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Lee TI, Kao YH, Chen YC, Huang JH, Hsiao FC, Chen YJ. Peroxisome proliferator-activated receptors modulate cardiac dysfunction in diabetic cardiomyopathy. Diabetes Res Clin Pract 2013; 100:330-9. [PMID: 23369225 DOI: 10.1016/j.diabres.2013.01.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Revised: 10/23/2012] [Accepted: 01/03/2013] [Indexed: 02/08/2023]
Abstract
Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM). Chronic inflammation and derangement of myocardial energy and lipid homeostasis are common features of DM. The transcription factors of peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily, which are important in regulating energy and lipid homeostasis. There are three PPAR isoforms, α, γ, and δ, and their roles have been increasingly recognized to be important in CVD. These three isoforms are expressed in the heart and play pivotal roles in myocardial lipid metabolism, as well as glucose and energy homeostasis, and contribute to extra metabolic roles with effects on inflammation and oxidative stress. Moreover, regulation of PPARs may have significant effects on cardiac electrical activity and arrhythmogenesis. This review describes the roles of PPARs and their agonists in DM cardiomyopathy, inflammation, and cardiac electrophysiology.
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Affiliation(s)
- T-I Lee
- Department of General Medicine, College of Medicine, Taipei Medical University, Taiwan
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102
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Noda K, Hosoya M, Nakajima S, Ohashi J, Fukumoto Y, Shimokawa H. Anti-atherogenic effects of the combination therapy with olmesartan and azelnidipine in diabetic apolipoprotein E-deficient mice. TOHOKU J EXP MED 2013; 228:305-15. [PMID: 23124103 DOI: 10.1620/tjem.228.305] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many studies have aimed to identify anti-atherogenic agents in cardiovascular medicine. We have recently demonstrated that the combination therapy with olmesartan (OLM), an angiotensin II receptor blocker, and azelnidipine (AZL), a dihydroprydine calcium-channel blocker, improves endothelial function in diabetic Apolipoprotein-deficient (ApoE(-/-)) mice. In the present study, we examined whether this combination therapy also inhibits atherosclerosis in mice. We used male control and streptozocin-induced diabetic ApoE(-/-) mice. Diabetic ApoE(-/-) mice were orally treated for 5 weeks with vehicle (Untreated), OLM (30 mg/kg/day), AZL (10 mg/kg/day), their combination (OLM+AZL), or hydralazine (HYD, 5 mg/kg/day) as an antihypertensive control. At 5 weeks, systolic blood pressure was significantly elevated in Untreated but was normalized in OLM+AZL and HYD. The atherosclerosis area in the thoracic aorta, perivascular fibrosis and medial thickness of the coronary arteries were increased in Untreated and were ameliorated in OLM+AZL but not in HYD. Staining with a fluorescent probe dihydroethidium showed that production of reactive oxygen species was increased in Untreated, and ameliorated in OLM+AZL. Consistent with these findings, macrophage infiltration in the kidney and the expression of receptor for advanced glycation end-products in the heart, kidney and liver were increased in Untreated and were all ameliorated in OLM+AZL, associated with up-regulation of endothelial NO syntheses (eNOS). In conclusion, the combination therapy with OLM and AZL exerts anti-atherogenic effect in diabetic ApoE(-/-) mice through suppression of oxidative stress and activation of eNOS, independent of its blood pressure-lowering effects. Clinically, this combination therapy may be useful for patients with hypertension, hyperlipidemia and diabetes.
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Affiliation(s)
- Kazuki Noda
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
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103
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van den Brom CE, Bulte CS, Loer SA, Bouwman RA, Boer C. Diabetes, perioperative ischaemia and volatile anaesthetics: consequences of derangements in myocardial substrate metabolism. Cardiovasc Diabetol 2013; 12:42. [PMID: 23452502 PMCID: PMC3599199 DOI: 10.1186/1475-2840-12-42] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 02/21/2013] [Indexed: 12/18/2022] Open
Abstract
Volatile anaesthetics exert protective effects on the heart against perioperative ischaemic injury. However, there is growing evidence that these cardioprotective properties are reduced in case of type 2 diabetes mellitus. A strong predictor of postoperative cardiac function is myocardial substrate metabolism. In the type 2 diabetic heart, substrate metabolism is shifted from glucose utilisation to fatty acid oxidation, resulting in metabolic inflexibility and cardiac dysfunction. The ischaemic heart also loses its metabolic flexibility and can switch to glucose or fatty acid oxidation as its preferential state, which may deteriorate cardiac function even further in case of type 2 diabetes mellitus.Recent experimental studies suggest that the cardioprotective properties of volatile anaesthetics partly rely on changing myocardial substrate metabolism. Interventions that target at restoration of metabolic derangements, like lifestyle and pharmacological interventions, may therefore be an interesting candidate to reduce perioperative complications. This review will focus on the current knowledge regarding myocardial substrate metabolism during volatile anaesthesia in the obese and type 2 diabetic heart during perioperative ischaemia.
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Affiliation(s)
- Charissa E van den Brom
- Department of Anesthesiology, Experimental Laboratory for VItal Signs, VU University Medical Center, De Boelelaan 1117, Amsterdam, the Netherlands.
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104
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Ilkun O, Boudina S. Cardiac dysfunction and oxidative stress in the metabolic syndrome: an update on antioxidant therapies. Curr Pharm Des 2013; 19:4806-17. [PMID: 23323621 DOI: 10.2174/1381612811319270003] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 01/10/2013] [Indexed: 01/14/2023]
Abstract
The metabolic syndrome (MetS) is a cluster of risk factors including obesity, insulin resistance, dyslipidemia, elevated blood pressure and glucose intolerance. The MetS increases the risk for cardiovascular disease (CVD) and type 2 diabetes. Each component of the MetS causes cardiac dysfunction and their combination carries additional risk. The mechanisms underlying cardiac dysfunction in the MetS are complex and might include lipid accumulation, increased fibrosis and stiffness, altered calcium homeostasis, abnormal autophagy, altered substrate utilization, mitochondrial dysfunction and increased oxidative stress. Mitochondrial and extra-mitochondrial sources of reactive oxygen species (ROS) and reduced antioxidant defense mechanisms characterize the myocardium of humans and animals with the MetS. The mechanisms for increased cardiac oxidative stress in the MetS are not fully understood but include increased fatty acid oxidation, mitochondrial dysfunction and enhanced NADPH oxidase activity. Therapies aimed to reduce oxidative stress and enhance antioxidant defense have been employed to reduce cardiac dysfunction in the MetS in animals. In contrast, large scale clinical trials using antioxidants therapies for the treatment of CVD have been disappointing because of the lack of efficacy and undesired side effects. The focus of this review is to summarize the current knowledge about the mechanisms underlying cardiac dysfunction in the MetS with a special interest in the role of oxidative stress. Finally, we will update the reader on the results obtained with natural antioxidant and mitochondria-targeted antioxidant therapies for the treatment of CVD in the MetS.
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Affiliation(s)
- Olesya Ilkun
- Division of Endocrinology, Metabolism and Diabetes, Program in Human Molecular Biology & Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
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105
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Boudina S, Han YH, Pei S, Tidwell TJ, Henrie B, Tuinei J, Olsen C, Sena S, Abel ED. UCP3 regulates cardiac efficiency and mitochondrial coupling in high fat-fed mice but not in leptin-deficient mice. Diabetes 2012; 61:3260-9. [PMID: 22912419 PMCID: PMC3501860 DOI: 10.2337/db12-0063] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
These studies investigate the role of uncoupling protein 3 (UCP3) in cardiac energy metabolism, cardiac O(2) consumption (MVO(2)), cardiac efficiency (CE), and mitochondrial uncoupling in high fat (HF)-fed or leptin-deficient mice. UCP3KO and wild-type (WT) mice were fed normal chow or HF diets for 10 weeks. Substrate utilization rates, MVO(2), CE, and mitochondrial uncoupling were measured in perfused working hearts and saponin-permeabilized cardiac fibers, respectively. Similar analyses were performed in hearts of ob/ob mice lacking UCP3 (U3OB mice). HF increased cardiac UCP3 protein. However, fatty acid (FA) oxidation rates were similarly increased by HF diet in WT and UCP3KO mice. By contrast, MVO(2) increased in WT, but not in UCP3KO with HF, leading to increased CE in UCP3KO mice. Consistent with increased CE, mitochondrial coupling was increased in the hearts of HF-fed UCP3KO mice. Unexpectedly, UCP3 deletion in ob/ob mice reduced FA oxidation but had no effect on MVO(2) or CE. In addition, FA-induced mitochondrial uncoupling was similarly enhanced in U3OB compared with ob/ob hearts and was associated with elevated mitochondrial thioesterase-1 protein content. These studies show that although UCP3 may mediate mitochondrial uncoupling and reduced CE after HF feeding, it does not mediate uncoupling in leptin-deficient states.
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Affiliation(s)
- Sihem Boudina
- Division of Endocrinology, Metabolism, and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA.
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Yang S, Chen C, Wang H, Rao X, Wang F, Duan Q, Chen F, Long G, Gong W, Zou MH, Wang DW. Protective effects of Acyl-coA thioesterase 1 on diabetic heart via PPARα/PGC1α signaling. PLoS One 2012; 7:e50376. [PMID: 23226270 PMCID: PMC3511550 DOI: 10.1371/journal.pone.0050376] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/19/2012] [Indexed: 12/16/2022] Open
Abstract
Background Using fatty acids (FAs) exclusively for ATP generation was reported to contribute to the development of diabetic cardiomyopathy. We studied the role of substrate metabolism related genes in the heart of the diabetes to find out a novel therapeutic target for diabetic cardiomyopathy. Methods and Results By microarray analysis of metabolic gene expression, acyl-CoA thioesterase 1 (acot1) was clearly upregulated in the myocardia of db/db mice, compared with normal control C57BL/Ks. Therefore, gain-of-function and loss-of-function approaches were employed in db/db mice to investigate the functions of ACOT1 in oxidative stress, mitochondrial dysfunction and heart function. We found that in the hearts of db/db mice which overexpressed ACOT1, H2O2 and malondialdehyde (MDA) were reduced, the activities of ATPases in mitochondria associated with mitochondrial function were promoted, the expression of uncoupling protein 3 (UCP3) contributing to oxygen wastage for noncontractile purposes was decreased, and cardiac dysfunction was attenuated, as determined by both hemodynamic and echocardiographic detections. Consistently, ACOT1 deficiency had opposite effects, which accelerated the cardiac damage induced by diabetes. Notably, by real-time PCR, we found that overexpression of ACOT1 in diabetic heart repressed the peroxisome proliferator-activated receptor alpha/PPARγ coactivator 1α (PPARα/PGC1α) signaling, as shown by decreased expression of PGC1α and the downstream genes involved in FAs use. Conclusion Our results demonstrated that ACOT1 played a crucial protective role in diabetic heart via PPARα/PGC1α signaling.
