Search

Detection of Superoxide in Vascular Tissue
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 22, Issue 111 November 2002

Abstract Export Citations PDF/EPUB

Abstract
During the past decade, it has become apparent that reactive oxygen species play a critical role in the genesis of many vascular diseases. The superoxide anion is among the most important of these, not only because of its rapid reaction with NO but also because it serves as a progenitor for many other reactive oxygen species. Although there are many approaches to detecting and quantifying superoxide in chemical systems, its detection in intact tissues is more difficult. The validity of the most popular and frequently used assay for this purpose, lucigenin-enhanced chemiluminescence, has been recently questioned. It has been suggested that lucigenin itself, especially at high concentrations (>50 μmol/L), may act as a source for superoxide via redox cycling. Lower lucigenin concentrations (5 μmol/L) do not participate in redox cycling to an important extent in intact tissues and, therefore, provide an accurate assessment of the rate of superoxide production in such samples. Other useful assays for superoxide include those using the fluorescent dye dihydroethidine, 2-methyl-6-phenyl-3,7-dihydroimidazo(1,2-α)pyrazin-3-one (CLA), and 2-(p-hydroxybenzyl)-6-(p-hydroxyphenyl) 8-benzylimidazo[1,2-α]pyrazin-3-one (coelenterazine). The chemiluminescent compound 5-amino-2,3-dihydroxy-1,4-phthalayineidone (luminol) may also be used to detect various reactive oxygen species and may be made specific for various oxidants, such as hydrogen peroxide, superoxide, and peroxynitrite, by altering the experimental conditions. Although each of these methods may be associated with potential artifacts, the use of ≥2 different techniques that yield similar results provides a reliable approach for the study of reactive oxygen species in intact vascular tissues.
Depolarization of Endothelial Cells Enhances Platelet Aggregation Through Oxidative Inactivation of Endothelial NTPDase
- Florian Krötz,
- Hae Young Sohn,
- Matthias Keller,
- Torsten Gloe,
- Steffen Sebastian Bolz,
- Bernhard F. Becker and
- Ulrich Pohl
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 22, Issue 121 December 2002

Abstract Export Citations PDF/EPUB

Abstract
Objective— The objective of this study was to investigate whether depolarization of cultured endothelial cells (human umbilical vein endothelial cells, HUVECs) affects their ectonucleotidase activity through superoxide (O₂⁻) production.Methods and Results— Depolarization by the cation channel gramicidin (100 nmol/L) or tetrabutylammonium chloride (1 mmol/L) induced O₂⁻ release from HUVECs (n=4), which was decreased by superoxide dismutase (SOD, 500 U/mL). The activity of endothelial ectonucleotidases was assessed by the production of inorganic phosphate from ADP, which was decreased by chronic depolarization by 25% (n=6, P<0.05) and the amount of AMP derived from ADP in the presence of the 5′-nucleotidase inhibitor α,β-methylene-5′-diphosphate (100 μmol/L). AMP was decreased by chronic depolarization from 0.54±0.16 to 0.39±0.11 μmol/min/mg protein (n=6, P<0.05). This was abolished in the continuous presence of SOD (n=6). NTPDase protein was predominantly expressed in HUVECs (n=4). Protein abundance, viability of cells, and apoptosis rates were not altered by depolarization (n=10). Only in the presence of depolarized HUVECs, but not with control cells or with HUVECs depolarized in the presence of SOD, did 5 μmol/L of ADP cause irreversible platelet aggregation. Increases in transmural pressure induced endothelial depolarization in intact hamster small arterioles.Conclusions— Depolarization causes the endothelial production of O₂⁻, which inhibits the activity of endothelial ectonucleotidases. Increases in transmural pressure induce endothelial depolarization. In chronically hypertensive diseases, depolarization might favor platelet aggregation.
Nebivolol Prevents Vascular NOS III Uncoupling in Experimental Hyperlipidemia and Inhibits NADPH Oxidase Activity in Inflammatory Cells
- Hanke Mollnau,
- Eberhard Schulz,
- Andreas Daiber,
- Stephan Baldus,
- Matthias Oelze,
- Michael August,
- Maria Wendt,
- Ulrich Walter,
- Carolin Geiger,
- Rahul Agrawal,
- Andrei L. Kleschyov,
- Thomas Meinertz and
- Thomas Münzel
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 23, Issue 41 April 2003

