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Adoga JO, Channa ML, Nadar A. Kolaviron attenuates cardiovascular injury in fructose-streptozotocin induced type-2 diabetic male rats by reducing oxidative stress, inflammation, and improving cardiovascular risk markers. Biomed Pharmacother 2021; 144:112323. [PMID: 34656062 DOI: 10.1016/j.biopha.2021.112323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 10/02/2021] [Accepted: 10/08/2021] [Indexed: 01/01/2023] Open
Abstract
The prevalence of cardiovascular disease among type-2 diabetic patients has become a source of major concern world over. This study explored the protective effect of kolaviron, a bioflavonoid, against oxidative cardiovascular injury in fructose- streptozotocin-induced type 2 diabetic male Sprague Dawley rats. After acclimatization, induction, and confirmation of type-2 diabetes, kolaviron was administered for 28days, after which the animals were anesthetized with Isofor and euthanized. Blood from each rat were collected, and blood samples were then centrifuged for serum and plasma. Cardiac troponin I (cTnI), creatine kinase myocardial band (CK-MB), Creatine phosphokinase (CK), and insulin levels were immediately determined in serum, while remaining samples (serum, plasma, and organs) were stored in the bio-freezer at - 80 °C and 10% formalin for enzyme-link immunosorbent assay (ELISA), biochemical, molecular, and histopathological studies. The results show that type-2 diabetes induction with fructose and streptozotocin led to increased blood glucose levels, decreased insulin levels and cardiac antioxidant enzyme activities, increased malondialdehyde levels, cardiac biomarkers and pro-inflammatory cytokines levels, resulted in abnormal lipid profile, increased blood pressure and angiotensin-converting enzyme (ACE) activity, and decreased plasma endothelial nitric oxide synthase (eNOS) concentration. The histopathological examination of the cardiac tissue revealed severe lesion, hypertrophy, and myofibrils degeneration. However, administration of kolaviron for 28days remarkably improved these conditions. Hence the result from the study validates the potency of kolaviron, and suggests it could serve as an alternative to existing remedy in ameliorating or protecting against cardiovascular injury in type-2 diabetes.
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MESH Headings
- Animals
- Anti-Inflammatory Agents/pharmacology
- Antioxidants/pharmacology
- Biomarkers/blood
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Blood Pressure/drug effects
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Diabetic Cardiomyopathies/etiology
- Diabetic Cardiomyopathies/metabolism
- Diabetic Cardiomyopathies/pathology
- Diabetic Cardiomyopathies/prevention & control
- Flavonoids/pharmacology
- Fructose
- Inflammation Mediators/blood
- Insulin/blood
- Lipids/blood
- Male
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Oxidative Stress/drug effects
- Peptidyl-Dipeptidase A/blood
- Rats, Sprague-Dawley
- Streptozocin
- Rats
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Affiliation(s)
- Jeffrey O Adoga
- Department of Physiology, School of Laboratory Medicine and Medical Science, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4001, South Africa.
| | - Mahendra L Channa
- Department of Physiology, School of Laboratory Medicine and Medical Science, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4001, South Africa
| | - Anand Nadar
- Department of Physiology, School of Laboratory Medicine and Medical Science, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4001, South Africa
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White MC, Fleeman R, Arnold AC. Sex differences in the metabolic effects of the renin-angiotensin system. Biol Sex Differ 2019; 10:31. [PMID: 31262355 PMCID: PMC6604144 DOI: 10.1186/s13293-019-0247-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/18/2019] [Indexed: 02/07/2023] Open
Abstract
Obesity is a global epidemic that greatly increases risk for developing cardiovascular disease and type II diabetes. Sex differences in the obese phenotype are well established in experimental animal models and clinical populations. While having higher adiposity and obesity prevalence, females are generally protected from obesity-related metabolic and cardiovascular complications. This protection is, at least in part, attributed to sex differences in metabolic effects of hormonal mediators such as the renin-angiotensin system (RAS). Previous literature has predominantly focused on the vasoconstrictor arm of the RAS and shown that, in contrast to male rodent models of obesity and diabetes, females are protected from metabolic and cardiovascular derangements produced by angiotensinogen, renin, and angiotensin II. A vasodilator arm of the RAS has more recently emerged which includes angiotensin-(1-7), angiotensin-converting enzyme 2 (ACE2), mas receptors, and alamandine. While accumulating evidence suggests that activation of components of this counter-regulatory axis produces positive effects on glucose homeostasis, lipid metabolism, and energy balance in male animal models, female comparison studies and clinical data related to metabolic outcomes are lacking. This review will summarize current knowledge of sex differences in metabolic effects of the RAS, focusing on interactions with gonadal hormones and potential clinical implications.
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Affiliation(s)
- Melissa C White
- Department of Comparative Medicine, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA, USA
| | - Rebecca Fleeman
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, 500 University Drive, Mail Code H109, Hershey, PA, 17033, USA
| | - Amy C Arnold
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, 500 University Drive, Mail Code H109, Hershey, PA, 17033, USA.
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Identification of protein phosphatase involvement in the AT 2 receptor-induced activation of endothelial nitric oxide synthase. Clin Sci (Lond) 2018. [PMID: 29540539 DOI: 10.1042/cs20171598] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The Angiotensin II type 2 receptor (AT2R) promotes vasodilation by nitric oxide (NO) release from endothelial cells. However, the mechanisms underlying the AT2R-induced stimulation of endothelial NO synthase (eNOS) is still not completely understood. Therefore, we investigated whether in addition to the known AT2R-mediated phosphorylation of eNOS at Ser1177, activation of phosphatases and dephosphorylation of eNOS at Tyr657 and Thr495 are also involved. Human aortic endothelial cells (HAEC) were stimulated with the AT2R-agonist Compound 21 (C21) (1 µM) in the presence or absence of either PD123319 (10 µM; AT2R antagonist), l-NG-Nitroarginine methyl ester (l-NAME) (10 µM; eNOS inhibitor), MK-2206 (100 nM; protein kinase B (Akt) inhibitor) sodium fluoride (NaF) (1 nM; serine/threonine phosphatase inhibitor) or sodium orthovanadate (Na3VO4) (10 nM; tyrosine phosphatase inhibitor). NO release was estimated by quantifying 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM) fluorescence. The phosphorylation status of activating (eNOS-Ser1177) or inhibitory eNOS residues (eNOS-Tyr657, eNOS-Thr495) was determined by Western blotting. Phosphorylation of Akt at Ser473 was measured to estimate Akt activity. AT2R stimulation significantly increased NO release from HAEC, which was blocked by PD123319, l-NAME and both phosphatase inhibitors. Intracellular calcium transients were not changed by C21. AT2R stimulation resulted in phosphorylation of eNOS-Ser1177 and dephosphorylation of eNOS-Tyr657 and eNOS-Thr495 Phosphorylation at eNOS-Ser1177 was prevented by inhibition of Akt with MK-2206. From these data, we conclude that AT2R stimulation in human endothelial cells increases eNOS activity through phosphorylation of activating eNOS residues (eNOS-Ser1177) by Akt, and through dephosphorylation of inactivating eNOS residues (eNOS-Tyr657, eNOS-Thr495) by serine/threonine and tyrosine phosphatases, thus increasing NO release.
