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Ca 2+ mishandling and mitochondrial dysfunction: a converging road to prediabetic and diabetic cardiomyopathy. Pflugers Arch 2022; 474:33-61. [PMID: 34978597 PMCID: PMC8721633 DOI: 10.1007/s00424-021-02650-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 11/17/2021] [Accepted: 12/03/2021] [Indexed: 12/16/2022]
Abstract
Diabetic cardiomyopathy is defined as the myocardial dysfunction that suffers patients with diabetes mellitus (DM) in the absence of hypertension and structural heart diseases such as valvular or coronary artery dysfunctions. Since the impact of DM on cardiac function is rather silent and slow, early stages of diabetic cardiomyopathy, known as prediabetes, are poorly recognized, and, on many occasions, cardiac illness is diagnosed only after a severe degree of dysfunction was reached. Therefore, exploration and recognition of the initial pathophysiological mechanisms that lead to cardiac dysfunction in diabetic cardiomyopathy are of vital importance for an on-time diagnosis and treatment of the malady. Among the complex and intricate mechanisms involved in diabetic cardiomyopathy, Ca2+ mishandling and mitochondrial dysfunction have been described as pivotal early processes. In the present review, we will focus on these two processes and the molecular pathway that relates these two alterations to the earlier stages and the development of diabetic cardiomyopathy.
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Bening C, Alhussini K, Mazalu EA, Yaqub J, Hamouda K, Radakovic D, Schimmer C, Hirnle G, Leyh R. Impact of diabetes mellitus on the contractile properties of the left and right atrial myofilaments. Eur J Cardiothorac Surg 2019; 54:826-831. [PMID: 29659778 DOI: 10.1093/ejcts/ezy154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 03/14/2018] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVES The incidence of diabetes mellitus in patients with ischaemic cardiomyopathy is increasing. To evaluate the impact of diabetes mellitus on contractility, we examined the calcium-induced force in left and right atrial myofilaments of patients with and without diabetes. METHODS We included 149 patients (106 without diabetes, 43 with diabetes), scheduled for elective coronary artery bypass grafting from August 2016 to June 2017. The left and right atria were excised and prepared for skinned fibre measurements (pCa-force curve). The unit for the force measurements is Millinewton (mN). Comprehensive demographic data as well as echocardiographic findings of the patients were collected. RESULTS We observed a significant decrease of left atrial force values in patients with diabetes, averaged over all calcium concentrations (patients with diabetes 0.50 ± 0.19 mN vs 0.68 ± 0.23 mN in patients without diabetes, P = 0.002) as well as in right atrial fibres (patients with diabetes 0.35 ± 0.17 mN vs 0.47 ± 0.21 mN in patients without diabetes, P = 0.005). There was a significant influence of repeated measurements (of the calcium concentrations) on force in left atrial myofilaments (P < 0.001). There was also a significant impact of diabetes on the force values of the different calcium concentrations in left atrial myofilaments (P 0.002). In right atrial myofilaments we also found a significant influence of repeated measurements (of the calcium concentrations) on force (P < 0.001). Additionally the impact of diabetes on the force values was significant (P = 0.005). CONCLUSIONS We demonstrated that diabetes mellitus has a significantly negative impact on calcium-induced force development in left and right atrial myofilaments.