Abstract Export Citations PDF/EPUB

Abstract
Objectives— Nebivolol, in contrast to other selective β₁-adrenergic receptor antagonists like atenolol, improves endothelial function in patients with oxidative stress within vascular tissue. With the present studies we sought to determine whether β receptor blockade with nebivolol may improve endothelial function in hyperlipidemia and whether this is attributable to reductions in vascular oxidative stress.Methods and Results— Watanabe heritable hyperlipidemic rabbits (WHHL) were treated with nebivolol (10 mg/kg per day for 8 weeks). New Zealand white rabbits (NZWR) served as controls. Nebivolol improved endothelial function, reduced vascular superoxide and vascular macrophage infiltration, and prevented NO synthase uncoupling in WHHL. Nebivolol treatment did not modify the expression of sGC or cGK-I but improved cGK-I activity (assessed by the phosphorylation state of the VAsodilator Stimulated Phosphoprotein at serine²³⁹, P-VASP). NAD(P)H oxidase activity in whole blood and isolated neutrophils was dose-dependently inhibited by nebivolol, whereas atenolol, metoprolol, and carvedilol were markedly less effective.Conclusions— Nebivolol therapy effectively prevents NO synthase III uncoupling and prevents activation of the neutrophil NAD(P)H oxidase and infiltration of inflammatory cells. These novel antioxidative stress actions of this compound may explain partly the beneficial effects on endothelial function in patients with enhanced vascular oxidative stress.
Low-Level Endotoxin Induces Potent Inflammatory Activation of Human Blood Vessels: Inhibition by Statins
- James B. Rice,
- Lynn L. Stoll,
- Wei-Gen Li,
- Gerene M. Denning,
- Jamie Weydert,
- Elizabeth Charipar,
- Wayne E. Richenbacher,
- Francis J. Miller and
- Neal L. Weintraub
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 23, Issue 91 September 2003

Abstract Export Citations PDF/EPUB

Abstract
Background— Low-level endotoxemia (ie, ≥50 pg/mL) in apparently healthy subjects was recently identified as a powerful, independent risk factor for atherosclerosis.Methods and Results— We treated human saphenous veins (HSVs) with low levels of endotoxin. Release of the proinflammatory chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. Superoxide was determined by using the fluorescent probe dihydroethidium (HE), and monocyte binding was assessed with calcein-labeled U-937 cells. Three- to 4-fold increases in MCP-1 and IL-8 release were observed at endotoxin concentrations of 100 pg/mL; these increases were inhibited by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin. Studies in cultured endothelial cells suggest that the mechanism is related to inhibition of isoprenylation (ie, geranylgeranylation) rather than cholesterol formation. Endotoxin produced dose-dependent increases in HE fluorescence that were inhibited by the superoxide dismutase mimics Tiron and MnTBAP. Endotoxin potently induced U-937 cell binding to HSV; binding was inhibited by both Tiron and atorvastatin. Toll-like receptor-4 expression was detected in cultured HSV endothelial and smooth muscle cells and in intact HSV.Conclusions— Clinically relevant levels of endotoxin, as reported in ambulatory populations, have profound inflammatory effects on intact HSV. Inhibition of endotoxin-induced vascular inflammation might contribute to the beneficial effects of statins in treating atherosclerosis.
Novel Vascular Biology of Third-Generation L-Type Calcium Channel Antagonists: Ancillary Actions of Amlodipine
- R.P. Mason,
- P. Marche and
- T.H. Hintze
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 23, Issue 121 December 2003

Abstract Export Citations PDF/EPUB

Abstract
Calcium channel blockers (CCBs) were developed as vasodilators, and their use in cardiovascular disease treatment remains largely based on that mechanism of action. More recently, with the evolution of second- and third-generation CCBs, pleiotropic effects have been observed, and at least some of CCBs’ benefit is attributable to these mechanisms. Understanding these effects has contributed greatly to elucidating disease mechanisms and the rationale for CCB use. Furthermore, this knowledge might clarify why drugs are useful in some disease states, such as atherosclerosis, but not in others, such as heart failure. Although numerous drugs used in the treatment of vascular disease, including statins and angiotensin-converting–enzyme inhibitors, have well-described pleiotropic effects universally accepted to contribute to their benefit, little attention has been paid to CCBs’ potentially similar effects. Accumulating evidence that at least 1 CCB, amlodipine, has pharmacologic actions distinct from L-type calcium channel blockade prompted us to investigate the pleiotropic actions of amlodipine and CCBs in general. There are several areas of research; foci here are (1) the physicochemical properties of amlodipine and its interaction with cholesterol and oxidants; (2) the mechanism by which amlodipine regulates NO production and implications; and (3) amlodipine’s role in controlling smooth muscle cell proliferation and matrix formation.
Regulation of Endogenous Reactive Oxygen Species in Platelets Can Reverse Aggregation
- Patricia Clutton,
- Anne Miermont and
- Jane E. Freedman
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 11 January 2004

