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Ungvari A, Gulej R, Csik B, Mukli P, Negri S, Tarantini S, Yabluchanskiy A, Benyo Z, Csiszar A, Ungvari Z. The Role of Methionine-Rich Diet in Unhealthy Cerebrovascular and Brain Aging: Mechanisms and Implications for Cognitive Impairment. Nutrients 2023; 15:4662. [PMID: 37960316 PMCID: PMC10650229 DOI: 10.3390/nu15214662] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 10/28/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023] Open
Abstract
As aging societies in the western world face a growing prevalence of vascular cognitive impairment and Alzheimer's disease (AD), understanding their underlying causes and associated risk factors becomes increasingly critical. A salient concern in the western dietary context is the high consumption of methionine-rich foods such as red meat. The present review delves into the impact of this methionine-heavy diet and the resultant hyperhomocysteinemia on accelerated cerebrovascular and brain aging, emphasizing their potential roles in cognitive impairment. Through a comprehensive exploration of existing evidence, a link between high methionine intake and hyperhomocysteinemia and oxidative stress, mitochondrial dysfunction, inflammation, and accelerated epigenetic aging is drawn. Moreover, the microvascular determinants of cognitive deterioration, including endothelial dysfunction, reduced cerebral blood flow, microvascular rarefaction, impaired neurovascular coupling, and blood-brain barrier (BBB) disruption, are explored. The mechanisms by which excessive methionine consumption and hyperhomocysteinemia might drive cerebromicrovascular and brain aging processes are elucidated. By presenting an intricate understanding of the relationships among methionine-rich diets, hyperhomocysteinemia, cerebrovascular and brain aging, and cognitive impairment, avenues for future research and potential therapeutic interventions are suggested.
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Affiliation(s)
- Anna Ungvari
- Department of Public Health, Semmelweis University, 1089 Budapest, Hungary
| | - Rafal Gulej
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Boglarka Csik
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Public Health, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
| | - Peter Mukli
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Public Health, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
| | - Sharon Negri
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Stefano Tarantini
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Public Health, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Andriy Yabluchanskiy
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Public Health, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Zoltan Benyo
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary;
- Cerebrovascular and Neurocognitive Disorders Research Group, Eötvös Loránd Research Network, Semmelweis University, 1094 Budapest, Hungary
| | - Anna Csiszar
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Translational Medicine, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
| | - Zoltan Ungvari
- Vascular Cognitive Impairment, Neurodegeneration and Healthy Brain Aging Program, Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (R.G.); (B.C.); (P.M.); (S.N.); (S.T.); (A.Y.); (A.C.); (Z.U.)
- Oklahoma Center for Geroscience and Healthy Brain Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- International Training Program in Geroscience, Department of Public Health, Doctoral School of Basic and Translational Medicine, Semmelweis University, 1089 Budapest, Hungary
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA
- Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Washington J, Ritch R, Liu Y. Homocysteine and Glaucoma. Int J Mol Sci 2023; 24:10790. [PMID: 37445966 DOI: 10.3390/ijms241310790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 06/10/2023] [Accepted: 06/11/2023] [Indexed: 07/15/2023] Open
Abstract
Elevated levels of homocysteine (Hcy), a non-proteinogenic amino acid, may lead to a host of manifestations across the biological systems, particularly the nervous system. Defects in Hcy metabolism have been associated with many neurodegenerative diseases including glaucoma, i.e., the leading cause of blindness. However, the pathophysiology of elevated Hcy and its eligibility as a risk factor for glaucoma remain unclear. We aimed to provide a comprehensive review of the relationship between elevated Hcy levels and glaucoma. Through a systemic search of the PubMed and Google Scholar databases, we found that elevated Hcy might play an important role in the pathogenesis of glaucoma. Further research will be necessary to help clarify the specific contribution of elevated Hcy in the pathogenesis of glaucoma. A discovery and conceptual understanding of Hcy-associated glaucoma could be the keys to providing better therapeutic treatment, if not prophylactic treatment, for this disease.
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Affiliation(s)
- Joshua Washington
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Robert Ritch
- New York Eye & Ear Infirmary, New York, NY 10003, USA
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- James & Jean Culver Vision Discovery Institute, 4 Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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Kavurma MM, Bursill C, Stanley CP, Passam F, Cartland SP, Patel S, Loa J, Figtree GA, Golledge J, Aitken S, Robinson DA. Endothelial cell dysfunction: Implications for the pathogenesis of peripheral artery disease. Front Cardiovasc Med 2022; 9:1054576. [PMID: 36465438 PMCID: PMC9709122 DOI: 10.3389/fcvm.2022.1054576] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 10/24/2022] [Indexed: 08/27/2023] Open
Abstract
Peripheral artery disease (PAD) is caused by occluded or narrowed arteries that reduce blood flow to the lower limbs. The treatment focuses on lifestyle changes, management of modifiable risk factors and vascular surgery. In this review we focus on how Endothelial Cell (EC) dysfunction contributes to PAD pathophysiology and describe the largely untapped potential of correcting endothelial dysfunction. Moreover, we describe current treatments and clinical trials which improve EC dysfunction and offer insights into where future research efforts could be made. Endothelial dysfunction could represent a target for PAD therapy.
