(Circulation. 2000;101:2206.)
© 2000 American Heart Association, Inc.
Basic Science Reports |
From the Department of Medicine and Therapeutics, University of Glasgow, Glasgow, UK.
Correspondence to Dr Colin Berry, Department of Medicine and Therapeutics, University of Glasgow, 44 Church St, Glasgow G11 6NT, Scotland, UK. E-mail colin.berry{at}clinmed.gla.ac.uk
| Abstract |
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Methods and ResultsInternal mammary arteries (IMAs) and saphenous veins (SVs) were collected at the time of cardiac surgery. Vessels were incubated in Krebs buffer at 37°C. ·O2- was measured by lucigenin chemiluminescence. Basal ·O2- concentrations were greater in IMAs than SVs. Inhibitors of NAD(P)H oxidase (10 µmol/L to 200 µmol/L diphenyleneiodonium) and xanthine oxidase (1 mmol/L allopurinol) caused reductions in ·O2- concentrations in both IMAs and SVs. Western blotting of superoxide dismutase proteins demonstrated similar expression in IMAs and SVs. Vessels were also incubated in the presence or absence of Ang II (1 pmol/L to 1 µmol/L). Ang II increased ·O2- production in IMAs at 4 hours of incubation (control, 978±117 pmol · min-1 · mg-1; 1 µmol/L of Ang II, 1690±213 pmol · min-1 · mg-1; n=27, P=0.0001, 95% CI 336, 925) but not in SVs. This effect was completely inhibited by coincubation of IMAs with DPI (100 µmol/L), a nonspecific Ang II antagonist ([sar1, thre8]Ang II, 1 µmol/L) and a specific Ang II type 1 (AT1) receptor antagonist (losartan, 1 µmol/L).
Conclusions ·O2- production is greater in human IMAs than in SVs. NAD(P)H oxidase and xanthine oxidase are sources of ·O2- production in these vessels. The vasoactive peptide Ang II increases ·O2- production in human arteries by an AT1 receptordependent mechanism.
Key Words: free radicals arteries veins angiotensin receptors
| Introduction |
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In experimental animals, the cellular sources of vascular ·O2- production in animals are the endothelium,8 vascular smooth muscle cells (VSMCs),9 and adventitial fibroblasts.10 The main enzymatic sources of ·O2- production within the vascular wall are NAD(P)H oxidase,11 xanthine oxidase,12 and endothelial NO synthase (eNOS) enzyme.13 Superoxide can be removed by reaction with other free radicals, such as NO, to form peroxynitrite1 or enzymatically by superoxide dismutase (SOD) to form H2O2.14 Three mammalian SODs exist: copper/zinc SOD (Cu/Zn-SOD), manganese SOD (Mn-SOD), and extracellular SOD (EC-SOD). Mn-SOD and Cu/Zn-SOD are major vascular isoforms and are important in both scavenging vascular ·O2- and enhancing the bioavailability of endothelial NO.15
Further evidence from animal studies suggests that the activity of one ·O2--producing enzyme, NAD(P)H oxidase, may be modulated by angiotensin II (Ang II) and that ·O2-, in turn, may play a role in the physiological and pathophysiological actions of this peptide. Ang II increases VSMC ·O2- production by activation of a membrane-bound NAD(P)H oxidase.16 In rats chronically infused with pressor and nonpressor doses of Ang II, increased vascular NAD(P)H oxidase ·O2- production contributed to the development of both endothelial dysfunction and hypertension.17 In rabbits, activation of the renin-angiotensin system also contributes to increased ·O2- production and vascular dysfunction.18
Superoxide production has recently been measured in human arteries but not in veins.19 The enzymatic sources of ·O2- generation in human blood vessels, however, have not been identified. Furthermore, it is not known whether Ang II alters ·O2- production in human blood vessels. We hypothesized that angiotensin II, in addition to its known physiological and pathophysiological effects, is able to stimulate ·O2- generation in human vessels and furthermore, that this mechanism can be inhibited with a specific Ang II type 1 (AT1) receptor antagonist.
Our aims in this study were first, to study the cellular and enzymatic sources of ·O2- production in human blood vessels; second, to quantify the amount of SOD protein present in arteries and veins to assess whether SOD expression might account for any differences in ·O2- measured; and finally, to investigate whether, and by what mechanism, Ang II might affect ·O2- production in human blood vessels.
| Methods |
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Vessel Preparation
Distal segments of left internal mammary artery (IMA) and
saphenous vein (SV), which were harvested at the time of routine
coronary artery revascularization surgery,
were immediately taken to the laboratory in Krebs-HEPES buffer on ice.
At this point and in these conditions, the blood vessels were then
carefully dissected free of loose connective tissue, divided into 4- to
5-mm segments, and weighed. The vessels were then incubated in Krebs
buffer at pH 7.4±2 and maintained in atmospheric conditions
(PO2 19±4 kPa;
PCO2 3±4 kPa) at 37°C.