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Erukainure OL, Hafizur RM, Kabir N, Choudhary MI, Atolani O, Banerjee P, Preissner R, Chukwuma CI, Muhammad A, Amonsou EO, Islam MS. Suppressive Effects of Clerodendrum volubile P Beauv. [Labiatae] Methanolic Extract and Its Fractions on Type 2 Diabetes and Its Complications. Front Pharmacol 2018; 9:8. [PMID: 29449808 PMCID: PMC5799276 DOI: 10.3389/fphar.2018.00008] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 01/04/2018] [Indexed: 01/01/2023] Open
Abstract
Type 2 diabetes is the most prominent of all diabetes types, contributing to global morbidity and mortality. Availability and cost of treatment with little or no side effect especially in developing countries, remains a huge burden. This has led to the search of affordable alternative therapies especially from medicinal plants. In this study, the antidiabetic effect of the methanolic extract, dichloromethane (DCM), butanol (BuOH) and aqueous fractions of Clerodendrum volubile leaves were investigated in type 2 diabetic rats for their effect on glucose homeostasis, serum insulin level and hepatic biomarkers, lipid profile, pancreatic redox balance and Ca2+ levels, and β-cell distribution and function. The DCM was further fractionated to isolate the active compounds, biochanin and 5,7,4'-trimethoxykaempferol. They were investigated for their toxicity and ADMET properties, α-glucosidase and angiotensin I converting enzyme (ACE) inhibitory activities in silico. There were significant (p < 0.05) decrease in blood glucose, cholesterol, LDL-C, vLDL-C, triglyceride, AST and ALT levels in all treated groups, with DCM fraction showing the best activity. All treated rats showed significantly (p < 0.05) improved anti-oxidative activities. Treatment with the DCM fraction led to significant (p < 0.05) increased serum insulin and pancreatic Ca2+ levels, as well as improved β-cell distribution and function. DCM fraction also showed improved glucose tolerance. DCM fraction dose-dependently inhibited ACE activity. The toxicity class of the isolated compounds was predicted to be 5. They were also predicted to be potent inhibitors of cytochrome P (CYPs) 1A2, 2D6 and 3A4. They docked well with α-glucosidase and ACE. These results indicate the therapeutic potential of the plant against type 2 diabetes, with the DCM fraction being the most potent which may be attributed to the isolated flavones. It further suggests antihypertensive potentials of the DCM fraction. However, inhibition of CYPs by the flavones may suggest caution in usage with other prescribed drugs metabolized by these enzymes.
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Affiliation(s)
- Ochuko L. Erukainure
- Nutrition and Toxicology Division, Federal Institute of Industrial Research Oshodi, Lagos, Nigeria
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
- Department of Biochemistry, School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Durban, South Africa
| | - Rahman M. Hafizur
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Nurul Kabir
- Faculty of Science, Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - M. Iqbal Choudhary
- H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Olubunmi Atolani
- Structural Bioinformatics Group, Institute for Physiology, Charité – University Medicine Berlin, Berlin, Germany
- Department of Chemistry, University of Ilorin, Ilorin, Nigeria
| | - Priyanka Banerjee
- Structural Bioinformatics Group, Institute for Physiology, Charité – University Medicine Berlin, Berlin, Germany
| | - Robert Preissner
- Structural Bioinformatics Group, Institute for Physiology, Charité – University Medicine Berlin, Berlin, Germany
| | - Chika I. Chukwuma
- Department of Food Technology, Durban University of Technology, Steve Biko Campus, Durban, South Africa
- Department of Pharmacology, University of the Free State, Bloemfontein, South Africa
| | - Aliyu Muhammad
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
- Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria
| | - Eric O. Amonsou
- Department of Food Technology, Durban University of Technology, Steve Biko Campus, Durban, South Africa
| | - Md. Shahidul Islam
- Department of Biochemistry, School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Durban, South Africa
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Lombardi C, Spigoni V, Gorga E, Dei Cas A. Novel insight into the dangerous connection between diabetes and heart failure. Herz 2017; 41:201-7. [PMID: 27071966 DOI: 10.1007/s00059-016-4415-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Heart failure (HF) affects approximately 1-2 % of the adult population. Diabetes mellitus (DM) is one of the most frequent comorbidities in HF, portending a worse prognosis. DM is associated with an increased risk of artery disease, and consequently of post-ischemic HF, but it may also alter directly the myocardial structure and function. Insights into the pathophysiological mechanisms of diabetic cardiomyopathy have been provided by both experimental and clinical investigations. In recent years, it has emerged that the fibrotic process is a result of the convergence of multiple neurohormonal alterations in diabetic cardiomyopathy at the basis of disease progression and phenotype determination: HF with reduced or preserved ejection fraction. Therapies for HF and DM should demonstrate an improved prognosis and have a neutral effect on glucose homeostasis and the risk of HF development.
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Affiliation(s)
- C Lombardi
- Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Parma and AOU of Parma, Parma, Italy
| | - V Spigoni
- Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Cardiology, University of Brescia, Brescia, Italy
| | - E Gorga
- Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Cardiology, University of Brescia, Brescia, Italy
| | - A Dei Cas
- , Via Gramsci 14, 43126, Parma, Italy.
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Fenofibrate Therapy Restores Antioxidant Protection and Improves Myocardial Insulin Resistance in a Rat Model of Metabolic Syndrome and Myocardial Ischemia: The Role of Angiotensin II. Molecules 2016; 22:molecules22010031. [PMID: 28036029 PMCID: PMC6155612 DOI: 10.3390/molecules22010031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/04/2016] [Accepted: 12/20/2016] [Indexed: 11/25/2022] Open
Abstract
Renin-angiotensin system (RAS) activation promotes oxidative stress which increases the risk of cardiac dysfunction in metabolic syndrome (MetS) and favors local insulin resistance. Fibrates regulate RAS improving MetS, type-2 diabetes and cardiovascular diseases. We studied the effect of fenofibrate treatment on the myocardic signaling pathway of Angiotensin II (Ang II)/Angiotensin II type 1 receptor (AT1) and its relationship with oxidative stress and myocardial insulin resistance in MetS rats under heart ischemia. Control and MetS rats were assigned to the following groups: (a) sham; (b) vehicle-treated myocardial infarction (MI) (MI-V); and (c) fenofibrate-treated myocardial infarction (MI-F). Treatment with fenofibrate significantly reduced triglycerides, non-high density lipoprotein cholesterol (non-HDL-C), insulin levels and insulin resistance index (HOMA-IR) in MetS animals. MetS and MI increased Ang II concentration and AT1 expression, favored myocardial oxidative stress (high levels of malondialdehyde, overexpression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), decreased total antioxidant capacity and diminished expression of superoxide dismutase (SOD)1, SOD2 and catalase) and inhibited expression of the insulin signaling cascade: phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PkB, also known as Akt)/Glut-4/endothelial nitric oxide synthase (eNOS). In conclusion, fenofibrate treatment favors an antioxidant environment as a consequence of a reduction of the Ang II/AT1/NOX4 signaling pathway, reestablishing the cardiac insulin signaling pathway. This might optimize cardiac metabolism and improve the vasodilator function during myocardial ischemia.