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Affiliation(s)
- Shenglan Yang
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Chen Chen
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Hong Wang
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Xiaoquan Rao
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Feng Wang
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Quanlu Duan
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Fuqiong Chen
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Guangwen Long
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Wei Gong
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
| | - Ming-Hui Zou
- Department of Medicine and Endocrinology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma, United States of America
| | - Dao Wen Wang
- Department of Internal Medicine and Gene Therapy Center, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, P. R. China
- * E-mail:
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107
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Han JC, Tran K, Taberner AJ, Nickerson DP, Kirton RS, Nielsen PMF, Ward ML, Nash MP, Crampin EJ, Loiselle DS. Myocardial twitch duration and the dependence of oxygen consumption on pressure-volume area: experiments and modelling. J Physiol 2012; 590:4603-22. [PMID: 22570375 PMCID: PMC3477760 DOI: 10.1113/jphysiol.2012.228965] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 05/02/2012] [Indexed: 11/08/2022] Open
Abstract
We tested the proposition that linear length dependence of twitch duration underlies the well-characterised linear dependence of oxygen consumption (V(O(2)) ) on pressure–volume area (PVA) in the heart. By way of experimental simplification, we reduced the problem from three dimensions to one by substituting cardiac trabeculae for the classically investigated whole-heart. This allowed adoption of stress–length area (SLA) as a surrogate for PVA, and heat as a proxy for V(O(2)) . Heat and stress (force per cross-sectional area), at a range of muscle lengths and at both 1 mM and 2 mM [Ca(2+)](o), were recorded from continuously superfused rat right-ventricular trabeculae undergoing fixed-end contractions. The heat–SLA relations of trabeculae (reported here, for the first time) are linear. Twitch duration increases monotonically (but not strictly linearly) with muscle length. We probed the cellular mechanisms of this phenomenon by determining: (i) the length dependence of the duration of the Ca(2+) transient, (ii) the length dependence of the rate of force redevelopment following a length impulse (an index of Ca(2+) binding to troponin-C), (iii) the effect on the simulated time course of the twitch of progressive deletion of length and Ca(2+)-dependent mechanisms of crossbridge cooperativity, using a detailed mathematical model of the crossbridge cycle, and (iv) the conditions required to achieve these multiple length dependencies, using a greatly simplified model of twitch mechano-energetics. From the results of these four independent investigations, we infer that the linearity of the heat–SLA relation (and, by analogy, the V(O(2))–PVA relation) is remarkably robust in the face of departures from linearity of length-dependent twitch duration.
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Affiliation(s)
- J-C Han
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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108
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Reil JC, Hohl M, Reil GH, Granzier HL, Kratz MT, Kazakov A, Fries P, Müller A, Lenski M, Custodis F, Gräber S, Fröhlig G, Steendijk P, Neuberger HR, Böhm M. Heart rate reduction by If-inhibition improves vascular stiffness and left ventricular systolic and diastolic function in a mouse model of heart failure with preserved ejection fraction. Eur Heart J 2012; 34:2839-49. [PMID: 22833515 DOI: 10.1093/eurheartj/ehs218] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIMS In diabetes mellitus, heart failure with preserved ejection fraction (HFPEF) is a significant comorbidity. No therapy is available that improves cardiovascular outcomes. The aim of this study was to characterize myocardial function and ventricular-arterial coupling in a mouse model of diabetes and to analyse the effect of selective heart rate (HR) reduction by If-inhibition in this HFPEF-model. METHODS AND RESULTS Control mice, diabetic mice (db/db), and db/db mice treated for 4 weeks with the If-inhibitor ivabradine (db/db-Iva) were compared. Aortic distensibility was measured by magnetic resonance imaging. Left ventricular (LV) pressure-volume analysis was performed in isolated working hearts, with biochemical and histological characterization of the cardiac and aortic phenotype. In db/db aortic stiffness and fibrosis were significantly enhanced compared with controls and were prevented by HR reduction in db/db-Iva. Left ventricular end-systolic elastance (Ees) was increased in db/db compared with controls (6.0 ± 1.3 vs. 3.4 ± 1.2 mmHg/µL, P < 0.01), whereas other contractility markers were reduced. Heart rate reduction in db/db-Iva lowered Ees (4.0 ± 1.1 mmHg/µL, P < 0.01), and improved the other contractility parameters. In db/db active relaxation was prolonged and end-diastolic capacitance was lower compared with controls (28 ± 3 vs. 48 ± 8 μL, P < 0.01). These parameters were ameliorated by HR reduction. Neither myocardial fibrosis nor hypertrophy were detected in db/db, whereas titin N2B expression was increased and phosphorylation of phospholamban was reduced both being prevented by HR reduction in db/db-Iva. CONCLUSION In db/db, a model of HFPEF, selective HR reduction by If-inhibition improved vascular stiffness, LV contractility, and diastolic function. Therefore, If-inhibition might be a therapeutic concept for HFPEF, if confirmed in humans.
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Affiliation(s)
- Jan-Christian Reil
- Klinik für Innere Medizin III, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes, Kirrberger Straße D 66421, Homburg/Saar, Germany
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109
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Persson MF, Franzén S, Catrina SB, Dallner G, Hansell P, Brismar K, Palm F. Coenzyme Q10 prevents GDP-sensitive mitochondrial uncoupling, glomerular hyperfiltration and proteinuria in kidneys from db/db mice as a model of type 2 diabetes. Diabetologia 2012; 55:1535-43. [PMID: 22311417 DOI: 10.1007/s00125-012-2469-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/29/2011] [Indexed: 01/16/2023]
Abstract
AIMS/HYPOTHESIS Increased oxygen consumption results in kidney tissue hypoxia, which is proposed to contribute to the development of diabetic nephropathy. Oxidative stress causes increased oxygen consumption in type 1 diabetic kidneys, partly mediated by uncoupling protein-2 (UCP-2)-induced mitochondrial uncoupling. The present study investigates the role of UCP-2 and oxidative stress in mitochondrial oxygen consumption and kidney function in db/db mice as a model of type 2 diabetes. METHODS Mitochondrial oxygen consumption, glomerular filtration rate and proteinuria were investigated in db/db mice and corresponding controls with and without coenzyme Q10 (CoQ10) treatment. RESULTS Untreated db/db mice displayed mitochondrial uncoupling, manifested as glutamate-stimulated oxygen consumption (2.7 ± 0.1 vs 0.2 ± 0.1 pmol O(2) s(-1) [mg protein](-1)), glomerular hyperfiltration (502 ± 26 vs 385 ± 3 μl/min), increased proteinuria (21 ± 2 vs 14 ± 1, μg/24 h), mitochondrial fragmentation (fragmentation score 2.4 ± 0.3 vs 0.7 ± 0.1) and size (1.6 ± 0.1 vs 1 ± 0.0 μm) compared with untreated controls. All alterations were prevented or reduced by CoQ10 treatment. Mitochondrial uncoupling was partly inhibited by the UCP inhibitor GDP (-1.1 ± 0.1 pmol O(2) s(-1) [mg protein](-1)). UCP-2 protein levels were similar in untreated control and db/db mice (67 ± 9 vs 67 ± 4 optical density; OD) but were reduced in CoQ10 treated groups (43 ± 2 and 38 ± 7 OD). CONCLUSIONS/INTERPRETATION db/db mice displayed oxidative stress-mediated activation of UCP-2, which resulted in mitochondrial uncoupling and increased oxygen consumption. CoQ10 prevented altered mitochondrial function and morphology, glomerular hyperfiltration and proteinuria in db/db mice, highlighting the role of mitochondria in the pathogenesis of diabetic nephropathy and the benefits of preventing increased oxidative stress.
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Affiliation(s)
- M Friederich Persson
- Department of Medical Cell Biology, Biomedical Center, Husargatan 3, Box 571, 751 23 Uppsala, Sweden.
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Sethumadhavan S, Vasquez-Vivar J, Migrino RQ, Harmann L, Jacob HJ, Lazar J. Mitochondrial DNA variant for complex I reveals a role in diabetic cardiac remodeling. J Biol Chem 2012; 287:22174-82. [PMID: 22544750 DOI: 10.1074/jbc.m111.327866] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Myocardial remodeling and dysfunction are serious complications of type 2 diabetes mellitus (T2DM). Factors controlling their development are not well established. To specifically address the role of the mitochondrial genome, we developed novel conplastic rat strains, i.e. strains with the same nuclear genome but a different mitochondrial genome. The new animals were named T2DN(mtFHH) and T2DN(mtWistar), where the acronym T2DN denotes their common nuclear genome (type 2 diabetic nephropathy (T2DN) rats) and mtFHH or mtWistar the origin of their mitochondria, Fawn Hooded Hypertensive (FHH) or Wistar rats, respectively. The T2DN(mtFHH) and T2DN(mtWistar) showed a similar progression of diabetes as determined by HbA1c, cholesterol, and triglycerides with normal blood pressure, thus enabling investigation of the specific role of the mitochondrial genome in cardiac function without the confounding effects of obesity or hypertension found in other models of diabetes. Echocardiographic analysis of 12-week-old animals showed no abnormalities, but at 12 months of age the T2DN(mtFHH) showed left ventricular remodeling that was verified by histology. Decreased complex I and complex IV but not complex II activity within the electron transport chain was found only in T2DN(mtFHH), which was not explained by differences in protein content. Decreased cardiac ATP levels in T2DN(mtFHH) were in agreement with a lower ATP synthetic capacity by isolated mitochondria. Together, our data provide experimental evidence that mtDNA sequence variations have an additional role in energetic heart deficiency. The mitochondrial DNA background may explain the increased susceptibility of certain T2DM patients to develop myocardial dysfunction.