Measurement of Superoxide Anion Production
Vascular ·O2- was
measured by lucigenin-enhanced chemiluminescence in a liquid
scintillation counter (Hewlett Packard model Tricarb 2100TR) as
previously described8 12 and recently revalidated by Li et
al.20 Absolute counts were quantified with a
xanthine/xanthine oxidase calibration curve for
·O2- generation and
reported as pmol · min-1 · mg
tissue-1. In all experiments,
·O2- production
was measured in paired samples with a matched control from the same
vessel in every case.
Effect of Varying Lucigenin Concentrations on
·O2 Production
Lucigenin itself has been reported to generate
·O2- at higher
concentrations.21 Therefore, a range of lucigenin
concentrations was used to assay
·O2- in a series of
samples from single vessels by use of xanthine/xanthine oxidase
calibration curves with the appropriate concentration of lucigenin in
each sample. Superoxide production in IMA was similar, with a
lucigenin concentration of either 5 µmol/L (1715±343 pmol
· min-1 · mg-1)
or 250 µmol/L (1410±93 pmol ·
min-1 · mg-1; n=6,
P=0.59). In SV, sufficient tissue was available to assess
the effect of lucigenin on
·O2- production
at lucigenin concentrations of 5 to 250 µmol/L. Superoxide
production was 311±67 pmol ·
min-1 · mg-1 with
5 µmol/L lucigenin, 208±27 pmol ·
min-1 · mg-1 with
15 µmol/L lucigenin, 300±33 pmol ·
min-1 · mg-1 with
50 µmol/L lucigenin, and 241±50 pmol ·
min-1 · mg-1 with
250 µmol/L lucigenin (n=10 for each lucigenin concentration;
P=NS between all groups). These data show that
·O2- production
in IMA and SV was not affected by the concentration of lucigenin under
these conditions.
Experimental Design
IMA and SV tissues were incubated at 37°C in the absence
(control) or presence of an inhibitor of SOD
(diethylenethiocarbamate [DETCA], 100 µmol/L), a free
radical scavenger (4,5-dihydroxy-1,3-benzene disulfonic acid salt
[Tiron], 10 mmol/L), an inhibitor of NAD(P)H oxidase
(diphenyleneiodonium [DPI], 10, 100, and 200 µmol/L), an
inhibitor of eNOS
(N
-nitro-L-arginine
methyl ester [L-NAME], 100 µmol/L), or an
inhibitor of xanthine oxidase (allopurinol [ALP], 1
mmol/L) for 1 hour before quantification of
·O2-. In addition, some
vessels were denuded of endothelium by rubbing. The
absence of the endothelium and the integrity of the
vessel wall were confirmed by histological
analysis in a subset of 20 vessels. Vessels were also incubated
in the absence (control) or presence of 1 pmol/L, 1 nmol/L, and 1
µmol/L of Ang II for 1 and 4 hours. Functional integrity of the
vessels was not compromised by this incubation. IMA tissues were also
incubated with 1 µmol/L of Ang II for 15 minutes. To assess the
effects of a positive control, IMAs were incubated in the absence or
presence of norepinephrine 1 µmol/L for 4 hours. In
addition, IMAs were coincubated with 1 µmol/L of Ang II and
either an AT1-specific and competitive receptor
antagonist (losartan, 1 µmol/L) or a
nonspecific receptor antagonist
(sar1, thre8 Ang II, 1
µmol/L).
Western Blotting
Five-millimeter segments of vessels were homogenized
in 200 µL of a boiling vanadate buffer. After
centrifugation at 14 000g for 60 seconds,
the supernatant was withdrawn and the protein concentration measured.
Ten micrograms of protein and prestained molecular weight standards
were separated by SDS-PAGE with a 12% gel. The proteins were
transferred overnight onto a polyvinylidene difluoride membrane
and sequentially probed with sheep monoclonal antiCuZn-SOD or rabbit
polyclonal antiMn-SOD or anti-actin antibodies. Protein bands were
visualized by enhanced chemiluminescence (GS-525 Biorad-Laboratories
Ltd).
Organ Bath Studies
Studies of the isometric tension development of isolated IMA and
SV rings were performed by methods previously described.3
Ang II dose-response curves (10 pmol/L to 100 nmol/L) were performed in
the presence and absence of 10 µmol/L losartan and
10 µmol/L [sar1,
thre8]Ang II.
Materials
Xanthine, xanthine oxidase, lucigenin, DETCA, Tiron, DPI,
L-NAME, ALP, [sar1,
thre8]Ang II, and norepinephrine
were purchased from Sigma-Aldrich. Losartan was obtained as
a gift from Merck, Sharp & Dohme (UK). DPI and ALP were dissolved in
DMSO, and all other drugs were dissolved in buffer. For studies with
DPI and ALP, the appropriate concentration of DMSO was added to control
samples. AntiMn-SOD was a gift from Professor Taniguchi (University
of Osaka, Japan) and antiCuZn-SOD was purchased from
Calbiochem.
