Endothelial Cell Oxidant Production: Effect of NADPH Oxidase Inhibitors

Abstract

The effects of known leukocyte NADPH oxidase inhibitors on general cellular oxidant production in cultured human endothelial cells (EC) has been investigated. EC were stimulated with 10 nM phorbol 12-myristate 13-acetate and cellular oxidant production measured in the presence and absence of inhibitors that act on various substituents of the oxidase complex and its activation pathways. The effects of the cytosolic oxidase subunit translocation inhibitors, catechols (3,4-dihydroxybenzaldehyde, caffeic acid, and protocatechuic acid), ortho-methoxy-substituted catechols (apocynin, vanillin, and 4-nitroguaiacol), and quinone, 1,4-naphthoquinone; flavoprotein inhibitors, diphenylene iodonium and quinacrine; haem ligands, imidazole and pyridine; directly acting thiol reagents, disulfiram and penicillamine; NADPH analogue, Cibacron Blue; redox active inhibitors, quercetin and esculetin; intracellular calcium antagonist, TMB-8; and calmodulin antagonists, W-7 and trifluoperazine, were determined. All compounds reduced oxidant production in stimulated EC. These findings add to previous observations suggesting the presence of a functionally active NADPH oxidase in EC. Identifying the major cellular reactive oxygen species source in perturbed EC will provide new insights into our understanding of endothelial dysfunction, which has been hypothesized to be a major contributing factor in the pathogenesis of atherosclerosis.

Interaction of myeloperoxidase with vascular NAD(P)H oxidase-derived reactive oxygen species in vasculature: implications for vascular diseases

“…However, under pathological conditions such as atherosclerosis, hypertension, and diabetes, the production of H 2 O 2 is much higher than its degradation. Thus the H 2 O 2 content in the vascular wall under the above-mentioned pathological conditions is much higher than in normal vessels, although the absolute tissue concentration needs to be determined (13,16,20,21). One recent report (26) indicates that vascular NAD(P)H oxidase-derived ROS might be more important than leukocyte NAD(P)H oxidase-derived ROS in the pathogenesis of atherosclerosis, because a deficiency in leukocyte NAD(P)H oxidase fails to inhibit atherosclerosis in mice with either diet-induced or genetic forms of hypercholesterolemia.…”

“…There are two different kinds of NAD(P)H oxidases: leukocyte-derived and nonleukocyte-derived NAD(P)H oxidase (13,37). Vascular NAD(P)H oxidases belong to the nonleukocyte-derived NAD(P)H oxidase and are the major sources of ROS in both atherosclerotic and diabetic vasculature (13,16,20,21,43). Vascular NAD(P)H oxidases-derived ROS such as H 2 O 2 have emerged as important molecules in pathogenesis of inflammatory vascular diseases.…”

NADPH oxidase(s): new source(s) of reactive oxygen species in the vascular system?

“…17 Vascular NADPH oxidase produced ROS in human in vitro studies PMA Apocynin, DPI, and other non-specific inhibitors attenuated ROS production in HUVEC cultures pretreated with PMA. 44 …”

Downregulation of Rac1 activation by caffeic acid in aortic smooth muscle cells

“…Recent reports indicated that caffeic acid-treatment enhances intracellular resistance to an oxidative challenge (Nardini et al, 1998), and blocked the intracellular redox-sensitive activation of EGF receptor at 4~5 h induced by the oxidized LDL (Vacaresse et al, 2001). Two groups indicated that caffeic acid might inhibit NADPH oxidase activation in human endothelial cells (Holland et al, 2000) and in human polymorphonuclear leukocytes (PMN) (Daniels et al, 1998).…”