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Affiliation(s)
- Savitha Sethumadhavan
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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111
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Pellieux C, Montessuit C, Papageorgiou I, Pedrazzini T, Lerch R. Differential effects of high-fat diet on myocardial lipid metabolism in failing and nonfailing hearts with angiotensin II-mediated cardiac remodeling in mice. Am J Physiol Heart Circ Physiol 2012; 302:H1795-805. [PMID: 22408021 DOI: 10.1152/ajpheart.01023.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Normal myocardium adapts to increase of nutritional fatty acid supply by upregulation of regulatory proteins of the fatty acid oxidation pathway. Because advanced heart failure is associated with reduction of regulatory proteins of fatty acid oxidation, we hypothesized that failing myocardium may not be able to adapt to increased fatty acid intake and therefore undergo lipid accumulation, potentially aggravating myocardial dysfunction. We determined the effect of high-fat diet in transgenic mice with overexpression of angiotensinogen in the myocardium (TG1306/R1). TG1306/R1 mice develop ANG II-mediated left ventricular hypertrophy, and at one year of age approximately half of the mice present heart failure associated with reduced expression of regulatory proteins of fatty acid oxidation and reduced palmitate oxidation during ex vivo working heart perfusion. Hypertrophied hearts from TG1306/R1 mice without heart failure adapted to high-fat feeding, similarly to hearts from wild-type mice, with upregulation of regulatory proteins of fatty acid oxidation and enhancement of palmitate oxidation. There was no myocardial lipid accumulation or contractile dysfunction. In contrast, hearts from TG1306/R1 mice presenting heart failure were unable to respond to high-fat feeding by upregulation of fatty acid oxidation proteins and enhancement of palmitate oxidation. This resulted in accumulation of triglycerides and ceramide in the myocardium, and aggravation of contractile dysfunction. In conclusion, hearts with ANG II-induced contractile failure have lost the ability to enhance fatty acid oxidation in response to increased fatty acid supply. The ensuing accumulation of lipid compounds may play a role in the observed aggravation of contractile dysfunction.
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Affiliation(s)
- Corinne Pellieux
- Cardiology Center, Department of Medicine and Foundation for Medical Research, University Hospitals of Geneva, Geneva.
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112
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von Bibra H, St John Sutton M. Impact of diabetes on postinfarction heart failure and left ventricular remodeling. Curr Heart Fail Rep 2012; 8:242-51. [PMID: 21842146 PMCID: PMC3208100 DOI: 10.1007/s11897-011-0070-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Diabetes mellitus, the metabolic syndrome, and the underlying insulin resistance are increasingly associated with diastolic dysfunction and reduced stress tolerance. The poor prognosis associated with heart failure in patients with diabetes after myocardial infarction is likely attributable to many factors, important among which is the metabolic impact from insulin resistance and hyperglycemia on the regulation of microvascular perfusion and energy generation in the cardiac myocyte. This review summarizes epidemiologic, pathophysiologic, diagnostic, and therapeutic data related to diabetes and heart failure in acute myocardial infarction and discusses novel perceptions and strategies that hold promise for the future and deserve further investigation.
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Affiliation(s)
- Helene von Bibra
- Klinic for Endocrinology, Diabetes and Vascular Medicine, Klinikum Bogenhausen, Städtische Klinikum München GmbH, Englschalkingerstrasse 77, 81925, München, Germany.
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113
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Bugger H, Riehle C, Jaishy B, Wende AR, Tuinei J, Chen D, Soto J, Pires KM, Boudina S, Theobald HA, Luptak I, Wayment B, Wang X, Litwin SE, Weimer BC, Abel ED. Genetic loss of insulin receptors worsens cardiac efficiency in diabetes. J Mol Cell Cardiol 2012; 52:1019-26. [PMID: 22342406 DOI: 10.1016/j.yjmcc.2012.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 01/31/2012] [Accepted: 02/01/2012] [Indexed: 01/07/2023]
Abstract
AIMS To determine the contribution of insulin signaling versus systemic metabolism to metabolic and mitochondrial alterations in type 1 diabetic hearts and test the hypothesis that antecedent mitochondrial dysfunction contributes to impaired cardiac efficiency (CE) in diabetes. METHODS AND RESULTS Control mice (WT) and mice with cardiomyocyte-restricted deletion of insulin receptors (CIRKO) were rendered diabetic with streptozotocin (WT-STZ and CIRKO-STZ, respectively), non-diabetic controls received vehicle (citrate buffer). Cardiac function was determined by echocardiography; myocardial metabolism, oxygen consumption (MVO(2)) and CE were determined in isolated perfused hearts; mitochondrial function was determined in permeabilized cardiac fibers and mitochondrial proteomics by liquid chromatography mass spectrometry. Pyruvate supported respiration and ATP synthesis were equivalently reduced by diabetes and genotype, with synergistic impairment in ATP synthesis in CIRKO-STZ. In contrast, fatty acid delivery and utilization was increased by diabetes irrespective of genotype, but not in non-diabetic CIRKO. Diabetes and genotype synergistically increased MVO(2) in CIRKO-STZ, leading to reduced CE. Irrespective of diabetes, genotype impaired ATP/O ratios in mitochondria exposed to palmitoyl carnitine, consistent with mitochondrial uncoupling. Proteomics revealed reduced content of fatty acid oxidation proteins in CIRKO mitochondria, which were induced by diabetes, whereas tricarboxylic acid cycle and oxidative phosphorylation proteins were reduced both in CIRKO mitochondria and by diabetes. CONCLUSIONS Deficient insulin signaling and diabetes mediate distinct effects on cardiac mitochondria. Antecedent loss of insulin signaling markedly impairs CE when diabetes is induced, via mechanisms that may be secondary to mitochondrial uncoupling and increased FA utilization.
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Affiliation(s)
- Heiko Bugger
- Division of Endocrinology, Metabolism and Diabetes, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
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Belke DD, Severson DL. Diabetes in mice with monogenic obesity: the db/db mouse and its use in the study of cardiac consequences. Methods Mol Biol 2012; 933:47-57. [PMID: 22893400 DOI: 10.1007/978-1-62703-068-7_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The leptin receptor deficient db/db mouse has served as a rodent model for obesity and type 2 diabetes for more than 40 years. Diabetic features in db/db mice follow an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. Diabetic db/db mice have been utilized to assess the cardiac consequences of diabetes, specifically evidence for a distinct diabetic cardiomyopathy. The db/db model is characterized by a contractile function deficit in the heart which becomes manifest 8-10 weeks after birth. Metabolic changes include an increased reliance on fatty acids and a decreased reliance on glucose as a fuel source for oxidative metabolism within the heart. As a mouse model for type 2 diabetes, both drug treatment and transgenic manipulation have proven beneficial towards improving metabolism and contractile function. The db/db mouse model has provided a useful resource to understand and treat the type 2 diabetic condition.
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Abstract
The main role of insulin in the heart under physiological conditions is obviously the regulation of substrate utilization. Indeed, insulin promotes glucose uptake and its utilization via glycolysis. Insulin, promoting glucose as the main cardiac energy substrate, reduces myocardial O(2) consumption and increases cardiac efficiency. Moreover, insulin seems to augment cardiomyocyte contraction, while it affects favorably myocardial relaxation, increases ribosomal biogenesis and protein synthesis, stimulates vascular endothelial growth factor (VEGF) and thereby angiogenesis, suppresses apoptosis, promotes cell survival and finally ameliorates both myocardial microcirculation and coronary artery resistance, leading to increased blood perfusion of myocardium. Thus, insulin acts directly on heart muscle, and this action is mediated principally through PKB/Akt signal pathway. Under pathological conditions, such as type 2 diabetes, myocardial ischaemia, and cardiac hypertrophy, insulin signal transduction pathways and action are clearly modified. In this review we summarize the evidence that the heart is an important target of insulin action and that elimination of these actions is important in disease states.
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Affiliation(s)
- Fotios Iliadis
- Diabetes Division, 1st Propedeutic Department of Internal Medicine, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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van de Weijer T, Schrauwen-Hinderling VB, Schrauwen P. Lipotoxicity in type 2 diabetic cardiomyopathy. Cardiovasc Res 2011; 92:10-8. [PMID: 21803867 DOI: 10.1093/cvr/cvr212] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
As obesity and type 2 diabetes are becoming an epidemic in westernized countries, the incidence and prevalence of obesity- and diabetes-related co-morbidities are increasing. In type 2 diabetes ectopic lipid accumulation in the heart has been associated with cardiac dysfunction and apoptosis, a process termed lipotoxicity. Since cardiovascular diseases are the main cause of death in diabetic patients, diagnosis and treatment become increasingly important. Although ischaemic heart disease is a major problem in diabetes, non-ischaemic heart disease (better known as diabetic cardiomyopathy) becomes increasingly important with respect to the impairment of cardiac function and mortality in type 2 diabetes. The underlying aetiology of diabetic cardiomyopathy is incompletely understood but is beginning to be elucidated. Various mechanisms have been proposed that may lead to lipotoxicity. Therefore, this review will focus on the mechanisms of cardiac lipid accumulation and its relation to the development of cardiomyopathy.
