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Suborno M Ghosh,
Vikas Kapil,
Isabel Fuentes-Calvo,
Kristen J Bubb,
Vanessa Pearl,
Alexandra B Milsom,
Rayomand Khambata,
Sheiva Maleki-Toyserkani,
Mubeen Yousuf,
Nigel Benjamin,
Andrew J Webb,
Mark J Caulfield,
Adrian J Hobbs, Amrita Ahluwalia
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ABSTRACT: Elevation of circulating nitrite (NO2(-)) levels causes vasodilatation and lowers blood pressure in healthy volunteers. Whether these effects and the underpinning mechanisms persist in hypertension is unknown. Therefore, we investigated the consequences of systemic nitrite elevation in spontaneously hypertensive rats and conducted proof-of-principle studies in patients. Nitrite caused dose-dependent blood pressure-lowering that was profoundly enhanced in spontaneously hypertensive rats versus normotensive Wistar Kyoto controls. This effect was virtually abolished by the xanthine oxidoreductase (XOR) inhibitor, allopurinol, and associated with hypertension-specific XOR-dependent nitrite reductase activity localized to the erythrocyte but not the blood vessel wall. To determine whether these pathways translate to human hypertension, we investigated the effects of elevation of circulating nitrite levels in 15 drug naïve grade 1 hypertensives. To elevate nitrite, we used a dose of dietary nitrate (≈3.5 mmol) that elevated nitrite levels ≈1.5-fold (P<0.01); a rise shown previously to exert no significant blood pressure-lowering effects in normotensives. This dose caused substantial reductions in systolic (≈12 mm Hg) and diastolic blood pressures (P<0.001) and pulse wave velocity (P<0.05); effects associated with elevations in erythrocytic XOR expression and XOR-dependent nitrite reductase activity. Our observations demonstrate the improved efficacy of inorganic nitrate and nitrite in hypertension as a consequence of increased erythrocytic XOR nitrite reductase activity and support the concept of dietary nitrate supplementation as an effective, but simple and inexpensive, antihypertensive strategy.
Hypertension 04/2013; · 6.21 Impact Factor
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ABSTRACT: The ELR+-CXCL chemokines have been described typically as potent chemoattractants and activators of neutrophils during the acute phase of inflammation. Their role in atherosclerosis, a chronic inflammatory vascular disease, has been largely unexplored. Using a mouse model of atherosclerosis, we found that CXCL5 expression was upregulated during disease progression, both locally and systemically, but was not associated with neutrophil infiltration. Unexpectedly, inhibition of CXCL5 was not beneficial but rather induced a significant macrophage foam cell accumulation in murine atherosclerotic plaques. Additionally, we demonstrated that CXCL5 modulated macrophage activation, increased expression of the cholesterol efflux regulatory protein ABCA1, and enhanced cholesterol efflux activity in macrophages. These findings reveal a protective role for CXCL5, in the context of atherosclerosis, centered on the regulation of macrophage foam cell formation.
The Journal of clinical investigation 02/2013; · 15.39 Impact Factor
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Circulation 01/2013; 127(2):e275. · 14.74 Impact Factor
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ABSTRACT: Circulating nitrate (NO(3)(-)), derived from dietary sources or endogenous nitric oxide production, is extracted from blood by the salivary glands, accumulates in saliva and is then reduced to nitrite (NO(2)(-)) by the oral microflora. This process has historically been viewed as harmful, since nitrite can promote formation of potentially carcinogenic N-nitrosamines. More recent research, however, suggests that nitrite can also serve as a precursor for systemic generation of vasodilatory nitric oxide, and exogenous administration of nitrate reduces blood pressure in humans. However, whether oral nitrate-reducing bacteria participate in 'setting' blood pressure is unknown. We investigated whether suppression of the oral microflora affects systemic nitrite levels and hence blood pressure in healthy individuals. We measured blood pressure (clinic, home and 24h ambulatory) in 19 healthy volunteers during an initial 7 day control period followed by a 7 day treatment period with a chlorhexidine-based antiseptic mouthwash. Oral nitrate-reducing capacity and nitrite levels were measured after each study period. Antiseptic mouthwash treatment reduced oral nitrite production by 90% (p<0.001) and plasma nitrite levels by 25% (p=0.001) compared to the control period. Systolic and diastolic blood pressure increased by 2-3.5mmHg; increases correlated to decrease in circulating nitrite concentrations (r(2)=0.56, p=0.002). The blood pressure effect appeared within one day of disruption of the oral microflora and was sustained during the 7 day mouthwash intervention. These results suggest that the recycling of endogenous nitrate by oral bacteria plays an important role in determination of plasma nitrite levels and thereby in the physiological control of blood pressure.