Statistical Analyses
All data are presented as mean±SEM or as percent change
from controls to facilitate comparison between groups. Statistical
analyses of vascular
·O2- concentrations were
undertaken by use of the Wilcoxon signed-rank test. The
relationships between risk factors and basal vascular
·O2- concentrations were
determined by use of the Pearson correlation coefficient
(r). A value of P<0.05 was considered
statistically significant.
| Results |
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1 risk factors for
CHD, and 92% of patients were on
1 types of antianginal therapy.
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Basal ·O2- Production in
Human Arteries and Veins
Superoxide production was greater in human arteries than
in veins: IMA, 1922±235 pmol ·
min-1 · mg-1
(n=55); SV, 662±179 pmol · min-1
· mg-1 (n=58); P<0.0001; 95% CI,
570, 1421 (Figure 1
). Basal
·O2- production
in human IMA was weakly associated with patient age (r=0.19,
P<0.1). No other relationships existed between basal
·O2- production
in either IMA or SV and any other patient characteristic.
|
Characterization of
·O2- Production
The free radical scavenger Tiron (10 mmol/L) reduced basal
·O2- concentrations in
both IMA (control, 1937±412; Tiron, 10 mmol/L 901±94; n=9,
P=0.018; 95% CI, -1919, -238) and SV (control,
350±85; Tiron 10 mmol/L, 149±39; n=13, P=0.002; 95%
CI, -311, -95). DETCA (100 µmol/L), an
inhibitor of SOD, increased
·O2- steady-state
concentrations in IMA (control, 853±208; DETCA 100 µmol/L,
1492±347; n=8, P=0.021; 95% CI, 186, 1149) and SV
(control, 551±145; DETCA 100 µmol/L, 945±245; n=14,
P=0.002; 95% CI, 67, 694). The NAD(P)H oxidase
inhibitor DPI (concentration range, 10 to 200
µmol/L) attenuated
·O2- generation in both
arteries (Table 2
) and veins (Table 3
). The xanthine oxidase
inhibitor ALP (1 mmol/L) attenuated
·O2- production
in both IMA and SV (Tables 2
and 3
).
|
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The effects on ·O2-
steady-state concentrations in IMA and SV of
endothelial denudation by rubbing and inhibition of
eNOS by incubation with L-NAME were more variable (Tables 2
and 3
). Incubation of IMA with L-NAME (100 µmol/L) and
endothelial denudation reduced
·O2- concentrations in 7
of 10 and 6 of 10 patients, respectively. In SV, these treatments
corresponded to a reduction in
·O2- concentrations in
12 of 16 and 10 of 14 patients. Sufficient tissue was available in
veins to study the effects of L-NAME treatment and
endothelium removal by rubbing in vessel segments from
the same patients. In these studies, both manipulations had similar
effects on ·O2-
concentrations in individual patients (r=0.85, n=12,
P<0.001). Furthermore, the difference in
·O2- concentrations
between IMA and SV was maintained after both
endothelial denudation and eNOS inhibition.
Quantification of SOD Proteins
Immunoblotting showed that single bands were
detected for both Mn-SOD and CuZn-SOD (Figure 2
). The intensity of CuZn-SOD bands
relative to an actin control was 4.04±0.31 in arteries versus
3.59±0.23 in veins (P=0.055). Mn-SOD expression was found
to have relative intensities of 3.14±0.25 versus 3.87±0.42
(P=0.056) in arteries and veins, respectively.
|
Effect of Ang II on ·O2-
Production
Ang II at concentrations of 1 µmol/L, 1 nmol/L, and 1
pmol/L increased ·O2-
production in IMA but not SV (Figure 3
, Table 4
). In IMA, Ang II had no effect on
·O2- production
after 15 minutes of incubation (control, 1173±239 pmol ·
min-1 · mg
tissue-1; 1 µmol/L of Ang II, 918±170
pmol · min-1 ·
mg-1; n=11, P=0.12; 95% CI, -680,
155) but increased ·O2-
production after 1 and 4 hours, respectively.
Norepinephrine (1 µmol/L), which was used as a
positive control, had no effect on
·O2- generation in
either arteries (control, 1581±899 pmol ·
min-1 · mg-1;
norepinephrine, 738±241 pmol ·
min-1 · mg-1;
n=11, P=0.45; 95% CI, -3590, 164) or veins (control,
360±218 pmol · min-1 ·
mg-1; norepinephrine, 249±118
pmol · min-1 ·
mg-1; n=7, P=0.18; 95% CI, -391,
45).
