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Vergara A, Jacobs-Cacha C, Llorens-Cebria C, Ortiz A, Martinez-Diaz I, Martos N, Dominguez-Báez P, Van den Bosch MM, Bermejo S, Pieper MP, Benito B, Soler MJ. Enhanced Cardiorenal Protective Effects of Combining SGLT2 Inhibition, Endothelin Receptor Antagonism and RAS Blockade in Type 2 Diabetic Mice. Int J Mol Sci 2022; 23:12823. [PMID: 36361612 PMCID: PMC9656616 DOI: 10.3390/ijms232112823] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 07/30/2023] Open
Abstract
Treatments with sodium-glucose 2 cotransporter inhibitors (SGLT2i) or endothelin receptor antagonists (ERA) have shown cardiorenal protective effects. The present study aimed to evaluate the cardiorenal beneficial effects of the combination of SGLT2i and ERA on top of renin-angiotensin system (RAS) blockade. Type 2 diabetic mice (db/db) were treated with different combinations of an SGLT2i (empagliflozin), an ERA (atrasentan), and an angiotensin-converting enzyme inhibitor (ramipril) for 8 weeks. Vehicle-treated diabetic mice and non-diabetic mice were included as controls. Weight, blood glucose, blood pressure, and kidney and heart function were monitored during the study. Kidneys and heart were collected for histological examination and to study the intrarenal RAS. Treatment with empagliflozin alone or combined significantly decreased blood glucose compared to vehicle-treated db/db. The dual and triple therapies achieved significantly greater reductions in diastolic blood pressure than ramipril alone. Compared to vehicle-treated db/db, empagliflozin combined with ramipril or in triple therapy significantly prevented GFR increase, but only the triple combination exerted greater protection against podocyte loss. In the heart, empagliflozin alone or combined reduced cardiac isovolumetric relaxation time (IVRT) and left atrium (LA) diameter as compared to vehicle-treated db/db. However, only the triple therapy was able to reduce cardiomyocyte area. Importantly, the add-on triple therapy further enhanced the intrarenal ACE2/Ang(1-7)/Mas protective arm of the RAS. These data suggest that triple therapy with empagliflozin, atrasentan and ramipril show synergistic cardiorenal protective effects in a type 2 diabetic mouse model.
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Affiliation(s)
- Ander Vergara
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
- Nephrology Department, Vall d’Hebron Hospital Universitari, Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Conxita Jacobs-Cacha
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Carmen Llorens-Cebria
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Alberto Ortiz
- IIS-Fundación Jiménez Diaz, Fundación Renal Iñigo Álvarez de Toledo-IRSIN, REDinREN, Instituto de Investigación Carlos III, Universidad Autónoma de Madrid, Av. de los Reyes Católicos 2, 28040 Madrid, Spain
| | - Irene Martinez-Diaz
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Nerea Martos
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Pamela Dominguez-Báez
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Mireia Molina Van den Bosch
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Sheila Bermejo
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
- Nephrology Department, Vall d’Hebron Hospital Universitari, Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
| | - Michael Paul Pieper
- Cardio-Metabolic Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Str. 65, 88397 Biberach an der Riß, Germany
| | - Begoña Benito
- Cardiology Research Group, Vall d’Hebron Institut de Recerca (VHIR), Vall d’Hebron Hospital Universitari, Vall d’Hebron Barcelona Hospital Campus, Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
- Cardiology Department, Vall d’Hebron Hospital Universitari, Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
- Deparment of Medicine, Universitat Autònoma de Barcelona, Av. de Can Domènech, 08193 Bellaterra, Spain
| | - Maria Jose Soler