Free radical biology & medicine 11/2012; · 5.42 Impact Factor
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ABSTRACT: Approximately one third of all deaths are attributed to cardiovascular disease (CVD), making it the biggest killer worldwide. Despite a number of therapeutic options available, the burden of CVD morbidity continues to grow indicating the need for continued research to address this unmet need. In this respect, investigation of the mechanisms underlying the protection that premenopausal females enjoy from cardiovascular-related disease and mortality is of interest. In this review, we discuss the essential role that rodent animal models play in enabling this field of research. In particular, we focus our discussion on models of hypertension and atherosclerosis.
British Journal of Pharmacology 05/2012; 167(2):298-312. · 4.41 Impact Factor
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ABSTRACT: Pulmonary hypertension (PH) is a multifactorial disease characterized by increased pulmonary vascular resistance and right ventricular failure; morbidity and mortality remain unacceptably high. Loss of nitric oxide (NO) bioactivity is thought to contribute to the pathogenesis of PH, and agents that augment pulmonary NO signaling are clinically effective in the disease. Inorganic nitrate (NO(3)(-)) and nitrite (NO(2)(-)) elicit a reduction in systemic blood pressure in healthy individuals; this effect is underpinned by endogenous and sequential reduction to NO. Herein, we determined whether dietary nitrate and nitrite might be preferentially reduced to NO by the hypoxia associated with PH, and thereby offer a convenient, inexpensive method of supplementing NO functionality to reduce disease severity.
Dietary nitrate reduced the right ventricular pressure and hypertrophy, and pulmonary vascular remodeling in wild-type mice exposed to 3 weeks of hypoxia; this beneficial activity was mirrored largely by dietary nitrite. The cytoprotective effects of dietary nitrate were associated with increased plasma and lung concentrations of nitrite and cGMP. The beneficial effects of dietary nitrate and nitrite were reduced in mice lacking endothelial NO synthase or treated with the xanthine oxidoreductase inhibitor allopurinol.
These data demonstrate that dietary nitrate, and to a lesser extent dietary nitrite, elicit pulmonary dilatation, prevent pulmonary vascular remodeling, and reduce the right ventricular hypertrophy characteristic of PH. This favorable pharmacodynamic profile depends on endothelial NO synthase and xanthine oxidoreductase -catalyzed reduction of nitrite to NO. Exploitation of this mechanism (ie, dietary nitrate/nitrite supplementation) represents a viable, orally active therapy for PH.
Circulation 05/2012; 125(23):2922-32. · 14.74 Impact Factor
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ABSTRACT: BACKGROUND AND PURPOSE Pre-menopausal females have a lower incidence of cardiovascular disease compared with age-matched males, implying differences in the mechanisms and pathways regulating vasoactivity. In small arteries, myogenic tone (constriction in response to raised intraluminal pressure) is a major determinant of vascular resistance. Endothelium-derived dilators, particularly NO, tonically moderate myogenic tone and, because the endothelium is an important target for female sex hormones, we investigated whether NO-mediated moderation of myogenic tone differed between the sexes. EXPERIMENTAL APPROACH Pressure-diameter or relaxation concentration-response curves to the NO donor spermine-NO or soluble guanylate cyclase (sGC) stimulation (BAY41-2272) were constructed before and following drug intervention in murine mesenteric resistance arteries. Hypotensive responses to activators of the NO-sGC pathway were determined. Quantitative PCR and Western blotting were used for expression analysis. KEY RESULTS NO synthase inhibition enhanced myogenic tone of arteries of both sexes while block of endothelium-derived hyperpolarizing factor (EDHF) enhanced responses in arteries of females only. Spermine-NO concentration-dependently relaxed mesenteric arteries isolated from either sex. However, while inhibition of sGC activity attenuated responses of arteries from male mice only, endothelial denudation attenuated responses of arteries from females only. BAY41-2272 and spermine-NO-induced vasodilatation and hypotension were greater in males than in females. CONCLUSIONS AND IMPLICATIONS NO moderated myogenic tone in arteries of male mice by a sGC-dependent pathway while EDHF was the predominant endothelial regulator in arteries of females. This is a potentially important sexual dimorphism in NO-mediated reactivity and further implicates EDHF as the predominant endothelial vasodilator in female resistance arteries.
