Published online before print July 21, 2003, doi: 10.1161/01.CIR.0000079165.84309.4D
(Circulation. 2003;108:1253.)
© 2003 American Heart Association, Inc.
Basic Science Reports |
High Pressure Induces Superoxide Production in Isolated Arteries Via Protein Kinase C–Dependent Activation of NAD(P)H Oxidase
From the Department of Physiology, New York Medical College, Valhalla, NY (Z.U., A.C., A.N., P.M.K., M.S.W., A.K.), and the Department of Pathophysiology, Semmelweis University, Budapest, Hungary (Z.U., A.C., A.K.).
Correspondence to Akos Koller MD, PhD, Department of Physiology, New York Medical College, Valhalla, NY 10595. E-mail koller{at}nymc.edu
Received February 3, 2003; revision received April 29, 2003; accepted May 2, 2003.
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Abstract |
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Background— Oxidative stress seems to be present in all forms of hypertension. Thus, we tested the hypothesis that high intraluminal pressure (Pi) itself, by activating vascular oxidases, elicits increased superoxide (O2·-) production interfering with flow-induced dilation.
Methods and Results— Isolated, cannulated rat femoral arterial branches were exposed in vitro (for 30 minutes) to normal Pi (80 mm Hg) or high Pi (160 mm Hg). High Pi significantly increased vascular O2·- production (as measured by lucigenin chemiluminescence and ethidium bromide fluorescence) and impaired endothelium-dependent dilations to flow; these effects could be reversed by superoxide dismutase. Administration of the NAD(P)H oxidase inhibitor diphenyleneiodonium, apocynin, the protein kinase C (PKC) inhibitor chelerythrine or staurosporin or the removal of extracellular Ca2+ during high Pi treatment prevented the increases in O2·- production, whereas administration of losartan or captopril had no effect. High Pi resulted in significant increases in intracellular Ca2+ ([Ca2+]i) in the vascular wall (fura 2 fluorescence) and phosphorylation of PKC
(Western blotting). The PKC activator phorbol myristate acetate significantly increased vascular O2·- production, which was inhibited by superoxide dismutase, diphenyleneiodonium, chelerythrine, or removal of extracellular Ca2+. Both high Pi and phorbol myristate acetate increased the phosphorylation of the NAD(P)H oxidase subunit p47phox.
Conclusion— High Pi itself elicits arterial O2·- production, most likely by PKC-dependent activation of NAD(P)H oxidase, thus providing a potential explanation for the presence of oxidative stress and endothelial dysfunction in various forms of hypertension and the vasculoprotective effect of antihypertensive agents of different mechanisms of action.
Key Words: signal transduction • hypertension • angiotensin • endothelium • peripheral vascular disease
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Introduction |
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Numerous studies in humans1 and animals2–6 suggest that increased superoxide (O2·-) production contributes significantly to the functional alterations of arteries present in hypertension. In peripheral arteries and arterioles, increased levels of O2·- have been shown to decrease the bioavailability of the endothelium-derived vasodilator nitric oxide to flow,6,7 thereby contributing to the maintenance of elevated peripheral resistance. However, the stimuli and mechanisms underlying increased O2·- production in hypertension are not completely understood.
The vascular effects of hypertension are complex and are likely to be induced, at least in part, by increased levels of neurohumoral factors. Among the humoral factors, angiotensin has been suggested to increase O2·- generation in vascular cells.3,4,8,9 However, oxidative stress seems to be present in virtually all forms of hypertension,4,5 including low-renin hypertension,10 despite the differences in plasma levels of circulating factors. Importantly, in angiotensin-infused rats, reduction of blood pressure with hydralazine or spironolactone (which is unlikely to affect angiotensin levels) normalized aortic O2·- production.8,11 Reduction of blood pressure in rats infused with both angiotensin and norepinephrine by hydralazine also normalized increased plasma levels of 8-epi-prostaglandin F2, a marker of oxidative stress in vivo.12 Thus, it is logical to hypothesize that high intraluminal pressure (Pi) itself can also promote vascular O2·- generation in hypertension. This idea is congruent with previous observations that even short-term increases in Pi, both in vivo and in vitro, impair endothelial function,13–16 an effect that can be prevented by superoxide dismutase (SOD).17 However, the possible role of high Pi alone in the upregulation of arterial O2·- production and the underlying signaling mechanisms has not yet been elucidated.
