu

Copyright © 2014 Xiaojia Ni et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 () 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 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.