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Affiliation(s)
- Constanze Bening
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany.,Comprehensive Heart Failure Centre (CHFC) Würzburg, University of Wuerzburg, Wuerzburg, Germany
| | - Khaled Alhussini
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany.,Comprehensive Heart Failure Centre (CHFC) Würzburg, University of Wuerzburg, Wuerzburg, Germany
| | - Elena-Aura Mazalu
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany.,Comprehensive Heart Failure Centre (CHFC) Würzburg, University of Wuerzburg, Wuerzburg, Germany
| | - Jonathan Yaqub
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany
| | - Khaled Hamouda
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany
| | - Dejan Radakovic
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany
| | - Christoph Schimmer
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany
| | - Grzegorz Hirnle
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany
| | - Rainer Leyh
- Department of Thoracic and Cardiovascular Surgery, University of Wuerzburg, Wuerzburg, Germany.,Comprehensive Heart Failure Centre (CHFC) Würzburg, University of Wuerzburg, Wuerzburg, Germany
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Gong G, Yuan H, Liu Y, Qi L. Investigation of the Effects and Mechanisms of Mai Tong Formula on Lower Limb Macroangiopathy in a Spontaneous Diabetic Rat Model. J Diabetes Res 2016; 2016:8076796. [PMID: 27995148 PMCID: PMC5138487 DOI: 10.1155/2016/8076796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/19/2016] [Indexed: 12/29/2022] Open
Abstract
A new Chinese herbal formula called Mai Tong Formulae (MTF) has recently been used to treat lower limb macroangiopathy in type 2 diabetes mellitus (T2DM) patients. In this study, we investigated the effect of MTF on lower limb macroangiopathy in a spontaneous diabetic rat model (GK rats). We found that MTF treatment significantly reduced serum fasting blood glucose (FBG), triglycerides (TG), total cholesterol (TC), IL6, and VEGF and increased serum insulin in this model. Histological and ultrastructural observations showed that MTF treatment significantly reduced vascular endothelial cell shedding and improved endothelium injuries. We further detect proteome alteration following MTF treatment. 25 differential proteins (DPs) abnormally expressed in GK rats were normalized by MTF treatment. These DPs significantly are enriched in biological processes and pathways that regulate muscle contraction and cGMP-PKG signaling pathway and so on. Additional protein-protein interaction (PPI) network analyses of the DPs showed that Fasn and Prkar2a are involved in the AMPK signaling pathway, and Gnas, Myh11, and Myh6 are involved in vascular smooth muscle contraction; these 5 DPs were validated by Western blotting. These results indicate that MTF treatment effectively treats lower limb macroangiopathy by regulating key proteins involved in AMPK signaling pathway and vascular smooth muscle contraction.
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Affiliation(s)
- Guangming Gong
- Endocrinology Department, Teaching Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610075, China
| | - Haipo Yuan
- Endocrinology Department, Teaching Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610075, China
| | - Ya Liu
- Endocrinology Department, Teaching Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610075, China
| | - Luguang Qi
- Endocrinology Department, Teaching Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610075, China
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Tian C, Alomar F, Moore CJ, Shao CH, Kutty S, Singh J, Bidasee KR. Reactive carbonyl species and their roles in sarcoplasmic reticulum Ca2+ cycling defect in the diabetic heart. Heart Fail Rev 2014; 19:101-12. [PMID: 23430128 PMCID: PMC4732283 DOI: 10.1007/s10741-013-9384-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Efficient and rhythmic cardiac contractions depend critically on the adequate and synchronized release of Ca(2+) from the sarcoplasmic reticulum (SR) via ryanodine receptor Ca(2+) release channels (RyR2) and its reuptake via sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a). It is well established that this orchestrated process becomes compromised in diabetes. What remain incompletely defined are the molecular mechanisms responsible for the dysregulation of RyR2 and SERCA2a in diabetes. Earlier, we found elevated levels of carbonyl adducts on RyR2 and SERCA2a isolated from hearts of type 1 diabetic rats and showed the presence of these posttranslational modifications compromised their functions. We also showed that these mono- and di-carbonyl reactive carbonyl species (RCS) do not indiscriminately react with all basic amino acid residues on RyR2 and SERCA2a; some residues are more susceptible to carbonylation (modification by RCS) than others. A key unresolved question in the field is which of the many RCS that are upregulated in the heart in diabetes chemically react with RyR2 and SERCA2a? This brief review introduces readers to the field of RCS and their roles in perturbing SR Ca(2+) cycling in diabetes. It also provides new experimental evidence that not all RCS that are upregulated in the heart in diabetes chemically react with RyR2 and SERCA2a, methylglyoxal and glyoxal preferentially do.