To test the hypothesis that the presence of high Pi per se, by activating vascular oxidases, elicits oxidative stress, we investigated pressure-induced O2·- production in isolated arteries in vitro, a condition in which neurohumoral factors are absent. Also, we aimed to elucidate the contribution of possible vascular sources of O2·-, including NAD(P)H oxidases,4,5 and the role of mechanosensitive pathways, such as Ca2+ and protein kinase C (PKC)–dependent signaling mechanisms.2,3,18
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Methods |
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Vessel Isolation and Functional Studies
Functional studies were conducted on pressurized branches of the femoral artery (diameter,
200 µm) that were isolated from male Wistar rats (n=20; 14 weeks old; Charles River Laboratories, Wilmington, Mass), as previously described.17,19,20 At normal Pi (80 mm Hg), flow-induced dilations were obtained; then, Pi was increased to 160 mm Hg for 30 minutes. In other experiments, vessels were exposed to high Pi in the presence of SOD (200 U/mL), apocynin (3x10-4 mol/L, a NAD(P)H oxidase inhibitor5,21), losartan (10-6 mol/L, an angiotensin II type 1 receptor inhibitor), or captopril (10-6 mol/L, an angiotensin-converting enzyme inhibitor). After the high Pi exposure, Pi was returned to 80 mm Hg, and flow-induced responses were reassessed. In separate experiments, arteries were incubated with Ca2+-free solution during high Pi treatment, then flow-induced responses were reassessed after readministering Ca2+ (at 80 mm Hg).
Measurement of Vascular O2·- Levels
Proximal arterial segments were isolated and cannulated, and the production of O2·- in response to step increases in Pi (from 0 mm Hg to 80 mm Hg or from 0 mm Hg to 160 mm Hg) was continuously measured by the real-time lucigenin (10 µmol/L) chemiluminescence method using a vessel-perfusion system coupled to a photomultiplier-based detector.21 Pressure-induced changes in lucigenin chemiluminescence were also measured in the presence of diphenyleneiodonium (DPI; 10-5 mol/L, an inhibitor of flavoprotein-containing oxidases, including NAD(P)H oxidases) or chelerythrine (10-6 mol/L, an inhibitor of PKC and PKC-induced NAD(P)H activity3) or in the absence of extracellular Ca2+.
In separate experiments, arteries were cannulated and pressurized to 80 mm Hg or 160 mm Hg (for 30 minutes) in the absence or presence of SOD (200 U/mL), chelerythrine (10-6 mol/L), apocynin (3x10-4 mol/L), staurosporine (10-6 mol/L, an inhibitor of PKC), Tiron (10 mmol/L, a O2·- scavenger), or losartan (10-6 mol/L) or in the absence of extracellular Ca2+. Then, post-pressure treatment lucigenin chemiluminescence was measured with a scintillation counter, as previously described.22 Also, in some experiments, lucigenin chemiluminescence was compared in arteries exposed to 80 mm Hg and 120 mm Hg. Further, arterial O2·- production was also assessed after incubation with the PKC activator phorbol myristate acetate (PMA; 10-6 mol/L, for 30 minutes, at 37°C) in the absence and presence of chelerythrine, SOD, or DPI or after removal of extracellular Ca2+. The effect of ionomycin (10-6 mol/L, a Ca2+ ionophore) on vascular O2·- levels was also determined.
Ethidium Bromide Fluorescence
Hydroethidine was used to localize pressure-induced O2·- production, as described previously.22 Identical branches of the left and right femoral arteries were cannulated, pressurized (to 80 or 160 mm Hg), and exposed to hydroethidine (2x10-6 mol/L, at 37°C, for 15 minutes). They were then embedded, snap-frozen in liquid nitrogen, and cryosectioned. The sections were immunostained for smooth muscle -actin. We used 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) for nuclear staining, and fluorescent images were collected. Normal and high Pi-exposed vessels were processed and imaged in parallel.
Measurement of Endothelial and Smooth Muscle Intracellular Ca2+
The smooth muscle or the endothelium of isolated, cannulated arteries were loaded with the Ca2+-sensitive fluorescent indicator fura 2 acetoxy-methyl, as described previously.20 Changes in intracellular Ca2+ {[Ca2+]i} in the arterial endothelium and smooth muscle in response to increases in Pi (from 0 to 80 mm Hg or to 160 mm Hg) were measured by the ratiometric fluorescence method using the Ionoptix Microfluorimeter System (Ionoptix Co).20 Responses were also reassessed in the absence of extracellular Ca2+.