Abstract Export Citations PDF/EPUB

Abstract
Objective— While much is known about the normal activation of platelets, there have been few observations demonstrating reversibility of the aggregation process. Inhibition of phosphoinositide 3-kinase (PI3-kinase) has been shown to cause platelet disaggregation. In addition, NO is a known potent inhibitor of platelet function. In this study, the role of PI3-kinase in the regulation of endogenous platelet NO and the relevance to platelet function was determined.Methods and Results— Incubation of platelets with PI3-kinase inhibitors led to a dose-dependent increase in platelet NO and cGMP levels that were temporally related to the period of platelet disaggregation. Addition of ferroheme myoglobin eliminated both the augmented NO release and disaggregation. PI3-kinase inhibition decreased the functional activation of NADPH oxidase and this corresponded to decreased superoxide release. To confirm these findings, platelets from NOS III-deficient mice were studied. These platelets did not release NO, and PI3-kinase inhibition led to decreased superoxide but not platelet disaggregation.Conclusion— Overall, these results indicate that platelet-derived NO contributes to the process of platelet disaggregation. PI3-kinase plays a role in regulating NADPH oxidase-generated superoxide in platelets and, by altering the bioactivity of platelet NO, may be a potential method for reversing platelet aggregation and thrombus formation.
Regulation of Endothelial Nitric Oxide Synthase by Tetrahydrobiopterin in Vascular Disease
- Nicholas J. Alp and
- Keith M. Channon
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 31 March 2004

Abstract Export Citations PDF/EPUB

Abstract
Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), is a key signaling molecule in vascular homeostasis. Loss of NO bioavailability due to reduced synthesis and increased scavenging by reactive oxygen species is a cardinal feature of endothelial dysfunction in vascular disease states. The pteridine cofactor tetrahydrobiopterin (BH4) has emerged as a critical determinant of eNOS activity: when BH4 availability is limiting, eNOS no longer produces NO but instead generates superoxide. In vascular disease states, there is oxidative degradation of BH4 by reactive oxygen species. However, augmentation of BH4 concentrations in vascular disease by pharmacological supplementation, by enhancement of its rate of de novo biosynthesis or by measures to reduce its oxidation, has been shown in experimental studies to enhance NO bioavailability. Thus, BH4 represents a potential therapeutic target in the regulation of eNOS function in vascular disease.
Dysfunction of Endothelial Nitric Oxide Synthase and Atherosclerosis
- Seinosuke Kawashima and
- Mitsuhiro Yokoyama
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 61 June 2004

Abstract Export Citations PDF/EPUB

Abstract
Atherosclerosis is associated with an impairment of endothelium-dependent relaxations, which represents the reduced bioavailability of nitric oxide (NO) produced from endothelial NO synthase (eNOS). Among various mechanisms implicated in the impaired EDR in atherosclerosis, superoxide generated from dysfunctional eNOS has attracted attention. Under conditions in which vascular tissue levels of tetrahydrobiopterin (BH4), a cofactor for NOS, are deficient or lacking, eNOS becomes dysfunctional and produces superoxide rather than NO. Experimental studies in vitro have revealed that NO from eNOS constitutes an anti-atherogenic molecule. A deficiency of eNOS was demonstrated to accelerate atherosclerotic lesion formation in eNOS knockout mice. In contrast, eNOS overexpression with hypercholesterolemia may promote atherogenesis via increased superoxide generation from dysfunctional eNOS. Thus, eNOS may have 2 faces in the pathophysiology of atherosclerosis depending on tissue BH4 metabolisms. An improved understanding of tissue BH4 metabolisms in atherosclerotic vessels is needed, which would help in developing new strategies for the inhibition and treatment of atherosclerosis.In hyperlipidemia and atherosclerosis, eNOS may become dysfunctional because of a lack or deficiency of tissue levels of tetrahydrobiopterin and produces superoxide rather than NO, which leads to the impaired endothelial function. The role of dysfunctional eNOS in atherogenesis is an important issue to be clarified.
Human Endothelial Progenitor Cells Tolerate Oxidative Stress Due to Intrinsically High Expression of Manganese Superoxide Dismutase
- Tongrong He,
- Timothy E. Peterson,
- Ekhson L. Holmuhamedov,
- Andre Terzic,
- Noel M. Caplice,
- Larry W. Oberley and
- Zvonimir S. Katusic
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 111 November 2004