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Dopamine D₄ receptors inhibit proliferation and migration of vascular smooth muscle cells induced by insulin via down-regulation of insulin receptor expression. Cardiovasc Diabetol 2014; 13:97. [PMID: 24888351 PMCID: PMC4078019 DOI: 10.1186/1475-2840-13-97] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/26/2014] [Indexed: 01/11/2023] Open
Abstract
Vascular smooth muscle cells (VSMCs) proliferation and migration, which are central in the development of vascular diseases, are regulated by numerous hormones and humoral factors. Activation of the insulin receptor stimulates VSMCs proliferation while dopamine receptors, via D1 and D3 receptors, inhibit the stimulatory effects of norepinephrine on VSMCs proliferation. We hypothesize that activation of the D4 dopamine receptor may also inhibit the proliferation and migration of VSMCs, therefore, inhibit atherosclerosis. Our current study found that insulin increased the proliferation and migration of A10 cells, an effect that was reduced in the presence of a D4 receptor agonist, PD168077. The negative effect of the D4 receptor on insulin’s action may be via decreasing insulin receptor expression, because activation of the D4 receptor inhibited insulin receptor protein and mRNA expressions, indicating that the regulation occured at the transcriptional or post-transcriptional levels. To determine whether or not the inhibition of D4 receptor on insulin-mediated proliferation and migration of VSMCs has physiological significance, hyper-insulinemic Sprague–Dawley rats with balloon-injured carotid artery were treated with a D4 agonist, PD168077, (6 mg/kg/d) for 14 days. We found that PD168077 significantly inhibited neointimal formation by inhibition of VSMC proliferation. This study suggests that activation of the D4 receptor suppresses the proliferation and migration of VSMCs, therefore, inhibit atherosclerosis. The D4 receptor may be a potential therapeutic target to reduce the effects of insulin on artery remodeling.
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Lee HY, Sakuma I, Ihm SH, Goh CW, Koh KK. Statins and renin-angiotensin system inhibitor combination treatment to prevent cardiovascular disease. Circ J 2014; 78:281-7. [PMID: 24401609 DOI: 10.1253/circj.cj-13-1494] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hypercholesterolemia and hypertension are common risk factors for cardiovascular disease (CVD). Updated guidelines emphasize target reductions of overall cardiovascular risks. Experimental studies have shown reciprocal relationships between insulin resistance (IR) and endothelial dysfunction. Hypercholesterolemia and hypertension have a synergistic deleterious effect on IR and endothelial dysfunction. Unregulated renin-angiotensin system (RAS) is important in the pathogenesis of atherosclerosis and hypertension. Various strategies with different classes of antihypertensive medications to reach target goals have failed to reduce residual CVD risk further. Of interest, treating moderate cholesterol elevations with low-dose statins in hypertensive patients reduced CVD risk by 35-40% further. Therefore, statins are important in reducing CVD risk. Unfortunately, statin therapy causes IR and increases the risk of type 2 diabetes mellitus. RAS inhibitors improve both endothelial dysfunction and IR. Further, cross-talk between hypercholesterolemia and RAS exists at multiple steps of IR and endothelial dysfunction. In this regard, combined therapy with statins and RAS inhibitors demonstrates additive/synergistic effects on endothelial dysfunction and IR in addition to lowering cholesterol levels and blood pressure when compared with either monotherapy in patients. This is mediated by both distinct and interrelated mechanisms. Therefore, combined therapy with statins and RAS inhibitors may be important in developing optimal management strategies in patients with hypertension, hypercholesterolemia, diabetes, metabolic syndrome, or obesity to prevent CVD.
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Affiliation(s)
- Hae-Young Lee
- Division of Cardiology, Seoul National University College of Medicine
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Roscioni SS, Heerspink HJL, de Zeeuw D. The effect of RAAS blockade on the progression of diabetic nephropathy. Nat Rev Nephrol 2013; 10:77-87. [PMID: 24296623 DOI: 10.1038/nrneph.2013.251] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The renin-angiotensin-aldosterone system (RAAS) has a key role in the regulation of blood pressure, sodium and water balance, and cardiovascular and renal homeostasis. In diabetic nephropathy, excessive activation of the RAAS results in progressive renal damage. RAAS blockade using angiotensin-converting-enzyme inhibitors or angiotensin-receptor blockers is the cornerstone of treatment of diabetic renal disease. Alternative RAAS-blockade strategies include renin inhibition and aldosterone blockade. Data from small initial studies of these agents are promising. However, single-agent interventions do not fully block the RAAS and patients treated with these therapies remain at high residual renal risk. Approaches to optimize drug responses include dietary changes and increasing dosages. The theoretically attractive option of combining different RAAS interventions has also been tested in clinical trials but long-term outcomes were disappointing. However, dual RAAS blockade might represent a good therapeutic option for specific patients. A better knowledge of the pathophysiology of the RAAS is crucial to fully understand the mechanisms of action of RAAS blockers and to exploit their renoprotective effects. Moreover, lifestyle interventions or diagnostic tools might be used to optimize RAAS blockade and identify those patients who are most likely to benefit from the therapy.
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Affiliation(s)
- Sara S Roscioni
- Department of Clinical Pharmacology, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, Netherlands
| | - Hiddo J Lambers Heerspink
- Department of Clinical Pharmacology, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, Netherlands
| | - Dick de Zeeuw
- Department of Clinical Pharmacology, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, Netherlands
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Xu YZ, Zhang X, Wang L, Zhang F, Qiu Q, Liu ML, Zhang GR, Wu XL. An increased circulating angiotensin II concentration is associated with hypoadiponectinemia and postprandial hyperglycemia in men with nonalcoholic fatty liver disease. Intern Med 2013; 52:855-61. [PMID: 23583988 DOI: 10.2169/internalmedicine.52.8839] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Nonalcoholic fatty liver disease (NAFLD) is a condition associated with type 2 diabetes (T2D). Insulin resistance, a common pathogenesis of NAFLD and T2D, is partially caused by alterations in angiotensin II (Ang II) and is accompanied by hypoadiponectinemia. We aimed to investigate whether the circulating Ang II and adiponectin concentrations are related to hyperglycemia in male NAFLD patients. METHODS Thirty-five controls and 85 NAFLD patients without prior known T2D were enrolled. All participants were non-smoking men who performed 75-g oral glucose tolerance tests. According to the American Diabetes Association (ADA) criteria, the NAFLD patients were divided into the euglycemia and hyperglycemia groups. The NAFLD patients with hyperglycemia were further divided into the isolated impaired fasting glucose (I-IFG) and postprandial hyperglycemia subgroups. The fasting serum Ang II and adiponectin concentrations were measured. RESULTS Among the 85 NAFLD patients, 40 (47%) had hyperglycemia, including I-IFG (18%) and postprandial hyperglycemia (29%). The serum Ang II concentrations in the euglycemia and hyperglycemia groups were significantly higher than those observed in the control and euglycemia groups, respectively; whereas the serum adiponectin concentrations were significantly lower. The serum Ang II concentrations were significantly higher in the postprandial hyperglycemia subgroup than in the I-IFG subgroup. The serum Ang II and adiponectin concentrations were found to be independent predictors of hyperglycemia in the NAFLD patients. The serum Ang II concentration was significantly associated with the serum adiponectin and 2-hour postprandial glucose concentrations in the NAFLD patients. CONCLUSION An increased circulating Ang II concentration is associated with hypoadiponectinemia and postprandial hyperglycemia in male NAFLD patients and may be involved in the pathogenesis of T2D in NAFLD patients.