- Nephrology and Kidney Transplantation Research Group, Vall d’Hebron Institut de Recerca (VHIR), Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
- Nephrology Department, Vall d’Hebron Hospital Universitari, Passeig Vall d’Hebron 119-129, 08035 Barcelona, Spain
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Ritter C, Zhang S, Finch JL, Liapis H, Suarez E, Ferder L, Delmez J, Slatopolsky E. Cardiac and renal effects of atrasentan in combination with enalapril and paricalcitol in uremic rats. Kidney Blood Press Res 2014; 39:340-52. [PMID: 25300759 PMCID: PMC4225010 DOI: 10.1159/000355811] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/04/2014] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND/AIMS The search for new therapies providing cardiorenal protection in chronic kidney disease (CKD) has led to treatments that combine conventional renin-angiotensin-aldosterone-system inhibitors with other drugs that exhibit potential in disease management. METHODS In rats made uremic by renal ablation, we examined the effects of addition of the endothelin-A receptor antagonist atrasentan to a previously examined combination of enalapril (angiotensin converting enzyme inhibitor) and paricalcitol (vitamin D receptor activator) on cardiac and renal parameters. The effects of the individual and combined drugs were examined after a 3-month treatment. RESULTS A decrease in systolic blood pressure, serum creatinine and proteinuria, and improvement of renal histology in uremic rats were attributed to enalapril and/or paricalcitol treatment; atrasentan alone had no effect. In heart tissue, individual treatment with the drugs blunted the increase in cardiomyocyte size, and combined treatment additively decreased cardiomyocyte size to normal levels. Perivascular fibrosis was blunted in uremic control rats with atrasentan or enalapril treatment. CONCLUSIONS We found distinct cardiac and renal effects of atrasentan. Combination treatment with atrasentan, enalapril and paricalcitol provided positive effects on cardiac remodeling in uremic rats, whereas combination treatment did not offer further protective effects on blood pressure, proteinuria or renal histology.
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Affiliation(s)
- Cynthia Ritter
- Renal Division, Washington University School of Medicine, St. Louis, MO, USA
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Elevated expression of liver X receptor alpha (LXRα) in myocardium of streptozotocin-induced diabetic rats. Inflammation 2012; 34:698-706. [PMID: 21136146 DOI: 10.1007/s10753-010-9281-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The present study was designed to investigate the myocardial expression of liver X receptor alpha (LXRα) in a streptozotocin (STZ)-induced diabetic rat model. Immunohistochemical staining, quantitative real-time RT-PCR, and Western blot analysis were used to determine the expression of LXRα in the myocardium of STZ-induced diabetic rats. The myocardial expression of LXRα target genes, long-chain acyl-CoA synthetase 3 (ACSL3), fatty acid transporter protein (FAT/CD36), ATP-binding cassette transporter A1 (ABCA1), and ABCG1 were also detected. Bisulfite sequencing analysis was employed to examine the methylation status of the CpG island at the LXRα promoter region in the myocardium of STZ-induced diabetic rats. We found that LXRα mRNA and protein expression in the left ventricles, right ventricles, and atria of diabetic rats were gradually increased during the progression of diabetic cardiomyopathy (DCM). The mRNA expression levels of ACSL3 and FAT/CD36 and the protein expression levels of ABCA1 and ABCG1 were also markedly increased in different heart chambers of diabetic rats. Moreover, there was a significant difference in the methylation status of LXRα gene between the ventricles of control and diabetic rats (P < 0.05). Our findings suggest that elevated expression of LXRα may be involved in the progression of DCM, and demethylation of LXRα is likely to be responsible for its increased expression in myocardial tissues.