British Journal of Pharmacology 04/2012; 167(4):805-17. · 4.41 Impact Factor
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ABSTRACT: Sex hormones underlie the lower incidence of cardiovascular disease in premenopausal women. Vascular inflammation is involved in the pathogenesis of several cardiovascular diseases and it has been reported that sex hormones modulate inflammatory responses but mechanisms responsible for these effects are not yet fully established. Herein, we assessed whether sex differences in leukocyte recruitment might exist and investigated the underlying mechanisms involved in this response.
Treatment with interleukin-1β (IL-1β) or tumor necrosis factor-α caused leukocyte rolling, adhesion, and emigration in mesenteric postcapillary venules in vivo that was substantially reduced in female mice compared with male mice; this difference was abolished by ovariectomy and partially restored by estrogen replacement. Deletion of endothelial nitric oxide (NO) synthase or cyclooxygenase-1 alone or in combination did not alter the leukocyte recruitment in IL-1β-treated females but significantly enhanced this response in male mice. Treatment of murine pulmonary endothelial cells with IL-1β increased expression of P-selectin in male but not female cells.
We have demonstrated a profound estrogen-dependent and NO and prostacyclin-independent suppression of leukocyte recruitment in females.
Arteriosclerosis Thrombosis and Vascular Biology 02/2011; 31(5):1075-83. · 6.37 Impact Factor
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Vikas Kapil,
Alexandra B Milsom,
Michael Okorie,
Sheiva Maleki-Toyserkani,
Farihah Akram,
Farkhanda Rehman,
Shah Arghandawi,
Vanessa Pearl,
Nigel Benjamin,
Stavros Loukogeorgakis,
Raymond Macallister,
Adrian J Hobbs,
Andrew J Webb, Amrita Ahluwalia
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ABSTRACT: Ingestion of dietary (inorganic) nitrate elevates circulating and tissue levels of nitrite via bioconversion in the entero-salivary circulation. In addition, nitrite is a potent vasodilator in humans, an effect thought to underlie the blood pressure-lowering effects of dietary nitrate (in the form of beetroot juice) ingestion. Whether inorganic nitrate underlies these effects and whether the effects of either naturally occurring dietary nitrate or inorganic nitrate supplementation are dose dependent remain uncertain. Using a randomized crossover study design, we show that nitrate supplementation (KNO(3) capsules: 4 versus 12 mmol [n=6] or 24 mmol of KNO(3) (1488 mg of nitrate) versus 24 mmol of KCl [n=20]) or vegetable intake (250 mL of beetroot juice [5.5 mmol nitrate] versus 250 mL of water [n=9]) causes dose-dependent elevation in plasma nitrite concentration and elevation of cGMP concentration with a consequent decrease in blood pressure in healthy volunteers. In addition, post hoc analysis demonstrates a sex difference in sensitivity to nitrate supplementation dependent on resting baseline blood pressure and plasma nitrite concentration, whereby blood pressure is decreased in male volunteers, with higher baseline blood pressure and lower plasma nitrite concentration but not in female volunteers. Our findings demonstrate dose-dependent decreases in blood pressure and vasoprotection after inorganic nitrate ingestion in the form of either supplementation or by dietary elevation. In addition, our post hoc analyses intimate sex differences in nitrate processing involving the entero-salivary circulation that are likely to be major contributing factors to the lower blood pressures and the vasoprotective phenotype of premenopausal women.