Detection of Pressure-Induced PKC Phosphorylation by Western Blotting
Phosphorylation of PKC was detected by Western blotting, as described previously.23 Arteries were cannulated in a dual-vessel chamber (model CH/1/QT, Living System Instrumentation), pressurized to 80 mm Hg or 160 mm Hg (for 30 minutes at 37°C), and then snap-frozen in liquid nitrogen. Nonpressurized vessels served as controls. Protein samples were prepared22,23 in the presence of Na3VO4 (1 mmol/L) and phosphatase inhibitors (Sigma). Equal amounts of protein (8 µg) were electrophoresed on 10% SDS-PAGE gels, and Western blotting was performed using a phosphorylation-specific primary antibody for PKC (Cell Signalling Technology, Beverly, Mass; 1:1000) and anti-rabbit IgG-horseradish peroxidase secondary antibody (Amersham Biosciences, Piscataway, NJ; 1:4000). Anti-ß-actin was used for normalization.
Immunofluorescent Labeling of Phospho-PKC
Isolated arteries pressurized to 160 mm Hg were treated with phosphatase inhibitors, embedded, snap-frozen in liquid nitrogen, and cryosectioned (thickness, 4 µm). Immunofluorescent labeling22 was performed with phospho-specific anti-PKC primary antibody. DAPI was used for nuclear staining.
Immunoprecipitation and Detection of Pressure-Induced p47phox Phosphorylation by Western Blotting
Isolated arteries were pressurized (for 30 minutes at 37°C) to 0, 80, or 160 mm Hg or 160 mm Hg plus 10-6 mol/L chelerythrine or 0 mm Hg plus 10-6 mol/L PMA, snap-frozen in liquid nitrogen, and lysed in a radio immunoprecipitation (RIPA) lysis buffer (Upstate USIA Inc) containing phosphatase inhibitors. Proteins were incubated with protein A beads (Amersham; 1 hour at 4°C) and with anti-p47phox primary antibody (5 µg, overnight at 4°C). Then, the samples were centrifuged (12 000g), the pellet was washed (3x RIPA and 1x 50 mmol/L Tris, pH 8.0), and the proteins were separated by SDS-PAGE, transferred to membranes, and probed with a primary antibody against phosphorylated serine residues (1:1000, 1 hour, Cell Signaling) and normalized for p47phox content.22,23
Materials
All chemicals, if otherwise not specified, were obtained from Sigma-Aldrich Co, and solutions were prepared on the day of the experiment. Final concentrations are reported in the text.
Data Analysis
Lucigenin chemiluminescence data and densitometric ratios were normalized to the respective control mean values. Selective portions of representative Western blots are shown for clarity. Data are expressed as the mean±SEM. Statistical analyses of data were performed by Student’s t test or by 2-way ANOVA followed by the Tukey post hoc test, as appropriate. P<0.05 was considered statistically significant.
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Results |
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Flow-Induced Dilation
In control conditions, increases in intraluminal flow elicited significant dilations. These dilations were significantly reduced after the vessels were exposed to high Pi (Figure 1). Previous studies demonstrated that agonist-induced nitric oxide–mediated dilations are also impaired in vessels that were previously exposed to high Pi in a similar manner.17 Administration of SOD or apocynin (but not losartan or captopril) or removal of extracellular Ca2+ prevented the high Pi–induced impairment of flow-induced dilation (Figure 1).
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Vascular O2·- Production
Real-time lucigenin chemiluminescence measurements showed that an increase in Pi from 0 mm Hg to 80 mm Hg resulted in minimal changes in vascular O2·- production. In contrast, exposure to high Pi (160 mm Hg) elicited biphasic increases in vascular O2·- generation, with a rapid peak increase followed by a plateau phase (Figures 2A and 2B). Incubation of the vessels with DPI or chelerythrine or removal of extracellular Ca2+ prevented high Pi–induced increases in O2·- levels (Figure 2C). Scintillation counter measurements showed that levels of O2·- remained significantly increased in vessels exposed to 160 mm Hg compared with arteries exposed to 80 mm Hg (Figure 3A). Pressurization of arteries to 120 mm Hg also resulted in moderate but significant increases (14±4%) in O2·- generation. Increased O2·- generation in high (160 mm Hg) Pi–pretreated vessels was inhibited by cotreatment with SOD, DPI, chelerythrine, apocynin, staurosporin, or Tiron or by removal of extracellular Ca2+ (Figures 3A and 3B), thus eliminating the difference between the groups. Increased O2·- generation in high Pi–treated vessels was unaffected by losartan (Figure 3B). Incubation of control arteries with PMA (for 30 minutes) significantly increased O2·- production, which could be inhibited by administration of chelerythrine, SOD, or DPI or by removal of extracellular Ca2+ (Figure 3C). The Ca2+ ionophore ionomycin also significantly increased vascular O2·- generation, although its effect was smaller than that of PMA (Figure 3C).
