This Article Full Text Full Text (PDF) All Versions of this Article: 51/2/172    most recent HYPERTENSIONAHA.107.103200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Touyz, R. M. Search for Related Content PubMed PubMed Citation Articles by Touyz, R. M. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Related Collections Cell biology/structural biology Hypertension - basic studies Other Vascular biology Related Article

(Hypertension. 2008;51:172.)
© 2008 American Heart Association, Inc.

Editorial Commentaries

Apocynin, NADPH Oxidase, and Vascular Cells

A Complex Matter

Rhian M. Touyz

From the Kidney Research Centre, Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada.

Correspondence to Rhian M. Touyz, Kidney Research Centre, University of Ottawa/Ottawa Health Research Institute, 451 Smyth Rd, Ottawa, Ontario, KIH 8M5 Canada. E-mail rtouyz@uottawa.ca

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Apocynin (4-hydroxy-3-methoxyacetophenone), isolated from the traditional medicinal plant Picrorhiza kurroa, is a naturally occurring methoxy-substituted catechol, experimentally used as an inhibitor of reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase.¹ Activated neutrophil NADPH oxidase, a multisubunit complex composed of membrane-associated gp91phox (Nox2) and p22phox and cytosolic subunits, p47phox, p67phox, and p40phox, produces superoxide anion, a precursor of microbicidal reactive oxygen species (ROS), thereby playing a crucial role in host defense. Apocynin inhibits the release of superoxide anion by NADPH oxidase by blocking migration of p47phox to the membrane, critically involved in initiating assembly of the functional NADPH oxidase complex.¹ The underlying chemistry of apocynin’s actions has been elucidated in phagocytic cells.² Apocynin needs to be activated (oxidized) for it to inhibit the oxidase. In the presence of H₂O₂ and myeloperoxidase (MPO), abundant in neutrophils, apocynin is oxidized and has as products dimer and trimer derivatives resulting in diapocynin formation, the metabolically active compound of apocynin. The reactivity of apocynin radical with thiol compounds is possibly the mechanism involved in the inhibitory effect of apocynin on the NADPH oxidase complex.^2,3

In the early 1990s, with the discovery that cardiovascular cells possess functionally active NADPH oxidase critically involved in ROS generation and oxidative stress in the vascular wall, many investigators extended neutrophil findings and used apocynin as a pharmacological agent to specifically inhibit the vascular cell oxidase. Convincing data from numerous in vitro studies demonstrated that, in endothelial cells, vascular smooth muscle cells, and adventitial fibroblasts, apocynin blocks NADPH oxidase activity and . . . [Full Text of this Article]

Related Article:

Apocynin Is Not an Inhibitor of Vascular NADPH Oxidases but an Antioxidant

Sabine Heumüller, Sven Wind, Eduardo Barbosa-Sicard, Harald H.H.W. Schmidt, Rudi Busse, Katrin Schröder, and Ralf P. Brandes
Hypertension 2008 51: 211-217. [Abstract] [Full Text] [PDF]

This article has been cited by other articles:

				S. J. Park, Y.-S. Chun, K. S. Park, S. J. Kim, S.-O. Choi, H.-L. Kim, and J.-W. Park Identification of subdomains in NADPH oxidase-4 critical for the oxygen-dependent regulation of TASK-1 K+ channels Am J Physiol Cell Physiol, October 1, 2009; 297(4): C855 - C864. [Abstract] [Full Text] [PDF]

				W. G. Mayhan, D. M. Arrick, G. M. Sharpe, and H. Sun Nitric oxide synthase-dependent responses of the basilar artery during acute infusion of nicotine Nicotine Tob Res, March 1, 2009; 11(3): 270 - 277. [Abstract] [Full Text] [PDF]

				P. Zhang, M. Hou, Y. Li, X. Xu, M. Barsoum, Y. Chen, and R. J. Bache NADPH oxidase contributes to coronary endothelial dysfunction in the failing heart Am J Physiol Heart Circ Physiol, March 1, 2009; 296(3): H840 - H846. [Abstract] [Full Text] [PDF]

				A. S. Godbole, X. Lu, X. Guo, and G. S. Kassab NADPH oxidase has a directional response to shear stress Am J Physiol Heart Circ Physiol, January 1, 2009; 296(1): H152 - H158. [Abstract] [Full Text] [PDF]

				C. S. Wilcox and A. Pearlman Chemistry and Antihypertensive Effects of Tempol and Other Nitroxides Pharmacol. Rev., December 1, 2008; 60(4): 418 - 469. [Abstract] [Full Text] [PDF]

				N. Tian, R. S. Moore, W. E. Phillips, L. Lin, S. Braddy, J. S. Pryor, R. L. Stockstill, M. D. Hughson, and R. D. Manning Jr. NADPH oxidase contributes to renal damage and dysfunction in Dahl salt-sensitive hypertension Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2008; 295(6): R1858 - R1865. [Abstract] [Full Text] [PDF]

				X. Zhou, H. G. Bohlen, S. J. Miller, and J. L. Unthank NAD(P)H oxidase-derived peroxide mediates elevated basal and impaired flow-induced NO production in SHR mesenteric arteries in vivo Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1008 - H1016. [Abstract] [Full Text] [PDF]