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Affiliation(s)
- Chengju Tian
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Fadhel Alomar
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
- Department of Pharmacology, University of Dammam, Kingdom of Saudi Arabia
| | - Caronda J Moore
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Chun Hong Shao
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Shelby Kutty
- Joint Division of Pediatric Cardiology, University of Nebraska/Creighton University and Children's Hospital and Medical Center, Omaha, Nebraska
| | - Jaipaul Singh
- School of Forensic and Investigative Sciences and School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston, UK
| | - Keshore R. Bidasee
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
- Department of Environmental, Agricultural and Occupational Health, University of Nebraska Medical Center, Omaha, NE 68198
- Nebraska Center for Redox Biology, N146 Beadle Center, Lincoln NE 68588-0662
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5
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Castellano J, Farré J, Fernandes J, Bayes-Genis A, Cinca J, Badimon L, Hove-Madsen L, Llorente-Cortés V. Hypoxia exacerbates Ca2+-handling disturbances induced by very low density lipoproteins (VLDL) in neonatal rat cardiomyocytes. J Mol Cell Cardiol 2011; 50:894-902. [DOI: 10.1016/j.yjmcc.2011.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 01/17/2011] [Accepted: 02/02/2011] [Indexed: 01/22/2023]
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Kockskämper J, Zima AV, Roderick HL, Pieske B, Blatter LA, Bootman MD. Emerging roles of inositol 1,4,5-trisphosphate signaling in cardiac myocytes. J Mol Cell Cardiol 2008; 45:128-47. [PMID: 18603259 PMCID: PMC2654363 DOI: 10.1016/j.yjmcc.2008.05.014] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/19/2023]
Abstract
Inositol 1,4,5-trisphosphate (IP(3)) is a ubiquitous intracellular messenger regulating diverse functions in almost all mammalian cell types. It is generated by membrane receptors that couple to phospholipase C (PLC), an enzyme which liberates IP(3) from phosphatidylinositol 4,5-bisphosphate (PIP(2)). The major action of IP(3), which is hydrophilic and thus translocates from the membrane into the cytoplasm, is to induce Ca(2+) release from endogenous stores through IP(3) receptors (IP(3)Rs). Cardiac excitation-contraction coupling relies largely on ryanodine receptor (RyR)-induced Ca(2+) release from the sarcoplasmic reticulum. Myocytes express a significantly larger number of RyRs compared to IP(3)Rs (~100:1), and furthermore they experience substantial fluxes of Ca(2+) with each heartbeat. Therefore, the role of IP(3) and IP(3)-mediated Ca(2+) signaling in cardiac myocytes has long been enigmatic. Recent evidence, however, indicates that despite their paucity cardiac IP(3)Rs may play crucial roles in regulating diverse cardiac functions. Strategic localization of IP(3)Rs in cytoplasmic compartments and the nucleus enables them to participate in subsarcolemmal, bulk cytoplasmic and nuclear Ca(2+) signaling in embryonic stem cell-derived and neonatal cardiomyocytes, and in adult cardiac myocytes from the atria and ventricles. Intriguingly, expression of both IP(3)Rs and membrane receptors that couple to PLC/IP(3) signaling is altered in cardiac disease such as atrial fibrillation or heart failure, suggesting the involvement of IP(3) signaling in the pathology of these diseases. Thus, IP(3) exerts important physiological and pathological functions in the heart, ranging from the regulation of pacemaking, excitation-contraction and excitation-transcription coupling to the initiation and/or progression of arrhythmias, hypertrophy and heart failure.
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Affiliation(s)
- Jens Kockskämper
- Division of Cardiology, Medical University of Graz,, Auenbruggerplatz 15, A-8036 Graz, Austria
| | - Aleksey V. Zima
- Department of Molecular Biophysics & Physiology, Rush University, 1750 W. Harrison St., Chicago, IL 60612, USA
| | - H. Llewelyn Roderick
- Laboratory of Molecular Signalling, Babraham Institute, Cambridge CB2 4AT, UK
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1 PD, UK
| | - Burkert Pieske
- Division of Cardiology, Medical University of Graz,, Auenbruggerplatz 15, A-8036 Graz, Austria
| | - Lothar A. Blatter
- Department of Molecular Biophysics & Physiology, Rush University, 1750 W. Harrison St., Chicago, IL 60612, USA
| | - Martin D. Bootman
- Laboratory of Molecular Signalling, Babraham Institute, Cambridge CB2 4AT, UK