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Affiliation(s)
- Mary M. Kavurma
- Heart Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Christina Bursill
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
- Faculty of Health and Medical Science, University of Adelaide, Adelaide, SA, Australia
| | | | - Freda Passam
- Heart Research Institute, The University of Sydney, Sydney, NSW, Australia
- Central Clinical School, Faculty of Health and Medicine, The University of Sydney, Sydney, NSW, Australia
| | - Siân P. Cartland
- Heart Research Institute, The University of Sydney, Sydney, NSW, Australia
| | - Sanjay Patel
- Heart Research Institute, The University of Sydney, Sydney, NSW, Australia
- Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Jacky Loa
- Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Gemma A. Figtree
- Faculty of Health and Medicine, The University of Sydney, Sydney, NSW, Australia
- Kolling Institute of Medical Research, Royal North Shore Hospital, Sydney, NSW, Australia
| | - Jonathan Golledge
- Queensland Research Centre for Peripheral Vascular Disease, College of Medicine and Dentistry, James Cook University, Townsville, QLD, Australia
- The Department of Vascular and Endovascular Surgery, Townsville University Hospital, Townsville, QLD, Australia
| | - Sarah Aitken
- Faculty of Health and Medicine, The University of Sydney, Sydney, NSW, Australia
- Concord Institute of Academic Surgery, Concord Hospital, Sydney, NSW, Australia
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Koller A, Laughlin MH, Cenko E, de Wit C, Tóth K, Bugiardini R, Trifunovits D, Vavlukis M, Manfrini O, Lelbach A, Dornyei G, Padro T, Badimon L, Tousoulis D, Gielen S, Duncker DJ. Functional and structural adaptations of the coronary macro- and micro-vasculature to regular aerobic exercise by activation of physiological, cellular and molecular mechanisms: Esc Working Group on Coronary Pathophysiology & Microcirculation Position Paper. Cardiovasc Res 2021; 118:357-371. [PMID: 34358290 DOI: 10.1093/cvr/cvab246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 06/01/2021] [Accepted: 08/04/2021] [Indexed: 11/14/2022] Open
Abstract
Regular aerobic exercise (RAEX) elicits several positive adaptations in all organs and tissues of the body, culminating in improved health and well-being. Indeed, in over half a century, many studies have shown the benefit of RAEX on cardiovascular outcome in terms of morbidity and mortality. RAEX elicits a wide range of functional and structural adaptations in the heart and its coronary circulation, all of which are to maintain optimal myocardial oxygen and nutritional supply during increased demand. Although there is no evidence suggesting that oxidative metabolism is limited by coronary blood flow (CBF) rate in the normal heart even during maximal exercise, increased CBF and capillary exchange capacities have been reported. Adaptations of coronary macro- and microvessels include outward remodeling of epicardial coronary arteries, increased coronary arteriolar size and density, and increased capillary surface area. In addition, there are adjustments in the neural and endothelial regulation of coronary macrovascular tone. Similarly, there are several adaptations at the level of microcirculation, including enhanced smooth muscle dependent pressure-induced myogenic constriction and upregulated endothelium-dependent flow-/shear-stress-induced dilation, increasing the range of diameter change. Alterations in the signaling interaction between coronary vessels and cardiac metabolism have also been described. At the molecular and cellular level, ion channels are key players in the local coronary vascular adaptations to RAEX, with enhanced activation of influx of Ca2+ contributing to the increased myogenic tone (via voltage gated Ca2+ channels) as well as the enhanced endothelium-dependent dilation (via TRPV4 channels). Finally, RAEX elicits a number of beneficial effects on several hemorheological variables that may further improve CBF and myocardial oxygen delivery and nutrient exchange in the microcirculation by stabilizing and extending the range and further optimizing the regulation of myocardial blood flow during exercise. These adaptations also act to prevent and/or delay the development of coronary and cardiac diseases.
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Affiliation(s)
- Akos Koller
- Department of Translational Medicine, Semmelweis University, Budapest, Hungary; Research Center for Sports Physiology, University of Physical Education, Budapest, Hungary; Department of Physiology, New York Medical College, Valhalla, NY, 10595, USA
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Edina Cenko
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Cor de Wit
- Institut für Physiologie, Universitat zu Lu ¨beck, Lu beck, Germany and15DZHK (German Center for Cardiovascular Research), partner site Hamburg/Kiel/Lu ¨beck, Lubeck, Germany
| | - Kálmán Tóth
- Division of Cardiology, 1st Department of Medicine, Medical School, University of Pécs, Pécs, Hungary
| | - Raffaele Bugiardini
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Danijela Trifunovits
- Cardiology Department, Clinical Centre of Serbia and Faculty of Medicine University of Belgrade, Belgrade, Serbia
| | - Marija Vavlukis
- University Clinic for Cardiology, Medical Faculty, Ss' Cyril andMethodius University, Skopje, Republic of Macedonia
| | - Olivia Manfrini
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Adam Lelbach
- Departmental Group of Geriatrics, Department of Internal Medicine and Oncology, Faculty of Medicine, Semmelweis University, Budapest, Dr. Rose Private Hospital, Budapest, Hungary
| | - Gabriella Dornyei
- Department of Morphology and Physiology, Faculty of Health Sciences, Semmelweis University, Budapest, Hungary
| | - Teresa Padro
- Cardiovascular Program-ICCC, Research Institute Hospital Santa Creu i Sant Pau; IIB-Sant Pau; CiberCV-Institute Carlos III; Barcelona, Spain
| | - Lina Badimon
- Cardiovascular Program-ICCC, Research Institute Hospital Santa Creu i Sant Pau; IIB-Sant Pau; CiberCV-Institute Carlos III; Barcelona, Spain
| | - Dimitris Tousoulis
- First Department of Cardiology, Hippokration Hospital, University of Athens Medical School, Athens, Greece
| | - Stephan Gielen
- Department of Cardiology, Angiology, and Intensive Care Medicine, Klinikum Lippe, Detmold, Germany
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Thoraxenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Looft-Wilson RC, Goodell CR, Mutch CA, Mutchler SM, Miller KL, Guraya M. Increased myoendothelial feedback is associated with increased connexin37 and IK1 channel expression in mesenteric arteries of diet-induced hyperhomocysteinemic mice. Microcirculation 2017; 24. [PMID: 28857417 DOI: 10.1111/micc.12398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 08/24/2017] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Previously, we found that diet-induced HHcy in mice caused decreased eNOS expression and signaling in mesenteric arteries, but greatly enhanced non-NOS, non-prostacyclin-dependent vasodilation, which involves MEJ communication. To further assess whether HHcy enhances MEJ communication, this study examined endothelium-dependent attenuation of phenylephrine-induced vasoconstriction (myoendothelial feedback) and key molecules involved. METHODS Myoendothelial feedback was examined in isolated mouse mesenteric arteries, after 6-weeks diet-induced HHcy, using pressure myography. Gap junction (Cx37, Cx40, Cx43), NOS (eNOS, nNOS, iNOS), and potassium channel (IK1) protein expression were measured with immunoblots, and connexin mRNAs with real-time PCR. Contribution of nNOS + iNOS to vasomotor responses was assessed using the drug TRIM. RESULTS Myoendothelial feedback was significantly (P < .05) enhanced in HHcy arteries compared to control, coincident with significantly greater Cx37 and IK1 protein and Cx37 mRNA. Cx43 protein, but not mRNA, was significantly less in HHcy, and Cx40 was not different. eNOS protein was significantly less in HHcy. nNOS and iNOS were not different. TRIM had little effect on vasomotor function. CONCLUSIONS Diet-induced HHcy enhanced myoendothelial feedback, and increased Cx37 and IK1 expression may contribute. nNOS or iNOS did not upregulate to compensate for decreased eNOS, and they had little involvement in vasomotor function.