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Affiliation(s)
- Tineke van de Weijer
- Department of Human Biology, Maastricht University Medical Centre, PO Box 616, 6200 MD Maastricht, The Netherlands
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Khalid AM, Hafstad AD, Larsen TS, Severson DL, Boardman N, Hagve M, Berge RK, Aasum E. Cardioprotective effect of the PPAR ligand tetradecylthioacetic acid in type 2 diabetic mice. Am J Physiol Heart Circ Physiol 2011; 300:H2116-22. [DOI: 10.1152/ajpheart.00357.2010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Tetradecylthioacetic acid (TTA) is a novel peroxisome proliferator-activated receptor (PPAR) ligand with marked hypolipidemic and insulin-sensitizing effects in obese models. TTA has recently been shown to attenuate dyslipidemia in patients with type 2 diabetes, corroborating the potential for TTA in antidiabetic therapy. In a recent study on normal mice, we showed that TTA increased myocardial fatty acid (FA) oxidation, which was associated with decreased cardiac efficiency and impaired postischemic functional recovery. The aim of the present study was, therefore, to elucidate the effects of TTA treatment (0.5%, 8 days) on cardiac metabolism and function in a hyperlipidemic type 2 diabetic model. We found that TTA treatment increased myocardial FA oxidation, not only in nondiabetic ( db/+) mice but also in diabetic ( db/db) mice, despite a clear lipid-lowering effect. Although TTA had deleterious effects in hearts from nondiabetic mice (decreased efficiency and impaired mitochondrial respiratory capacity), these effects were not observed in db/db hearts. In db/db hearts, TTA improved ischemic tolerance, an effect that is most likely related to the antioxidant property of TTA. The present study strongly advocates the need for investigation of the cardiac effects of PPAR ligands used in antidiabetic/hypolipidemic therapy, because of their pleiotropic properties.
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Affiliation(s)
- Ahmed M. Khalid
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
| | - Anne Dragøy Hafstad
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
| | - Terje S. Larsen
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
| | - David L. Severson
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Neoma Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
| | - Martin Hagve
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
| | - Rolf K. Berge
- The Lipid Research Group, Institute of Medicine, University of Bergen, Norway; and
| | - Ellen Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø
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McGill JB, Peterson LR, Herrero P, Saeed IM, Recklein C, Coggan AR, DeMoss AJ, Schechtman KB, Dence CS, Gropler RJ. Potentiation of abnormalities in myocardial metabolism with the development of diabetes in women with obesity and insulin resistance. J Nucl Cardiol 2011; 18:421-9; quiz 432-3. [PMID: 21516378 PMCID: PMC3811030 DOI: 10.1007/s12350-011-9362-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 02/16/2011] [Indexed: 01/22/2023]
Abstract
BACKGROUND Because studies in animal models of type-2 diabetes mellitus (DM) show that excessive myocardial fatty acid (FA) metabolism (at the expense of glucose metabolism) cause cardiac dysfunction, we hypothesized that women with DM would have more FA and less glucose myocardial metabolism than normal or even obese (OB) women. RESEARCH DESIGN AND METHODS Women who were lean volunteers (NV) (N = 14; age 35 ± 17 years, body mass index 23 ± 1 kg/m(2)), OB (N = 28;31 ± 6 years, BMI 39 ± 7 kg/m2), and DM (n = 22; 54 ± 11 years, BMI 38 ± 5 kg/m2) were studied. Cardiac positron emission tomography was performed for the determination of myocardial blood flow, oxygen consumption, FA and glucose metabolism. Cardiac work was measured by echocardiography and efficiency by the ratio of work to myocardial oxygen consumption. RESULTS Fractional glucose uptake was comparable between NV and OB but lower in DM (P < .05 versus NV). Myocardial FA utilization and oxidation were both higher in DM compared with NV and OB (P < .0001). Myocardial FA utilization and oxidation had positive correlations with HOMA (R = 0.35, P = .005 and R = 0.40, P = .001, respectively) whereas fractional glucose uptake exhibited an inverse correlation (R = -.31, P = .01). Cardiac work and efficiency were similar among the three groups. CONCLUSIONS In women, the presence of OB and DM compared with OB alone is associated with a greater reliance on myocardial FA metabolism at the expense of glucose metabolism. These perturbations in myocardial metabolism are not associated in a decline left ventricular efficiency or function suggesting that the metabolic perturbations may precede an eventual decline left ventricular function as is seen in animal models of DM.
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Affiliation(s)
- Janet B. McGill
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Linda R. Peterson
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Pilar Herrero
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Ibrahim M. Saeed
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Carol Recklein
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Andrew R. Coggan
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Amanda J. DeMoss
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | | | - Carmen S. Dence
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
| | - Robert J. Gropler
- Division of Cardiovascular Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Division of Radiological Sciences, Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
- Cardiovascular Imaging Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO
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Boardman NT, Larsen TS, Severson DL, Essop MF, Aasum E. Chronic and acute exposure of mouse hearts to fatty acids increases oxygen cost of excitation-contraction coupling. Am J Physiol Heart Circ Physiol 2011; 300:H1631-6. [DOI: 10.1152/ajpheart.01190.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of the present study was to evaluate the underlying processes involved in the oxygen wasting induced by inotropic drugs and acute and chronic elevation of fatty acid (FA) supply, using unloaded perfused mouse hearts from normal and type 2 diabetic ( db/db) mice. We found that an acute elevation of the FA supply in normal hearts, as well as a chronic (in vivo) exposure to elevated FA as in db/db hearts, increased myocardial oxygen consumption (MV̇o2unloaded) due to increased oxygen cost for basal metabolism and for excitation-contraction (EC) coupling. Isoproterenol stimulation, on top of a high FA supply, led to an additive increase in MV̇o2unloaded, because of a further increase in oxygen cost for EC coupling. In db/db hearts, the acute elevation of FA did not further increase MV̇o2. Since the elevation in the FA supply is accompanied by increased rates of myocardial FA oxidation, the present study compared MV̇o2 following increased FA load versus FA oxidation rate by exposing normal hearts to normal and high FA concentration (NF and HF, respectively) and to compounds that either stimulate (GW-610742) or inhibit [dichloroacetate (DCA)] FA oxidation. While HF and NF + GW-610742 increased FA oxidation to the same extent, only HF increased MV̇o2unloaded. Although DCA counteracted the HF-induced increase in FA oxidation, DCA did not reduce MV̇o2unloaded. Thus, in normal hearts, acute FA-induced oxygen waste is 1) due to an increase in the oxygen cost for both basal metabolism and EC coupling and 2) not dependent on the myocardial FA oxidation rate per se, but on processes initiated by the presence of FAs. In diabetic hearts, chronic exposure to elevated circulating FAs leads to adaptations that afford protection against the detrimental effect of an acute FA load, suggesting different underlying mechanisms behind the increased MV̇o2 following acute and chronic FA load.
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Affiliation(s)
- Neoma T. Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Terje S. Larsen
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - David L. Severson
- Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Canada; and
| | - M. Faadiel Essop
- Cardio-Metabolic Research Group, Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Ellen Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
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120
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Myocardial Oxygenation Imaging: New Methods for Ischemia Detection. CURRENT CARDIOVASCULAR IMAGING REPORTS 2011. [DOI: 10.1007/s12410-010-9063-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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121
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Cole MA, Murray AJ, Cochlin LE, Heather LC, McAleese S, Knight NS, Sutton E, Jamil AA, Parassol N, Clarke K. A high fat diet increases mitochondrial fatty acid oxidation and uncoupling to decrease efficiency in rat heart. Basic Res Cardiol 2011; 106:447-57. [PMID: 21318295 PMCID: PMC3071466 DOI: 10.1007/s00395-011-0156-1] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/12/2010] [Accepted: 12/23/2010] [Indexed: 12/03/2022]
Abstract
Elevated levels of cardiac mitochondrial uncoupling protein 3 (UCP3) and decreased cardiac efficiency (hydraulic power/oxygen consumption) with abnormal cardiac function occur in obese, diabetic mice. To determine whether cardiac mitochondrial uncoupling occurs in non-genetic obesity, we fed rats a high fat diet (55% kcal from fat) or standard laboratory chow (7% kcal from fat) for 3 weeks, after which we measured cardiac function in vivo using cine MRI, efficiency in isolated working hearts and respiration rates and ADP/O ratios in isolated interfibrillar mitochondria; also, measured were medium chain acyl-CoA dehydrogenase (MCAD) and citrate synthase activities plus uncoupling protein 3 (UCP3), mitochondrial thioesterase 1 (MTE-1), adenine nucleotide translocase (ANT) and ATP synthase protein levels. We found that in vivo cardiac function was the same for all rats, yet oxygen consumption was 19% higher in high fat-fed rat hearts, therefore, efficiency was 21% lower than in controls. We found that mitochondrial fatty acid oxidation rates were 25% higher, and MCAD activity was 23% higher, in hearts from rats fed the high fat diet when compared with controls. Mitochondria from high fat-fed rat hearts had lower ADP/O ratios than controls, indicating increased respiratory uncoupling, which was ameliorated by GDP, a UCP3 inhibitor. Mitochondrial UCP3 and MTE-1 levels were both increased by 20% in high fat-fed rat hearts when compared with controls, with no significant change in ATP synthase or ANT levels, or citrate synthase activity. We conclude that increased cardiac oxygen utilisation, and thereby decreased cardiac efficiency, occurs in non-genetic obesity, which is associated with increased mitochondrial uncoupling due to elevated UCP3 and MTE-1 levels.