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Affiliation(s)
- Yi-Zhi Xu
- Department of Gastroenterology and Hepatology, the Second Affiliated Hospital of Chongqing Medical University, China
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Increased cord blood angiotensin II concentration is associated with decreased insulin sensitivity in the offspring of mothers with gestational diabetes mellitus. J Perinatol 2013; 33:9-14. [PMID: 22499083 DOI: 10.1038/jp.2012.40] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To determine cord blood angiotensin II (Ang II) concentration and assess its relationship to fetal insulin sensitivity in the offspring of mothers with gestational diabetes mellitus (GDM) at birth. STUDY DESIGN Thirty women with GDM and 30 healthy women were evaluated at elective cesarean delivery. Cord blood was obtained for measurement of Ang II, glucose and insulin. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated and used to estimate fetal insulin sensitivity. RESULT The offspring of mothers with GDM had higher ponderal index (PI), HOMA-IR and cord Ang II and insulin concentrations than the offspring of healthy mothers. Cord insulin concentration and HOMA-IR were positively associated with PI in all the offspring. Cord Ang II concentration was positively associated with HOMA-IR in the offspring of mothers with GDM. CONCLUSION Increased cord Ang II concentration is associated with decreased insulin sensitivity in the offspring of mothers with GDM.
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Abstract
Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at increased risk of stroke, heart disease and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Reducing dietary salt is effective in lowering blood pressure in salt-sensitive individuals. Insulin resistance and altered glucose metabolism are common features of hypertension in humans and animal models, with or without salt sensitivity. Altered glucose metabolism leads to increased formation of advanced glycation end products. Insulin resistance is also linked to oxidative stress, and alterations in the nitric oxide pathway and renin angiotensin system. A diet rich in protein containing the semiessential amino acid, arginine, and arginine treatment, lowers blood pressure in humans and in animal models. This may be due to the ability of arginine to improve insulin resistance, decrease advanced glycation end products formation, increase nitric oxide, and decrease levels of angiotensin II and oxidative stress, with improved endothelial cell function and decreased peripheral vascular resistance. The Dietary Approaches to Stop Hypertension (DASH) study demonstrated that the DASH diet, rich in vegetables, fruits and low-fat dairy products; low in fat; and including whole grains, poultry, fish and nuts, lowered blood pressures even more than a typical North American diet with similar reduced sodium content. The DASH diet is rich in protein; the blood pressure-lowering effect of the DASH diet may be due to its higher arginine-containing protein, higher antioxidants and low salt content.
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Affiliation(s)
- Sudesh Vasdev
- Discipline of Medicine, Faculty of Medicine, Health Sciences Centre, Memorial University, St John's, Newfoundland
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Abstract
Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease and kidney failure. Essential hypertension results from a combination of genetic and lifestyle factors. One such lifestyle factor is diet, and its role in the control of blood pressure has come under much scrutiny. Just as increased salt and sugar are known to elevate blood pressure, other dietary factors may have antihypertensive effects. Studies including the Optimal Macronutrient Intake to Prevent Heart Disease (OmniHeart) study, Multiple Risk Factor Intervention Trial (MRFIT), International Study of Salt and Blood Pressure (INTERSALT) and Dietary Approaches to Stop Hypertension (DASH) study have demonstrated an inverse relationship between dietary protein and blood pressure. One component of dietary protein that may partially account for its antihypertensive effect is the nonessential amino acid cysteine. Studies in hypertensive humans and animal models of hypertension have shown that N-acetylcysteine, a stable cysteine analogue, lowers blood pressure, which substantiates this idea. Cysteine may exert its antihypertensive effects directly or through its storage form, glutathione, by decreasing oxidative stress, improving insulin resistance and glucose metabolism, lowering advanced glycation end products, and modulating levels of nitric oxide and other vasoactive molecules. Therefore, adopting a balanced diet containing cysteine-rich proteins may be a beneficial lifestyle choice for individuals with hypertension. An example of such a diet is the DASH diet, which is low in salt and saturated fat; includes whole grains, poultry, fish and nuts; and is rich in vegetables, fruits and low-fat dairy products.
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Affiliation(s)
- Sudesh Vasdev
- Discipline of Medicine, Faculty of Medicine, Health Sciences Centre, Memorial University, St John's, Newfoundland
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Zhou MS, Schulman IH, Zeng Q. Link between the renin-angiotensin system and insulin resistance: implications for cardiovascular disease. Vasc Med 2012; 17:330-41. [PMID: 22814999 DOI: 10.1177/1358863x12450094] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The incidence of metabolic syndrome is rapidly increasing in the United States and worldwide. The metabolic syndrome is a complex metabolic and vascular disorder that is associated with inappropriate activation of the renin-angiotensin-aldosterone system (RAAS) in the cardiovascular (CV) system and increased CV morbidity and mortality. Insulin activation of the phosphatidylinositol-3-kinase (PI3K) pathway promotes nitric oxide (NO) production in the endothelium and glucose uptake in insulin-sensitive tissues. Angiotensin (Ang) II inhibits insulin-mediated PI3K pathway activation, thereby impairing endothelial NO production and Glut-4 translocation in insulin-sensitive tissues, which results in vascular and systemic insulin resistance, respectively. On the other hand, Ang II enhances insulin-mediated activation of the mitogen-activated protein kinase (MAPK) pathway, which leads to vasoconstriction and pathologic vascular cellular growth. Therefore, the interaction of Ang II with insulin signaling is fully operative not only in insulin-sensitive tissues but also in CV tissues, thereby linking insulin resistance and CV disease. This notion is further supported by an increasing number of experimental and clinical studies indicating that pharmacological blockade of RAAS improves insulin sensitivity and endothelial function, as well as reduces the incidence of new-onset diabetes in high-risk patients with CV disease. This article reviews experimental and clinical data elucidating the physiological and pathophysiological role of the interaction between insulin and RAAS in the development of insulin resistance as well as CV disease.
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Affiliation(s)
- Ming-Sheng Zhou
- Nephrology-Hypertension Section, Veterans Affairs Medical Center, University of Miami Miller School of Medicine, Miami, FL 33125, USA.
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Emond ZM, Kibbe MR. Clinical science review article: understanding the implications of diabetes on the vascular system. Vasc Endovascular Surg 2011; 45:481-9. [PMID: 21571777 DOI: 10.1177/1538574411408354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Patients with diabetes comprise an extremely complex subset of patients for the vascular surgeon. Often, they have numerous comorbidities that can further complicate matters. The diabetic environment is highly complex and the interplay of various diseases makes this an extremely challenging condition to manage. Knowing the mechanisms by which diabetes inflicts adverse microscopic changes in the vasculature allows the clinician to anticipate problems and minimize the heightened risks observed in diabetic patients undergoing surgery. In this review, we will illustrate how diabetes affects the vasculature and how the molecular and cellular derangements that occur in diabetic environments lead to these pathophysiologic consequences.