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Affiliation(s)
- Robin C Looft-Wilson
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Cara R Goodell
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Christina A Mutch
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Stephanie M Mutchler
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Kayla L Miller
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
| | - Monique Guraya
- Department of Kinesiology and Health Sciences, The College of William & Mary, Williamsburg, VA, USA
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Borges MC, Hartwig FP, Oliveira IO, Horta BL. Is there a causal role for homocysteine concentration in blood pressure? A Mendelian randomization study. Am J Clin Nutr 2016; 103:39-49. [PMID: 26675774 PMCID: PMC4691668 DOI: 10.3945/ajcn.115.116038] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/28/2015] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND An understanding of whether homocysteine is a cause or a marker of increased blood pressure is relevant because blood homocysteine can be effectively lowered by safe and inexpensive interventions (e.g., vitamin B-6, B-9, and B-12 supplementation). OBJECTIVE The aim was to assess the causal influence of homocysteine on systolic and diastolic blood pressure (SBP and DBP, respectively) in adults with the use of Mendelian randomization (MR). DESIGN Data from the 1982 Pelotas Birth Cohort (Brazil) were used. A total of 4297 subjects were evaluated in 2004-2005 (mean age: 22.8 y). The association of homocysteine concentration with SBP and DBP was assessed by conventional ordinary least-squares (OLS) linear regression and 2-stage least-squares (2SLS) regression (MR analysis). The single nucleotide polymorphism (SNP) methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133) was used as proxy for homocysteine concentration. We also applied MR to data from the International Consortium for Blood Pressure (ICBP) genomewide association studies (>69,000 participants) using rs1801133 and additional homocysteine-associated SNPs as instruments. RESULTS In OLS regression, a 1-SD unit increase in log homocysteine concentration was associated with an increase of 0.9 (95% CI: 0.4, 1.4) mm Hg in SBP and of 1.0 (95% CI: 0.6, 1.4) mm Hg in DBP. In 2SLS regression, for the same increase in homocysteine, the coefficients were -1.8 mm Hg for SBP (95% CI: -3.9, 0.4 mm Hg; P = 0.01) and 0.1 mm Hg for DBP (95% CI: -1.5, 1.7 mm Hg; P = 0.24). In the MR analysis of ICBP data, homocysteine concentration was not associated with SBP (β = 0.6 mm Hg for each 1-SD unit increase in log homocysteine; 95% CI: -0.8, 1.9 mm Hg) but was positively associated with DBP (β = 1.1 mm Hg; 95% CI: 0.2, 1.9 mm Hg). The association of genetically increased homocysteine with DBP was not consistent across different SNPs. CONCLUSION Overall, the present findings do not corroborate the hypothesis that homocysteine has a causal role in blood pressure, especially in SBP.
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Affiliation(s)
| | | | - Isabel O Oliveira
- Postgraduate Program in Epidemiology and Department of Physiology and Pharmacology, Institute of Biology, Universidade Federal de Pelotas, Pelotas, Brazil
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Abstract
Basal and activity-dependent cerebral blood flow changes are coordinated by the action of critical processes, including cerebral autoregulation, endothelial-mediated signaling, and neurovascular coupling. The goal of our study was to determine whether astrocytes contribute to the regulation of parenchymal arteriole (PA) tone in response to hemodynamic stimuli (pressure/flow). Cortical PA vascular responses and astrocytic Ca(2+) dynamics were measured using an in vitro rat/mouse brain slice model of perfused/pressurized PAs; studies were supplemented with in vivo astrocytic Ca(2+) imaging. In vitro, astrocytes responded to PA flow/pressure increases with an increase in intracellular Ca(2+). Astrocytic Ca(2+) responses were corroborated in vivo, where acute systemic phenylephrine-induced increases in blood pressure evoked a significant increase in astrocytic Ca(2+). In vitro, flow/pressure-evoked vasoconstriction was blunted when the astrocytic syncytium was loaded with BAPTA (chelating intracellular Ca(2+)) and enhanced when high Ca(2+) or ATP were introduced to the astrocytic syncytium. Bath application of either the TRPV4 channel blocker HC067047 or purinergic receptor antagonist suramin blunted flow/pressure-evoked vasoconstriction, whereas K(+) and 20-HETE signaling blockade showed no effect. Importantly, we found TRPV4 channel expression to be restricted to astrocytes and not the endothelium of PA. We present evidence for a novel role of astrocytes in PA flow/pressure-evoked vasoconstriction. Our data suggest that astrocytic TRPV4 channels are key molecular sensors of hemodynamic stimuli and that a purinergic, glial-derived signal contributes to flow/pressure-induced adjustments in PA tone. Together our results support bidirectional signaling within the neurovascular unit and astrocytes as key modulators of PA tone.
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Hill-Eubanks DC, Gonzales AL, Sonkusare SK, Nelson MT. Vascular TRP channels: performing under pressure and going with the flow. Physiology (Bethesda) 2015; 29:343-60. [PMID: 25180264 DOI: 10.1152/physiol.00009.2014] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endothelial cells and smooth muscle cells of resistance arteries mediate opposing responses to mechanical forces acting on the vasculature, promoting dilation in response to flow and constriction in response to pressure, respectively. In this review, we explore the role of TRP channels, particularly endothelial TRPV4 and smooth muscle TRPC6 and TRPM4 channels, in vascular mechanosensing circuits, placing their putative mechanosensitivity in context with other proposed upstream and downstream signaling pathways.
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Affiliation(s)
| | - Albert L Gonzales
- Department of Pharmacology, University of Vermont, Burlington, Vermont
| | | | - Mark T Nelson
- Department of Pharmacology, University of Vermont, Burlington, Vermont
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9
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Basu A, Jenkins AJ, Stoner JA, Thorpe SR, Klein RL, Lopes-Virella MF, Garvey WT, Lyons TJ. Plasma total homocysteine and carotid intima-media thickness in type 1 diabetes: a prospective study. Atherosclerosis 2014; 236:188-195. [PMID: 25063949 PMCID: PMC4134979 DOI: 10.1016/j.atherosclerosis.2014.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 06/15/2014] [Accepted: 07/02/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Plasma total homocysteine (tHcy) has been positively associated with carotid intima-media thickness (IMT) in non-diabetic populations and in a few cross-sectional studies of diabetic patients. We investigated cross-sectional and prospective associations of a single measure of tHcy with common and internal carotid IMT over a 6-year period in type 1 diabetes. RESEARCH DESIGN AND METHODS tHcy levels were measured once, in plasma obtained in 1997-1999 from patients (n = 599) in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, the observational follow-up of the Diabetes Control and Complications Trial (DCCT). Common and internal carotid IMT were determined twice, in EDIC "Year 6" (1998-2000) and "Year 12" (2004-2006), using B-mode ultra-sonography. RESULTS After adjustment, plasma tHcy [median (interquartile range): 6.2 (5.1, 7.5) μmol/L] was significantly correlated with age, diastolic blood pressure, renal dysfunction, and smoking (all p < 0.05). In an unadjusted model only, increasing quartiles of tHcy correlated with common and internal carotid IMT, again at both EDIC time-points (p < 0.01). However, multivariate logistic regression revealed no significant associations between increasing quartiles of tHcy and the 6-year change in common and internal carotid IMT (highest vs. lowest quintile) when adjusted for conventional risk factors. CONCLUSIONS In a type 1 diabetes cohort from the EDIC study, plasma tHcy measured in samples drawn in 1997-1999 was associated with measures of common and internal carotid IMT measured both one and seven years later, but not with IMT progression between the two time-points. The data do not support routine measurement of tHcy in people with Type 1 diabetes.