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Affiliation(s)
- Mark A Cole
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
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122
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Dunn ME, Manfredi TG, Cosmas AC, Vetter FJ, King JN, Rodgers RL. Mechanical function, glycolysis, and ultrastructure of perfused working mouse hearts following thoracic aortic constriction. Cardiovasc Pathol 2011; 20:343-51. [PMID: 21296006 DOI: 10.1016/j.carpath.2010.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/02/2010] [Accepted: 12/13/2010] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Glycolytic flux in the mouse heart during the progression of left ventricular hypertrophy (LVH) and mechanical dysfunction has not been described. METHODS The main objectives of this study were to characterize the effects of thoracic aortic banding, of 3- and 6-week duration, on: (1) left ventricular (LV) systolic and diastolic function of perfused working hearts quantified by analysis of pressure-volume loops; (2) glycolytic flux in working hearts expressed as the rate of conversion of (3)H-glucose to (3)H(2)O, and (3) ultrastructure of LV biopsies assessed by quantitative and qualitative analysis of light and electron micrographs. RESULTS Results revealed that (1) indexes of systolic function, including LV end-systolic pressure, cardiac output, and rate of LV pressure development and decline, were depressed to similar degrees at 3 and 6 weeks post-banding; (2) diastolic dysfunction, represented by elevated LV end-diastolic pressure and volume, was more severe at 6 than at 3 weeks, consistent with a transition to failure; (3) a progressive decline in glycolytic flux that was roughly half the control rate by 6 weeks post-banding; and (4) structural derangements, manifested by increases in interstitial collagen content and myocyte Z-band disruption, that were more marked at 3 weeks than at 6 weeks. CONCLUSION The results are consistent with the view that myocyte damage, fibrosis, and suppressed glycolytic flux represent maladaptive structural and metabolic remodeling that contribute to the development of failure in high pressure load-induced LVH in the mouse.
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Affiliation(s)
- Michael E Dunn
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
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123
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Sack MN. Caloric excess or restriction mediated modulation of metabolic enzyme acetylation-proposed effects on cardiac growth and function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1279-85. [PMID: 21295620 DOI: 10.1016/j.bbamcr.2011.01.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 01/19/2011] [Accepted: 01/26/2011] [Indexed: 12/16/2022]
Abstract
Caloric excess has been postulated to disrupt cardiac function via (i) the generation of toxic intermediates, (ii) via protein glycosylation and (iii) through the generation of reactive oxygen species. It is now increasingly being recognized that the nutrient intermediates themselves may modulate metabolic pathways through the post-translational modifications of metabolic enzymes. In light of the high energy demand of the heart, these nutrient mediated modulations in metabolic pathway functioning may play an important role in cardiac function and in the capacity of the heart to adapt to biomechanical stressors. In this review the role of protein acetylation and deacetylation in the control of metabolic programs is explored. Although not extensively investigated directly in the heart, the emerging data support that these nutrient mediated post-translational regulatory events (i) modulate cardiac metabolic pathways, (ii) integrate nutrient flux mediated post-translational effects with cardiac function and (iii) may be important in the development of cardiac pathology. Areas of investigation that need to be explored are highlighted. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Michael N Sack
- Translational Medicine Branch, NHLBI, NIH, Bld 10-CRC, Room 5–3150, 10 Center Drive, Bethesda, MD, 20892-1454, USA.
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124
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Heather LC, Clarke K. Metabolism, hypoxia and the diabetic heart. J Mol Cell Cardiol 2011; 50:598-605. [PMID: 21262230 DOI: 10.1016/j.yjmcc.2011.01.007] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Revised: 01/06/2011] [Accepted: 01/11/2011] [Indexed: 12/18/2022]
Abstract
The diabetic heart becomes metabolically remodelled as a consequence of exposure to abnormal circulating substrates and hormones. Fatty acid uptake and metabolism are increased in the type 2 diabetic heart, resulting in accumulation of intracellular lipid intermediates and an increased contribution of fatty acids towards energy generation. Cardiac glucose uptake and oxidation are decreased, predominantly due to increased fatty acid metabolism, which suppresses glucose utilisation via the Randle cycle. These metabolic changes decrease cardiac efficiency and energetics in both humans and animal models of diabetes. Diabetic hearts have decreased recovery following ischemia, indicating a reduced tolerance to oxygen-limited conditions. There is evidence that diabetic hearts have a compromised hypoxia signalling pathway, as hypoxia-inducible factor (HIF) and downstream signalling from HIF are reduced following ischemia. Failure to activate HIF under oxygen-limited conditions results in less angiogenesis, and an inability to upregulate glycolytic ATP generation. Given that glycolysis is already suppressed in the diabetic heart under normoxic conditions, the inability to upregulate glycolysis in response to hypoxia may have deleterious effects on ATP production. Thus, impaired HIF signalling may contribute to metabolic and energetic abnormalities, and impaired collateral vessel development following myocardial infarction in the type 2 diabetic heart.
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Affiliation(s)
- Lisa C Heather
- Cardiac Metabolism Research Group, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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125
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Jaswal JS, Keung W, Wang W, Ussher JR, Lopaschuk GD. Targeting fatty acid and carbohydrate oxidation--a novel therapeutic intervention in the ischemic and failing heart. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1333-50. [PMID: 21256164 DOI: 10.1016/j.bbamcr.2011.01.015] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 12/16/2010] [Accepted: 01/11/2011] [Indexed: 12/19/2022]
Abstract
Cardiac ischemia and its consequences including heart failure, which itself has emerged as the leading cause of morbidity and mortality in developed countries are accompanied by complex alterations in myocardial energy substrate metabolism. In contrast to the normal heart, where fatty acid and glucose metabolism are tightly regulated, the dynamic relationship between fatty acid β-oxidation and glucose oxidation is perturbed in ischemic and ischemic-reperfused hearts, as well as in the failing heart. These metabolic alterations negatively impact both cardiac efficiency and function. Specifically there is an increased reliance on glycolysis during ischemia and fatty acid β-oxidation during reperfusion following ischemia as sources of adenosine triphosphate (ATP) production. Depending on the severity of heart failure, the contribution of overall myocardial oxidative metabolism (fatty acid β-oxidation and glucose oxidation) to adenosine triphosphate production can be depressed, while that of glycolysis can be increased. Nonetheless, the balance between fatty acid β-oxidation and glucose oxidation is amenable to pharmacological intervention at multiple levels of each metabolic pathway. This review will focus on the pathways of cardiac fatty acid and glucose metabolism, and the metabolic phenotypes of ischemic and ischemic/reperfused hearts, as well as the metabolic phenotype of the failing heart. Furthermore, as energy substrate metabolism has emerged as a novel therapeutic intervention in these cardiac pathologies, this review will describe the mechanistic bases and rationale for the use of pharmacological agents that modify energy substrate metabolism to improve cardiac function in the ischemic and failing heart. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Jagdip S Jaswal
- Mazankowski Alberta Heart Institute, Departments of Pediatrics and Pharmacology, University of Alberta, Edmonton, Alberta, Canada
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126
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Duncan JG. Mitochondrial dysfunction in diabetic cardiomyopathy. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1351-9. [PMID: 21256163 DOI: 10.1016/j.bbamcr.2011.01.014] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 12/21/2010] [Accepted: 01/11/2011] [Indexed: 12/26/2022]
Abstract
Cardiovascular disease is common in patients with diabetes and is a significant contributor to the high mortality rates associated with diabetes. Heart failure is common in diabetic patients, even in the absence of coronary artery disease or hypertension, an entity known as diabetic cardiomyopathy. Evidence indicates that myocardial metabolism is altered in diabetes, which likely contributes to contractile dysfunction and ventricular failure. The mitochondria are the center of metabolism, and recent data suggests that mitochondrial dysfunction may play a critical role in the pathogenesis of diabetic cardiomyopathy. This review summarizes many of the potential mechanisms that lead to mitochondrial dysfunction in the diabetic heart. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Jennifer G Duncan
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA.
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128
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Nishimura M, Tsukamoto K, Tamaki N, Kikuchi K, Iwamoto N, Ono T. Risk stratification for cardiac death in hemodialysis patients without obstructive coronary artery disease. Kidney Int 2010; 79:363-71. [PMID: 20944544 DOI: 10.1038/ki.2010.392] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The incidence of cardiac death is higher among patients receiving dialysis compared with the general population. Although obstructive coronary artery disease is involved in cardiac deaths in the general population, deaths in hemodialysis patients occur in the apparent absence of obstructive coronary artery disease. To study this further, we prospectively enrolled 155 patients receiving hemodialysis after angiography had confirmed the absence of obstructive coronary lesions. All patients were examined by single-photon emission computed tomography using the iodinated fatty acid analog, BMIPP, the uptake of which was graded in 17 standard myocardial segments and assessed as summed scores. Insulin resistance was determined using the homeostasis model assessment index of insulin resistance (HOMA-IR). During a mean follow-up of 5.1 years, 42 patients died of cardiac events. Stepwise Cox hazard analysis associated cardiac death with reduced BMIPP uptake and increased insulin resistance. Patients were assigned to subgroups based on BMIPP summed scores and HOMA-IR cutoff values for cardiac death of 12 and 5.1, respectively, determined by receiver operating characteristic analysis. Cardiac death-free survival rates at 5 years were the lowest (32.2%) in the subgroup with both a summed score and assessment equal to or above the cutoff values compared with any other combination (52.9-98.7%) above, equal to, or below the thresholds. Thus, impaired myocardial fatty acid metabolism and insulin resistance may be associated with cardiac death among hemodialysis patients without obstructive coronary artery disease.
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129
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Abstract
Being independent of coronary artery disease and hypertension, diabetic cardiomyopathy is a distinct primary disease process, which precedes the development of congestive heart failure. Epidemiologic as well as clinical studies confirmed the close link between diabetes mellitus and heart failure. Altered cardiac structure and function are common diagnoses in patients with type 2 diabetes mellitus. Hyperglycemia leading to the formation of advanced glycation end products and hyperlipidemia resulting in lipotoxicity are of structural and functional impact on cardiac muscle and cardiomyocytes. New and more sensitive methods of diagnosis identify early diastolic dysfunction as a precursor of the development of congestive heart failure. This review focuses on the mechanistic approach to understand the molecular basis of diabetic cardiomyopathy in patients with type 2 diabetes mellitus.