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Hydroethidine Fluorescence
In sections of arteries exposed to 160 mm Hg, ethidium bromide staining of nuclei was stronger than in sections of arteries exposed to 80 mm Hg (representative ethidium bromide fluorescent images are shown in Figures 2D and 2E). Overlaying of ethidium bromide–stained fluorescent images (red) with images of the same vessel sections stained for smooth muscle -actin (green) showed that high Pi increased O2·- levels in both the media and intima of arteries (Figure 2D).
Measurement of Endothelial and Smooth Muscle [Ca2+]i
Smooth muscle [Ca2+]i was significantly greater at 160 mm Hg Pi than at 80 mm Hg Pi (Figure 4B), which corresponded to our previous findings,20 whereas increases in Pi had only a slight effect on [Ca2+]i in the endothelium (Figure 4A). In the absence of extracellular Ca2+, both endothelial and smooth muscle [Ca2+]i were substantially decreased and were unaffected by changes in Pi (Figures 4A and 4B).
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Pressure-Induced Phosphorylation of PKC
Increases in Pi resulted in significantly increased phosphorylation of PKC in arteries (Figure 5A). In arteries pressurized to 160 mm Hg, PKC phosphorylation was significantly greater than in vessels exposed to 80 mm Hg (Figure 5A). Immunofluorescent labeling of sections of arteries pressurized to 160 mm Hg showed that phospho-PKC was predominantly located in the media and the intima, whereas immunostaining of the adventitia was less evident (Figure 5B).
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Pressure-Induced Phosphorylation of p47phox
The phosphorylation of p47phox in isolated arteries was analyzed by detecting phosphorylation of serine residues after p47phox immunoprecipitation and SDS-PAGE. Pressurization of arteries resulted in significantly increased phosphorylation of p47phox compared with nonpressurized vessels (Figure 5C), as determined by densitometry analysis. In arteries pressurized to 160 mm Hg, p47phox phosphorylation was substantially greater than in vessels exposed to 80 mm Hg. Chelerythrine prevented high Pi–induced p47phox phosphorylation, whereas PMA stimulation of nonpressurized vessels triggered the phosphorylation of p47phox (Figure 5C).
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Discussion |
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The new findings in the present study are that in high Pi–exposed isolated arteries, there is (1) an increased chelerythrine- and DPI-sensitive, Ca2+-dependent O2·- production that impairs flow-induced nitric oxide–mediated dilation; (2) elevated smooth muscle [Ca2+]i and enhanced phosphorylation of PKC
; and (3) enhanced chelerythrine-sensitive phosphorylation of the p47phox subunit of NAD(P)H oxidase.
Pressure-Induced Increase in Arterial O2·- Generation
In isolated arteries, SOD-reversible endothelial dysfunction could be elicited in vitro in the absence of circulating factors by increasing Pi to a hypertensive level (Figure 1), thus confirming our previous findings.17 Other studies also showed that in the coronary and cerebral circulation, short-term increases in Pi in vivo also impair endothelial function.13–16 Mechanosensitive production of reactive oxygen species has also been linked to pressure-induced constriction of arterioles.24,25 To provide further evidence for high Pi–induced oxidative stress, we demonstrated with real-time lucigenin chemiluminescence measurements that high Pi itself induced significant increases in arterial O2·- generation (Figures 2A and 2B), whereas normal levels of Pi had minimal effect. High Pi induced a rapid peak increase in O2·- production that was followed by a plateau phase (Figure 2A). Importantly, arterial O2·- levels measured after exposure to high Pi also remained elevated (Figure 3A). We have found a similar, sustained O2·- generation recently in vascular ring preparations after short-term stretching,21 thus suggesting that mechanical activation-induced O2·- production is not readily reversible. High Pi increased vascular O2·- production in the endothelium and the smooth muscle, as shown by ethidium bromide staining (Figure 2D), thus suggesting that similar mechanosensitive pro-oxidant pathways are present in both cell types.