|
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Losartan (1 µmol/L), a competitive
AT1-specific receptor antagonist, had
no effect on basal ·O2-
production but blocked the Ang IImediated increase of
·O2- production
(Figure 4
). [Sar1,
thre8]Ang II (1 µmol/L), a nonspecific
Ang II receptor antagonist, also blocked Ang IImediated
increase of ·O2-
production ([sar1,
thre8]Ang II, 1 µmol/L, 1252±276
pmol · min-1 ·
mg-1; [sar,1
thre8]Ang II, 1 µmol/L + Ang II, 1
µmol/L, 1281±204 pmol · min-1 ·
mg-1; n=15, P=0.63; 95% CI, -200,
305). Isometric tension studies in IMA rings confirmed that both
antagonists were effective in blocking Ang IIinduced
vasoconstriction. Incubation of IMA for 4 hours with DPI 100
µmol/L, but not DPI 10 µmol/L, blocked Ang IImediated
increase of ·O2-
production (Figure 5
).
|
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| Discussion |
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In the present study, the higher basal ·O2- concentrations in arteries, compared with those in veins, were maintained after endothelial denudation by rubbing. This suggests that VSMCs may be an important source of ·O2- generation, as arteries have a proportionately greater content of VSMCs than veins. The balance between ·O2- generation and degradation determines superoxide steady-state concentrations. In this study, the levels of Mn-SOD and CuZn-SOD proteins were quantitatively similar in arteries and veins. The activity and amount of EC-SOD protein are significantly higher in human arteries than veins.22 Taken together with our results, this would suggest that the elevated concentrations of ·O2- observed in arteries compared with veins were not a consequence of a reduced capacity for enzymatic removal but rather occurred through increased ·O2- production.
We also sought to characterize the mechanisms of ·O2- production in human IMA and SV. Endothelial NOS activity was inhibited by removal of the endothelium by rubbing and by incubating vessels with L-NAME. This failed to reduce ·O2- steady-state concentrations in all patients. The lack of effect of these treatments on ·O2- production in the blood vessels of some patients suggests that VSMCs and adventitial fibroblasts were alternative sources of ·O2- generation. Inhibition of NAD(P)H oxidase and xanthine oxidase, by incubation of arteries and veins with DPI and ALP, respectively, resulted in similar reductions in basal ·O2- steady-state concentrations in both of these tissues. This suggests that both NAD(P)H and xanthine oxidases are sources of ·O2- generation in human arteries and veins. Observations from in vitro studies suggest that the activity of xanthine oxidase may be increased in endothelial cells subject to ischemia-reperfusion injury.23 Findings from in vivo human studies suggest that patients with risk factors for CAD also have increased vascular xanthine oxidasemediated ·O2- production, which may contribute to impaired endothelium-dependent vasodilation in these patients.24 Considered together with our findings, this suggests that xanthine oxidase may be an important source of vascular ·O2- production in patients who have CAD.
In the present study, basal ·O2- concentrations in IMA were weakly related to patient age. The variation in basal vascular ·O2- concentrations observed in this and other human studies19 and the lack of correlation of ·O2- production with some atherosclerotic risk factors, treatment with nitrates, and other therapies may be due to the heterogeneous clinical characteristics of patients with CAD. Such patients have differences in their genetic backgrounds, their atherosclerotic risk factors, their disease duration and severity, and their drug therapy.
We also investigated whether a vasoactive hormone, such as Ang II, could affect ·O2- production in human blood vessels. Ang II induced isometric contractions in both arteries and veins but increased ·O2- production only in arteries. These effects are unlikely to be due to a reduction in AT1 receptor expression in veins, because the constrictor effect of Ang II in human saphenous veins, which is known to be AT1-dependent,25 may be greater in SV than IMA.26 Ang II exerts different effects in distinct vascular beds.27 One explanation for our observations may be that the intracellular mechanisms by which Ang II activates NAD(P)H oxidase may differ in human arteries and veins. In vitro studies in human VSMCs have suggested that Ang II may increase ·O2- production in these cells by activation of NAD(P)H oxidase.28 Our observations may also be substantiated by a report that the pressor effect of intrabrachial artery infusion of Ang II in humans is attenuated by the coinfusion of vitamin C.29 This study, however, failed to identify a specific Ang II receptor or to evaluate a positive control (ie, another vasoconstrictor, such as norepinephrine).
Experimental studies have demonstrated that the Ang IImediated increase in ·O2- production is of functional importance. The Ang IIstimulated increase in ·O2- production contributes to its trophic effect of on rat VSMCs16 and mesangial cells30 and also contributes to the pressor effect of this hormone in a hypertensive rat model.17
We have shown that Ang II increases ·O2- production in human arteries by an AT1-dependent mechanism. The mechanism of Ang IImediated increase of ·O2- production differs in other species. An AT1-dependent Ang IImediated increase of ·O2- production has been reported in the aorta17 and mesangium30 of Sprague-Dawley rats and aorta of hypercholesterolemic rabbits.18 However, the Ang IIinduced increase in ·O2- production in normocholesterolemic rabbit aortic adventitial fibroblasts is mediated by a non-AT1non-AT2receptor mechanism.18 31 The species differences in the mechanism of Ang IImediated increase in ·O2- production emphasize the importance of human investigations, as is the case in the present study.