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Affiliation(s)
- Bernd Stratmann
- Heart and Diabetes Center NRW, Ruhr, University of Bochum, Bochum, Germany
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130
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Essop MF, Chan WA, Hattingh S. Proteomic analysis of mitochondrial proteins in a mouse model of type 2 diabetes. Cardiovasc J Afr 2010; 22:175-8. [PMID: 20859605 PMCID: PMC3721950 DOI: 10.5830/cvja-2010-058] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 07/12/2010] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Impaired mitochondrial function may contribute to the onset of contractile dysfunction with insulin resistance/type 2 diabetes. Our aim was therefore to determine alterations in the mitochondrial proteome of a mouse model of obesity/type 2 diabetes. METHODS Mitochondrial proteins were isolated from hearts collected from 18- to 20-week-old female db/db mice and compared to matched controls. We performed two-dimensional polyacrylamide gel electrophoresis to determine differentially expressed proteins. Peptides of interest were further analysed by mass spectrometry and Mascot software was employed to identify protein matches. RESULTS Our data showed that ATP synthase D chain, ubiquinol cytochrome-C reductase core protein 1 and electron transfer flavoprotein subunit alpha peptide levels were altered with obesity. Moreover, we found coordinate downregulation of contractile proteins in the obese heart, i.e. α-smooth muscle actin, α-cardiac actin, myosin heavy-chain α and myosin-binding protein C. CONCLUSION We propose that decreased contractile protein levels may contribute to contractile dysfunction of hearts from diabetic mice.
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Affiliation(s)
- M F Essop
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.
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131
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Daniels A, van Bilsen M, Janssen BJA, Brouns AE, Cleutjens JPM, Roemen THM, Schaart G, van der Velden J, van der Vusse GJ, van Nieuwenhoven FA. Impaired cardiac functional reserve in type 2 diabetic db/db mice is associated with metabolic, but not structural, remodelling. Acta Physiol (Oxf) 2010; 200:11-22. [PMID: 20175764 DOI: 10.1111/j.1748-1716.2010.02102.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AIM To identify the initial alterations in myocardial tissue associated with the early signs of diabetic cardiac haemodynamic dysfunction, we monitored changes in cardiac function, structural remodelling and gene expression in hearts of type 2 diabetic db/db mice. METHODS Cardiac dimensions and function were determined echocardiographically at 8, 12, 16 and 18 weeks of age. Left ventricular pressure characteristics were measured at 18 weeks under baseline conditions and upon dobutamine infusion. RESULTS The db/db mice were severely diabetic already at 8 weeks after birth, showing elevated fasting blood glucose levels and albuminuria. Nevertheless, echocardiography revealed no significant changes in cardiac function up to 18 weeks of age. At 18 weeks of age, left ventricular pressure characteristics were not significantly different at baseline between diabetic and control mice. However, dobutamine stress test revealed significantly attenuated cardiac inotropic and lusitropic responses in db/db mice. Post-mortem cardiac tissue analyses showed minor structural remodelling and no significant changes in gene expression levels of the sarcoplasmic reticulum calcium ATPase (SERCA2a) or beta1-adrenoceptor (beta1-AR). Moreover, the phosphorylation state of known contractile protein targets of protein kinase A (PKA) was not altered, indicating unaffected cardiac beta-adrenergic signalling activity in diabetic animals. By contrast, the substantially increased expression of uncoupling protein-3 (UCP3) and angiopoietin-like-4 (Angptl4), along with decreased phosphorylation of AMP-activated protein kinase (AMPK) in the diabetic heart, is indicative of marked changes in cardiac metabolism. CONCLUSION db/db mice show impaired cardiac functional reserve capacity during maximal beta-adrenergic stimulation which is associated with unfavourable changes in cardiac energy metabolism.
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Affiliation(s)
- A Daniels
- Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
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132
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Abstract
Diabetes mellitus increases the risk of developing cardiovascular diseases such as coronary artery disease and heart failure. Studies have shown that the heart failure risk is increased in diabetic patients even after adjusting for coronary artery disease and hypertension. Although the cause of this increased heart failure risk is multifactorial, increasing evidence suggests that derangements in cardiac energy metabolism play an important role. In particular, abnormalities in cardiomyocyte mitochondrial energetics appear to contribute substantially to the development of cardiac dysfunction in diabetes. This review will summarize these abnormalities in mitochondrial function and discuss potential underlying mechanisms.
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Affiliation(s)
- Heiko Bugger
- Department of Cardiology, University of Freiburg, Freiburg, Germany
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133
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Improvement of mechanical heart function by trimetazidine in db/db mice. Acta Pharmacol Sin 2010; 31:560-9. [PMID: 20383170 DOI: 10.1038/aps.2010.31] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
AIM To investigate the influence of trimetazidine, which is known to be an antioxidant and modulator of metabolism, on cardiac function and the development of diabetic cardiomyopathy in db/db mouse. METHODS Trimetazidine was administered to db/db mice for eight weeks. Cardiac function was measured by inserting a Millar catheter into the left ventricle, and oxidative stress and AMP-activated protein kinase (AMPK) activity in the myocardium were evaluated. RESULTS Untreated db/db mice exhibited a significant decrease in cardiac function compared to normal C57 mice. Oxidative stress and lipid deposition were markedly increased in the myocardium, concomitant with inactivation of AMPK and increased expression of peroxisome proliferator-activated receptor coactivator-1 alpha (PGC-1 alpha). Trimetazidine significantly improved systolic and diastolic function in hearts of db/db mice and led to reduced production of reactive oxygen species and deposition of fatty acid in cardiomyocytes. Trimetazidine also caused AMPK activation and reduced PGC-1 alpha expression in the hearts of db/db mice. CONCLUSION The data suggest that trimetazidine significantly improves cardiac function in db/db mice by attenuating lipotoxicity and improving the oxidation status of the heart. Activation of AMPK and decreased expression of PGC-1 alpha were involved in this process. Furthermore, our study suggests that trimetazidine suppresses the development of diabetic cardiomyopathy, which warrants further clinical investigation.
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134
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Ito M, Jaswal JS, Lam VH, Oka T, Zhang L, Beker DL, Lopaschuk GD, Rebeyka IM. High levels of fatty acids increase contractile function of neonatal rabbit hearts during reperfusion following ischemia. Am J Physiol Heart Circ Physiol 2010; 298:H1426-37. [DOI: 10.1152/ajpheart.00284.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the neonatal heart the transition from using carbohydrates to using fatty acids has not fully matured and oxidative metabolism/ATP generation may be limiting contractile function after ischemia. This study tested the hypothesis that increasing fatty acid availability increases recovery of left ventricular (LV) work by increasing palmitate oxidation, tricarboxylic acid (TCA) cycle activity, and ATP generation. Isolated working hearts from 7-day-old rabbits were perfused with Krebs solution containing low (0.4 mM) or high (2.4 mM) palmitate and 5.5 mM glucose. Hearts were subjected to 35-min global ischemia before 40-min reperfusion, and rates of glycolysis, glucose oxidation, and palmitate oxidation were assessed. LV work was similar before ischemia but was greater during reperfusion in hearts perfused with 2.4 mM palmitate compared with hearts perfused with 0.4 mM palmitate [6.98 ± 0.14 ( n = 15) vs. 3.01 ± 0.23 ( n = 16) mJ·beat−1·g dry wt−1; P < 0.05]. This was accompanied by increased LV energy expenditure during reperfusion [35.98 ± 0.16 ( n = 8) vs. 19.92 ± 0.18 ( n = 6) mJ·beat−1·g dry wt−1; P < 0.05]. During reperfusion the rates of palmitate oxidation [237.5 ± 28.10 ( n = 7) vs. 86.0 ± 9.7 ( n = 6) nmol·g dry wt−1·min−1; P < 0.05], total TCA cycle activity [2.65 ± 0.39 ( n = 7) vs. 1.36 ± 0.14 ( n = 6) μmol acetyl-CoA·g dry wt−1·min−1; P < 0.05], and ATP generation attributable to palmitate oxidation [26.6 ± 3.1 ( n = 7) vs. 12.6 ± 1.7 ( n = 6) μmol·g dry wt−1·min−1; P < 0.05] were greater in hearts perfused with 2.4 mM palmitate. These data indicate that the neonatal heart has decreased energy reserve, and, in contrast to the mature heart, increasing availability of fatty acid substrate increases energy production and improves recovery of function after ischemia.
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Affiliation(s)
- Masayoshi Ito
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Jagdip S. Jaswal
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Victoria H. Lam
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Tatsujiro Oka
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
| | - Liyan Zhang
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Donna L. Beker
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Division of Cardiac Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Gary D. Lopaschuk
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Pharmacology and
| | - Ivan M. Rebeyka
- Mazankowski Alberta Heart Institute, Departments of 1Pediatrics and
- Division of Cardiac Surgery, University of Alberta, Edmonton, Alberta, Canada
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135
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Abstract
Diabetes is associated with increased incidence of heart failure even after controlling for coronary artery disease and hypertension. Thus, as diabetic cardiomyopathy has become an increasingly recognized entity among clinicians, a better understanding of its pathophysiology is necessary for early diagnosis and the development of treatment strategies for diabetes-associated cardiovascular dysfunction. We will review recent basic and clinical research into the manifestations and the pathophysiological mechanisms of diabetic cardiomyopathy. The discussion will be focused on the structural, functional and metabolic changes that occur in the myocardium in diabetes and how these changes may contribute to the development of diabetic cardiomyopathy in affected humans and relevant animal models.