Abstract Export Citations PDF/EPUB

Abstract
Objective— Endothelial progenitor cells (EPCs) display a unique aptitude to promote angiogenesis and restore endothelial function of injured vessels. How progenitor cells can execute a regenerative program in the unfavorable environment of injury/inflammation-induced oxidative stress is poorly understood. We hypothesized that EPCs are resistant to oxidative stress and that this resistance is due to high expression and activity of antioxidant enzymes.Methods and Results— EPCs outgrown from human blood of healthy subjects demonstrated a marked resistance to cytotoxic effect of LY83583 (an generator), tumor necrosis factor-α, and serum depletion. LY83583 inhibited in vitro tube formation by human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells (CAECs), but not by EPCs. Compared with HUVECs and CAECs, EPCs exhibited ≈3- to 4-fold higher expression and activity of manganese superoxide dismutase (MnSOD), but not copper zinc superoxide dismutase (CuZnSOD) or catalase. The antioxidant profile in EPCs was associated with preservation of the mitochondrial network when exposed to LY83583. Moreover, cytotoxic effects of LY83583 on CAECs and HUVECs were reversed by adenoviral overexpression of MnSOD.Conclusions— Human EPCs are resistant to oxidative stress. High intrinsic expression of MnSOD is a critical mechanism protecting EPCs against oxidative stress.We provide evidence that human endothelial progenitor cells (EPCs) are resistant to oxidative stress imposed by induced concentration of superoxide anions. Analysis of this phenomenon demonstrated that high intrinsic expression of manganese superoxide dismutase in EPCs is a critical mechanism underlying EPCs resistance to oxidative stress.
Hypochlorous Acid Impairs Endothelium-Derived Nitric Oxide Bioactivity Through a Superoxide-Dependent Mechanism
- Roland Stocker,
- Annong Huang,
- Erin Jeranian,
- Jing Yun Hou,
- Tina T. Wu,
- Shane R. Thomas and
- John F. Keaney
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 111 November 2004

Abstract Export Citations PDF/EPUB

Abstract
Objective— To determine how hypochlorous acid (HOCl), the principal product of myeloperoxidase, modulates vascular function.Methods and Results— Rabbit arterial rings exposed to HOCl (0 to 500 μmol/L) exhibited dose- and time-dependent impairment of endothelium-dependent arterial relaxation to acetylcholine and A23187, but not the NO donor, diethylamine NONOate, suggesting that HOCl targets the endothelium. This effect was not because of cytotoxicity, as HOCl treatment produced no significant change in endothelial cell morphology or lactate dehydrogenase release. We observed HOCl-mediated endothelial cell protein oxidation by immunoreactivity to HOP-1, a monoclonal antibody specific for HOCl-oxidized protein. In support of this notion, known HOCl scavengers, such as methionine and N-acetylcysteine, partially preserved endothelium-derived NO bioactivity in response to HOCl. In an unanticipated observation, HOCl-mediated impairment of NO bioactivity was prevented by manganese superoxide dismutase in a manner dependent on its enzymatic activity. Finally, we found that HOCl reduced endothelial nitric oxide synthase dimer stability, an effect that was also inhibited by superoxide dismutase.Conclusions— Taken together, these data indicate that HOCl imparts a defect in endothelial NO production due to a superoxide-dependent reduction in endothelial nitric oxide synthase dimer stability. These data provide another mechanism whereby myeloperoxidase-derived oxidants can contribute to the impairment of NO bioactivity that is characteristic of atherosclerosis.We found that hypochlorous acid (HOCl), the principal product of myleoperoxidase, produces impairment of endothelial NO bioactivity by reducing endothelial nitric oxide synthase dimer stability. This effect of HOCl was superoxide-dependent as it was inhibited by superoxide dismutase. Thus HOCl targets endothelial nitric oxide synthase in a superoxide-dependent manner.
Inhibitory Effect of High Concentration of Glucose on Relaxations to Activation of ATP-Sensitive K⁺ Channels in Human Omental Artery
- Hiroyuki Kinoshita,
- Toshiharu Azma,
- Katsutoshi Nakahata,
- Hiroshi Iranami,
- Yoshiki Kimoto,
- Mayuko Dojo,
- Osafumi Yuge and
- Yoshio Hatano
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 24, Issue 121 December 2004