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Lacombe VA, Viatchenko-Karpinski S, Terentyev D, Sridhar A, Emani S, Bonagura JD, Feldman DS, Györke S, Carnes CA. Mechanisms of impaired calcium handling underlying subclinical diastolic dysfunction in diabetes. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1787-97. [PMID: 17761517 PMCID: PMC2413069 DOI: 10.1152/ajpregu.00059.2007] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Isolated diastolic dysfunction is found in almost half of asymptomatic patients with well-controlled diabetes and may precede diastolic heart failure. However, mechanisms that underlie diastolic dysfunction during diabetes are not well understood. We tested the hypothesis that isolated diastolic dysfunction is associated with impaired myocardial Ca(2+) handling during type 1 diabetes. Streptozotocin-induced diabetic rats were compared with age-matched placebo-treated rats. Global left ventricular myocardial performance and systolic function were preserved in diabetic animals. Diabetes-induced diastolic dysfunction was evident on Doppler flow imaging, based on the altered patterns of mitral inflow and pulmonary venous flows. In isolated ventricular myocytes, diabetes resulted in significant prolongation of action potential duration compared with controls, with afterdepolarizations occurring in diabetic myocytes (P < 0.05). Sustained outward K(+) current and peak outward component of the inward rectifier were reduced in diabetic myocytes, while transient outward current was increased. There was no significant change in L-type Ca(2+) current; however, Ca(2+) transient amplitude was reduced and transient decay was prolonged by 38% in diabetic compared with control myocytes (P < 0.05). Sarcoplasmic reticulum Ca(2+) load (estimated by measuring the integral of caffeine-evoked Na(+)-Ca(2+) exchanger current and Ca(2+) transient amplitudes) was reduced by approximately 50% in diabetic myocytes (P < 0.05). In permeabilized myocytes, Ca(2+) spark amplitude and frequency were reduced by 34 and 20%, respectively, in diabetic compared with control myocytes (P < 0.05). Sarco(endo)plasmic reticulum Ca(2+)-ATPase-2a protein levels were decreased during diabetes. These data suggest that in vitro impairment of Ca(2+) reuptake during myocyte relaxation contributes to in vivo diastolic dysfunction, with preserved global systolic function, during diabetes.
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8
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Sarcoplasmic Ca2+ release is prolonged in nonfailing myocardium of diabetic patients. Mol Cell Biochem 2007; 308:141-9. [DOI: 10.1007/s11010-007-9622-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Accepted: 10/03/2007] [Indexed: 10/22/2022]
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Durham WJ, Wehrens XHT, Sood S, Hamilton SL. Diseases associated with altered ryanodine receptor activity. Subcell Biochem 2007; 45:273-321. [PMID: 18193641 DOI: 10.1007/978-1-4020-6191-2_10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Mutations in two intracellular Ca2+ release channels or ryanodine receptors (RyR1 and RyR2) are associated with a number of human skeletal and cardiac diseases. This chapter discusses these diseases in terms of known mechanisms, controversies, and unanswered questions. We also compare the cardiac and skeletal muscle diseases to explore common mechanisms.
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Affiliation(s)
- W J Durham
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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10
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Dincer UD, Araiza AG, Knudson JD, Molina PE, Tune JD. Sensitization of coronary alpha-adrenoceptor vasoconstriction in the prediabetic metabolic syndrome. Microcirculation 2006; 13:587-95. [PMID: 16990217 DOI: 10.1080/10739680600885228] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE This study tested whether alpha -adrenoceptor-mediated coronary vasoconstriction is augmented in the metabolic syndrome and is accompanied by the alteration of specific alpha(1)- and alpha(2)-coronary adrenoceptors. METHODS Studies were conducted in control and chronically high-fat-fed (6 weeks of 60% calories from fat) dogs with metabolic syndrome. Alterations in coronary alpha(1B)-, alpha(1D)-, and alpha(2A)-adrenoceptor mRNA and protein expression were examined by real-time PCR and Western analyses, respectively. Coronary blood flow and its response to intracoronary infusion of either the alpha1-adrenoceptor agonist methoxamine (0.1-3 mg) or the alpha(2)-adrenoceptor agonist BHT-933 (0.1-3 mg) were measured in anesthetized dogs. RESULTS Basal plasma epinephrine and norepinephrine levels were higher in the high-fat-fed dogs compared to controls. Real-time PCR revealed no alterations of coronary artery or arteriole alpha1B-, alpha(1D)-, and alpha(2A)-adrenoceptor mRNA expression. However, Western blot analysis showed a significant decrease in alpha(2A)-adrenoceptor protein density with no change in alpha(1B)- or alpha(1D)-adrenoceptors. Methoxamine and BHT-933 produced dose-dependent decreases in coronary blood flow, but the decrease in coronary flow to methoxamine was significantly greater (approximately 20%) in dogs with the metabolic syndrome. No differences in the coronary flow response to BHT-933 were noted. CONCLUSIONS These results indicate that the metabolic syndrome is associated with sensitization of alpha1- and alpha2-adrenoceptor signaling that could significantly limit control of coronary blood flow when the sympathetic nervous system is activated.