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Affiliation(s)
- Zachary M Emond
- Department of Surgery, University of Illinois at Chicago, IL, USA
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Ennezat PV, Vannesson C, Bouabdallaoui N, Maréchaux S, Asseman P, LeJemtel TH. Imagine how many lives you save: angiotensin-converting enzyme inhibition for atherosclerotic vascular disease in the present era of risk reduction. Expert Opin Pharmacother 2011; 12:883-97. [PMID: 21348772 DOI: 10.1517/14656566.2011.543675] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Angiotensin-converting enzyme (ACE) inhibition is clearly beneficial in patients with hypertension, heart failure, and post-myocardial infarction left ventricular (LV) dysfunction. However, whereas initial trials had reported a benefit of ACE inhibition in high-risk vascular patients, current trials of ACE inhibition have failed to demonstrate a clear benefit in vascular patients who are receiving risk-reduction interventions. The purpose of this review is to analyze the reasons behind the failure of the most recent trials of ACE inhibitors in vascular patients without overt LV dysfunction. The reader will gain an understanding of the time-dependent trend towards a reduction in the absolute benefit conferred by ACE inhibition in patients with vascular atherosclerosis as risk reduction interventions are increasingly implemented. AREAS COVERED Major trials with a follow-up period of at least 1 year assessing the use of ACE inhibitors in patients with a history of cardiac or vascular events were identified via a PubMed literature search. All-cause and cardiovascular mortality outcomes were reported for each trial, as well as the use of aspirin, lipid-lowering drugs and β-blockers, and the mean LV ejection fraction. EXPERT OPINION The findings of recent trials do not support the use of ACE inhibitors in vascular patients who, adherent with risk reduction therapy, do not have hypertension, diabetes, or LV dysfunction.
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Affiliation(s)
- Pierre Vladimir Ennezat
- Cardiology Intensive Care Unit, Hôpital Cardiologique, Bd Pr J. Leclercq, 59000 Lille, France.
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Pu Q, Zhuang D, Thakran S, Hassid A. Mechanisms related to NO-induced motility in differentiated rat aortic smooth muscle cells. Am J Physiol Heart Circ Physiol 2010; 300:H101-8. [PMID: 21037226 DOI: 10.1152/ajpheart.00342.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) is thought to play an important role as an inhibitor of vascular cell proliferation, motility, and neointima formation. This effect is mediated, in part, via the upregulation of protein tyrosine phosphatase (PTP)1B. Conversely, studies have reported that in presumably hyperinsulinemic mice fed a high-fat diet, NO enhances vascular remodeling, whereas a deficit of NO attenuates vascular remodeling. We have reported that in differentiated cultured smooth muscle cells treated with insulin, NO induces a motogenic effect that is dependent on Src homology-2 domain PTP 2 (SHP2) upregulation. In the present study, we describe novel mechanisms relevant to the motogenic effect of NO. Treatment of cultured cells with the selective angiontensin type 1 receptor antagonist losartan, but not with the selective angiotensin type 2 receptor antagonist PD-123319, blocked the comotogenic capacity of NO and insulin. Insulin and NO increased the secretion of ANG II into the culture media by 2- and 2.5-fold (P < 0.05), respectively, whereas treatment of cells with ANG II uncovered the motogenic effect of NO (1.4-fold above control, P < 0.05) and decreased the levels of PTP1B to 45% of control (P < 0.05). Suppression of PTP1B function was sufficient to uncover the motogenic effect of NO. The capacity of insulin to suppress PTP1B activity was blocked by losartan, implicating ANG II function in mediating this effect. Both insulin and ANG II induced the upregulation of phosphatidyl inositol 3-kinase (PI3K)-δ by two- to threefold (P < 0.05), and this effect was both necessary and sufficient to uncover NO-induced motogenesis. Finally, suppression of PTP1B function potentiated, whereas overexpression of PTP1B inhibited, SHP2-induced motogenesis. These results support the hypothesis that the comotogenic effect of insulin and NO occurs via an ANG II-mediated effect involving the suppression of PTP1B and upregulation of PI3K-δ and SHP2.
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Affiliation(s)
- Qinghua Pu
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Albertoni G, Maquigussa E, Pessoa E, Barreto JA, Borges F, Schor N. Soluble uric acid increases intracellular calcium through an angiotensin II-dependent mechanism in immortalized human mesangial cells. Exp Biol Med (Maywood) 2010; 235:825-32. [DOI: 10.1258/ebm.2010.010007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hyperuricemia is associated with increases in cardiovascular risk and renal disease. Mesangial cells regulate glomerular filtration rates through the release of hormones and vasoactive substances. This study evaluates the signaling pathway of uric acid (UA) in immortalized human mesangial cells (ihMCs). To evaluate cell proliferation, ihMCs were exposed to UA (6–10 mg/dL) for 24–144 h. In further experiments, ihMCs were treated with UA (6–10 mg/dL) for 12 and 24 h simultaneously with losartan (10−7 mmol/L). Angiotensin II (AII) and endothelin-1 (ET-1) were assessed using the enzyme-linked immunosorbent assay (ELISA) technique. Pre-pro-ET mRNA was evaluated by the real-time PCR technique. It was observed that soluble UA (8 and 10 mg/dL) stimulated cellular proliferation. UA (10 mg/dL) for 12 h significantly increased AII protein synthesis and ET-1 expression and protein production was increased after 24 h. Furthermore, UA increased [Ca2+]i, and this effect was significantly blocked when ihMCs were preincubated with losartan. Our results suggested that UA triggers reactions including AII and ET-1 production in mesangial cells. In addition, UA can potentially affect glomerular function due to UA-induced proliferation and contraction of mesangial cells. The latter mechanism could be related to the long-term effects of UA on renal function and chronic kidney disease.
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Affiliation(s)
- Guilherme Albertoni
- Department of Medicine, Nephrology Division, Federal University of São Paulo (UNIFESP)
- Associação Beneficente de Coleta de Sangue (Colsan), São Paulo, Brazil
| | - Edgar Maquigussa
- Department of Medicine, Nephrology Division, Federal University of São Paulo (UNIFESP)
| | - Edson Pessoa
- Department of Medicine, Nephrology Division, Federal University of São Paulo (UNIFESP)
| | | | - Fernanda Borges
- Department of Medicine, Nephrology Division, Federal University of São Paulo (UNIFESP)
| | - Nestor Schor
- Department of Medicine, Nephrology Division, Federal University of São Paulo (UNIFESP)
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D1-like receptors inhibit insulin-induced vascular smooth muscle cell proliferation via down-regulation of insulin receptor expression. J Hypertens 2009; 27:1033-41. [PMID: 19293728 DOI: 10.1097/hjh.0b013e3283293c7b] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Vascular smooth muscle cell (VSMC) proliferation is central to the development of vascular diseases, including hypertension, which is regulated by numerous hormones and humoral factors. Our previous study showed that the stimulatory effect of norepinephrine on VSMC proliferation is inhibited by D1-like receptors and the D3 dopamine receptor, a member of the D2-like receptor family. Insulin is a proliferative hormone but it is not known if there is any interaction between insulin and D1-like receptors. We hypothesized that Dl-like receptors may have an inhibitory effect on the insulin-induced VSMC proliferation; aberrant insulin and Dl-like receptor functions could be involved in the pathogenesis of essential hypertension. METHODS VSMC proliferation was determined by [H]-thymidine incorporation; insulin receptor mRNA and protein expressions were determined by RT-PCR, immunoblotting, and immunohistochemistry. RESULTS Insulin increased VSMC proliferation in immortalized aortic A10 cells, determined by [H]-thymidine incorporation. Although the D1-like receptor, by itself, had no effect on VSMC proliferation, stimulation with fenoldopam, a D1-like receptor agonist, inhibited the stimulatory effect of insulin. The inhibitory effect of fenoldopam on insulin-mediated VSMC proliferation was receptor specific, because its effect could be blocked by SCH23390, a D1-like receptor antagonist. Fenoldopam also inhibited insulin receptor mRNA and protein expression, which was time dependent and concentration dependent. A PKC or MAP kinase inhibitor blocked the inhibitory effect of fenoldopam on insulin receptor expression, indicating that PKC and MAP kinase were involved in the signaling pathway. CONCLUSION The inhibitory effect of D1-like receptors on insulin-mediated VSMC proliferation may play an important role in the regulation of blood pressure.