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Affiliation(s)
- Arpita Basu
- Department of Nutritional Sciences, Oklahoma State University, Stillwater, Oklahoma
| | - Alicia J Jenkins
- University of Sydney, NHMRC Clinical Trials Centre, Camperdown, Sydney, NSW, Australia
- Centre for Experimental Medicine, Queen's University of Belfast, N. Ireland, UK
| | - Julie A Stoner
- Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Suzanne R Thorpe
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina
| | - Richard L Klein
- Division of Endocrinology, Medical University of South Carolina, Charleston, South Carolina
- The Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina
| | - Maria F Lopes-Virella
- Division of Endocrinology, Medical University of South Carolina, Charleston, South Carolina
- The Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina
| | - W Timothy Garvey
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama
| | - Timothy J Lyons
- Centre for Experimental Medicine, Queen's University of Belfast, N. Ireland, UK
- Section of Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Jacomella V, Wasila M, Husmann M, Gitzelmann G, Meier T, Amann-Vesti B. Plasma Homocysteine is Not Related to the Severity of Microangiopathy in Secondary Raynaud Phenomenon. Open Rheumatol J 2012; 5:64-8. [PMID: 22216066 PMCID: PMC3245410 DOI: 10.2174/1874312901105010064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 09/28/2011] [Accepted: 10/10/2011] [Indexed: 11/29/2022] Open
Abstract
Introduction: The role of elevated homocysteine in primary and secondary Raynaud phenomenon (RP) and in patients with atherosclerosis has been reported controversially. In secondary RP due to connective tissue disease specific alterations of nailfold capillaries might be present. An association between these microvascular changes and homocysteine has been suggested. Aim: The aim of this study was to determine whether homocysteine level differs between patients with primary and secondary RP and to test the hypothesis that homocysteine or other cardiovascular risk factors are associated with specific features of microangiopathy in secondary RP. Patients and Methods Eighty-one consecutive patients with RP referred for vascular assessment were studied by nailfold capillaroscopy. Homocysteine, C-reactive protein and cholesterol were measured and other cardiovascular risk factors and comorbidities assessed. Results: Homocysteine, C-reactive-protein and cholesterol levels did not differ between patients with primary (n=60) and secondary RP (n=21). Likewise, no differences in the prevalence of cardiovascular risk factors and comorbidities were found. In secondary RP no correlation was found between microvascular involvement and homocysteine or C-reactive protein. Conclusion: Plasma homocysteine is not different in patients with either primary or secondary RP and is therefore not a marker for the distinction of these diseases. The extent of microvascular involvement in secondary RP does not correlate with plasma homocysteine.
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Raaf L, Noll C, Cherifi MEH, Samuel JL, Delcayre C, Delabar JM, Benazzoug Y, Janel N. Myocardial fibrosis and TGFB expression in hyperhomocysteinemic rats. Mol Cell Biochem 2010; 347:63-70. [DOI: 10.1007/s11010-010-0612-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Accepted: 09/28/2010] [Indexed: 12/25/2022]
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Colleran PN, Li Z, Yang HT, Laughlin MH, Terjung RL. Vasoresponsiveness of collateral vessels in the rat hindlimb: influence of training. J Physiol 2010. [PMID: 20194126 DOI: 10.1113/jphysiol.2009.18624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Exercise training is known to be an effective means of improving functional capacity and quality of life in patients with peripheral arterial insufficiency (PAI). However, the specific training-induced physiological adaptations occurring within collateral vessels remain to be clearly defined. The purpose of this study was to determine the effect of exercise training on vasomotor properties of isolated peripheral collateral arteries. We hypothesized that daily treadmill exercise would improve the poor vasodilatory capacity of collateral arteries isolated from rats exposed to surgical occlusion of the femoral artery. Following femoral artery ligation, animals were either kept sedentary or exercise trained daily for a period of 3 weeks. Hindlimb collateral arteries were then isolated, cannulated and pressurized via hydrostatic reservoirs to an intravascular pressure of either 45 or 120 cmH(2)O. Non-occluded contralateral vessels of the sedentary animals served as normal Control. Vasodilatory responses to acetylcholine (ACh; 1 x 10(9)-1 x 10(5)m) and sodium nitroprusside (SNP; 1 x 10(9)-1 x 10(4)m), constrictor responses to phenylephrine (PE; 1 x 10(9)-1 x 10(4)m), and flow-induced vasodilatation were determined. Endothelium-mediated vasodilatation responses were significantly greater to either ACh (P < 0.02) or intravascular flow (P < 0.001) in collateral arteries of trained rats. Neither blockade of cyclooxygenase with indomethacin (Indo; 5 microm) nor blockade of endothelial nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME; 300 microm) eliminated this ACh- or flow-induced vasodilatation. The depressed vasodilatory response to SNP caused by vascular occlusion was reversed with training. These data indicate that exercise training improves endothelium-mediated vasodilatory capacity of hindlimb collateral arteries, apparently by enhanced production of the putative endothelium-derived hyperpolarizing factor(s). If these findings were applicable to patients with PAI, they could contribute to an improved collateral vessel function and enhance exercise tolerance during routine physical activity.
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Affiliation(s)
- Patrick N Colleran
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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Colleran PN, Li Z, Yang HT, Laughlin MH, Terjung RL. Vasoresponsiveness of collateral vessels in the rat hindlimb: influence of training. J Physiol 2010; 588:1293-307. [PMID: 20194126 DOI: 10.1113/jphysiol.2009.186247] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Exercise training is known to be an effective means of improving functional capacity and quality of life in patients with peripheral arterial insufficiency (PAI). However, the specific training-induced physiological adaptations occurring within collateral vessels remain to be clearly defined. The purpose of this study was to determine the effect of exercise training on vasomotor properties of isolated peripheral collateral arteries. We hypothesized that daily treadmill exercise would improve the poor vasodilatory capacity of collateral arteries isolated from rats exposed to surgical occlusion of the femoral artery. Following femoral artery ligation, animals were either kept sedentary or exercise trained daily for a period of 3 weeks. Hindlimb collateral arteries were then isolated, cannulated and pressurized via hydrostatic reservoirs to an intravascular pressure of either 45 or 120 cmH(2)O. Non-occluded contralateral vessels of the sedentary animals served as normal Control. Vasodilatory responses to acetylcholine (ACh; 1 x 10(9)-1 x 10(5)m) and sodium nitroprusside (SNP; 1 x 10(9)-1 x 10(4)m), constrictor responses to phenylephrine (PE; 1 x 10(9)-1 x 10(4)m), and flow-induced vasodilatation were determined. Endothelium-mediated vasodilatation responses were significantly greater to either ACh (P < 0.02) or intravascular flow (P < 0.001) in collateral arteries of trained rats. Neither blockade of cyclooxygenase with indomethacin (Indo; 5 microm) nor blockade of endothelial nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME; 300 microm) eliminated this ACh- or flow-induced vasodilatation. The depressed vasodilatory response to SNP caused by vascular occlusion was reversed with training. These data indicate that exercise training improves endothelium-mediated vasodilatory capacity of hindlimb collateral arteries, apparently by enhanced production of the putative endothelium-derived hyperpolarizing factor(s). If these findings were applicable to patients with PAI, they could contribute to an improved collateral vessel function and enhance exercise tolerance during routine physical activity.