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136
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Hosoya M, Ohashi J, Sawada A, Takaki A, Shimokawa H. Combination therapy with olmesartan and azelnidipine improves EDHF-mediated responses in diabetic apolipoprotein E-deficient mice. Circ J 2010; 74:798-806. [PMID: 20154404 DOI: 10.1253/circj.cj-09-0862] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND The endothelium modulates vascular tone by synthesizing and releasing several vasodilating factors, including vasodilator prostaglandins, nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). In the present study, we examined whether an angiotensin-receptor blocker, a calcium-channel blocker or their combination improved EDHF-mediated responses in diabetic apolipoprotein E-deficient (ApoE(-/-)) mice. METHODS AND RESULTS We used male C57BL/6N (control) and streptozocin-induced diabetic ApoE(-/-) mice. The diabetic ApoE(-/-) mice were administered oral vehicle (untreated), olmesartan (OLM, 30 mgxkg(-1)xday(-1)), azelnidipine (AZL, 10 mgxkg(-1)xday(-1)), their combination (OLM + AZL), or hydralazine (HYD 5 mgxkg(-1)xday(-1)) for 5 weeks. In the untreated group, systolic blood pressure was significantly higher and both EDHF-mediated relaxation and endothelium-dependent hyperpolarization were markedly reduced as compared with the control group. Although EDHF-mediated relaxation was not significantly improved in the HYD, OLM and AZL groups, it was significantly improved in the OLM + AZL group, as was also the case with phosphorylation of Akt and endothelial NO synthase (eNOS). In contrast, the endothelium-independent relaxation response to sodium nitroprusside or NS-1619 (a direct opener of K(Ca) channels) was unaltered in any group. CONCLUSIONS OLM + AZL may improve the severely impaired EDHF-mediated responses in diabetic ApoE(-/-) mice, in which activation of the endothelial Akt - eNOS pathway may be involved.
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Affiliation(s)
- Maki Hosoya
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
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137
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Lopaschuk GD, Ussher JR, Folmes CDL, Jaswal JS, Stanley WC. Myocardial fatty acid metabolism in health and disease. Physiol Rev 2010; 90:207-58. [PMID: 20086077 DOI: 10.1152/physrev.00015.2009] [Citation(s) in RCA: 1437] [Impact Index Per Article: 102.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the beta-oxidation of long-chain fatty acids. The control of fatty acid beta-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via beta-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and beta-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid beta-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid beta-oxidation and how alterations in fatty acid beta-oxidation can contribute to heart disease. The implications of inhibiting fatty acid beta-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.
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Affiliation(s)
- Gary D Lopaschuk
- Cardiovascular Research Group, Mazankowski Alberta Heart Institute, University of Alberta, Alberta T6G 2S2, Canada.
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138
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Mellor KM, Ritchie RH, Delbridge LMD. Reactive oxygen species and insulin-resistant cardiomyopathy. Clin Exp Pharmacol Physiol 2010; 37:222-8. [DOI: 10.1111/j.1440-1681.2009.05274.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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139
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Abstract
Diabetic cardiomyopathy increases the risk of heart failure in individuals with diabetes, independently of co-existing coronary artery disease and hypertension. The underlying mechanisms for this cardiac complication are incompletely understood. Research on rodent models of type 1 and type 2 diabetes, and the use of genetic engineering techniques in mice, have greatly advanced our understanding of the molecular mechanisms responsible for human diabetic cardiomyopathy. The adaptation of experimental techniques for the investigation of cardiac physiology in mice now allows comprehensive characterization of these models. The focus of the present review will be to discuss selected rodent models that have proven to be useful in studying the underlying mechanisms of human diabetic cardiomyopathy, and to provide an overview of the characteristics of these models for the growing number of investigators who seek to understand the pathology of diabetes-related heart disease.
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Affiliation(s)
- Heiko Bugger
- Division of Endocrinology, Metabolism and Diabetes, and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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140
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Substrate-specific derangements in mitochondrial metabolism and redox balance in the atrium of the type 2 diabetic human heart. J Am Coll Cardiol 2009; 54:1891-8. [PMID: 19892241 DOI: 10.1016/j.jacc.2009.07.031] [Citation(s) in RCA: 310] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 06/24/2009] [Accepted: 07/06/2009] [Indexed: 12/18/2022]
Abstract
OBJECTIVES The aim of this study was to determine the impact of diabetes on oxidant balance and mitochondrial metabolism of carbohydrate- and lipid-based substrates in myocardium of type 2 diabetic patients. BACKGROUND Heart failure represents a major cause of death among diabetic patients. It has been proposed that derangements in cardiac metabolism and oxidative stress may underlie the progression of this comorbidity, but scarce evidence exists in support of this mechanism in humans. METHODS Mitochondrial oxygen (O(2)) consumption and hydrogen peroxide (H(2)O(2)) emission were measured in permeabilized myofibers prepared from samples of the right atrial appendage obtained from nondiabetic (n = 13) and diabetic (n = 11) patients undergoing nonemergent coronary artery bypass graft surgery. RESULTS Mitochondria in atrial tissue of type 2 diabetic individuals show a sharply decreased capacity for glutamate and fatty acid-supported respiration, in addition to an increased content of myocardial triglycerides, as compared to nondiabetic patients. Furthermore, diabetic patients show an increased mitochondrial H(2)O(2) emission during oxidation of carbohydrate- and lipid-based substrates, depleted glutathione, and evidence of persistent oxidative stress in their atrial tissue. CONCLUSIONS These findings are the first to directly investigate the effects of type 2 diabetes on a panoply of mitochondrial functions in the human myocardium using cellular and molecular approaches, and they show that mitochondria in diabetic human hearts have specific impairments in maximal capacity to oxidize fatty acids and glutamate, yet increased mitochondrial H(2)O(2) emission, providing insight into the role of mitochondrial dysfunction and oxidative stress in the pathogenesis of heart failure in diabetic patients.
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141
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Essop MF, Anna Chan WY, Valle A, García-Palmer FJ, Du Toit EF. Impaired contractile function and mitochondrial respiratory capacity in response to oxygen deprivation in a rat model of pre-diabetes. Acta Physiol (Oxf) 2009; 197:289-96. [PMID: 19645752 DOI: 10.1111/j.1748-1716.2009.02024.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
AIM Obesity is a major contributor to the global burden of disease and is closely associated with the development of type 2 diabetes and cardiovascular diseases. This study tested the hypothesis that mitochondrial respiratory capacity of the pre-diabetic heart is decreased leading to impaired contractile function and tolerance to ischaemia/reperfusion. METHODS Eight-week-old male Wistar rats were fed a high caloric diet for 16 weeks after which anthropometric, metabolic, cardiac and mitochondrial parameters were evaluated vs. age-matched lean controls. Cardiac function (working heart perfusions) and mitochondrial respiratory capacity were assessed at baseline and in response to acute oxygen deprivation. RESULTS Rats fed the high caloric diet exhibited increased body weight and visceral fat vs. the control group. Heart weights of obese rats were also increased. Triglyceride, fasting plasma insulin and free fatty acid levels were elevated, while high-density lipoprotein cholesterol levels were reduced in the obese group. Contractile function was attenuated at baseline and further decreased after subjecting hearts to ischaemia-reperfusion. Myocardial infarct sizes were increased while ADP phosphorylation rates were diminished in obese rats. However, no differences were found for mtDNA levels and the degree of oxidative stress-induced damage. CONCLUSIONS These data show that decreased mitochondrial bioenergetic capacity in pre-diabetic rat hearts may impair respiratory capacity and reduce basal contractile function and tolerance to acute oxygen deprivation.
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Affiliation(s)
- M F Essop
- Department of Physiological Sciences, Stellenbosch University, South Africa.
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142
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Yeih DF, Yeh HI, Hsin HT, Lin LY, Chiang FT, Tseng CD, Chu SH, Tseng YZ. Dimethylthiourea normalizes velocity-dependent, but not force-dependent, index of ventricular performance in diabetic rats: role of myosin heavy chain isozyme. Am J Physiol Heart Circ Physiol 2009; 297:H1411-20. [PMID: 19633204 DOI: 10.1152/ajpheart.01269.2008] [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: 02/05/2023]
Abstract
Hydroxyl radicals and hydrogen peroxide are involved in the pathogenesis of systolic dysfunction in diabetic rats, but the precise mechanisms and the effect of antioxidant therapy in diabetic subjects have not been elucidated. We aimed to evaluate the effects of dimethylthiourea (DMTU), a potent hydroxyl radical scavenger, on both force-dependent and velocity-dependent indexes of cardiac contractility in streptozotocin (STZ)-induced early and chronic diabetic rats. Seventy-two hours and 8 wk after STZ (55 mg/kg) injection, diabetic rats were randomized to either DMTU (50 mg x kg(-1) x day(-1) ip) or vehicle treatment for 6 and 12 wk, respectively. All rats were then subjected to invasive hemodynamic studies. Maximal systolic elastance (E(max)) and maximum theoretical flow (Q(max)) were assessed by curve-fitting techniques in terms of the elastance-resistance model. Both normalized E(max) (E(maxn)) and afterload-adjusted Q(max) (Q(maxad)) were depressed in diabetic rats, concomitant with altered myosin heavy chain (MHC) isoform composition and its upstream regulators, such as myocyte enhancer factor-2 (MEF-2) and heart autonomic nervous system and neural crest derivatives (HAND). In chronic diabetic rats, DMTU markedly attenuated the impairment in Q(maxad) and normalized the expression of MEF-2 and eHAND and MHC isoform composition but exerted an insignificant benefit on E(maxn). Regarding preventive treatment, DMTU significantly ameliorated both E(maxn) and Q(maxad) in early diabetic rats. In conclusion, our study shows that DMTU has disparate effects on Q(maxad) and E(maxn) in chronic diabetic rats. The advantage of DMTU in chronic diabetic rats might involve normalization of MEF-2 and eHAND, as well as reversal of MHC isoform switch.
