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Locatelli J, Monteiro de Assis LV, Morais Araújo C, Carvalho Alzamora A, Wanderson Geraldo de Lima, Campagnole-Santos MJ, Augusto dos Santos R, Isoldi MC. Swimming training promotes cardiac remodeling and alters the expression of mRNA and protein levels involved in calcium handling in hypertensive rats. Life Sci 2015; 117:67-74. [PMID: 25283082 DOI: 10.1016/j.lfs.2014.09.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 09/09/2014] [Accepted: 09/20/2014] [Indexed: 11/26/2022]
Abstract
AIM The aim of this study was to identify the effects of swimming training on the mRNA expression and protein levels of the calcium handling proteins in the hearts of renovascular hypertensive rats submitted to swimming protocol during 6 weeks. MAIN METHODS Fischer rats with renovascular hypertension 2-kidney 1-clip (2K1C) and SHAM groups were divided among sedentary and exercised groups. The exercise protocol lasted for 6 weeks (1 h/day, 5×/week), and the mean arterial pressure, cardiomyocytes hypertrophy parameters, mRNA expression and protein levels of some calcium handling proteins in the left ventricle were evaluated. KEY FINDINGS Swimming training was able to reduce the levels of mean arterial pressure in the hypertensive group compared to 2K1C SED, and to promote cardiac hypertrophy in SHAM EX and 2K1C EX groups in comparison to the respective control groups. The mRNA levels of B-type natriuretic peptide were reduced in the 2K1C EX when compared to 2K1C SED. The mRNA and protein levels of the sarcoplasmic reticulum Ca2 +-ATPase increased after the swimming training in SHAM and 2K1C groups. The mRNA and protein levels of phospholamban, displayed an increase in their levels in the exercised SHAM and in hypertensive rats in comparison to their respective controls; while mRNA levels of Na+/Ca2 + exchanger was reduced in the left ventricle comparing to the sedentary hypertensive rats. SIGNIFICANCE Taken altogether, we provide evidence that the aerobic training may lead to cardiac remodeling, and modulate the calcium handling proteins expression in the heart of hypertensive rats.
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Magi S, Nasti AA, Gratteri S, Castaldo P, Bompadre S, Amoroso S, Lariccia V. Gram-negative endotoxin lipopolysaccharide induces cardiac hypertrophy: Detrimental role of Na+–Ca2+ exchanger. Eur J Pharmacol 2015; 746:31-40. [DOI: 10.1016/j.ejphar.2014.10.054] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 10/22/2014] [Accepted: 10/25/2014] [Indexed: 01/18/2023]
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Locatelli J, de Assis LVM, Isoldi MC. Calcium handling proteins: structure, function, and modulation by exercise. Heart Fail Rev 2014; 19:207-25. [PMID: 23436107 DOI: 10.1007/s10741-013-9373-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Heart failure is a serious public health issue with a growing prevalence, and it is related with the aging of the population. Hypertension is identified as the main precursor of left ventricular hypertrophy and therefore can lead to diastolic dysfunction and heart failure. Scientific studies have confirmed the beneficial effects of the physical exercise by reducing the blood pressure and improving the functional status of the heart in hypertension. Several proteins are involved in the mobilization of calcium during the coupling excitation-contraction process in the heart among those are sarcoplasmic reticulum Ca(2+)-ATPase, phospholamban, calsequestrin, sodium-calcium exchanger, L-type calcium's channel, and ryanodine receptors. Our goal is to address the beneficial effects of exercise on the calcium handling proteins in a heart with hypertension.
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Affiliation(s)
- Jamille Locatelli
- Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Ouro Prêto, Brazil
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Menick DR, Li MS, Chernysh O, Renaud L, Kimbrough D, Kasiganesan H, Mani SK. Transcriptional pathways and potential therapeutic targets in the regulation of Ncx1 expression in cardiac hypertrophy and failure. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:125-35. [PMID: 23224875 PMCID: PMC3624972 DOI: 10.1007/978-1-4614-4756-6_11] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Changes in cardiac gene expression contribute to the progression of heart failure by affecting cardiomyocyte growth, function, and survival. The Na(+)-Ca(2+) exchanger gene (Ncx1) is upregulated in hypertrophy and is often found elevated in end-stage heart failure. Studies have shown that the change in its expression contributes to contractile dysfunction. Several transcriptional pathways mediate Ncx1 expression in pathological cardiac remodeling. Both α-adrenergic receptor (α-AR) and β-adrenergic receptor (β-AR) signaling can play a role in the regulation of calcium homeostasis in the cardiomyocyte, but chronic activation in periods of cardiac stress contributes to heart failure by mechanisms which include Ncx1 upregulation. Our studies have even demonstrated that NCX1 can directly act as a regulator of "activity-dependent signal transduction" mediating changes in its own expression. Finally, we present evidence that histone deacetylases (HDACs) and histone acetyltransferases (HATs) act as master regulators of Ncx1 expression. We show that many of the transcription factors regulating Ncx1 expression are important in cardiac development and also in the regulation of many other genes in the so-called fetal gene program, which are activated by pathological stimuli. Importantly, studies have revealed that the transcriptional network regulating Ncx1 expression is also mediating many of the other changes in genetic remodeling contributing to the development of cardiac dysfunction and revealed potential therapeutic targets for the treatment of hypertrophy and failure.