Abstract Export Citations PDF/EPUB

Abstract
Objective— The present study was designed to examine in the human omental artery whether high concentrations of D-glucose inhibit the activity of ATP-sensitive K⁺ channels in the vascular smooth muscle and whether this inhibitory effect is mediated by the production of superoxide.Methods and Results— Human omental arteries without endothelium were suspended for isometric force recording. Changes in membrane potentials were recorded and production of superoxide was evaluated. Glibenclamide abolished vasorelaxation and hyperpolarization in response to levcromakalim. D-glucose (10 to 20 mmol/L) but not l-glucose (20 mmol/L) reduced these vasorelaxation and hyperpolarization. Tiron and diphenyleneiodonium, but not catalase, restored vasorelaxation and hyperpolarization in response to levcromakalim in arteries treated with D-glucose. Calphostin C and Gö6976 simultaneously recovered these vasorelaxation and hyperpolarization in arteries treated with D-glucose. Phorbol 12-myristate 13 acetate (PMA) inhibited the vasorelaxation and hyperpolarization, which are recovered by calphostin C as well as Gö6976. D-glucose and PMA, but not l-glucose, significantly increased superoxide production from the arteries, whereas such increased production was reversed by Tiron.Conclusions— These results suggest that in the human visceral artery, acute hyperglycemia modulates vasodilation mediated by ATP-sensitive K⁺ channels via the production of superoxide possibly mediated by the activation of protein kinase C.Our results regarding the acute effects of high glucose on the human omental artery indicate that in the human visceral artery, acute hyperglycemia modulates vasodilation mediated by ATP-sensitive K⁺ channels via the production of superoxide, possibly mediated by the activation of protein kinase C.
Redox Mechanisms in Blood Vessels
- Cornelius F.H. Mueller,
- Karine Laude,
- J. Scott McNally and
- David G. Harrison
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 25, Issue 21 February 2005

Abstract Export Citations PDF/EPUB

Abstract
Reactive oxygen species have been implicated in the pathogenesis of virtually every stage of vascular lesion formation, hypertension, and other vascular diseases. We are currently gaining insight into important sources of reactive oxygen species in the vessel wall, including the NADPH oxidases, xanthine oxidase, uncoupled nitric oxide synthase, and mitochondrial sources. Although various reactive oxygen species have pathological roles, some serve as important signaling molecules that modulate vascular tone, growth, and remodeling. In the next several months, a series of articles in Arteriosclerosis, Thrombosis, and Vascular Biology attempt to further elucidate how reactive oxygen species are produced by vascular cells and the roles of these in vascular homeostasis. This series promises to provide a valuable update on a wide variety of issues related to the biochemistry, molecular biology, and physiology of these important and fascinating molecules.Reactive oxygen species have been implicated in the pathogenesis of virtually every stage of vascular lesion formation, hypertension, and other vascular diseases. Upcoming series of articles in Arteriosclerosis, Thrombosis, and Vascular Biology help elucidate how reactive oxygen species are produced by vascular cells and their role in vascular homeostasis.
NO Generation From Nitrite and Its Role in Vascular Control
- Jon O. Lundberg and
- Eddie Weitzberg
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 25, Issue 51 May 2005

Abstract Export Citations PDF/EPUB

Abstract
NO generated from l-arginine by NO synthases (NOSs) in the endothelium and in other cells plays a central role in several aspects of vascular biology. The biological activity of NO is acutely terminated by oxidation to nitrite and nitrate, and these compounds have long been considered only as inert end-products of NO. However, this dogma is now being challenged because recent research convincingly has shown that the nitrite ion can be recycled back to bioactive NO again in blood and tissues. Nitrite reduction to NO can occur via several routes involving enzymes, proteins, vitamins, or even simple protons. This pathway may serve as a backup system for NO generation in conditions such as hypoxia, in which the NOS/l-arginine system is compromised, but detrimental effects can also be foreseen. With this new knowledge, nitrate and nitrite should probably be viewed as storage pools for NO rather than inert waste products. Here we discuss novel aspects of nitrite-dependent NO generation in vivo and its role in vascular control.NO generated from l-arginine by NO synthases in the endothelium and in other cells plays a central role in several aspects of vascular biology. The biological activity of NO is acutely terminated by oxidation to nitrite and nitrate, and these compounds have long been considered only as inert end-products of NO. However, this dogma is now being challenged, as new knowledge suggests that nitrate and nitrite should probably be viewed as storage pools for NO rather than inert waste products. Here we discuss novel aspects of nitrite-dependent NO generation in vivo and its role in vascular control.
At Least 2 Distinct Pathways Generating Reactive Oxygen Species Mediate Vascular Cell Adhesion Molecule-1 Induction by Advanced Glycation End Products
- Giuseppina Basta,
- Guido Lazzerini,
- Serena Del Turco,
- Gian Michele Ratto,
- Ann Marie Schmidt and
- Raffaele De Caterina
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 25, Issue 71 July 2005