Role of NAD(P)H Oxidase
Because high Pi–induced endothelial dysfunction (Figure 1) and increased O2·- generation (Figures 2C and 3A
) could be prevented by apocynin and DPI, it is likely that high Pi itself activates NAD(P)H oxidases. The in vivo importance of high Pi–induced activation of oxidases is supported by recent findings showing increased NAD(P)H oxidase-dependent vascular O2·- production in virtually all forms of hypertension,2,5,7,8,26 which can be reduced or prevented by lowering Pi.8,11 Studies on cultured endothelial and smooth muscle cells27 and on aortic rings21 showing stretch-induced O2·- generation also suggest that mechanosensitive pathways are coupled to NAD(P)H oxidase activity in both the arterial endothelium and smooth muscle. Previous studies suggested a role for locally produced angiotensin in vascular oxidative stress and modulation of flow-mediated responses.28 Thus, we incubated the vessels with losartan and captopril to exclude the contribution of a local renin-angiotensin system, yet high Pi still activated O2·- generation (Figure 3B) and induced endothelial dysfunction (Figure 1), providing further evidence for the direct role of high Pi.
Role of Ca2+ and PKC-Dependent Signal Transduction
We found that removal of Ca2+ and inhibition of PKC prevented high Pi-induced O2·- production (Figures 3A and 3B), indicating a role for mechanosensitive Ca2+ signaling and PKC-dependent pathways in high Pi–induced upregulation of NAD(P)H oxidase activity. This idea is consistent with the findings that high Pi elicited significantly greater increases in smooth muscle [Ca2+]i than normal levels of Pi (Figure 4). The important role of Ca2+ signaling is also supported by the finding that administration of a Ca2+ ionophore resulted in significantly increased arterial O2·- production (Figure 3C). Further, pharmacological activation of PKC2 elicited substantial increases in arterial NAD(P)H oxidase-derived O2·- generation (Figure 3C). Because removal of Ca2+ during high-pressure treatment prevented endothelial dysfunction (Figure 1) and increases in O2·- production in high Pi–exposed arteries (Figure 3A) and phorbol ester–stimulated O2·- generation in normotensive arteries could also be reduced by removal of Ca2+ (Figure 3C), it is likely that Ca2+-dependent PKC isoforms are involved in the high Pi–induced upregulation of arterial NAD(P)H oxidase activity. This idea is further supported by the findings that high Pi elicited phosphorylation of PKC23 (Figure 5A), the most abundant Ca2+–dependent PKC isoform in arteries. It seems that high Pi induces phosphorylation and activation of PKC in both the endothelium and smooth muscle, as indicated by immunostaining (Figure 5B) that leads to increased O2·- production in both cell types (Figure 2D).
The activity of NAD(P)H oxidases is thought to be regulated by phosphorylation of the cytosolic regulatory p47phox subunit29 that facilitates association of the membrane-bound and cytoplasmic subunits of the enzyme.21 We found that high Pi substantially increased phosphorylation of serine residues of p47phox, an effect that could be prevented by inhibition of the serine/threonine kinase PKC2,3 (Figure 5C). Correspondingly, pharmacological activation of PKC resulted in phosphorylation of the p47phox subunit (Figure 5C) and increased NAD(P)H oxidase-dependent O2·- production (Figure 3C).
Thus, we conclude that hypertensive levels of Pi itself are a sufficient stimulus for increased arterial O2·- production, likely by inducing Ca2+- and PKC-dependent of phosphorylation and activation of the NAD(P)H oxidase (Figure 5D). This mechanism may contribute to the increased O2·- levels and endothelial dysfunction in hypertension, regardless of its cause. In addition, high Pi–induced NAD(P)H oxidase function in vivo is likely also stimulated by increased pulsatility27,30 and/or by increased levels of humoral factors, such as angiotensin II,3,29 that increase PKC activity via G protein-coupled receptors. One can speculate that chronic high Pi–induced O2·- generation by stimulating redox-sensitive gene expression also contributes to structural remodeling, because a reduction of systemic blood pressure could reverse morphological changes.31 Finally, our findings also provide an explanation for the similar vasculoprotective effects of blood pressure lowering by pharmacological treatments with different mechanisms of action (eg, calcium antagonists, diuretics, and ACE inhibitors) in various forms of human hypertension.