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Affiliation(s)
- Patrick N Colleran
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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Abstract
Hyperhomocysteinemia (HHcy) is a significant and independent risk factor for cardiovascular diseases. Endothelial dysfunction (ED) is the earliest indicator of atherosclerosis and vascular diseases. We and others have shown that HHcy induced ED in human and in animal models of HHcy induced by either high-methionine load or genetic deficiency. Six mechanisms have been suggested explaining HHcy-induced ED. These include 1) nitric oxide inhibition, 2) prostanoids regulation, 3) endothelium-derived hyperpolarizing factors suppression, 4) angiotensin II receptor-1 activation, 5) endothelin-1 induction, and 6) oxidative stress. The goal of this review is to elaborate these mechanisms and to discuss biological and molecular events related to HHcy-induced ED.
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Affiliation(s)
- Zhongjian Cheng
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
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de Andrade CR, Leite PF, Montezano AC, Casolari DA, Yogi A, Tostes RC, Haddad R, Eberlin MN, Laurindo FRM, de Souza HP, Corrêa FMA, de Oliveira AM. Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia. Br J Pharmacol 2009; 157:568-80. [PMID: 19371338 DOI: 10.1111/j.1476-5381.2009.00165.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries. EXPERIMENTAL APPROACH Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1. KEY RESULTS HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO. CONCLUSIONS AND IMPLICATIONS Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.
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Affiliation(s)
- C R de Andrade
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Bonaventura D, Tirapelli CR, de Oliveira AM. Chronic methionine load-induced hyperhomocysteinemia impairs the relaxation induced by bradykinin in the isolated rat carotid. Amino Acids 2008; 37:617-27. [DOI: 10.1007/s00726-008-0181-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 09/06/2008] [Indexed: 11/29/2022]
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Abstract
We hypothesized that there is a correlation between the magnitude of endothelial-mediated dilation of brachial artery and erectile function in patients. Thus, flow-mediated dilation of the brachial artery (FMD)-used to assess the function of endothelium-was measured in 56 patients (aged approximately 35 years) having erectile dysfunction for 6-12 months. The patients were grouped based on International Index of Erectile Dysfunction: severe (5-10), moderate (11-16), mild to moderate (17-21), and mild (22-25). As compared to the mild group (8.8 +/- 1.7%), FMD was significantly reduced in the mild-to-moderate group (5.7 +/- 1.1%), moderate group (5.3 +/- 0.8%), and severe group (4.4 +/- 0.6%). Also, there was a positive correlation between the magnitude of endothelial and erectile dysfunction. Patients were treated with the 5-phosphodiesterase inhibitor sildenafil, known to elevate vascular cGMP level and thus the vascular efficacy of internal nitric oxide, for 3 to 6 months prior to the study. The mean doses of sildenafil used were as follows: severe group, 100 mg/event; moderate group, 86.1 +/- 21.4 mg/event; mild-to-moderate group, 71.8 +/- 23.2 mg/event; mild group, 25 mg/event. We found a positive correlation between the sildenafil dose requirement and the severity of erectile dysfunction. On the bases on these findings, together with the known mechanism of action of sildenafil, we propose that vascular endothelial dysfunction could contribute to erectile dysfunction and that erectile dysfunction may be an early marker of peripheral vascular disease.
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Abstract
Mildly elevated homocysteine levels (Hcy) increase the risk for atherothrombotic vascular disease in the coronary, cerebrovascular, and peripheral arterial circulations. The molecular mechanisms responsible for decreased bioavailability of endothelium-derived nitric oxide (NO) by Hcy involve an increase of vascular oxidant stress and inhibition of important antioxidant capacity. Glutathione peroxidase-1 (GPx-1), a selenocysteine-containing antioxidant enzyme, may be a key target of Hcy's deleterious actions, and several experimental and clinical studies have demonstrated a complex relationship between plasma total homocysteine (tHcy), GPx-1, and endothelial dysfunction. Hcy may promote endothelial dysfunction, in part by decreasing GPx-1 expression; however, there is evidence to suggest that overexpression of GPx-1 can compensate for these effects. This review summarizes the current knowledge of the metabolism of Hcy, the effects of hyperhomocysteinemia observed in in vitro and in vivo models that lead to endothelial dysfunction and the possible mechanisms for these actions, and the role of GPx-1 in the pathogenesis of Hcy-induced cardiovascular disease (CVD).
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Affiliation(s)
- Edith Lubos
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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Ozkan Y, Fırat H, Şimşek B, Torun M, Yardim-Akaydin S. Circulating nitric oxide (NO), asymmetric dimethylarginine (ADMA), homocysteine, and oxidative status in obstructive sleep apnea–hypopnea syndrome (OSAHS). Sleep Breath 2007; 12:149-54. [DOI: 10.1007/s11325-007-0148-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Toth E, Racz A, Toth J, Kaminski PM, Wolin MS, Bagi Z, Koller A. Contribution of polyol pathway to arteriolar dysfunction in hyperglycemia. Role of oxidative stress, reduced NO, and enhanced PGH(2)/TXA(2) mediation. Am J Physiol Heart Circ Physiol 2007; 293:H3096-104. [PMID: 17873009 DOI: 10.1152/ajpheart.01335.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hyperglycemia increases glucose metabolism via the polyol pathway, which results in elevations of intracellular sorbitol concentration. Thus we hypothesized that elevated level of sorbitol contributes to the development of hyperglycemia-induced dysfunction of microvessels. In isolated, pressurized (80 mmHg) rat gracilis muscle arterioles (approximately 150 microm), high glucose treatment (25 mM) induced reduction in flow-dependent dilation (from maximum of 39 +/- 2% to 15 +/- 1%), which was significantly mitigated by an aldose reductase inhibitor, zopolrestat (maximum 27 +/- 2%). Increasing doses of sorbitol (10(-10)-10(-4) M) elicited dose-dependent constrictions (maximum 22 +/- 3%), which were abolished by endothelium removal, a prostaglandin H(2)/thromboxane A(2) (PGH(2)/TXA(2)) receptor (TP) antagonist SQ-29548, or superoxide dismutase (SOD) plus catalase (CAT). Incubation of arterioles with sorbitol (10(-7) M) reduced flow-dependent dilations (from maximum of 39 +/- 2% to 20 +/- 1.5%), which was not further affected by inhibition of nitric oxide synthase by N(omega)-nitro-l-arginine methyl ester but was prevented by SOD plus CAT and mitigated by SQ-29548. Nitric oxide donor sodium nitroprusside-induced (10(-9)-10(-6) M) dilations were also decreased in a SQ-29548 and SOD plus CAT-reversible manner, whereas adenosine dilations were not affected by sorbitol exposure. Sorbitol significantly increased arterial superoxide production detected by lucigenin-enhanced chemiluminescence, which was inhibited by SOD plus CAT. Sorbitol treatment also increased arterial formation of 3-nitrotyrosine. We suggest that hyperglycemia by elevating intracellular sorbitol induces oxidative stress, which interferes with nitric oxide bioavailability and promotes PGH(2)/TXA(2) release, both of which affect regulation of vasomotor responses of arterioles. Thus increased activity of the polyol pathway may contribute to the development of microvascular dysfunction in diabetes mellitus.