In conclusion, we have characterized cellular and enzyme sources of ·O2- production in human arteries and veins. We have demonstrated that Ang II increases ·O2- production at physiological and pharmacological concentrations in human arteries. This effect, which is mediated by NAD(P)H oxidase, is completely inhibited by the AT1 receptor antagonist losartan. These observations suggest a putative therapeutic role for AT1 receptor antagonists in reducing oxidative stress in cardiovascular disease.
| Acknowledgments |
|---|
Received September 14, 1999; revision received December 6, 1999; accepted December 22, 1999.
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Q. Zhang, P. Malik, D. Pandey, S. Gupta, D. Jagnandan, E. B. de Chantemele, B. Banfi, M. B. Marrero, R. D. Rudic, D. W. Stepp, et al. Paradoxical Activation of Endothelial Nitric Oxide Synthase by NADPH Oxidase Arterioscler Thromb Vasc Biol, September 1, 2008; 28(9): 1627 - 1633. [Abstract] [Full Text] [PDF] |
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S. Chrissobolis, S. P. Didion, D. A. Kinzenbaw, L. I. Schrader, S. Dayal, S. R. Lentz, and F. M. Faraci Glutathione Peroxidase-1 Plays a Major Role in Protecting Against Angiotensin II-Induced Vascular Dysfunction Hypertension, April 1, 2008; 51(4): 872 - 877. [Abstract] [Full Text] [PDF] |
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S. A. Cooper, A. Whaley-Connell, J. Habibi, Y. Wei, G. Lastra, C. Manrique, S. Stas, and J. R. Sowers Renin-angiotensin-aldosterone system and oxidative stress in cardiovascular insulin resistance Am J Physiol Heart Circ Physiol, October 1, 2007; 293(4): H2009 - H2023. [Abstract] [Full Text] [PDF] |
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S. M. Zemse, R. H. P. Hilgers, and R. C. Webb Interleukin-10 counteracts impaired endothelium-dependent relaxation induced by ANG II in murine aortic rings Am J Physiol Heart Circ Physiol, June 1, 2007; 292(6): H3103 - H3108. [Abstract] [Full Text] [PDF] |
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M. Sanchez, F. Lodi, R. Vera, I. C. Villar, A. Cogolludo, R. Jimenez, L. Moreno, M. Romero, J. Tamargo, F. Perez-Vizcaino, et al. Quercetin and Isorhamnetin Prevent Endothelial Dysfunction, Superoxide Production, and Overexpression of p47phox Induced by Angiotensin II in Rat Aorta J. Nutr., April 1, 2007; 137(4): 910 - 915. [Abstract] [Full Text] [PDF] |
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Y. Li, G. Lappas, and M. B. Anand-Srivastava Role of oxidative stress in angiotensin II-induced enhanced expression of Gi{alpha} proteins and adenylyl cyclase signaling in A10 vascular smooth muscle cells Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1922 - H1930. [Abstract] [Full Text] [PDF] |
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C. Yzydorczyk, F. Gobeil Jr., G. Cambonie, I. Lahaie, N. L. O. Le, S. Samarani, A. Ahmad, J. C. Lavoie, L. L. Oligny, P. Pladys, et al. Exaggerated vasomotor response to ANG II in rats with fetal programming of hypertension associated with exposure to a low-protein diet during gestation Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R1060 - R1068. [Abstract] [Full Text] [PDF] |
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T. J. Guzik, J. Sadowski, B. Guzik, A. Jopek, B. Kapelak, P. Przybylowski, K. Wierzbicki, R. Korbut, D. G. Harrison, and K. M. Channon Coronary Artery Superoxide Production and Nox Isoform Expression in Human Coronary Artery Disease Arterioscler Thromb Vasc Biol, February 1, 2006; 26(2): 333 - 339. [Abstract] [Full Text] [PDF] |
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S. Al-Benna, C. A. Hamilton, J. D. McClure, P. N. Rogers, G. A. Berg, I. Ford, C. Delles, and A. F. Dominiczak Low-Density Lipoprotein Cholesterol Determines Oxidative Stress and Endothelial Dysfunction in Saphenous Veins From Patients With Coronary Artery Disease Arterioscler Thromb Vasc Biol, January 1, 2006; 26(1): 218 - 223. [Abstract] [Full Text] [PDF] |
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S. P. Didion, D. A. Kinzenbaw, and F. M. Faraci Critical Role for CuZn-Superoxide Dismutase in Preventing Angiotensin II-Induced Endothelial Dysfunction Hypertension, November 1, 2005; 46(5): 1147 - 1153. [Abstract] [Full Text] [PDF] |
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A. G. Herman and S. Moncada Therapeutic potential of nitric oxide donors in the prevention and treatment of atherosclerosis Eur. Heart J., October 1, 2005; 26(19): 1945 - 1955. [Abstract] [Full Text] [PDF] |