Abstract Export Citations PDF/EPUB

Abstract
Objective— The interaction of advanced glycation end products (AGEs) with their main receptor RAGE in endothelial cells induces intracellular generation of reactive oxygen species (ROS) and the expression of vascular cell adhesion molecule (VCAM)-1. We investigated the role of distinct sources of ROS, including the mitochondrial electron transport chain, NAD(P)H oxidase, xanthine oxidase, and arachidonic acid metabolism, in AGE-induced VCAM-1 expression.Methods and Results— The induction of ROS and VCAM-1 by AGEs in cultured human umbilical vein endothelial cells was specifically blocked by an anti-RAGE antibody. The inhibition of NAD(P)H oxidase by apocynin and diphenylene iodonium, and of the mitochondrial electron transport system at complex II by thenoyltrifluoroacetone (TTFA), significantly inhibited both AGE-induced ROS production and VCAM-1 expression, whereas these effects were potentiated by rotenone and antimycin A, specific inhibitors of mitochondrial complex I and III, respectively. The inhibition of Cu/Zn superoxide dismutase inhibited both ROS and VCAM-1 induction, indicating that H₂O₂ by this source is involved as a mediator of VCAM-1 expression by AGEs.Conclusions— Altogether, these results demonstrate that ROS generated by both NAD(P)H-oxidase and the mitochondrial electron transport system are involved in AGE signaling through RAGE, and indicate potential targets for the inhibition of the atherogenic signals triggered by AGE-RAGE interaction.We investigated the role of distinct sources of reactive oxygen species (ROS), including the mitochondrial electron transport chain, NADPH oxidase, xanthine oxidase, and arachidonic acid metabolism, in advanced glycation end product (AGE)-induced VCAM-1 expression. ROS generated both by NAD(P)H oxidase and the mitochondrial electron transport system are involved in AGE signaling.
NADPH Oxidase–Dependent Superoxide Production Is Associated With Carotid Intima-Media Thickness in Subjects Free of Clinical Atherosclerotic Disease
- Guillermo Zalba,
- Oscar Beloqui,
- Gorka San José,
- María U. Moreno,
- Ana Fortuño and
- Javier Díez
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 25, Issue 71 July 2005

Abstract Export Citations PDF/EPUB

Abstract
Objective— Oxidative stress plays a critical role in the pathogenesis of atherosclerosis. The NADPH oxidase constitutes the main source of superoxide in phagocytic and vascular cells. This study aimed to investigate the levels of NADPH oxidase–mediated superoxide production in phagocytic cells and the association between phagocytic superoxide production and carotid intima-media thickness (IMT), a surrogate marker of asymptomatic atherosclerosis.Methods and Results— NADPH oxidase–mediated superoxide production was determined by a chemiluminescence assay using lucigenin and associated with IMT for 184 asymptomatic subjects free of overt clinical atherosclerotic disease. Compared with individuals in the lowest tertile of superoxide production, those in the upper tertile (>20 counts/sec) showed significantly higher IMT (P<0.05). In correlation analysis, a positive relationship was found between superoxide production and carotid IMT. Superoxide production also correlated positively (P<0.05) with body mass index (BMI). In multivariate analysis, the association of superoxide production with carotid IMT remained significant after adjustment for age, sex, systolic blood pressure, BMI, triglycerides, glucose, and smoking.Conclusions— In a population sample of adults without clinically overt atherosclerotic disease, increased NADPH oxidase activity was associated with enhanced carotid IMT, suggesting a relationship between phagocytic NADPH oxidase–mediated oxidative stress and the development of atherosclerosis.Oxidative stress plays a critical role in the pathogenesis of atherosclerosis. In a population sample of 184 adults without clinically overt atherosclerotic disease, increased NADPH oxidase–derived superoxide production from phagocytic cells associated with enhanced carotid intima-media thickness, thus suggesting a relationship between phagocytic NADPH oxidase and the development of atherosclerosis.
Oxidative Stress Promotes Endothelial Cell Apoptosis and Loss of Microvessels in the Spontaneously Hypertensive Rats
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 25, Issue 101 October 2005

Abstract Export Citations PDF/EPUB

Abstract
Objective— Endothelial cell apoptosis caused by oxidative stress may lead to the loss of microvessels (rarefaction) in hypertension. We examine here the effects of antioxidants on cell apoptosis and rarefaction.Methods and Results— The juvenile spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were treated with superoxide scavengers, Tempol or Tiron, during growth. After the treatment, oxidative stress status, endothelial cell apoptosis rate, and microvessel length density in skeletal muscle and mesentery were evaluated in comparison with age-matched controls. Untreated 16-week-old SHR had higher oxidative stress (P<0.01) and cell apoptosis rate (P<0.05) and lower microvessel length density (371±17 mm/mm³ [P<0.01]) compared with age-matched WKY rats (435±15 mm/mm³). In the SHR, but not in WKY rats, systemically applied antioxidants attenuated oxidative stress and cell apoptosis rate (P<0.05 versus untreated controls) and prevented the loss of microvessels (411±15 mm/mm³ for Tempol [P<0.01 versus untreated control] and 399±17 mm/mm³ for Tiron [P<0.05]).Conclusions— Antioxidant treatment with cell-permeable superoxide scavengers inhibits endothelial cell apoptosis and prevents microvessel rarefaction in the SHR during growth.Loss of microvessels contributes to the development of hypertensive disease. Antioxidants suppressed endothelial cell apoptosis in microvessels and preserved vessel length density in the spontaneously hypertensive rats. Oxidative stress seems to promote endothelial cell apoptosis and loss of microvessels during the development of hypertension.
Urokinase Plasminogen Activator Stimulates Vascular Smooth Muscle Cell Proliferation Via Redox-Dependent Pathways
- Mikhail Menshikov,
- Olga Plekhanova,
- Hua Cai,
- Karel Chalupsky,
- Yelena Parfyonova,
- Pavel Bashtrikov,
- Vsevolod Tkachuk and
- Bradford C. Berk
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 26, Issue 41 April 2006