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Rodríguez-Pascual F, Busnadiego O, Lagares D, Lamas S. Role of endothelin in the cardiovascular system. Pharmacol Res 2011; 63:463-72. [DOI: 10.1016/j.phrs.2011.01.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/13/2011] [Accepted: 01/29/2011] [Indexed: 01/22/2023]
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Karasu Ç. Glycoxidative stress and cardiovascular complications in experimentally-induced diabetes: effects of antioxidant treatment. Open Cardiovasc Med J 2010; 4:240-56. [PMID: 21270942 PMCID: PMC3026340 DOI: 10.2174/1874192401004010240] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 09/24/2010] [Accepted: 10/04/2010] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus (DM) is a common metabolic disease, representing a serious risk factor for the development of cardiovascular complications, such as coronary heart disease, peripheral arterial disease and hypertension. Oxidative stress (OS), a feature of DM, is defined as an increase in the steady-state levels of reactive oxygen species (ROS) and may occur as a result of increased free radical generation and/or decreased anti-oxidant defense mechanisms. Increasing evidence indicates that hyperglycemia is the initiating cause of the tissue damage in DM, either through repeated acute changes in cellular glucose metabolism, or through long-term accumulation of glycated biomolecules and advanced glycation end products (AGEs). AGEs are formed by the Maillard process, a non-enzymatic reaction between ketone group of the glucose molecule or aldehydes and the amino groups of proteins that contributes to the aging of proteins and to the pathological complications of DM. In the presence of uncontrolled hyperglycemia, the increased formation of AGEs and lipid peroxidation products exacerbate intracellular OS and results in a loss of molecular integrity, disruption in cellular signaling and homeostasis, followed by inflammation and tissue injury such as endothelium dysfunction, arterial stiffening and microvascular complications. In addition to increased AGE production, there is also evidence of multiple pathways elevating ROS generation in DM, including; enhanced glucose auto-oxidation, increased mitochondrial superoxide production, protein kinase C-dependent activation of NADPH oxidase, uncoupled endothelial nitric oxide synthase (eNOS) activity, increased substrate flux through the polyol pathway and stimulation of eicosanoid metabolism. It is, therefore, not surprising that the correction of these variables can result in amelioration of diabetic cardiovascular abnormalities. A linking element between these phenomena is cellular redox imbalance due to glycoxidative stress (GOS). Thus, recent interest has focused on strategies to prevent, reverse or retard GOS in order to modify the natural history of diabetic cardiovascular abnormalities. This review will discuss the links between GOS and diabetes-induced cardiovascular disorders and the effect of antioxidant therapy on altering the development of cardiovascular complications in diabetic animal models.
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Affiliation(s)
- Çimen Karasu
- The Leader of Antioxidants in Diabetes-Induced Complications (ADIC) Study Group. Cellular Stress Response & Signal Transduction Research Laboratory, Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
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Bukowska A, Röcken C, Erxleben M, Röhl FW, Hammwöhner M, Huth C, Ebert MP, Lendeckel U, Goette A. Atrial expression of endothelial nitric oxide synthase in patients with and without atrial fibrillation. Cardiovasc Pathol 2010; 19:e51-60. [DOI: 10.1016/j.carpath.2008.12.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 12/12/2008] [Accepted: 12/24/2008] [Indexed: 10/21/2022] Open
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Neuhofer W, Pittrow D. Endothelin receptor selectivity in chronic kidney disease: rationale and review of recent evidence. Eur J Clin Invest 2009; 39 Suppl 2:50-67. [PMID: 19335747 DOI: 10.1111/j.1365-2362.2009.02121.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelin (ET) is a potent vasoconstrictory peptide with proinflammatory and profibrotic properties that exerts its biological effects through two pharmacologically distinct receptor subtypes, namely ET(A) and ET(B). In addition to its substantial contribution to normal renal function, a large body of evidence suggests that derangement of the renal ET system is involved in the initiation and progression of chronic kidney disease (CKD) in diabetes, hypertension and glomerulonephritis. Thus, the use of ET receptor antagonists (ERAs) may offer potential novel treatment strategies in CKD. Recent literature on the role of the renal ET system in the healthy kidney was reviewed. In addition, an unbiased PubMed search was performed for studies published during the last 5 years that addressed the effects of ERAs in CKD. A particular objective was to extract information regarding whether selective or nonselective ERAs may have therapeutic potential in humans. ET-1 acts primarily as an autocrine or paracrine factor in the kidney. In normal physiology, ET-1 promotes diuresis and natriuresis by local production and action through ET(B) receptors in the renal medulla. In pathology, ET-1 mediates vasoconstriction, mesangial-cell proliferation, extracellular matrix production and inflammation, effects that are primarily conveyed by ET(A) receptors. Results obtained in animal models and in humans with the use of ERAs in CKD are encouraging; nevertheless, it is still under debate which receptor subtype should be targeted. According to most studies, selective inhibition of ET(A) receptors appears superior compared with nonselective ERAs because this approach does not interfere with the natriuretic, antihypertensive and ET clearance effects of ET(B) receptors. Although preliminary data in humans are promising, the potential role of ERAs in patients with CKD and the question of which receptor subtype should be targeted can only be clarified in randomized clinical trials.
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Affiliation(s)
- W Neuhofer
- Department of Internal Medicine, University of Munich, Munich, Germany.