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M. W. McBride, M. J. Brosnan, J. Mathers, L. I. McLellan, W. H. Miller, D. Graham, N. Hanlon, C. A. Hamilton, J. M. Polke, W. K. Lee, et al. Reduction of Gstm1 Expression in the Stroke-Prone Spontaneously Hypertension Rat Contributes to Increased Oxidative Stress Hypertension, April 1, 2005; 45(4): 786 - 792. [Abstract] [Full Text] [PDF] |
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B. Somoza, M. C. Gonzalez, J. M. Gonzalez, F. Abderrahim, S. M. Arribas, and M. S. Fernandez-Alfonso Modulatory role of the adventitia on noradrenaline and angiotensin II responses: Role of endothelium and AT2 receptors Cardiovasc Res, February 1, 2005; 65(2): 478 - 486. [Abstract] [Full Text] [PDF] |
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K. Savary, A. Michaud, J. Favier, E. Larger, P. Corvol, and J.-M. Gasc Role of the renin-angiotensin system in primitive erythropoiesis in the chick embryo Blood, January 1, 2005; 105(1): 103 - 110. [Abstract] [Full Text] [PDF] |
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S. Patil, M. Bunderson, J. Wilham, and S. M. Black Important role for Rac1 in regulating reactive oxygen species generation and pulmonary arterial smooth muscle cell growth Am J Physiol Lung Cell Mol Physiol, December 1, 2004; 287(6): L1314 - L1322. [Abstract] [Full Text] [PDF] |
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H. S. Lim, R. J. MacFadyen, and G. Y. H. Lip Diabetes Mellitus, the Renin-Angiotensin-Aldosterone System, and the Heart Arch Intern Med, September 13, 2004; 164(16): 1737 - 1748. [Abstract] [Full Text] [PDF] |
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T. J. Guzik, J. Sadowski, B. Kapelak, A. Jopek, P. Rudzinski, R. Pillai, R. Korbut, and K. M. Channon Systemic Regulation of Vascular NAD(P)H Oxidase Activity and Nox Isoform Expression in Human Arteries and Veins Arterioscler Thromb Vasc Biol, September 1, 2004; 24(9): 1614 - 1620. [Abstract] [Full Text] [PDF] |
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F Violi, L Loffredo, L Musella, and A Marcoccia Should antioxidant status be considered in interventional trials with antioxidants? Heart, June 1, 2004; 90(6): 598 - 602. [Abstract] [Full Text] [PDF] |
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U. Landmesser, B. Hornig, and H. Drexler Endothelial Function: A Critical Determinant in Atherosclerosis? Circulation, June 1, 2004; 109(21_suppl_1): II-27 - II-33. [Abstract] [Full Text] [PDF] |
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J. R. Sowers Insulin resistance and hypertension Am J Physiol Heart Circ Physiol, May 1, 2004; 286(5): H1597 - H1602. [Abstract] [Full Text] [PDF] |
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B. Rodriguez-Iturbe, N. D. Vaziri, J. Herrera-Acosta, and R. J. Johnson Oxidative stress, renal infiltration of immune cells, and salt-sensitive hypertension: all for one and one for all Am J Physiol Renal Physiol, April 1, 2004; 286(4): F606 - F616. [Abstract] [Full Text] [PDF] |
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B. Lopez, M. G. Salom, B. Arregui, F. Valero, and F. J. Fenoy Role of Superoxide in Modulating the Renal Effects of Angiotensin II Hypertension, December 1, 2003; 42(6): 1150 - 1156. [Abstract] [Full Text] [PDF] |
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O. Mangoush, K. Nakamura, S. Al-Ruzzeh, T. Athanasiou, A. Chester, and M. Amrani Effect of ascorbic acid on endothelium-dependent vasodilatation of human arterial conduits for coronary artery bypass grafting Eur. J. Cardiothorac. Surg., October 1, 2003; 24(4): 541 - 546. [Abstract] [Full Text] [PDF] |
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M. Tepel Oxidative stress: does it play a role in the genesis of essential hypertension and hypertension of uraemia? Nephrol. Dial. Transplant., August 1, 2003; 18(8): 1439 - 1442. [Full Text] [PDF] |
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S. P. Didion and F. M. Faraci Angiotensin II Produces Superoxide-Mediated Impairment of Endothelial Function in Cerebral Arterioles Stroke, August 1, 2003; 34(8): 2038 - 2042. [Abstract] [Full Text] [PDF] |
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J.-M. Li and A. M. Shah ROS Generation by Nonphagocytic NADPH Oxidase: Potential Relevance in Diabetic Nephropathy J. Am. Soc. Nephrol., August 1, 2003; 14(90003): S221 - 226. [Abstract] [Full Text] [PDF] |
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A. Wiecek, J. Chudek, and F. Kokot Role of angiotensin II in the progression of diabetic nephropathy--therapeutic implications Nephrol. Dial. Transplant., July 1, 2003; 18(90005): v16 - 20. [Full Text] [PDF] |