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Affiliation(s)
- Erika Toth
- Department of Physiology, Semmelweis University, Budapest, Hungary
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Liu YH, You Y, Song T, Wu SJ, Liu LY. Impairment of Endothelium-Dependent Relaxation of Rat Aortas by Homocysteine Thiolactone and Attenuation by Captopril. J Cardiovasc Pharmacol 2007; 50:155-61. [PMID: 17703131 DOI: 10.1097/fjc.0b013e31805c9410] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To explore the effects of angiotensin-converting enzyme (ACE) inhibitors on endothelial dysfunction induced by homocysteine thiolactone (HTL). Both endothelium-dependent relaxation and nondependent relaxation of thoracic aortic rings in rats induced by acetylcholine (Ach) or sodium nitroprusside (SNP) and biochemical parameters including malondialdehyde (MDA) and nitric oxide (NO) were measured in rat isolated aorta. Exposure of aortic rings to HTL (3 to 30 mM) for 90 minutes made a significant inhibition of endothelium-dependent relaxation induced by Ach, decreased contents of NO, and increased MDA concentration in aortic tissue. After incubation of aortic rings with captopril (0.003 to 0.03 mM) attenuated the inhibition of endothelium-dependent relaxation (EDR) and significantly resisted the decrease of NO content and elevation of MDA concentration caused by HTL (30 mmol/L) in aortic tissues, a similarly protective effect was observed when the aortic rings were incubated with both N-acetylcysteine (0.05 mM). Treatment with enalaprilat (0.003 to 0.01 mM) made no significant difference with the HTL (30 mM) group regarding EDR, but enalaprilat (0.03 mM) and losartan (0.03 mM) could partly restore the EDR in response to HTL (30 mM). Captopril was more effective than enalaprilat and losartan in attenuation of the inhibition of on acetylcholine-stimulated aortic relaxation by HTL in the same concentration. Moreover, superoxide dismutase (SOD, 200 U/mL), which is a scavenger of superoxide anions, apocynin (0.03 mM), which is an inhibitor of NADPH oxidase, and l-Arginine (3 mmol/L), a precursor of nitric oxide (NO), could reduce HTL (30 mM)-induced inhibition of EDR. After pretreatment with not only the NO synthase inhibitor Nomega-nitro-l-arginine methyl ester (L-NAME, 0.01 mM) but also the free sulfhydryl group blocking agent p-hydroxymercurybenzoate (PHMB, 0.05 mM) could abolish the protection of captopril and N-acetylcysteine, respectively. These results suggest that mechanisms of endothelial dysfunction induced by HTL may include the decrease of NO and the generation of oxygen free radicals and that captopril can restore the inhibition of EDR induced by HTL in isolated rat aorta, which may be related to scavenging oxygen free radicals and may be sulfhydryl-dependent.
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Affiliation(s)
- Yu-Hui Liu
- Department of Pharmacology, Pharmaceutical College, Central South University, Changsha, Hunan, PR China.
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Zhang BQ, Hu SJ, Qiu LH, Zhu JH, Xie XJ, Sun J, Zhu ZH, Xia Q, Bian K. Effects of Astragalus membranaceus and its main components on the acute phase endothelial dysfunction induced by homocysteine. Vascul Pharmacol 2006; 46:278-85. [PMID: 17196887 DOI: 10.1016/j.vph.2006.11.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 10/14/2006] [Accepted: 11/02/2006] [Indexed: 11/18/2022]
Abstract
OBJECTIVE This study was designed to investigate the effects of Astragalus membranaceus (AM) and its main components, astragalus saponin (ASP), astragalus polysaccharide (APS) and aminobutyric acid (GABA), on homocysteine (Hcy) induced acute impairment of vascular tone and to explore whether the antioxidant mechanism was involved in AM protective effect. METHODS Inhibitory effects of Hcy and protective effects of AM and its main components on endothelium-dependent relaxation of aortic rings were determined by isometric tension recordings and nitric oxide signaling was assayed with 125I-cGMP RIA Kit. Furthermore, generation of reactive oxygen species (ROS) in endothelial cells was detected using 5-(6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCF-DA). RESULTS Hcy significantly inhibited endothelium-dependent relaxation to acetylcholine (ACh) in a dose-dependent manner, and decreased cGMP levels increased by ACh in aorta. Furthermore, superoxide dismutase (SOD), AM, and ASP markedly attenuated inhibition of vasorelaxation and downregulation of cGMP level by Hcy, and APS exerted a tendency to reverse both of the depressive responses, while GABA had no similar effects. Additionally, partially impaired relaxation by Hcy was completely blocked due to the presence of N(omega)-nitro-L-arginine-methyl ester (L-NAME), which could not be further altered by treatment with AM, ASP, APS or GABA. Finally, Hcy significantly increased intracellular ROS levels in endothelial cells as measured by CM-H2DCF-DA fluorescence. SOD, AM, ASP, and APS, but not GABA, inhibited Hcy-stimulated ROS generation. CONCLUSION This study demonstrated that AM and ASP, potently protected endothelium-dependent relaxation against the acute injury from Hcy through nitric oxide regulatory pathways, in which antioxidation played a key role.
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Affiliation(s)
- Bi-Qi Zhang
- Department of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79, Qingchun St, Hangzhou 310003, Zhejiang, PR China
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Rush JWE, Denniss SG, Graham DA. Vascular nitric oxide and oxidative stress: determinants of endothelial adaptations to cardiovascular disease and to physical activity. ACTA ACUST UNITED AC 2005; 30:442-74. [PMID: 16258183 DOI: 10.1139/h05-133] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cardiovascular disease is the single leading cause of death and morbidity for Canadians. A universal feature of cardiovascular disease is dysfunction of the vascular endothelium, thus disrupting control of vasodilation, tissue perfusion, hemostasis, and thrombosis. Nitric oxide bioavailability, crucial for maintaining vascular endothelial health and function, depends on the processes controlling synthesis and destruction of nitric oxide as well as on the sensitivity of target tissue to nitric oxide. Evidence supports a major contribution by oxidative stress-induced destruction of nitric oxide to the endothelial dysfunction that accompanies a number of cardiovascular disease states including hypertension, diabetes, chronic heart failure, and atherosclerosis. Regular physical activity (exercise training) reduces cardiovascular disease risk. Numerous studies support the hypothesis that exercise training improves vascular endothelial function, especially when it has been impaired by preexisting risk factors. Evidence is emerging to support a role for improved nitric oxide bioavailability with training as a result of enhanced synthesis and reduced oxidative stress-mediated destruction. Molecular targets sensitive to the exercise training effect include the endothelial nitric oxide synthase and the antioxidant enzyme superoxide dismutase. However, many fundamental details of the cellular and molecular mechanisms linking exercise to altered molecular and functional endothelial phenotypes have yet to be discovered. The working hypothesis is that some of the cellular mechanisms contributing to endothelial dysfunction in cardiovascular disease can be targeted and reversed by signals associated with regular increases in physical activity. The capacity for exercise training to regulate vascular endothelial function, nitric oxide bioavailability, and oxidative stress is an example of how lifestyle can complement medicine and pharmacology in the prevention and management of cardiovascular disease.