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Acknowledgments |
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This study was supported by grants NIH-PO-1-HL-43023, HL-46813, and HL-59417; AHA-00-500849T, 00-20144T, and 01-20166T; and Hungarian National Scientific Research Fund (NSRF/OTKA) grants T-033117 and T-034779.
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References |
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 Q. Zeng, Q. Zhou, F. Yao, S. T. O'Rourke, and C. Sun Endothelin-1 Regulates Cardiac L-Type Calcium Channels via NAD(P)H Oxidase-Derived Superoxide J. Pharmacol. Exp. Ther., September 1, 2008; 326(3): 732 - 738. [Abstract] [Full Text] [PDF]
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A. Csiszar, N. Labinskyy, H. Jo, P. Ballabh, and Z. Ungvari Differential proinflammatory and prooxidant effects of bone morphogenetic protein-4 in coronary and pulmonary arterial endothelial cells Am J Physiol Heart Circ Physiol, August 1, 2008; 295(2): H569 - H577. [Abstract] [Full Text] [PDF]
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Z. Bagi, N. Erdei, and A. Koller High intraluminal pressure via H2O2 upregulates arteriolar constrictions to angiotensin II by increasing the functional availability of AT1 receptors Am J Physiol Heart Circ Physiol, August 1, 2008; 295(2): H835 - H841. [Abstract] [Full Text] [PDF]
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 J W Kim, H S Seo, J O Na, S Y Suh, C U Choi, E J Kim, S-W Rha, C G Park, and D J Oh Myocardial bridging is related to endothelial dysfunction but not to plaque as assessed by intracoronary ultrasound Heart, June 1, 2008; 94(6): 765 - 769. [Abstract] [Full Text] [PDF]
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A. Csiszar, N. Labinskyy, A. Podlutsky, P. M. Kaminski, M. S. Wolin, C. Zhang, P. Mukhopadhyay, P. Pacher, F. Hu, R. de Cabo, et al. Vasoprotective effects of resveratrol and SIRT1: attenuation of cigarette smoke-induced oxidative stress and proinflammatory phenotypic alterations Am J Physiol Heart Circ Physiol, June 1, 2008; 294(6): H2721 - H2735. [Abstract] [Full Text] [PDF]
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A. Jacobson, C. Yan, Q. Gao, T. Rincon-Skinner, A. Rivera, J. Edwards, A. Huang, G. Kaley, and D. Sun Aging enhances pressure-induced arterial superoxide formation Am J Physiol Heart Circ Physiol, September 1, 2007; 293(3): H1344 - H1350. [Abstract] [Full Text] [PDF]
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A. Csiszar, N. Labinskyy, Z. Orosz, Z. Xiangmin, R. Buffenstein, and Z. Ungvari Vascular aging in the longest-living rodent, the naked mole rat Am J Physiol Heart Circ Physiol, August 1, 2007; 293(2): H919 - H927. [Abstract] [Full Text] [PDF]
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Z. Ungvari, Z. Orosz, A. Rivera, N. Labinskyy, Z. Xiangmin, S. Olson, A. Podlutsky, and A. Csiszar Resveratrol increases vascular oxidative stress resistance Am J Physiol Heart Circ Physiol, May 1, 2007; 292(5): H2417 - H2424. [Abstract] [Full Text] [PDF]
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 A. Csiszar, N. Labinskyy, K. E. Smith, A. Rivera, E. N.T.P. Bakker, H. Jo, J. Gardner, Z. Orosz, and Z. Ungvari Downregulation of Bone Morphogenetic Protein 4 Expression in Coronary Arterial Endothelial Cells: Role of Shear Stress and the cAMP/Protein Kinase A Pathway Arterioscler Thromb Vasc Biol, April 1, 2007; 27(4): 776 - 782. [Abstract] [Full Text] [PDF]
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 A. Csiszar, N. Labinskyy, K. Smith, A. Rivera, Z. Orosz, and Z. Ungvari Vasculoprotective Effects of Anti-Tumor Necrosis Factor-{alpha} Treatment in Aging Am. J. Pathol., January 1, 2007; 170(1): 388 - 698. [Abstract] [Full Text] [PDF]