Abstract Export Citations PDF/EPUB

Abstract
Objective— We showed previously that increased urokinase plasminogen activator (uPA) expression contributes to vascular smooth muscle cell (VSMC) proliferation and neointima formation after injury. Proliferation of cultured rat aortic VSMCs induced by uPA was inhibited by the antioxidant ebselen. Because increases in VSMC reactive oxygen species (ROS) contribute to VSMC proliferation, we hypothesized that uPA increases ROS generation by regulating expression or activity of cellular oxidases.Methods and Results— uPA stimulated ROS production to levels equivalent to angiotensin II as measured by electron spin resonance and fluorescent redox indicators (dichlorofluorescein diacetate, lucigenin, and hydroethidine). The increase in ROS was biphasic, with the first peak at 30 minutes and the second peak at 4 hours. uPA increased expression of the NAD(P)H oxidases Nox1 and Nox4 as measured by RT-PCR and Western blot analysis. Knockdown of Nox1 and Nox4 expression with small interfering RNA showed that both isoforms (Nox1>Nox4) contributed significantly to uPA-stimulated ROS production and VSMC proliferation. Transfection of VSMCs with uPA cDNA to increase endogenous uPA expression enhanced ROS production dramatically, suggesting that autocrine uPA production may be an important mechanism for uPA-mediated VSMC events.Conclusion— These data show that uPA is an autocrine VSMC growth factor that increases ROS generated by both Nox1 and Nox4 oxidases.uPA stimulates VSMC proliferation after vascular injury. uPA biphasically stimulated ROS production (which was partly inhibited by Nox1 or Nox4 siRNA) and increased expression of the oxidases Nox1 and Nox4. Transfection with uPA cDNA enhanced ROS production, suggesting that uPA-mediated autocrine ROS production contributes to vascular remodeling.
MnSOD Deficiency Increases Endothelial Dysfunction in ApoE-Deficient Mice
- Masuo Ohashi,
- Marschall S. Runge,
- Frank M. Faraci and
- Donald D. Heistad
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 26, Issue 101 October 2006

Abstract Export Citations PDF/EPUB

Abstract
Objective— In mice that are heterozygous for mitochondrial superoxide dismutase (SOD2^+/−) with apoE deficiency (apoE^−/−), mitochondrial DNA damage increases formation of atherosclerotic lesions. The purpose of this study was to determine whether SOD2 provides protection against increased vascular superoxide and endothelial dysfunction in apoE-deficient mice.Methods and Results— Four groups of mice [apoE^−/−/SOD2^+/− (apoe/sod2), apoE^−/−/SOD2^+/+ (apoe/SOD2), apoE^+/+/SOD2^+/− (apoE/sod2), and apoE^+/+/SOD2^+/+ (apoE/SOD2)] were fed normal chow diet, and studied at 15 to 17 months of age. Serum cholesterol levels were similar in apoe/sod2 and apoe/SOD2 mice, and also were similar in apoE/sod2 and apoE/SOD2 mice. Intimal area was increased in aorta, but not carotid artery, of apoe/sod2 and apoe/SOD2 mice. In carotid artery, superoxide was increased (67±5.2 relative fluorescence intensity/vessel area [RI] in apoe/sod2 mice, 31±3.1 RI in apoE/SOD2 mice, P<0.05), and relaxation to acetylcholine was impaired in apoe/sod2 mice versus apoe/ SOD2, apoE/sod2, apoE/SOD2 mice. Tiron improved relaxation to acetylcholine. In aorta, superoxide levels were increased and relaxation to acetylcholine was impaired in apoe/sod2 and apoe/SOD2 mice, but responses were similar in apoe/sod2 and apoe/SOD2 mice.Conclusion— SOD2 protects against oxidative stress and endothelial dysfunction in carotid artery of apoE-deficient mice.The purpose of this study was to determine whether SOD2 provides protection against increased vascular superoxide and endothelial dysfunction in apoE-deficient mice. Superoxide was increased and relaxation to acetylcholine was impaired more in carotid artery of apoE^−/−SOD2^+/− mice than apoE^−/−SOD2^+/+ mice. These findings indicate that SOD2 protects against oxidative stress and endothelial dysfunction in atherosclerosis.
Phagocytic NADPH Oxidase-Dependent Superoxide Production Stimulates Matrix Metalloproteinase-9: Implications for Human Atherosclerosis
- Guillermo Zalba,
- Ana Fortuño,
- Josune Orbe,
- Gorka San José,
- María U. Moreno,
- Miriam Belzunce,
- José Antonio Rodríguez,
- Oscar Beloqui,
- José Antonio Páramo and
- Javier Díez
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 27, Issue 31 March 2007