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Affiliation(s)
- James W E Rush
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Durga J, Verhoef P, Bots ML, Schouten E. Homocysteine and carotid intima-media thickness: a critical appraisal of the evidence. Atherosclerosis 2004; 176:1-19. [PMID: 15306169 DOI: 10.1016/j.atherosclerosis.2003.11.022] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2003] [Revised: 10/22/2003] [Accepted: 11/21/2003] [Indexed: 10/26/2022]
Abstract
UNLABELLED This review examines the relationship between hyperhomocysteinemia, a risk factor for vascular disease, and carotid intima-media thickness (CIMT), a valid marker of generalized atherosclerosis and future vascular disease risk. The relationship between two important determinants of hyperhomocysteinemia in the general population-folate status and the 677C --> T methylenetetrahydrofolate reductase (MTHFR) polymorphism-and CIMT is also covered. METHODS We searched literature databases for articles examining homocysteine and CIMT published before September 2003. RESULTS We identified 54 studies. Observational studies generally failed to demonstrate a relationship between homocysteine and CIMT in homocystinuric, uremic, hypercholesterolemic or non-insulin-dependent diabetes mellitus patients or in subjects with insulin insensitivity. Weak associations, but usually only in certain sub-populations were found in vascular disease patients and in population-based studies. B vitamins reduce the progression of CIMT in renal transplant recipients and vascular disease patients as demonstrated by two trials. The majority of studies demonstrated increased CIMT in individuals with the MTHFR 677TT genotype. Folate status showed no relation to CIMT. DISCUSSION In non-patient populations, hyperhomocysteinemia is weakly associated with CIMT. The association of the 677 C--> T MTHFR polymorphism with CIMT further supports this finding. Lastly, folate levels may need to reach a critically low status before an association can be found between folate and CIMT. Larger trials in various population types are needed to determine whether folate alone or in combination with Vitamins B6 and B12 will slow down or even reverse atherosclerotic progression.
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Affiliation(s)
- Jane Durga
- Division of Human Nutrition, Wageningen Centre for Food Sciences, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands.
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Cseko C, Bagi Z, Koller A. Biphasic effect of hydrogen peroxide on skeletal muscle arteriolar tone via activation of endothelial and smooth muscle signaling pathways. J Appl Physiol (1985) 2004; 97:1130-7. [PMID: 15208297 DOI: 10.1152/japplphysiol.00106.2004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that hydrogen peroxide (H2O2) has a role in the local regulation of skeletal muscle blood flow, thus significantly affecting the myogenic tone of arterioles. In our study, we investigated the effects of exogenous H2O2 on the diameter of isolated, pressurized (at 80 mmHg) rat gracilis skeletal muscle arterioles (diameter of approximately 150 microm). Lower concentrations of H2O2 (10(-6)-3 x 10(-5) M) elicited constrictions, whereas higher concentrations of H2O2 (6 x 10(-5)-3 x 10(-4) M), after initial constrictions, caused dilations of arterioles (at 10(-4) M H2O2, -19 +/- 1% constriction and 66 +/- 4% dilation). Endothelium removal reduced both constrictions (to -10 +/- 1%) and dilations (to 33 +/- 3%) due to H2O2. Constrictions due to H2O2 were completely abolished by indomethacin and the prostaglandin H2/thromboxane A2 (PGH2/TxA2) receptor antagonist SQ-29548. Dilations due to H2O2 were significantly reduced by inhibition of nitric oxide synthase (to 38 +/- 7%) but were unaffected by clotrimazole or sulfaphenazole (inhibitors of cytochrome P-450 enzymes), indomethacin, or SQ-29548. In endothelium-denuded arterioles, clotrimazole had no effect, whereas H2O2-induced dilations were significantly reduced by charybdotoxin plus apamin, inhibitors of Ca(2+)-activated K+ channels (to 24 +/- 3%), the selective blocker of ATP-sensitive K+ channels glybenclamide (to 14 +/- 2%), and the nonselective K(+)-channel inhibitor tetrabutylammonium (to -1 +/- 1%). Thus exogenous administration of H2O2 elicits 1) release of PGH2/TxA2 from both endothelium and smooth muscle, 2) release of nitric oxide from the endothelium, and 3) activation of K+ channels, such as Ca(2+)-activated and ATP-sensitive K+ channels in the smooth muscle resulting in biphasic changes of arteriolar diameter. Because H2O2 at low micromolar concentrations activates several intrinsic mechanisms, we suggest that H2O2 contributes to the local regulation of skeletal muscle blood flow in various physiological and pathophysiological conditions.
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MESH Headings
- Animals
- Arteries/anatomy & histology
- Arteries/drug effects
- Arteries/physiology
- Dose-Response Relationship, Drug
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/physiology
- Hydrogen Peroxide/pharmacology
- In Vitro Techniques
- Male
- Muscle Tonus/drug effects
- Muscle Tonus/physiology
- Muscle, Skeletal/anatomy & histology
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/physiology
- Muscle, Smooth, Vascular/anatomy & histology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Rats
- Rats, Wistar
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- Csongor Cseko
- Department of Physiology, New York Medical College, Valhalla, New York 10595, USA
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Weiss N, Heydrick SJ, Postea O, Keller C, Keaney JF, Loscalzo J. Influence of hyperhomocysteinemia on the cellular redox state--impact on homocysteine-induced endothelial dysfunction. Clin Chem Lab Med 2004; 41:1455-61. [PMID: 14656025 DOI: 10.1515/cclm.2003.223] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis. An increasing body of evidence has implicated oxidative stress as being contributory to homocysteine's deleterious effects on the vasculature. Elevated levels of homocysteine may lead to increased generation of superoxide by a biochemical mechanism involving nitric oxide synthase, and, to a lesser extent, by an increase in the chemical oxidation of homocysteine and other aminothiols in the circulation. The resultant increase in superoxide levels is further amplified by homocysteine-dependent alterations in the function of cellular antioxidant enzymes such as cellular glutathione peroxidase or extracellular superoxide dismutase. One direct clinical consequence of elevated vascular superoxide levels is the inactivation of the vasorelaxant messenger nitric oxide, leading to endothelial dysfunction. Scavenging of superoxide anion by either superoxide dismutase or 4,5-dihydroxybenzene 1,3-disulfonate (Tiron) reverses endothelial dysfunction in hyperhomocysteinemic animal models and in isolated aortic rings incubated with homocysteine. Similarly, homocysteine-induced endothelial dysfunction is also reversed by increasing the concentration of the endogenous antioxidant glutathione or overexpressing cellular glutathione peroxidase in animal models of mild hyperhomocysteinemia. Taken together, these findings strongly suggest that the adverse vascular effects of homocysteine are at least partly mediated by oxidative inactivation of nitric oxide.