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Affiliation(s)
- U Deniz Dincer
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, USA
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Pereira L, Matthes J, Schuster I, Valdivia HH, Herzig S, Richard S, Gómez AM. Mechanisms of [Ca2+]i transient decrease in cardiomyopathy of db/db type 2 diabetic mice. Diabetes 2006; 55:608-15. [PMID: 16505222 DOI: 10.2337/diabetes.55.03.06.db05-1284] [Citation(s) in RCA: 197] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cardiovascular disease is the leading cause of death in the diabetic population. However, molecular mechanisms underlying diabetic cardiomyopathy remain unclear. We analyzed Ca2+-induced Ca2+ release and excitation-contraction coupling in db/db obese type 2 diabetic mice and their control littermates. Echocardiography showed a systolic dysfunction in db/db mice. Two-photon microscopy identified intracellular calcium concentration ([Ca2+]i) transient decrease in cardiomyocytes within the whole heart, which was also found in isolated myocytes by confocal microscopy. Global [Ca2+]i transients are constituted of individual Ca2+ sparks. Ca2+ sparks in db/db cardiomyocytes were less frequent than in +/+ myocytes, partly because of a depression in sarcoplasmic reticulum Ca2+ load but also because of a reduced expression of ryanodine receptor Ca2+ channels (RyRs), revealed by [3H]ryanodine binding assay. Ca2+ efflux through Na+/Ca2+ exchanger was increased in db/db myocytes. Calcium current, I(Ca), triggers sarcoplasmic reticulum Ca2+ release and is also involved in sarcoplasmic reticulum Ca2+ refilling. Macroscopic I(Ca) was reduced in db/db cells, but single Ca2+ channel activity was similar, suggesting that diabetic myocytes express fewer functional Ca2+ channels, which was confirmed by Western blots. These results demonstrate that db/db mice show depressed cardiac function, at least in part, because of a general reduction in the membrane permeability to Ca2+. As less Ca2+ enters the cell through I(Ca), less Ca2+ is released through RyRs.
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Affiliation(s)
- Laetitia Pereira
- Institut National de la Santé et de la Recherche Médicale U-637, University of Montpellier 1, France
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Knudson JD, Rogers PA, Dincer UD, Bratz IN, Araiza AG, Dick GM, Tune JD. Coronary Vasomotor Reactivity to Endothelin-1 in the Prediabetic Metabolic Syndrome. Microcirculation 2006; 13:209-18. [PMID: 16627363 DOI: 10.1080/10739680600556894] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
OBJECTIVE The purpose of the present investigation was to test the hypothesis that coronary vasoconstrictor responses to endothelin-1 are augmented in the prediabetic metabolic syndrome. METHODS ELISA was used to measure plasma endothelin-1 and intracoronary endothelin-1 dose-response experiments were conducted in vivo on normal control and high-fat-fed prediabetic dogs. Additionally, isolated left circumflex (LCX) coronary arteries and arterioles (< 160 microm) were used for in vitro functional studies and molecular analyses (quantitative real-time PCR and Western blotting). RESULTS Plasma endothelin-1 concentrations were not different between control and prediabetic dogs. Coronary vasoconstriction to endothelin-1 was similar in control and prediabetic dogs, both in vivo and in isolated arterioles. Nonetheless, real-time PCR analysis revealed significant decreases in ET(A) receptor transcript levels in LCX coronary arteries and arterioles. Also, Western blotting revealed a significant decrease in ET(A) receptor protein in LCX coronary arteries. CONCLUSIONS The findings of the present investigation indicate that although ET(A) receptor-signaling is sensitized by induction of the metabolic syndrome, endothelin-mediated coronary vasoconstriction does not significantly contribute to coronary dysfunction at this early stage of prediabetes.