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Affiliation(s)
- Dong-Feng Yeih
- 1Department of Cardiology, Far Eastern Memorial Hospital, Pan-Chiao, Taipei County, Taiwan, Republic of China
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143
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Jaswal JS, Ussher JR, Lopaschuk GD. Myocardial fatty acid utilization as a determinant of cardiac efficiency and function. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/clp.09.18] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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144
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145
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Niu YG, Evans RD. Myocardial metabolism of triacylglycerol-rich lipoproteins in type 2 diabetes. J Physiol 2009; 587:3301-15. [PMID: 19433573 DOI: 10.1113/jphysiol.2009.173542] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Cardiac utilisation of very-low-density lipoprotein (VLDL) and chylomicrons (CM) was investigated in the ZDF rat model of type 2 diabetes, in order to define the role of triacylglycerol (TAG) metabolism in the development of contractile dysfunction. Hearts from obese diabetic and lean littermate control rats were perfused with VLDL and CM from diabetic and control rats. Metabolic fate of the lipoprotein TAG and contractile function were examined. Myocardial utilisation of both VLDL- and CM-TAG was increased in the diabetic state. Diabetic hearts oxidised diabetic lipoprotein-TAG to a greater extent than control lipoproteins; glucose oxidation was decreased. There was no difference in lipoprotein-TAG assimilation into diabetic heart lipids; diabetic lipoproteins were, however, a poor substrate for control heart tissue lipid accumulation. Although the proportion of exogenous lipid incorporated into tissue TAG was increased in diabetic hearts perfused with control lipoproteins, this effect was not seen in diabetic hearts perfused with diabetic lipoproteins. Myocardial heparin-releasable lipoprotein lipase (LPL) activity was moderately increased in the diabetic state, and diabetic lipoproteins increased tissue-residual LPL activity. Cardiac hydraulic work was decreased only in diabetic hearts perfused with diabetic CM. Compositional analysis of diabetic variant lipoproteins indicated changes in size and apoprotein content. Alterations in cardiac TAG-rich lipoprotein metabolism in type 2 diabetes are due to changes in both the diabetic myocardium and the diabetic lipoprotein particle; decreased contractile function is not related to cardiac lipid accumulation from TAG-rich lipoproteins but may be associated with changes in TAG-fatty acid oxidation.
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Affiliation(s)
- You-Guo Niu
- Department of Physiology, Development and Neuroscience, University of Cambridge, UK
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146
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Boardman N, Hafstad AD, Larsen TS, Severson DL, Aasum E. Increased O2 cost of basal metabolism and excitation-contraction coupling in hearts from type 2 diabetic mice. Am J Physiol Heart Circ Physiol 2009; 296:H1373-9. [DOI: 10.1152/ajpheart.01264.2008] [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: 02/05/2023]
Abstract
We have reported previously that hearts from type 2 diabetic ( db/ db) mice show decreased cardiac efficiency due to increased work-independent myocardial O2 consumption (unloaded MV̇o2), indicating higher O2 use for nonmechanical processes such as basal metabolism (MV̇o2BM) and excitation-contraction coupling (MV̇o2ECC). Although alterations in cardiac metabolism and/or Ca2+ handling may contribute to increased energy expenditure in diabetic hearts, direct measurements of the O2 cost for these individual processes have not been determined. In this study, we 1) validate a procedure for measuring unloaded MV̇o2 directly (MV̇o2unloaded) and for determining MV̇o2BM and MV̇o2ECC separately in isolated perfused mouse hearts and 2) determine O2 cost for these processes in hearts from db/ db mice. Unloaded MV̇o2, extrapolated from the relationship between cardiac work (measured as pressure-volume area, PVA) and MV̇o2, was found to correspond with MV̇o2 measured directly in unloaded retrograde perfused hearts (MV̇o2unloaded). MV̇o2 in K+-arrested hearts was defined as MV̇o2BM; the difference between MV̇o2unloaded and MV̇o2BM represented MV̇o2ECC. This procedure was validated by demonstrating that elevations in perfusate fatty acid (FA) and/or Ca2+ concentrations resulted in changes in either MV̇o2BM and/or MV̇o2ECC. The higher MV̇o2unloaded in db/ db mice was due to both a higher MV̇o2BM and MV̇o2ECC. Elevation of glucose and insulin decreased FA oxidation and reduced both MV̇o2unloaded and MV̇o2BM. In conclusion, this study provides direct evidence that MV̇o2BM and MV̇o2ECC are elevated in diabetes and that acute metabolic interventions can have a therapeutic benefit in diabetic hearts due to a MV̇o2-lowering effect.
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147
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Hafstad AD, Khalid AM, Hagve M, Lund T, Larsen TS, Severson DL, Clarke K, Berge RK, Aasum E. Cardiac peroxisome proliferator-activated receptor-alpha activation causes increased fatty acid oxidation, reducing efficiency and post-ischaemic functional loss. Cardiovasc Res 2009; 83:519-26. [PMID: 19398469 DOI: 10.1093/cvr/cvp132] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Myocardial fatty acid (FA) oxidation is regulated acutely by the FA supply and chronically at the transcriptional level owing to FA activation of peroxisome proliferator-activated receptor-alpha (PPARalpha). However, in vivo administration of PPARalpha ligands has not been shown to increase cardiac FA oxidation. In this study we have examined the cardiac response to in vivo administration of tetradecylthioacetic acid (TTA, 0.5% w/w added to the diet for 8 days), a PPAR agonist with primarily PPARalpha activity. METHODS AND RESULTS Despite the fact that TTA treatment decreased plasma concentrations of lipids [FA and triacylglycerols (TG)], hearts from TTA-treated mice showed increased mRNA expression of PPARalpha target genes. Cardiac substrate utilization, ventricular function, cardiac efficiency, and susceptibility to ischaemia-reperfusion were examined in isolated perfused hearts. In accordance with the mRNA changes, myocardial FA oxidation was increased 2.5-fold with a concomitant reduction in glucose oxidation. This increase in FA oxidation was abolished in PPARalpha-null mice. Thus, it appears that the metabolic effects of TTA on the heart must be owing to a direct stimulatory effect on cardiac PPARalpha. Hearts from TTA-treated mice also showed a marked reduction in cardiac efficiency (because of a two-fold increase in unloaded myocardial oxygen consumption) and decreased recovery of ventricular contractile function following low-flow ischaemia. CONCLUSION This study for the first time observed that in vivo administration of a synthetic PPARalpha ligand elevated FA oxidation, an effect that was also associated with decreased cardiac efficiency and reduced post-ischaemic functional recovery.
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Affiliation(s)
- Anne D Hafstad
- Department of Medical Physiology, Institute of Medical Biology, University of Tromsø, Tromsø N-9037, Norway
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148
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Type 2 diabetes, mitochondrial biology and the heart. J Mol Cell Cardiol 2009; 46:842-9. [PMID: 19217910 DOI: 10.1016/j.yjmcc.2009.02.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 02/05/2009] [Accepted: 02/06/2009] [Indexed: 11/22/2022]
Abstract
Diabetes is recognized as an independent risk factor for cardiovascular morbidity and mortality. This is due, in large part, to premature atherosclerosis, enhanced thrombogenicity and activation of systemic inflammatory programs with resultant vascular dysfunction. More enigmatic mechanisms underpinning diabetes-associated cardiac pathophysiology include the direct metabolic consequences of this disease on the myocardium. Nevertheless, a role for diabetes-associated disruption in cardiac contractile mechanics and in increasing cardiomyocyte susceptibility to ischemic-stress has been implicated independent of vascular pathology. This review will focus broadly on the direct effects of diabetes on the cardiac myocardium with more specific reference to the role of the modulation of cardiomyocyte mitochondrial function in these disease processes. This focus in part, stems from the growing recognition that in some instances mitochondrial dysfunction is central to the development of insulin resistance and diabetes, and in others, diabetes associated disruption in mitochondrial function exacerbates and accentuates the pathophysiology of diabetes.
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149
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Evidence for a causal role of oxidative stress in the myocardial complications of insulin resistance. Heart Lung Circ 2008; 18:11-8. [PMID: 19119069 DOI: 10.1016/j.hlc.2008.11.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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150
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Bugger H, Boudina S, Hu XX, Tuinei J, Zaha VG, Theobald HA, Yun UJ, McQueen AP, Wayment B, Litwin SE, Abel ED. Type 1 diabetic akita mouse hearts are insulin sensitive but manifest structurally abnormal mitochondria that remain coupled despite increased uncoupling protein 3. Diabetes 2008; 57:2924-32. [PMID: 18678617 PMCID: PMC2570388 DOI: 10.2337/db08-0079] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Fatty acid-induced mitochondrial uncoupling and oxidative stress have been proposed to reduce cardiac efficiency and contribute to cardiac dysfunction in type 2 diabetes. We hypothesized that mitochondrial uncoupling may also contribute to reduced cardiac efficiency and contractile dysfunction in the type 1 diabetic Akita mouse model (Akita). RESEARCH DESIGN AND METHODS Cardiac function and substrate utilization were determined in isolated working hearts and in vivo function by echocardiography. Mitochondrial function and coupling were determined in saponin-permeabilized fibers, and proton leak kinetics was determined in isolated mitochondria. Hydrogen peroxide production and aconitase activity were measured in isolated mitochondria, and total reactive oxygen species (ROS) were measured in heart homogenates. RESULTS Resting cardiac function was normal in Akita mice, and myocardial insulin sensitivity was preserved. Although Akita hearts oxidized more fatty acids, myocardial O(2) consumption was not increased, and cardiac efficiency was not reduced. ADP-stimulated mitochondrial oxygen consumption and ATP synthesis were decreased, and mitochondria showed grossly abnormal morphology in Akita. There was no evidence of oxidative stress, and despite a twofold increase in uncoupling protein 3 (UCP3) content, ATP-to-O ratios and proton leak kinetics were unchanged, even after perfusion of Akita hearts with 1 mmol/l palmitate. CONCLUSIONS Insulin-deficient Akita hearts do not exhibit fatty acid-induced mitochondrial uncoupling, indicating important differences in the basis for mitochondrial dysfunction between insulin-responsive type 1 versus insulin-resistant type 2 diabetic hearts. Increased UCP3 levels do not automatically increase mitochondrial uncoupling in the heart, which supports the hypothesis that fatty acid-induced mitochondrial uncoupling as exists in type 2 diabetic hearts requires a concomitant increase in ROS generation.
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MESH Headings
- Animals
- Blotting, Western
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Echocardiography
- Insulin/metabolism
- Ion Channels/genetics
- Ion Channels/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/ultrastructure
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Myocardium/metabolism
- Myocardium/ultrastructure
- Oxidative Stress
- Oxygen Consumption
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reactive Oxygen Species/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Uncoupling Protein 2
- Uncoupling Protein 3
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Affiliation(s)
- Heiko Bugger
- Division of Endocrinology, Metabolism, and Diabetes, Program in Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, Utah, USA
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