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R.M. Touyz, G. Yao, and E.L. Schiffrin c-Src Induces Phosphorylation and Translocation of p47phox: Role in Superoxide Generation by Angiotensin II in Human Vascular Smooth Muscle Cells Arterioscler Thromb Vasc Biol, June 1, 2003; 23(6): 981 - 987. [Abstract] [Full Text] [PDF] |
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U. Landmesser, S. Spiekermann, S. Dikalov, H. Tatge, R. Wilke, C. Kohler, D. G. Harrison, B. Hornig, and H. Drexler Vascular Oxidative Stress and Endothelial Dysfunction in Patients With Chronic Heart Failure: Role of Xanthine-Oxidase and Extracellular Superoxide Dismutase Circulation, December 10, 2002; 106(24): 3073 - 3078. [Abstract] [Full Text] [PDF] |
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N. Kalinina, A. Agrotis, E. Tararak, Y. Antropova, P. Kanellakis, O. Ilyinskaya, M. T. Quinn, V. Smirnov, and A. Bobik Cytochrome b558-Dependent NAD(P)H Oxidase-Phox Units in Smooth Muscle and Macrophages of Atherosclerotic Lesions Arterioscler Thromb Vasc Biol, December 1, 2002; 22(12): 2037 - 2043. [Abstract] [Full Text] [PDF] |
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T. Ogihara, T. Asano, K. Ando, Y. Chiba, H. Sakoda, M. Anai, N. Shojima, H. Ono, Y. Onishi, M. Fujishiro, et al. Angiotensin II-Induced Insulin Resistance Is Associated With Enhanced Insulin Signaling Hypertension, December 1, 2002; 40(6): 872 - 879. [Abstract] [Full Text] [PDF] |
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U. Rueckschloss, M. T. Quinn, J. Holtz, and H. Morawietz Dose-Dependent Regulation of NAD(P)H Oxidase Expression by Angiotensin II in Human Endothelial Cells: Protective Effect of Angiotensin II Type 1 Receptor Blockade in Patients With Coronary Artery Disease Arterioscler Thromb Vasc Biol, November 1, 2002; 22(11): 1845 - 1851. [Abstract] [Full Text] [PDF] |
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S. Delbosc, J.-P. Cristol, B. Descomps, A. Mimran, and B. Jover Simvastatin Prevents Angiotensin II-Induced Cardiac Alteration and Oxidative Stress Hypertension, August 1, 2002; 40(2): 142 - 147. [Abstract] [Full Text] [PDF] |
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U. Landmesser and H. Drexler Allopurinol and Endothelial Function in Heart Failure: Future or Fantasy? Circulation, July 9, 2002; 106(2): 173 - 175. [Full Text] [PDF] |
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J. R. Sowers Hypertension, Angiotensin II, and Oxidative Stress N. Engl. J. Med., June 20, 2002; 346(25): 1999 - 2001. [Full Text] [PDF] |
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R. M. Touyz, X. Chen, F. Tabet, G. Yao, G. He, M. T. Quinn, P. J. Pagano, and E. L. Schiffrin Expression of a Functionally Active gp91phox-Containing Neutrophil-Type NAD(P)H Oxidase in Smooth Muscle Cells From Human Resistance Arteries: Regulation by Angiotensin II Circ. Res., June 14, 2002; 90(11): 1205 - 1213. [Abstract] [Full Text] [PDF] |
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W. Doehner, N. Schoene, M. Rauchhaus, F. Leyva-Leon, D. V. Pavitt, D. A. Reaveley, G. Schuler, A. J.S. Coats, S. D. Anker, and R. Hambrecht Effects of Xanthine Oxidase Inhibition With Allopurinol on Endothelial Function and Peripheral Blood Flow in Hyperuricemic Patients With Chronic Heart Failure: Results From 2 Placebo-Controlled Studies Circulation, June 4, 2002; 105(22): 2619 - 2624. [Abstract] [Full Text] [PDF] |
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T. J. Guzik, N. E.J. West, R. Pillai, D. P. Taggart, and K. M. Channon Nitric Oxide Modulates Superoxide Release and Peroxynitrite Formation in Human Blood Vessels Hypertension, June 1, 2002; 39(6): 1088 - 1094. [Abstract] [Full Text] [PDF] |
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A D Struthers, P T Donnan, P Lindsay, D McNaughton, J Broomhall, and T M MacDonald Effect of allopurinol on mortality and hospitalisations in chronic heart failure: a retrospective cohort study Heart, March 1, 2002; 87(3): 229 - 234. [Abstract] [Full Text] [PDF] |
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D. JAVESGHANI, S. A. MAGDER, E. BARREIRO, M. T. QUINN, and S. N. A. HUSSAIN Molecular Characterization of a Superoxide-Generating NAD(P)H Oxidase in the Ventilatory Muscles Am. J. Respir. Crit. Care Med., February 1, 2002; 165(3): 412 - 418. [Abstract] [Full Text] [PDF] |
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C. Berry, R. Touyz, A. F. Dominiczak, R. C. Webb, and D. G. Johns Angiotensin receptors: signaling, vascular pathophysiology, and interactions with ceramide Am J Physiol Heart Circ Physiol, December 1, 2001; 281(6): H2337 - H2365. [Abstract] [Full Text] [PDF] |