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Matayoshi T, Kamide K, Takiuchi S, Horio T, Yoshihara F, Nakamura S, Nakahama H, Kawano Y. Relationship between Insulin Resistance and the Renin-Angiotensin System: Analysis for Patients with Essential and Renovascular Hypertension. Clin Exp Hypertens 2009; 29:479-87. [DOI: 10.1080/10641960701616186] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Schulman IH, Zhou MS. Vascular insulin resistance: a potential link between cardiovascular and metabolic diseases. Curr Hypertens Rep 2009; 11:48-55. [PMID: 19146801 DOI: 10.1007/s11906-009-0010-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The physiologic actions of insulin in the vasculature serve to couple regulation of metabolic and hemodynamic homeostasis. Insulin activation of the phosphatidylinositol-3-kinase (PI3K) pathway promotes glucose uptake in insulin-responsive tissues and nitric oxide (NO) production in the endothelium. NO induces vasodilation and inhibits platelet aggregation and vascular smooth muscle cell growth. In contrast, insulin activation of the mitogen-activated protein kinase (MAPK) leads to vasoconstriction and pathologic vascular cellular growth. In states of insulin resistance, insulin activation of PI3K is selectively impaired, whereas the MAPK pathway is spared and activated normally. In the endothelium, selective impairment of insulin-mediated NO production may contribute to the development of hypertension, endothelial dysfunction, atherogenesis, and insulin resistance. This article reviews experimental and clinical data elucidating the physiologic and pathophysiologic role of insulin in the vasculature and the mechanisms contributing to the development of vascular and metabolic diseases.
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Affiliation(s)
- Ivonne Hernandez Schulman
- Vascular Biology Institute, University of Miami Miller School of Medicine, Veterans Affairs Medical Center, Nephrology-Hypertension Section, 1201 Northwest 16th Street, Miami, FL 33125, USA.
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The Pleiotropic Effects of Antihypertensive Agents: Do They Account for Additional Cardiovascular Benefit Beyond BP Reduction? South Med J 2008; 101:818-23. [DOI: 10.1097/smj.0b013e31817b6622] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Uric acid stimulates vascular smooth muscle cell proliferation and oxidative stress via the vascular renin-angiotensin system. J Hypertens 2008; 26:269-75. [PMID: 18192841 DOI: 10.1097/hjh.0b013e3282f240bf] [Citation(s) in RCA: 520] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Plasma uric acid has been associated with hypertension in a variety of disorders, and has been shown to be predictive of hypertension. The mechanistic role of uric acid in the development of hypertension is not known however. METHOD We tested the hypothesis that uric acid stimulates vascular smooth muscle cell (VSMC) proliferation and oxidative stress by stimulating the vascular renin-angiotensin system (RAS). Rat VSMC were exposed to 0-300 micromol uric acid for 48 h. RESULTS Uric acid (200 and 300 micromol) stimulated the proliferation of VSMC as measured by thymidine uptake. This effect was prevented by 10(-6) mol losartan or by 10(-6) mol captopril. Incubation of VSMC with uric acid for 48 h also increased angiotensinogen messenger RNA expression and intracellular concentrations of angiotensin II. These responses were also inhibited by losartan and captopril. Increased expression of angiotensinogen mRNA was also inhibited by co-incubation with PD 98059, a mitogen-activated protein (MAP) kinase inhibitor. Uric acid stimulated the production of hydrogen peroxide and 8-isoprostane in VSMC. These increases in oxidative stress indicators were significantly reduced by co-incubating the cells with captopril or losartan. Uric acid also decreased nitrite and nitrate concentrations in the culture medium, an effect that was prevented by losartan and captopril. CONCLUSION These results demonstrate that uric acid stimulates proliferation, angiotensin II production, and oxidative stress in VSMC through tissue RAS. This suggests that uric acid causes cardiovascular disorders by stimulating the vascular RAS, and this stimulation may be mediated by the MAP kinase pathway.
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Cooper SA, Whaley-Connell A, Habibi J, Wei Y, Lastra G, Manrique C, Stas S, Sowers JR. Renin-angiotensin-aldosterone system and oxidative stress in cardiovascular insulin resistance. Am J Physiol Heart Circ Physiol 2007; 293:H2009-23. [PMID: 17586614 DOI: 10.1152/ajpheart.00522.2007] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hypertension commonly occurs in conjunction with insulin resistance and other components of the cardiometabolic syndrome. Insulin resistance plays a significant role in the relationship between hypertension, Type 2 diabetes mellitus, chronic kidney disease, and cardiovascular disease. There is accumulating evidence that insulin resistance occurs in cardiovascular and renal tissue as well as in classical metabolic tissues (i.e., skeletal muscle, liver, and adipose tissue). Activation of the renin-angiotensin-aldosterone system and subsequent elevations in angiotensin II and aldosterone, as seen in cardiometabolic syndrome, contribute to altered insulin/IGF-1 signaling pathways and reactive oxygen species formation to induce endothelial dysfunction and cardiovascular disease. This review examines currently understood mechanisms underlying the development of resistance to the metabolic actions of insulin in cardiovascular as well as skeletal muscle tissue.
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Affiliation(s)
- Shawna A Cooper
- Department of Internal Medicine, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
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Perlstein TS, Gerhard-Herman M, Hollenberg NK, Williams GH, Thomas A. Insulin Induces Renal Vasodilation, Increases Plasma Renin Activity, and Sensitizes the Renal Vasculature to Angiotensin Receptor Blockade in Healthy Subjects. J Am Soc Nephrol 2007; 18:944-51. [PMID: 17287426 DOI: 10.1681/asn.2006091026] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Insulin stimulates the renin-angiotensin system and induces renal vasodilation. The relationship between these opposing influences of insulin on renal vascular tone has not been explored. A hyperinsulinemic euglycemic clamp and sham insulin clamp each of 270 min duration were performed in 15 healthy individuals during high sodium balance. An angiotensin receptor blocker was administered at time 180 min. Renal plasma flow and plasma renin activity were measured serially. The response to insulin or sham insulin infusion was defined as the change from time 0 to 180 min; the response to angiotensin receptor blockade (ARB) was defined as the change from time 180 to 270 min. Insulin infusion increased plasma renin activity (P < 0.01) and renal plasma flow (P < 0.01); the latter effect plateaued by time 150 min. ARB caused a greater vasodilator response during insulin infusion compared with during sham insulin infusion (P = 0.02). Increasing renin response to insulin predicted blunting of the renal vasodilator response to insulin infusion (R(2) = 0.36, P = 0.02) and sensitizing of the renal vasodilator response to ARB during insulin infusion (R(2) = 0.59, P < 0.01). Insulin-induced activation of the renin-angiotensin system modulates insulin-induced renal vasodilation in healthy individuals. Further studies are warranted to address this balance in states of insulin resistance and the possible implications for the association of insulin resistance with risk for chronic kidney disease.