Hypertension 08/2010; 56(2):274-81. · 6.21 Impact Factor
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ABSTRACT: Hypercholesterolemia is associated with decreased nitric oxide (NO) bioavailability and endothelial dysfunction, a phenomenon thought to have a major role in the altered cerebral blood flow evident in stroke. Therefore, strategies that increase endothelial NO production have potential utility. Vascular reactivity of the middle cerebral artery (MCA) from C57BL/6J wild-type (WT) mice, apolipoprotein-E knockout (ApoE(-/-)) mice, and mice treated with the phosphodiesterase inhibitor cilostazol (100 mg/kg) was analyzed using the tension myograph. Contractile responses to endothelin-1 were significantly enhanced in MCA from ApoE(-/-) mice compared with WT mice (P<0.01), an effect absent in cilostazol-treated ApoE(-/-) mice. Acetylcholine-induced relaxation (which is entirely NO-dependent) was significantly impaired in MCA of ApoE(-/-) mice compared with WT mice (P<0.05), again an effect prevented by cilostazol treatment. Endothelial NOS phosphorylation at Ser(1179) was decreased in the aorta of ApoE(-/-) mice compared with WT mice (P<0.05), an effect normalized by cilostazol. Taken together, our data suggest that the endothelial dysfunction observed in MCA associated with hypercholesterolemia is prevented by cilostazol, an effect likely due to the increase in eNOS phosphorylation and, therefore, activity.
Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 03/2010; 30(8):1494-503. · 5.46 Impact Factor
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Jon O Lundberg,
Mark T Gladwin, Amrita Ahluwalia,
Nigel Benjamin,
Nathan S Bryan,
Anthony Butler,
Pedro Cabrales,
Angela Fago,
Martin Feelisch,
Peter C Ford, [......],
Valentin P Reutov,
George B Richter-Addo,
Alan Schechter,
Sruti Shiva,
Koichiro Tsuchiya,
Ernst E van Faassen,
Andrew J Webb,
Brian S Zuckerbraun,
Jay L Zweier,
Eddie Weitzberg
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ABSTRACT: Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent 2-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm.
Nature Chemical Biology 11/2009; 5(12):865-869. · 14.69 Impact Factor
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Ross C Laxton,
Yanhua Hu,
Johan Duchene,
Feng Zhang,
Zhongyi Zhang,
Kit-Yi Leung,
Qingzhong Xiao,
Ramona S Scotland,
Conrad P Hodgkinson,
Katherine Smith,
Johann Willeit,
Carlos López-Otín,
Iain A Simpson,
Stefan Kiechl, Amrita Ahluwalia,
Qingbo Xu,
Shu Ye
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ABSTRACT: Atherosclerotic lesions express matrix metalloproteinase (MMP)8, which possesses proteolytic activity on matrix proteins particularly fibrillar collagens and on nonmatrix proteins such as angiotensin (Ang) I.
We studied whether MMP8 plays a role in atherogenesis.
In atherosclerosis-prone apolipoprotein E-deficient mice, inactivating MMP8 resulted in a substantial reduction in atherosclerotic lesion formation. Immunohistochemical examinations showed that atherosclerotic lesions in MMP8-deficient mice had significantly fewer macrophages but increased collagen content. In line with results of in vitro assays showing that Ang I cleavage by MMP8 generated Ang II, MMP8 knockout mice had lower Ang II levels and lower blood pressure. In addition, we found that products of Ang I cleavage by MMP8 increased vascular cell adhesion molecule (VCAM)-1 expression and that MMP8-deficient mice had reduced VCAM-1 expression in atherosclerotic lesions. Intravital microscopy analysis showed that leukocyte rolling and adhesion on vascular endothelium was reduced in MMP8 knockout mice. Furthermore, we detected an association between MMP8 gene variation and extent of coronary atherosclerosis in patients with coronary artery disease. A relationship among MMP8 gene variation, plasma VCAM-1 level, and atherosclerosis progression was also observed in a population-based, prospective study.
These results indicate that MMP8 is an important player in atherosclerosis.
Circulation Research 10/2009; 105(9):921-9. · 9.49 Impact Factor
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Johan Duchene,
Cécile Cayla,
Sandrine Vessillier,
Ramona Scotland,
Kazuo Yamashiro,
Florence Lecomte,
Irfan Syed,
Phuong Vo,
Alessandra Marrelli,
Costantino Pitzalis,
Francesco Cipollone,
Joost Schanstra,
Jean-Loup Bascands,
Adrian J Hobbs,
Mauro Perretti, Amrita Ahluwalia
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ABSTRACT: The proinflammatory phenotype induced by low laminar shear stress (LSS) is implicated in atherogenesis. The kinin B1 receptor (B1R), known to be induced by inflammatory stimuli, exerts many proinflammatory effects including vasodilatation and leukocyte recruitment. We investigated whether low LSS is a stimulus for endothelial B1R expression and function.