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G. Zalba, G. S. Jose, M. U. Moreno, M. A. Fortuno, A. Fortuno, F. J. Beaumont, and J. Diez Oxidative Stress in Arterial Hypertension: Role of NAD(P)H Oxidase Hypertension, December 1, 2001; 38(6): 1395 - 1399. [Abstract] [Full Text] [PDF] |
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S. P. Didion, C. A. Hathaway, and F. M. Faraci Superoxide levels and function of cerebral blood vessels after inhibition of CuZn-SOD Am J Physiol Heart Circ Physiol, October 1, 2001; 281(4): H1697 - H1703. [Abstract] [Full Text] [PDF] |
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C. BERRY, N. ANDERSON, A. J B KIRK, A. F DOMINICZAK, and J. J V MCMURRAY Renin angiotensin system inhibition is associated with reduced free radical concentrations in arteries of patients with coronary heart disease Heart, August 1, 2001; 86(2): 217 - 220. [Full Text] [PDF] |
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J. Kajstura, F. Fiordaliso, A. M. Andreoli, B. Li, S. Chimenti, M. S. Medow, F. Limana, B. Nadal-Ginard, A. Leri, and P. Anversa IGF-1 Overexpression Inhibits the Development of Diabetic Cardiomyopathy and Angiotensin II-Mediated Oxidative Stress Diabetes, June 1, 2001; 50(6): 1414 - 1424. [Abstract] [Full Text] |
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C. A. Hamilton, A. R. McPhaden, G. Berg, V. Pathi, and A. F. Dominiczak Is hydrogen peroxide an EDHF in human radial arteries? Am J Physiol Heart Circ Physiol, June 1, 2001; 280(6): H2451 - H2455. [Abstract] [Full Text] [PDF] |
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E. K. Jackson and W. A. Herzer Regional Vascular Selectivity of Angiotensin II J. Pharmacol. Exp. Ther., April 12, 2001; 297(2): 736 - 745. [Abstract] [Full Text] |
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A. K. Nightingale, D. J. Blackman, G. R. Ellis, M. Schmitt, J. A. Morris-Thurgood, E. A. Jones, and M. P. Frenneaux Preservation of venous endothelial function in the forearm venous capacitance bed of patients with chronic heart failure despite arterial endothelial dysfunction J. Am. Coll. Cardiol., March 15, 2001; 37(4): 1062 - 1068. [Abstract] [Full Text] [PDF] |
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M.-S. Zhou, A. Adam, and L. Raij Review: Interaction among angiotensin II, nitric oxide and oxidative stress Journal of Renin-Angiotensin-Aldosterone System, March 1, 2001; 2(1_suppl): S59 - S63. [PDF] |
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C. A. Hamilton, M. J. Brosnan, M. McIntyre, D. Graham, and A. F. Dominiczak Superoxide Excess in Hypertension and Aging : A Common Cause of Endothelial Dysfunction Hypertension, February 1, 2001; 37(2): 529 - 534. [Abstract] [Full Text] [PDF] |
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A. Frustaci, J. Kajstura, C. Chimenti, I. Jakoniuk, A. Leri, A. Maseri, B. Nadal-Ginard, and P. Anversa Myocardial Cell Death in Human Diabetes Circ. Res., December 8, 2000; 87(12): 1123 - 1132. [Abstract] [Full Text] [PDF] |
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P. R. Sage, I. S. de la Lande, I. Stafford, C. L. Bennett, G. Phillipov, J. Stubberfield, and J. D. Horowitz Nitroglycerin Tolerance in Human Vessels : Evidence for Impaired Nitroglycerin Bioconversion Circulation, December 5, 2000; 102(23): 2810 - 2815. [Abstract] [Full Text] [PDF] |
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L. Cominacini, A. Rigoni, A. F. Pasini, U. Garbin, A. Davoli, M. Campagnola, A. M. Pastorino, V. Lo Cascio, and T. Sawamura The Binding of Oxidized Low Density Lipoprotein (ox-LDL) to ox-LDL Receptor-1 Reduces the Intracellular Concentration of Nitric Oxide in Endothelial Cells through an Increased Production of Superoxide J. Biol. Chem., April 20, 2001; 276(17): 13750 - 13755. [Abstract] [Full Text] [PDF] |
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S. P. Didion and F. M. Faraci Effects of NADH and NADPH on superoxide levels and cerebral vascular tone Am J Physiol Heart Circ Physiol, February 1, 2002; 282(2): H688 - H695. [Abstract] [Full Text] [PDF] |
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D. Sorescu, D. Weiss, B. Lassegue, R. E. Clempus, K. Szocs, G. P. Sorescu, L. Valppu, M. T. Quinn, J. D. Lambeth, J. D. Vega, et al. Superoxide Production and Expression of Nox Family Proteins in Human Atherosclerosis Circulation, March 26, 2002; 105(12): 1429 - 1435. [Abstract] [Full Text] [PDF] |
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