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Affiliation(s)
- Todd S Perlstein
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Sarafidis PA, Bakris GL. The antinatriuretic effect of insulin: an unappreciated mechanism for hypertension associated with insulin resistance? Am J Nephrol 2007; 27:44-54. [PMID: 17245074 DOI: 10.1159/000098955] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2006] [Accepted: 12/13/2006] [Indexed: 12/24/2022]
Abstract
Insulin resistance is proposed to be causally related to the metabolic syndrome disorders, but a direct cause-and-effect relationship between insulin resistance and hypertension was not originally obvious. Previous data suggested that insulin promotes sodium retention from the kidney, and thus research efforts focused on this action among several other possible pathways connecting insulin resistance and hyperinsulinemia with hypertension. A review of numerous studies provides evidence that this antinatriuretic effect of insulin is preserved in states of metabolic insulin resistance, representing a major mechanism for blood pressure elevation. More recent experimental and clinical studies have added data about the exact tubular sites of this insulin action, its relation with the respective insulin action on potassium handling, its possible role in the development of salt sensitivity in essential hypertension, as well as the involvement of oxidant stress in these associations. This review summarizes the current state of knowledge in this area and attempts to highlight an important but rather overlooked pathway for hypertension development in the metabolic syndrome, the influence of high insulin levels leading to volume expansion.
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Affiliation(s)
- Pantelis A Sarafidis
- First Department of Medicine, AHEPA University Hospital, Aristotle University, Thessaloniki, Greece.
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Karagiannis A, Mikhailidis DP, Athyros VG, Kakafika AI, Tziomalos K, Liberopoulos EN, Florentin M, Elisaf M. The role of renin–angiotensin system inhibition in the treatment of hypertension in metabolic syndrome: are all the angiotensin receptor blockers equal? Expert Opin Ther Targets 2007; 11:191-205. [PMID: 17227234 DOI: 10.1517/14728222.11.2.191] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The metabolic syndrome (MetS) is a strong predictor of cardiovascular morbidity and mortality, as well as new Type 2 diabetes. MetS consists of visceral obesity, elevated blood pressure, impaired glucose metabolism, atherogenic dyslipidaemia (elevated triglycerides and low levels of high-density lipoprotein cholesterol), as well as other metabolic abnormalities. The underlying pathophysiology seems to be largely, but not uniquely, attributable to insulin resistance. Existing antihypertensive drugs were designed to lower blood pressure rather than to modify the metabolic abnormalities associated with hypertension. This review considers the role of renin-angiotensin system inhibition and especially the use of angiotensin receptor blockers (ARBs) in the treatment of hypertension in MetS. There are differences among ARBs. Among them is the uricosuric effect of losartan. Furthermore, telmisartan may function as a partial agonist of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma).
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Affiliation(s)
- Asterios Karagiannis
- Second Propedeutic Department of Internal Medicine, Medical School, Aristotle University of Thessaloniki, Hippokration Hospital, Thessaloniki, Greece
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Nyby MD, Abedi K, Smutko V, Eslami P, Tuck ML. Vascular Angiotensin Type 1 Receptor Expression Is Associated with Vascular Dysfunction, Oxidative Stress and Inflammation in Fructose-Fed Rats. Hypertens Res 2007; 30:451-7. [PMID: 17587757 DOI: 10.1291/hypres.30.451] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study determined whether or not oxidative stress and vascular dysfunction in fructose-induced hyperinsulinemic rats are associated with activation of the vascular renin-angiotensin system (RAS). Four groups of rats were used. CONT rats were fed normal rat chow, CONT+CAP were fed normal rat chow and given 500 mg/L captopril in their drinking water, fructose-fed rats (FFR) were fed a high-fructose diet and FFR+CAP were fed the high-fructose diet plus captopril in water. After 8 weeks, the vascular reactivity of mesenteric artery segments was measured. Blood was analyzed for insulin, glucose, hydrogen peroxide and 8-isoprostane. Aortic and heart tissue were used for subjected to quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. Systolic blood pressure was significantly higher in FFR (p<0.05), and captopril treatment inhibited the blood pressure increase. Mesenteric artery dose-response curves to acetylcholine were shifted to the right in FFR (p<0.05) and were normal in FFR+CAP. Plasma insulin (p<0.05), hydrogen peroxide (p<0.02) and 8-isoprostane (p<0.05) were increased in FFR. Captopril treatment reducd hydrogen peroxide and 8-isoprostane concentrations. Aortic tissue mRNA expression levels were increased for angiotensin-converting enzyme (ACE, p<0.05), angiotensin type 1 receptor (AT1R, p<0.02), NOX4 (p<0.02) and VCAM-1 (p<0.05) in FFR aortic samples. Captopril treatment reduced AT1R, NOX4 and VCAM-1 expression in FFR to levels not different from CONT. Similar changes in heart tissue mRNA expression for angiotensinogen, AT1R and NOX4 were also observed. These results demonstrate that vascular RAS is upregulated in FFR and support the hypothesis that vascular RAS mediates vascular dysfunction and vascular oxidative stress in FFR.
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Affiliation(s)
- Michael D Nyby
- David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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Ornskov D, Nexo E, Sorensen BS. Insulin-induced proliferation of bladder cancer cells is mediated through activation of the epidermal growth factor system. FEBS J 2006; 273:5479-89. [PMID: 17116246 DOI: 10.1111/j.1742-4658.2006.05539.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism behind the growth-promoting effect of insulin is a subject of debate. Employing RT4 bladder cancer cells, we examined the cross-talk between insulin and the epidermal growth factor system. We found that insulin induced a time- and dose-dependent (25-1000 nmol.L(-1) insulin) increase in mRNA expression of three ligands from the epidermal growth factor system. Times for peak increase and fold increase after incubation with 250 nmol.L(-1) insulin were as follows: heparin-binding epidermal growth factor-like growth factor, 0.5 h, 1.4-fold, P < 0.05; epiregulin, 3 h, 14-fold, P < 0.0001; and amphiregulin, 3 h, 12-fold, P < 0.001. Induction of heparin-binding epidermal growth factor-like growth factor and amphiregulin was verified at the protein level. We demonstrate that incubation of RT4 bladder cancer cells for 24 h with 250 nmol.L(-1) insulin increases proliferation by 43% (P < 0.0001) as compared to untreated cells. At the same time, phosphorylation and thereby activation of the epidermal growth factor receptor (HER1) was observed. Both phosphorylation and insulin-induced proliferation were almost completely inhibited by the HER1 inhibitor Iressa (P < 0.0001). This shows that insulin leads to activation of HER1, and that HER1 plays an essential role in mediating the growth-promoting effect of insulin. Iressa inhibited not only the activation of HER1 caused by insulin but also the insulin-induced increase in the three ligands (heparin-binding epidermal growth factor-like growth factor, epiregulin and amphiregulin). As heparin-binding epidermal growth factor-like growth factor was induced before epiregulin and amphiregulin upon insulin stimulation, we speculated that the insulin-induced heparin-binding epidermal growth factor-like growth factor initiated the activation of HER1, and that this in turn led to increased expression of epiregulin and amphiregulin and thereby to continued activation of HER1. Earlier reports have shown that insulin-like growth factor receptor can activate HER1 via its ligand heparin-binding epidermal growth factor-like growth factor. In accord with this, we found that treatment of RT4 cells with recombinant heparin-binding epidermal growth factor-like growth factor mimicked the effect of insulin, with induction of mRNA for the three ligands. However, the insulin-induced increase in mRNA expression of amphiregulin and epiregulin could not be prevented by the heparin-binding epidermal growth factor-like growth factor inhibitor CRM197, demonstrating that heparin-binding epidermal growth factor-like growth factor is not essential for the insulin-induced increase in the expression of these ligands. In conclusion, we show that insulin-induced growth in RT4 cells requires activated HER1. Furthermore, activation of HER1 is required for the insulin-induced increase in expression of the HER1 ligands heparin-binding epidermal growth factor-like growth factor, amphiregulin and epiregulin.