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N. Labinskyy, A. Csiszar, Z. Orosz, K. Smith, A. Rivera, R. Buffenstein, and Z. Ungvari Comparison of endothelial function, O2-{middle dot} and H2O2 production, and vascular oxidative stress resistance between the longest-living rodent, the naked mole rat, and mice. Am J Physiol Heart Circ Physiol, December 1, 2006; 291(6): H2698 - H2704. [Abstract] [Full Text] [PDF]
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 I. Kovacs, J. Toth, J. Tarjan, and A. Koller Correlation of flow mediated dilation with inflammatory markers in patients with impaired cardiac function. Beneficial effects of inhibition of ACE Eur J Heart Fail, August 1, 2006; 8(5): 451 - 459. [Abstract] [Full Text] [PDF]
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M. Oelze, A. Warnholtz, J. Faulhaber, P. Wenzel, A. L. Kleschyov, M. Coldewey, U. Hink, O. Pongs, I. Fleming, S. Wassmann, et al. NADPH Oxidase Accounts for Enhanced Superoxide Production and Impaired Endothelium-Dependent Smooth Muscle Relaxation in BK{beta}1-/- Mice Arterioscler Thromb Vasc Biol, August 1, 2006; 26(8): 1753 - 1759. [Abstract] [Full Text] [PDF]
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 T. M. Paravicini and R. M. Touyz Redox signaling in hypertension Cardiovasc Res, July 15, 2006; 71(2): 247 - 258. [Abstract] [Full Text] [PDF]
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 C. Brueckl, S. Kaestle, A. Kerem, H. Habazettl, F. Krombach, H. Kuppe, and W. M. Kuebler Hyperoxia-Induced Reactive Oxygen Species Formation in Pulmonary Capillary Endothelial Cells In Situ Am. J. Respir. Cell Mol. Biol., April 1, 2006; 34(4): 453 - 463. [Abstract] [Full Text] [PDF]
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N. E. Taylor, P. Glocka, M. Liang, and A. W. Cowley Jr NADPH Oxidase in the Renal Medulla Causes Oxidative Stress and Contributes to Salt-Sensitive Hypertension in Dahl S Rats Hypertension, April 1, 2006; 47(4): 692 - 698. [Abstract] [Full Text] [PDF]
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A. Csiszar, M. Ahmad, K. E. Smith, N. Labinskyy, Q. Gao, G. Kaley, J. G. Edwards, M. S. Wolin, and Z. Ungvari Bone Morphogenetic Protein-2 Induces Proinflammatory Endothelial Phenotype Am. J. Pathol., February 1, 2006; 168(2): 629 - 638. [Abstract] [Full Text] [PDF]
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 J. Q. Liu, I. N. Zelko, E. M. Erbynn, J. S. K. Sham, and R. J. Folz Hypoxic pulmonary hypertension: role of superoxide and NADPH oxidase (gp91phox) Am J Physiol Lung Cell Mol Physiol, January 1, 2006; 290(1): L2 - L10. [Abstract] [Full Text] [PDF]
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Y. E. Lau, J. J. Galligan, D. L. Kreulen, and G. D. Fink Activation of ETB receptors increases superoxide levels in sympathetic ganglia in vivo Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R90 - R95. [Abstract] [Full Text] [PDF]
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C. S. Wilcox Oxidative stress and nitric oxide deficiency in the kidney: a critical link to hypertension? Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2005; 289(4): R913 - R935. [Abstract] [Full Text] [PDF]
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 Y Shimoni, D Hunt, M Chuang, K. Y Chen, G Kargacin, and D. L Severson Modulation of potassium currents by angiotensin and oxidative stress in cardiac cells from the diabetic rat J. Physiol., August 15, 2005; 567(1): 177 - 190. [Abstract] [Full Text] [PDF]
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 J. R. Alegria, J. Herrmann, D. R. Holmes Jr, A. Lerman, and C. S. Rihal Myocardial bridging Eur. Heart J., June 2, 2005; 26(12): 1159 - 1168. [Abstract] [Full Text] [PDF]
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R. A. Oeckler, E. Arcuino, M. Ahmad, S. C. Olson, and M. S. Wolin Cytosolic NADH redox and thiol oxidation regulate pulmonary arterial force through ERK MAP kinase Am J Physiol Lung Cell Mol Physiol, June 1, 2005; 288(6): L1017 - L1025. [Abstract] [Full Text] [PDF]
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M. S. Wolin Loss of Vascular Regulation by Soluble Guanylate Cyclase Is Emerging as a Key Target of the Hypertensive Disease Process Hypertension, June 1, 2005; 45(6): 1068 - 1069. [Full Text] [PDF]