Human and mouse atherosclerotic plaques expressed high level of B1R mRNA and protein. In addition, B1R expression was upregulated in the aortic arch (low LSS region) of ApoE(-/-) mice fed a high-fat diet compared to vascular regions of high LSS and animals fed normal chow. Of interest, a greater expression of B1R was noticed in endothelial cells from regions of low LSS in aortic arch of ApoE(-/-) mice. B1R was also upregulated in human umbilical vein endothelial cells (HUVECs) exposed to low LSS (0 to 2 dyn/cm(2)) compared to physiological LSS (6 to 10 dyn/cm(2)): an effect similarly evident in murine vascular tissue perfused ex vivo. Functionally, B1R activation increased prostaglandin and CXCL5 expression in cells exposed to low, but not physiological, LSS. IL-1beta and ox-LDL induced B1R expression and function in HUVECs, a response substantially enhanced under low LSS conditions and inhibited by blockade of NFkappaB activation.
Herein, we show that LSS is a major determinant of functional B1R expression in endothelium. Furthermore, whereas physiological high LSS is a powerful repressor of this inflammatory receptor, low LSS occurring [corrected] at sites of atheroma is associated with substantial upregulation, identifying this receptor as a potential therapeutic target.
Arteriosclerosis Thrombosis and Vascular Biology 09/2009; 29(11):1757-63. · 6.37 Impact Factor
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ABSTRACT: The kinin B(1) receptor plays an important role in mediating the inflammatory effects of the kallikrein-kinin pathway. The recent development of orally available non-peptidic antagonists and genetically modified mice deficient in B(1) receptor expression have demonstrated that the receptor plays a pivotal role in the cellular, particularly neutrophil, recruitment associated with an acute inflammatory response. These tools have also enabled elucidation of the pathways involved in mediating this effect and have highlighted a major role for chemokines, particularly CXCL5 and CCL2. Neutrophil recruitment is involved in the pathogenesis of renal disease and has very recently been implicated in the early stages of atherosclerosis. In this review we discuss the most recent evidence linking the B(1) receptor with the pathogenesis of these two inflammatory cardiovascular diseases and highlight the therapeutic potential of the kinin B(1) receptor in these disease states.
Current Opinion in Pharmacology 02/2009; 9(2):125-31. · 6.86 Impact Factor
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Andrew J Webb,
Alexandra B Milsom,
Krishnaraj S Rathod,
Wai Lum Chu,
Shehla Qureshi,
Matthew J Lovell,
Florence M J Lecomte,
David Perrett,
Carmelo Raimondo,
Espeed Khoshbin,
Zubair Ahmed,
Rakesh Uppal,
Nigel Benjamin,
Adrian J Hobbs, Amrita Ahluwalia
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ABSTRACT: Reduction of nitrite (NO(2)(-)) provides a major source of nitric oxide (NO) in the circulation, especially in hypoxemic conditions. Our previous studies suggest that xanthine oxidoreductase (XOR) is an important nitrite reductase in the heart and kidney. Herein, we have demonstrated that conversion of nitrite to NO by blood vessels and RBCs was enhanced in the presence of the XOR substrate xanthine (10 micromol/L) and attenuated by the XOR inhibitor allopurinol (100 micromol/L) in acidic and hypoxic conditions only. Whereas endothelial nitric oxide synthase (eNOS) inhibition had no effect on vascular nitrite reductase activity, in RBCs L-NAME, L-NMMA, and L-arginine inhibited nitrite-derived NO production by >50% (P<0.01) at pH 7.4 and 6.8 under hypoxic conditions. Western blot and immunohistochemical analysis of RBC membranes confirmed the presence of eNOS and abundant XOR on whole RBCs. Thus, XOR and eNOS are ideally situated on the membranes of RBCs and blood vessels to generate intravascular vasodilator NO from nitrite during ischemic episodes. In addition to the proposed role of deoxyhemoglobin, our findings suggest that the nitrite reductase activity within the circulation, under hypoxic conditions (at physiological pH), is mediated by eNOS; however, as acidosis develops, a substantial role for XOR becomes evident.