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Affiliation(s)
- Dorthe Ornskov
- Department of Clinical Biochemistry, Aarhus Sygehus, University Hospital in Aarhus, Denmark
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Fonseca VA. Review Paper � CME. Insulin Resistance, Diabetes, Hypertension, and Renin?Angiotensin System Inhibition: Reducing Risk for Cardiovascular Disease. J Clin Hypertens (Greenwich) 2006; 8:713-20; quiz 721-2. [PMID: 17028485 PMCID: PMC8109563 DOI: 10.1111/j.1524-6175.2006.05583.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Insulin resistance, diabetes mellitus, and hypertension are associated with significant cardiovascular morbidity and mortality. Lifestyle modifications effectively decrease the risk of progression to diabetes in high-risk patients, but intensive interventions can be costly and difficult for patients to maintain. The addition of pharmacotherapy is often necessary to treat hyperglycemia and hypertension and lower the risk of cardiovascular complications. Clinical trial data suggest the use of insulin-sensitizing and antihyperglycemic agents to delay the progression to diabetes. Similarly, analysis of data from clinical trials of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers indicate that the use of these agents results in fewer cases of new-onset diabetes among patients with hypertension, when compared with other antihypertensive agents. Angiotensin II has direct and indirect effects on insulin and its signaling pathways, providing support for the biologic mechanism underlying the benefits of renin-angiotensin system inhibition in preventing diabetes and cardiovascular events. Clinical trials now under way will further evaluate the role of renin-angiotensin system inhibition in preventing diabetes and its microvascular and macrovascular complications.
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Affiliation(s)
- Vivian A Fonseca
- Diabetes Program, Tulane University Medical Center, New Orleans, LA 70112-2699, USA.
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Abuissa H, Jones PG, Marso SP, O'Keefe JH. Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers for prevention of type 2 diabetes: a meta-analysis of randomized clinical trials. J Am Coll Cardiol 2005; 46:821-6. [PMID: 16139131 DOI: 10.1016/j.jacc.2005.05.051] [Citation(s) in RCA: 317] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 04/28/2005] [Accepted: 05/10/2005] [Indexed: 12/14/2022]
Abstract
OBJECTIVES We sought to investigate the role of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) in preventing the new onset of type 2 diabetes mellitus. BACKGROUND Diabetes is a public health problem of epidemic proportions and its prevalence is on the rise. The typical American born today has a one in three chance of developing type 2 diabetes. This diagnosis is associated with an adverse cardiovascular prognosis and is considered the risk equivalent of established coronary disease. Even in high-risk individuals, diabetes is a preventable disease. Several studies have shown that ACE inhibitors and ARBs decrease the incidence of new-onset type 2 diabetes. However, the exact role of these agents in diabetes prevention has not yet been fully elucidated. METHODS We conducted a meta-analysis of 12 randomized controlled clinical trials of ACE inhibitors or ARBs, identified through a MEDLINE search and a review of reports from scientific meetings, to study the efficacy of these medications in diabetes prevention. RESULTS This showed that ACE inhibitors and ARBs were associated with reductions in the incidence of newly diagnosed diabetes by 27% and 23%, respectively, and by 25% in the pooled analysis. CONCLUSIONS The use of an ACE inhibitor or ARB should be considered in patients with pre-diabetic conditions such as metabolic syndrome, hypertension, impaired fasting glucose, family history of diabetes, obesity, congestive heart failure, or coronary heart disease.
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Affiliation(s)
- Hussam Abuissa
- Mid America Heart Institute, Cardiovascular Consultants, Kansas City, Missouri 64111, USA.
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Hunyady L, Catt KJ. Pleiotropic AT1 receptor signaling pathways mediating physiological and pathogenic actions of angiotensin II. Mol Endocrinol 2005; 20:953-70. [PMID: 16141358 DOI: 10.1210/me.2004-0536] [Citation(s) in RCA: 401] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Angiotensin II (Ang II) activates a wide spectrum of signaling responses via the AT1 receptor (AT1R) that mediate its physiological control of blood pressure, thirst, and sodium balance and its diverse pathological actions in cardiovascular, renal, and other cell types. Ang II-induced AT1R activation via Gq/11 stimulates phospholipases A2, C, and D, and activates inositol trisphosphate/Ca2+ signaling, protein kinase C isoforms, and MAPKs, as well as several tyrosine kinases (Pyk2, Src, Tyk2, FAK), scaffold proteins (G protein-coupled receptor kinase-interacting protein 1, p130Cas, paxillin, vinculin), receptor tyrosine kinases, and the nuclear factor-kappaB pathway. The AT1R also signals via Gi/o and G11/12 and stimulates G protein-independent signaling pathways, such as beta-arrestin-mediated MAPK activation and the Jak/STAT. Alterations in homo- or heterodimerization of the AT1R may also contribute to its pathophysiological roles. Many of the deleterious actions of AT1R activation are initiated by locally generated, rather than circulating, Ang II and are concomitant with the harmful effects of aldosterone in the cardiovascular system. AT1R-mediated overproduction of reactive oxygen species has potent growth-promoting, proinflammatory, and profibrotic actions by exerting positive feedback effects that amplify its signaling in cardiovascular cells, leukocytes, and monocytes. In addition to its roles in cardiovascular and renal disease, agonist-induced activation of the AT1R also participates in the development of metabolic diseases and promotes tumor progression and metastasis through its growth-promoting and proangiogenic activities. The recognition of Ang II's pathogenic actions is leading to novel clinical applications of angiotensin-converting enzyme inhibitors and AT1R antagonists, in addition to their established therapeutic actions in essential hypertension.
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Affiliation(s)
- László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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Abstract
Type 2 diabetes mellitus is a public health problem of epidemic proportions and its prevalence is on the rise. The typical American born today has a one in three chance of developing type 2 diabetes. This diagnosis is associated with an adverse cardiovascular prognosis and is considered the risk equivalent of established coronary disease. Many risk factors, including the metabolic syndrome, have been implicated in its development. Even in high-risk individuals, type 2 diabetes is a preventable disease. Diet and exercise have been consistently shown to decrease the incidence of diabetes in large randomized controlled studies. Additionally, new-onset diabetes was reduced by several oral pharmacologic anti-diabetic agents including metformin, acarbose and troglitazone in randomized trials which studied patients with impaired glucose tolerance. More interestingly, multiple large prospective studies have also reported a reduction in the development of type 2 diabetes in patients treated with anti-hypertensive agents, predominantly angiotensin converting enzyme inhibitors and angiotensin receptor blockers. In this review, we will discuss some of these important trials and the speculative mechanisms whereby those medications prevent type 2 diabetes. Such observations, if proven to be true, may represent preventive strategies which can be considered in patients with pre-diabetic conditions such as the metabolic syndrome, hypertension, impaired fasting glucose, family history of diabetes, obesity, congestive heart failure or other risks for the development of type 2 diabetes.
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Affiliation(s)
- Hussam Abuissa
- Mid America Heart Institute, Cardiovascular Consultants, Kansas City, MO 64111, USA.
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