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Affiliation(s)
- Norbert Weiss
- Medizinische Poliklinik--Innenstadt, Klinikum der Universität München, Munich, Germany.
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Bagi Z, Cseko C, Tóth E, Koller A. Oxidative stress-induced dysregulation of arteriolar wall shear stress and blood pressure in hyperhomocysteinemia is prevented by chronic vitamin C treatment. Am J Physiol Heart Circ Physiol 2003; 285:H2277-83. [PMID: 12869370 DOI: 10.1152/ajpheart.00448.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We aimed to test the hypothesis that an enhanced level of reactive oxygen species (ROS) is primarily responsible for the impairment of nitric oxide (NO)-mediated regulation of arteriolar wall shear stress (WSS) in hyperhomocysteinemia (HHcy). Thus flow/WSS-induced dilations of pressurized gracilis muscle arterioles (basal diameter: approximately 170 microm) isolated from control (serum Hcy: 6 +/- 1 microM), methionine diet-induced HHcy rats (4 wk, serum Hcy: 30 +/- 6 microM), and HHcy rats treated with vitamin C, a known antioxidant (4 wk, 150 mg. kg body wt-1.day-1; serum Hcy: 32 +/- 10 microM), were investigated. In vessels of HHcy rats, increases in intraluminal flow/WSS-induced dilations were converted to constrictions. Constrictions were unaffected by inhibition of NO synthesis by N omega-nitro-L-arginine methyl ester (L-NAME). Vitamin C treatment of HHcy rats reversed the WSS-induced arteriolar constrictions to L-NAME-sensitive dilations but did not affect control responses. Similar changes in responses were obtained for the calcium ionophore A-23187. In addition, diastolic and mean arterial blood pressure and serum 8-isoprostane levels (a marker of in vivo oxidative stress) were significantly elevated in rats with HHcy, changes that were normalized by vitamin C treatment. Taken together, our data show that in chronic HHcy long-term vitamin C treatment, by decreasing oxidative stress in vivo, enhanced NO bioavailability, restored the regulation of shear stress in arterioles, and normalized systemic blood pressure. Thus our study provides evidence that oxidative stress is an important in vivo mechanism that is primarily responsible for the development of endothelial dysregulation of WSS in HHcy.
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Affiliation(s)
- Zsolt Bagi
- Department of Physiology, New York Medical College, Valhalla, NY 10595, USA
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Weiss N, Keller C, Hoffmann U, Loscalzo J. Endothelial dysfunction and atherothrombosis in mild hyperhomocysteinemia. Vasc Med 2002; 7:227-39. [PMID: 12553746 DOI: 10.1191/1358863x02vm428ra] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Mildly elevated plasma homocysteine levels are an independent risk factor for atherothrombotic vascular disease in the coronary, cerebrovascular, and peripheral arterial circulation. Endothelial dysfunction as manifested by impaired endothelium-dependent regulation of vascular tone and blood flow, by increased recruitment and adhesion of circulating inflammatory cells to the endothelium, and by a loss of endothelial cell antithrombotic function contributes to the vascular disorders linked to hyperhomocysteinemia. Increased vascular oxidant stress through imbalanced thiol redox status and inhibition of important antioxidant enzymes by homocysteine results in decreased bioavailability of the endothelium-derived signaling molecule nitric oxide via oxidative inactivation. This plays a central role in the molecular mechanisms underlying the effects of homocysteine on endothelial function. Supplementation of folic acid and vitamin B12 has been demonstrated to be efficient in lowering mildly elevated plasma homocysteine levels and in reversing homocysteine-induced impairment of endothelium-dependent vasoreactivity. Results from ongoing intervention trials will determine whether homocysteine-lowering therapies contribute to the prevention and reduction of atherothrombotic vascular disease and may thereby provide support for the causal relationship between hyperhomocysteinemia and atherothrombosis.
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Affiliation(s)
- Norbert Weiss
- Medical Policlinic, Division of Angiology, University Hospital, Innenstadt, Munich, Germany.
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Ungvari Z, Csiszar A, Bagi Z, Koller A. Impaired nitric oxide-mediated flow-induced coronary dilation in hyperhomocysteinemia: morphological and functional evidence for increased peroxynitrite formation. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 161:145-53. [PMID: 12107099 PMCID: PMC1850707 DOI: 10.1016/s0002-9440(10)64166-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hyperhomocysteinemia (HHcy) is a newly recognized risk factor for myocardial infarction, however, the effect of HHcy on endothelium-dependent flow-induced dilation of coronary arteries is not known. Thus, changes in diameter of small intramural coronary arteries (diameter, approximately 145 microm) isolated from control rats and rats with methionine diet-induced HHcy were investigated by videomicroscopy. Increases in intraluminal flow (from 0 to 40 microl/min) elicited dilations of control vessels (maximum, 25 +/- 2 microm), responses that were absent in HHcy arteries. The nitric oxide (NO) synthase inhibitor L-NAME inhibited flow-induced dilation of control coronaries, whereas it had no effect on responses of HHcy arteries. Dilations of control and HHcy arteries to the NO donor sodium nitroprusside were not different. Responses to flow in HHcy coronary arteries were unaffected by administration of L-arginine or the prostaglandin H(2)/thromboxane A(2) receptor antagonist SQ 29,548. However, in the presence of superoxide dismutase (plus catalase) or the superoxide scavenger Tiron increases in flow elicited L-NAME-sensitive dilations of HHcy coronaries (maximum, 18 +/- 5 microm). Also, superoxide dismutase significantly reduced the enhanced superoxide production of HHcy coronaries (measured by the lucigenin chemiluminescence method). Single vessel Western blotting showed an increased tyrosine nitrosation (a stable biomarker of tissue peroxynitrite formation) in HHcy coronaries. Also, extensive prevalence of 3-nitrotyrosine immunoreactivity was observed in HHcy coronaries that was confined primarily to the subendothelial layers of smooth muscle. We propose that in HHcy an increased level of superoxide scavenges NO forming peroxynitrite, which increases protein nitrosation. The reduced bioavailability of NO impairs flow-induced dilations of coronary arteries, which may contribute to the development of coronary atherosclerosis and ischemic heart disease.
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Affiliation(s)
- Zoltan Ungvari
- Department of Pathophysiology, Semmelweis University, Budapest, Hungary
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