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Affiliation(s)
- Jarrod D Knudson
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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Knudson JD, Dincer UD, Dick GM, Shibata H, Akahane R, Saito M, Tune JD. Leptin resistance extends to the coronary vasculature in prediabetic dogs and provides a protective adaptation against endothelial dysfunction. Am J Physiol Heart Circ Physiol 2005; 289:H1038-46. [PMID: 15894577 DOI: 10.1152/ajpheart.00244.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hyperleptinemia, associated with prediabetes, is an independent risk factor for coronary artery disease and a mediator of coronary endothelial dysfunction. We previously demonstrated that acutely raising the leptin concentration to levels comparable with those observed in human obesity significantly attenuates coronary dilation/relaxation to acetylcholine (ACh) both in vivo in anesthetized dogs and in vitro in isolated canine coronary rings. Accordingly, the purpose of this investigation was to extend these studies to a model of prediabetes with chronic hyperleptinemia. In the present investigation, experiments were conducted on control and high-fat-fed dogs. High-fat feeding caused a significant increase (131%) in plasma leptin concentration. Furthermore, in high-fat-fed dogs, exogenous leptin did not significantly alter vascular responses to ACh in vivo or in vitro. Coronary vasodilator responses to ACh (0.3–30.0 μg/min) and sodium nitroprusside (1.0–100.0 μg/min) were not significantly different from those observed in control dogs. Also, high-fat feeding did not induce a switch to an endothelium-derived hyperpolarizing factor as a major mediator of muscarinic coronary vasodilation, because dilation to ACh was abolished by combined pretreatment with Nω-nitro-l-arginine methyl ester (150 μg/min ic) and indomethacin (10 mg/kg iv). Quantitative, real-time PCR revealed no significant difference in coronary artery leptin receptor gene expression between control and high-fat-fed dogs. In conclusion, high-fat feeding induces resistance to the coronary vascular effects of leptin, and this represents an early protective adaptation against endothelial dysfunction. The resistance is not due to altered endothelium-dependent or -independent coronary dilation, increased endothelium-derived hyperpolarizing factor, or changes in coronary leptin receptor mRNA levels.
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Affiliation(s)
- Jarrod D Knudson
- Department of Physiology, Louisiana State University Health Sciences Center, 1901 Perdido St., New Orleans, LA 70112-1393, USA
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Zhang C, Knudson JD, Setty S, Araiza A, Dincer UD, Kuo L, Tune JD. Coronary arteriolar vasoconstriction to angiotensin II is augmented in prediabetic metabolic syndrome via activation of AT1 receptors. Am J Physiol Heart Circ Physiol 2005; 288:H2154-62. [PMID: 15653764 DOI: 10.1152/ajpheart.00987.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The metabolic syndrome is associated with activation of the renin-angiotensin system. However, whether the coronary vascular response to ANG II is altered under this condition is unknown. Experiments were conducted in control and chronically high-fat-fed dogs with the prediabetic metabolic syndrome both in vitro (isolated coronary arterioles, 60-110 microm) and in vivo (anesthetized and conscious). We found that plasma renin activity and ANG II levels are elevated in high-fat-fed dogs and that this increase in ANG II is associated with a significant increase in ANG II-mediated coronary vasoconstriction in isolated coronary arterioles and in anesthetized open-chest dogs. The vasoconstriction to ANG II is abolished by ANG II type 1 (AT1) receptor blockade. In conscious chronically instrumented dogs, AT1 receptor blockade with telmisartan improved the balance between coronary blood flow and myocardial oxygen consumption in the high-fat-fed dogs but not in normal control dogs, i.e., the relationship between coronary venous Po2 and myocardial oxygen consumption was shifted upward, toward normal control values. Quantitative assessment of coronary arteriolar AT1 and ANG II type 2 (AT2) receptor mRNA levels by real-time PCR revealed no significant difference between normal control and high-fat-fed dogs; however, Western blot analysis showed a significant increase in AT1 receptor protein level with no change in AT2 receptor protein density. These findings indicate that AT1 receptor-mediated coronary constriction is augmented in the prediabetic metabolic syndrome and contributes to impaired control of coronary blood flow via increases in circulating ANG II and/or coronary arteriolar AT1 receptor density.
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Affiliation(s)
- Cuihua Zhang
- Department of Medical Physiology, Cardiovascular Research Institute, College of Medicine, Texas A&M University System Health Science Center, Temple, Texas, USA
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