Abstract Export Citations PDF/EPUB

Abstract
Objective— Data suggest that matrix metalloproteinase-9 (MMP-9) has a role in atherosclerosis. The phagocytic NADPH oxidase has been also associated with atherosclerosis. This study aimed to investigate the association between phagocytic NADPH oxidase and MMP-9 in human atherosclerosis.Methods and Results— In vitro experiments performed in human monocytes showed that NADPH oxidase activation enhanced MMP-9 secretion and activity, determined by enzyme-linked immunosorbent assay and zymography, respectively. Immunohistochemical study showed that phagocytic NADPH oxidase localized with MMP-9 in endarterectomies from patients with carotid stenosis. In addition, a positive relationship (P<0.001) was found between phagocytic NADPH oxidase-dependent superoxide production determined with lucigenin and plasma MMP-9 levels in 188 asymptomatic subjects free of overt clinical atherosclerosis. In multivariate analysis, this association remained significant after adjustment for cardiovascular risk factors. Interestingly, subjects in the upper quartile of superoxide production exhibited the highest values of MMP-9, oxidized low-density lipoprotein, nitrotyrosine, carotid intima media thickness, and an increased presence of carotid plaques.Conclusions— Enhanced NADPH oxidase-dependent ·O₂⁻ production stimulates MMP-9 in monocytes and this relationship may be relevant in the atherosclerotic process. Moreover, MMP-9 emerges as an important mediator of the phagocytic NADPH oxidase-dependent oxidative stress in atherosclerosis.Enhanced ·O₂⁻ production increased MMP-9 activation in monocytes. NADPH oxidase and MMP-9 colocalized in atherosclerotic plaques. Enhanced NADPH oxidase-dependent ·O₂⁻ production associated with enhanced plasma MMP-9 levels in asymptomatic individuals. Interestingly, subjects in the upper quartile of ·O₂⁻ production associated with subclinical carotid atherosclerosis.
The Interstitium of the Human Arterial Wall Contains Very Large Amounts of Extracellular Superoxide Dismutase
- Pontus Strålin,
- Kurt Karlsson,
- Bengt O. Johansson and
- Stefan L. Marklund
Arteriosclerosis, Thrombosis, and Vascular Biology Volume 15, Issue 111 November 1995

Abstract Export Citations PDF/EPUB

Abstract
Abstract The levels of the secreted, interstitially located extracellular superoxide dismutase (EC-SOD), the cytosolic copper-and-zinc–containing SOD (CuZn-SOD), and the mitochondrial manganese-containing SOD (Mn-SOD) were measured in the walls of human coronary arteries, proximal thoracic aortas, and saphenous veins. The blood vessel walls, particularly the arteries, were found to contain exceptionally large amounts of EC-SOD, whereas the levels of CuZn-SOD and Mn-SOD were relatively low compared with other tissues. Analysis of EC-SOD by immunohistochemistry indicates an even distribution in the vessel wall, including large amounts in the arterial intima. Arterial smooth muscle cells were found to secrete large amounts of EC-SOD and likely are the principal source of the enzyme in the vascular wall. The EC-SOD concentration in the human arterial wall extracellular space is high enough to efficiently suppress the putative pathological effects of the superoxide radical, such as oxidation of LDL and reaction with nitric oxide to form the deleterious peroxynitrite. The levels of EC-SOD in the aortic wall are found to vary widely among species and were on average 6440 U/g in humans, 4340 U/g in the cow, 2660 U/g in the pig, 160 U/g in the dog, 770 U/g in the cat, 2390 U/g in the rabbit, 90 U/g in the rat, and 3400 U/g in the mouse. There were only moderate differences in the amounts of CuZn-SOD and Mn-SOD. This wide variation in EC-SOD content suggests that the susceptibility to pathologies induced by superoxide radicals in the vascular wall interstitium should vary widely among species.

Search

Narrow Results

Applied FiltersReset all

Journal Title

Article Type

Subject

Date Range

Author

Export Citation

Advanced

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Export Citation