Circulation Research 10/2008; 103(9):957-64. · 9.49 Impact Factor
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ABSTRACT: The vascular endothelium plays a crucial role in the regulation of vascular homeostasis by controlling vascular tone, coagulation, and inflammatory responses. These actions are exerted by endothelial factors including nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor (EDHF). The greater incidence of cardiovascular disease (CVD) in men and postmenopausal women compared with premenopausal women implies a vasoprotective phenotype of females, which may be influenced by sex hormones. These hormones, particularly estrogen, have modulatory effects on the endothelium and circulating cells that have been implicated in vascular inflammation and in the development of CVD. EDHF seems to be the predominant endothelial factor in the resistance vasculature of females and this mediator could afford the beneficial cardiovascular risk profile observed in premenopausal woman. In this review, we discuss sex differences in EDHF biology and how sex hormones can modulate EDHF responses. We also review the implication of sex hormone-dependent regulation of EDHF in inflammatory processes, platelet function, and repair after vascular damage, each of which have a critical role in several aspects of the pathogenesis of CVD.
Journal of Endocrinology 07/2008; 197(3):447-62. · 3.55 Impact Factor
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Andrew J Webb,
Nakul Patel,
Stavros Loukogeorgakis,
Mike Okorie,
Zainab Aboud,
Shivani Misra,
Rahim Rashid,
Philip Miall,
John Deanfield,
Nigel Benjamin,
Raymond MacAllister,
Adrian J Hobbs, Amrita Ahluwalia
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ABSTRACT: Diets rich in fruits and vegetables reduce blood pressure (BP) and the risk of adverse cardiovascular events. However, the mechanisms of this effect have not been elucidated. Certain vegetables possess a high nitrate content, and we hypothesized that this might represent a source of vasoprotective nitric oxide via bioactivation. In healthy volunteers, approximately 3 hours after ingestion of a dietary nitrate load (beetroot juice 500 mL), BP was substantially reduced (Delta(max) -10.4/8 mm Hg); an effect that correlated with peak increases in plasma nitrite concentration. The dietary nitrate load also prevented endothelial dysfunction induced by an acute ischemic insult in the human forearm and significantly attenuated ex vivo platelet aggregation in response to collagen and ADP. Interruption of the enterosalivary conversion of nitrate to nitrite (facilitated by bacterial anaerobes situated on the surface of the tongue) prevented the rise in plasma nitrite, blocked the decrease in BP, and abolished the inhibitory effects on platelet aggregation, confirming that these vasoprotective effects were attributable to the activity of nitrite converted from the ingested nitrate. These findings suggest that dietary nitrate underlies the beneficial effects of a vegetable-rich diet and highlights the potential of a "natural" low cost approach for the treatment of cardiovascular disease.
Hypertension 04/2008; 51(3):784-90. · 6.21 Impact Factor
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ABSTRACT: Recent evidence implicates the neuronal transient receptor potential vanilloid receptor 1 (TRPV1), expressed on sensory C-fibers, as playing an important endogenous protective role in limiting the damaging effects of myocardial I/R injury. In neurons the 12-lipoxygenase (12-LOX) arachidonic acid (AA) metabolite, 12(S)-HpETE, has been proposed as the endogenous ligand for TRPV1. However, whether 12(S)-HpETE underlies TRPV1 channel activation during I/R is unknown. Treatment of isolated Langendorff rat hearts with a 12-LOX/AA cocktail significantly attenuated I/R injury (approximately 40% inhibition of infarct size), an effect reversed by the 12-LOX inhibitor baicalein or after chemical desensitization of local sensory C-fiber afferents using capsaicin. Both 12(S)-HpETE and AA caused dose-dependent coronary vasodilatation (approximately EC50s of 6x10(-19) and 1x10(-7), respectively) that was profoundly suppressed by the TRPV1 antagonist capsazepine, in hearts of TRPV1 knockout mice compared with wild-type mice, or by treatment with a CGRP antagonist. In addition, I/R itself stimulates up-regulation of TRPV1 expression in both the cell bodies located within the dorsal root ganglia and locally within the myocardium. Together, our data identify a novel 12-LOX/AA/TRPV1 pathway activated and up-regulated during I/R injury, providing an endogenous damage-limiting mechanism whose targeting may prove useful in treating myocardial infarction.