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Ban CR, Twigg SM. Fibrosis in diabetes complications: pathogenic mechanisms and circulating and urinary markers. Vasc Health Risk Manag 2008; 4:575-96. [PMID: 18827908 PMCID: PMC2515418 DOI: 10.2147/vhrm.s1991] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Diabetes mellitus is characterized by a lack of insulin causing elevated blood glucose, often with associated insulin resistance. Over time, especially in genetically susceptible individuals, such chronic hyperglycemia can cause tissue injury. One pathological response to tissue injury is the development of fibrosis, which involves predominant extracellular matrix (ECM) accumulation. The main factors that regulate ECM in diabetes are thought to be pro-sclerotic cytokines and protease/anti-protease systems. This review will examine the key markers and regulators of tissue fibrosis in diabetes and whether their levels in biological fluids may have clinical utility.
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Affiliation(s)
- Camelia R Ban
- Discipline of Medicine and Department of Endocrinology, The University of Sydney and Royal Prince Alfred Hospital Sydney, New South Wales, 2006, Australia
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Dai HY, Guo XG, Ge ZM, Li ZH, Yu XJ, Tang MX, Zhang Y. Elevated expression of urotensin II and its receptor in diabetic cardiomyopathy. J Diabetes Complications 2008; 22:137-43. [PMID: 18280445 DOI: 10.1016/j.jdiacomp.2006.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 10/13/2006] [Accepted: 10/16/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVE Urotensin II (UII) is a somatostatin-like peptide recently identified to have several cardiovascular effects, including potent vasoactive, cardiac inotropic and chronotropic properties. Our aim was to determine the degree of expression of UII and UII receptor (UT) in the myocardium of rats with streptozotocin (STZ)-induced diabetes. METHODS Real-time polymerase chain reaction, Western blot, and immunohistochemistry were used to determine the degree of expression and location of UII and UT in the myocardium of STZ-induced diabetic rats. RESULTS UII and UT expression were significantly enhanced in the myocardium of rats with diabetes compared with healthy controls on both messenger RNA and protein levels. Both UII and UT protein expression were mainly concentrated in the cardiomyocytes, endothelial cells, cardiac fibroblasts, and smooth muscle cells of diabetic cardiomyopathy (DCM). CONCLUSIONS Our results suggest a possible role for the UII/UT system in the pathophysiology of DCM.
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Affiliation(s)
- Hong-Yan Dai
- Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Qilu Hospital, Shandong University, Jinan, Shandong, China
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Abstract
There is now increasing evidence that endothelial dysfunction is an early event in the pathophysiology of cardiovascular diseases and can be corrected with certain therapies such as angiotensin converting enzyme inhibitors angiotensin type I receptor antagonists and stains independently of blood pressure lowering effects. Restoring endothelial function appears to be a crucial target since endothelial dysfunction predicts cardiovascular events in various situations such as coronary artery disease peripheral artery disease, or hypertension and in patients undergoing vascular surgery. Preclinical and clinical data strongly support that endothelin receptor antagonists belong to this restricted class of pharmacological agents able to act on the endothelium, and offer a potential therapeutic approach for numerous diseases associated with endothelial dysfunction. The purpose of this review will be therefore, 1) to propose mechanisms by which ET-1 can cause endothelial dysfunction; 2) to provide an overview of pathological situations associated with endothelial dysfunction related to ET-1; and 3) to assemble evidence on efficacy of endothelin receptor antagonists for improvement of endothelial function.