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A. Csiszar, K. E. Smith, A. Koller, G. Kaley, J. G. Edwards, and Z. Ungvari Regulation of Bone Morphogenetic Protein-2 Expression in Endothelial Cells: Role of Nuclear Factor-{kappa}B Activation by Tumor Necrosis Factor-{alpha}, H2O2, and High Intravascular Pressure Circulation, May 10, 2005; 111(18): 2364 - 2372. [Abstract] [Full Text] [PDF]
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 K. Fujimori, K. Kadoyama, and Y. Urade Protein Kinase C Activates Human Lipocalin-type Prostaglandin D Synthase Gene Expression through De-repression of Notch-HES Signaling and Enhancement of AP-2{beta} Function in Brain-derived TE671 Cells J. Biol. Chem., May 6, 2005; 280(18): 18452 - 18461. [Abstract] [Full Text] [PDF]
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D. D. Gutterman, H. Miura, and Y. Liu Redox Modulation of Vascular Tone: Focus of Potassium Channel Mechanisms of Dilation Arterioscler Thromb Vasc Biol, April 1, 2005; 25(4): 671 - 678. [Abstract] [Full Text] [PDF]
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R.M. Touyz, G. Yao, M.T. Quinn, P.J. Pagano, and E.L. Schiffrin p47phox Associates With the Cytoskeleton Through Cortactin in Human Vascular Smooth Muscle Cells: Role in NAD(P)H Oxidase Regulation by Angiotensin II Arterioscler Thromb Vasc Biol, March 1, 2005; 25(3): 512 - 518. [Abstract] [Full Text] [PDF]
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C. Rask-Madsen and G. L. King Proatherosclerotic Mechanisms Involving Protein Kinase C in Diabetes and Insulin Resistance Arterioscler Thromb Vasc Biol, March 1, 2005; 25(3): 487 - 496. [Abstract] [Full Text] [PDF]
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R. P. Brandes and J. Kreuzer Vascular NADPH oxidases: molecular mechanisms of activation Cardiovasc Res, January 1, 2005; 65(1): 16 - 27. [Abstract] [Full Text] [PDF]
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J. Herrmann, S. T. Higano, R. J. Lenon, C. S. Rihal, and A. Lerman Myocardial bridging is associated with alteration in coronary vasoreactivity Eur. Heart J., December 1, 2004; 25(23): 2134 - 2142. [Abstract] [Full Text] [PDF]
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 S. Adler and H. Huang Oxidant stress in kidneys of spontaneously hypertensive rats involves both oxidase overexpression and loss of extracellular superoxide dismutase Am J Physiol Renal Physiol, November 1, 2004; 287(5): F907 - F913. [Abstract] [Full Text] [PDF]
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 C. Cseko, Z. Bagi, and A. Koller Biphasic effect of hydrogen peroxide on skeletal muscle arteriolar tone via activation of endothelial and smooth muscle signaling pathways J Appl Physiol, September 1, 2004; 97(3): 1130 - 1137. [Abstract] [Full Text] [PDF]
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G. S. Jose, M. U. Moreno, S. Olivan, O. Beloqui, A. Fortuno, J. Diez, and G. Zalba Functional Effect of the p22phox -930A/G Polymorphism on p22phox Expression and NADPH Oxidase Activity in Hypertension Hypertension, August 1, 2004; 44(2): 163 - 169. [Abstract] [Full Text] [PDF]
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Z. Ungvari, A. Csiszar, P. M. Kaminski, M. S. Wolin, and A. Koller Chronic High Pressure-Induced Arterial Oxidative Stress: Involvement of Protein Kinase C-Dependent NAD(P)H Oxidase and Local Renin-Angiotensin System Am. J. Pathol., July 1, 2004; 165(1): 219 - 226. [Abstract] [Full Text] [PDF]
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S. Veerareddy, C.-L. M. Cooke, P. N. Baker, and S. T. Davidge Gender differences in myogenic tone in superoxide dismutase knockout mouse: animal model of oxidative stress Am J Physiol Heart Circ Physiol, July 1, 2004; 287(1): H40 - H45. [Abstract] [Full Text] [PDF]
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