The FASEB Journal 10/2007; 21(11):2695-703. · 5.71 Impact Factor
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ABSTRACT: The kinin B1 receptor is an inducible receptor not normally expressed but induced by inflammatory stimuli and plays a major role in neutrophil recruitment, particularly in response to the cytokine IL-1beta. However, the exact mechanism involved in this response is unclear. The aim of this study was to dissect the molecular mechanism involved, in particular to determine whether specific ELR-CXCL chemokines (specific neutrophil chemoattractants) played a role. Using intravital microscopy, we demonstrated that IL-1beta-induced leukocyte rolling, adherence, and emigration in mesenteric venules of wild-type (WT) mice, associated with an increase in B1 receptor mRNA expression, were substantially attenuated (>80%) in B1 receptor knockout mice (B1KO). This effect in B1KO mice was correlated with a selective down-regulation of IL-1beta-induced CXCL5 mRNA and protein expression compared with WT mice. Furthermore a selective neutralizing CXCL5 Ab caused profound suppression of leukocyte emigration in IL-1beta-treated WT mice. Finally, treatment of human endothelial cells with IL-1beta enhanced mRNA expression of the B1 receptor and the human (h) CXCL5 homologues (hCXCL5 and hCXCL6). This response was suppressed by approximately 50% when cells were pretreated with the B1 receptor antagonist des-Arg9-[Leu8]-bradykinin while treatment with des-Arg9-bradykinin, the B1 receptor agonist, caused a concentration-dependent increase in hCXCL5 and hCXCL6 mRNA expression. This study unveils a proinflammatory pathway centered on kinin B1 receptor activation of CXCL5 leading to leukocyte trafficking and highlights the B1 receptor as a potential target in the therapeutics of inflammatory disease.
The Journal of Immunology 10/2007; 179(7):4849-56. · 5.79 Impact Factor
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ABSTRACT: C-type natriuretic peptide (CNP) has recently been suggested to represent an endothelium-derived hyperpolarising factor (EDHF) in the mammalian resistance vasculature and, as such, important in the regulation of local blood flow and systemic blood pressure. Additionally, this peptide has been shown to protect against ischaemia-reperfusion injury and inhibits leukocyte and platelet activation. Herein, we use a novel, selective natriuretic peptide receptor-C (NPR-C) antagonist (M372049) to highlight the pivotal contribution of CNP/NPR-C signalling in the EDHF-dependent regulation of vascular tone and investigate the mechanism(s) underlying the release and biological activity of CNP.
In vitro pharmacological investigation was conducted in rat (Sprague-Dawley) aorta and mesenteric resistance arteries. Relaxant responses to CNP, atrial natriuretic peptide (ANP), the nitric oxide donor spermine-NONOate (SPER-NO) and the endothelium-dependent vasodilator, acetylcholine (ACh) were examined in the absence and presence of M372049 or inhibitor cocktails shown previously to block endothelium-dependent dilatation in the resistance vasculature. RT-PCR was employed to characterize the expression of NPR subtypes in the vessels studied.
M372049 produced concentration-dependent inhibition of the vasorelaxant activity of CNP in rat isolated mesenteric resistance arteries but not aorta; in contrast, M372049 did not affect relaxations to ANP or SPER-NO in either vessel. M372049 or ouabain alone produced small, significant inhibition of EDHF-dependent relaxations in mesenteric arteries and in combination acted synergistically to abolish such responses. A combination of M372049 with established inhibitors of EDHF-dependent relaxation revealed that multiple, distinct pathways coordinate the bioactivity of EDHF in the resistance vasculature, and that CNP/NPR-C signalling represents a major component.
These data substantiate CNP/NPR-C signalling as a fundamental pathway underlying EDHF-dependent regulation of vascular tone in the rat mesenteric resistance vasculature. An increased understanding of the physiological roles of CNP/NPR-C signalling in the vasculature (now facilitated by the identification of a selective NPR-C antagonist) should aid determination of the (patho)physiological importance of EDHF and might provide the rationale for the design of novel therapeutics.
Cardiovascular Research 06/2007; 74(3):515-25. · 6.06 Impact Factor