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Wölkart G, Pang X, Stessel H, Kirchengast M, Brunner F. Chronic endothelin-A receptor antagonism is as protective as angiotensin converting enzyme inhibition against cardiac dysfunction in diabetic rats. Br J Pharmacol 2007; 151:1187-97. [PMID: 17572700 PMCID: PMC2189828 DOI: 10.1038/sj.bjp.0707325] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 04/23/2007] [Accepted: 05/02/2007] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Diabetes mellitus is associated with a specific cardiomyopathy. We compared the cardioprotective effects of an endothelin-A receptor blocker (ET(A)-RB) with those of an angiotensin-converting enzyme inhibitor (ACE-I) in rats with streptozotocin (STZ)-induced diabetes. EXPERIMENTAL APPROACH Diabetic rats were left untreated or received either the ET(A)-RB atrasentan or the ACE-I ramipril (each 3 mg kg(-1) per day) orally for 8 weeks. Isolated isovolumic heart function was studied during normoxia and in response to ischaemia-reperfusion. Cardiac fibrosis, tissue oxidative stress and tissue nitric oxide synthase (NOS) activity were determined. KEY RESULTS Basal left ventricular systolic contractility was lower in diabetic compared to nondiabetic hearts and ET(A)-RB or ACE-I treatment significantly antagonised the decline. Following 15 min of no-flow ischaemia, reperfusion systolic function was depressed and left-ventricular end-diastolic pressure (LVEDP) was elevated in diabetic hearts. ET(A)-RB or ACE-I treatment significantly improved recovery of reperfusion systolic and diastolic function, without differences between groups. Hydroxyproline (an index of tissue fibrosis) and malondialdehyde (a measure of tissue oxidative stress) were elevated at the end of reperfusion in diabetic, compared to nondiabetic hearts. Either treatment reduced hydroxyproline and malondialdehyde to control level. Constitutive NOS activity was similar in nondiabetic and diabetic hearts and unaffected by ET(A)-RB or ACE-I treatment. CONCLUSIONS AND IMPLICATIONS These results suggest that in experimental type 1 diabetes ET(A)-RB is as effective as an ACE-I in ameliorating myocardial functions during normoxia and ischaemia-reperfusion. Combining the two treatments neither afforded additive effects, nor diminished any protection effect seen with either drug.
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Affiliation(s)
- G Wölkart
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - X Pang
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - H Stessel
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - M Kirchengast
- PRA International Mannheim, Germany
- Faculty of Clinical Medicine, Department of Pharmacology and Toxicology, Mannheim Ruprecht-Karls-University Heidelberg Mannheim, Germany
| | - F Brunner
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
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Pozo-Navas B, Stessel H, Wölkart G, Brunner F. Role of myocardial nitric oxide in diabetic ischemia-reperfusion dysfunction: studies in mice with myocyte-specific overexpression of endothelial nitric-oxide synthase. J Pharmacol Exp Ther 2006; 319:729-38. [PMID: 16857730 DOI: 10.1124/jpet.106.107854] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the role of nitric oxide (NO) in myocardial ischemia-reperfusion injury of diabetic mice with myocyte-specific overexpression of endothelial NO synthase (NOS). Four weeks after diabetes induction with streptozotocin (blood glucose approximately 29 mM), isolated isovolumic heart function and cellular NO metabolites in response to brief normothermic ischemia-reperfusion were determined. Under normoxic conditions transgenic (TG) hearts from nondiabetic and diabetic animals generated less left-ventricular developed pressure compared with wild-type (WT) control hearts, and this abnormality was unaffected by NOS inhibition. During ischemia, the rise in end-diastolic pressure was less in the TG than WT group of nondiabetic hearts, whereas the transgene had no effect in the diabetic group. Similarly, the transgene also improved reperfusion systolic and diastolic function in nondiabetic but not in diabetic hearts. NOS inhibition worsened reperfusion function in diabetic hearts. Postischemic nitrite and cGMP formation were higher in nondiabetic TG than WT hearts, but in diabetic hearts cGMP was no longer elevated. The formation of reactive oxygen species (superoxide and peroxynitrite) during early reperfusion, measured by electron spin resonance spectroscopy, was similar in nondiabetic WT and TG hearts, but it was significantly higher in diabetic TG hearts. Stimulating endogenous NO production with 10 microM bradykinin more strongly reduced myocardial O(2) consumption in diabetic TG than diabetic WT hearts perfused in normoxia, whereas there was no difference after ischemia-reperfusion. Thus, providing additional endogenous NO is sufficient to protect nondiabetic hearts against ischemia-induced injury, but for a similar protection in diabetic hearts, effective scavenging of reactive oxygen species is also important.
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Affiliation(s)
- Beatriz Pozo-Navas
- Department of Pharmacology and Toxicology, Universität Graz, Universitätsplatz 2, A-8010 Graz, Austria
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