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5
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Aurora AB, Mahmoud AI, Luo X, Johnson BA, van Rooij E, Matsuzaki S, Humphries KM, Hill JA, Bassel-Duby R, Sadek HA, Olson EN. MicroRNA-214 protects the mouse heart from ischemic injury by controlling Ca²⁺ overload and cell death. J Clin Invest 2012; 122:1222-32. [PMID: 22426211 PMCID: PMC3314458 DOI: 10.1172/jci59327] [Citation(s) in RCA: 307] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 02/01/2012] [Indexed: 12/17/2022] Open
Abstract
Early reperfusion of ischemic cardiac tissue remains the most effective intervention for improving clinical outcome following myocardial infarction. However, abnormal increases in intracellular Ca²⁺ during myocardial reperfusion can cause cardiomyocyte death and consequent loss of cardiac function, referred to as ischemia/reperfusion (IR) injury. Therapeutic modulation of Ca²⁺ handling provides some cardioprotection against the paradoxical effects of restoring blood flow to the heart, highlighting the significance of Ca²⁺ overload to IR injury. Cardiac IR is also accompanied by dynamic changes in the expression of microRNAs (miRNAs); for example, miR-214 is upregulated during ischemic injury and heart failure, but its potential role in these processes is unknown. Here, we show that genetic deletion of miR-214 in mice causes loss of cardiac contractility, increased apoptosis, and excessive fibrosis in response to IR injury. The cardioprotective roles of miR-214 during IR injury were attributed to repression of the mRNA encoding sodium/calcium exchanger 1 (Ncx1), a key regulator of Ca²⁺ influx; and to repression of several downstream effectors of Ca²⁺ signaling that mediate cell death. These findings reveal a pivotal role for miR-214 as a regulator of cardiomyocyte Ca²⁺ homeostasis and survival during cardiac injury.
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Affiliation(s)
- Arin B. Aurora
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Ahmed I. Mahmoud
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Xiang Luo
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Brett A. Johnson
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Eva van Rooij
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Satoshi Matsuzaki
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Kenneth M. Humphries
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Joseph A. Hill
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Rhonda Bassel-Duby
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Hesham A. Sadek
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
| | - Eric N. Olson
- Department of Molecular Biology and
Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
miRagen Therapeutics, Boulder, Colorado, USA.
Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA
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Lu YM, Huang J, Shioda N, Fukunaga K, Shirasaki Y, Li XM, Han F. CaMKIIδB mediates aberrant NCX1 expression and the imbalance of NCX1/SERCA in transverse aortic constriction-induced failing heart. PLoS One 2011; 6:e24724. [PMID: 21931829 PMCID: PMC3172303 DOI: 10.1371/journal.pone.0024724] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 08/19/2011] [Indexed: 12/04/2022] Open
Abstract
Ca2+/calmodulin-dependent protein kinase II δB (CaMKIIδB) is one of the predominant isoforms of CaMKII in the heart. The precise role of CaMKIIδB in the transcriptional cross-talk of Ca2+-handling proteins during heart failure remains unclear. In this work, we aim to determine the mechanism of CaMKIIδB in modulating the expression of sarcolemmal Na+–Ca2+ exchange (NCX1). We also aim to address the potential effects of calmodulin antagonism on the imbalance of NCX1 and sarcoendoplasmic reticulum Ca2+ ATPase (SERCA) during heart failure. Eight weeks after transverse aortic constriction (TAC)-induced heart failure in mice, we found that the heart weight/tibia length (HW/TL) ratio and the lung weight/body weight (LW/BW) ratio increased by 59% and 133%, respectively. We further found that the left ventricle-shortening fraction decreased by 40% compared with the sham-operated controls. Immunoblotting revealed that the phosphorylation of CaMKIIδB significantly increased 8 weeks after TAC-induced heart failure. NCX1 protein levels were also elevated, whereas SERCA2 protein levels decreased in the same animal model. Moreover, transfection of active CaMKIIδB significantly increased NCX1 protein levels in adult mouse cardiomyocytes via class IIa histone deacetylase (HDAC)/myocyte enhancer factor-2 (MEF2)-dependent signaling. In addition, pharmacological inhibition of calmodulin/CaMKIIδB activity improved cardiac function in TAC mice, which partially normalized the imbalance between NCX1 and SERCA2. These data identify NCX1 as a cellular target for CaMKIIδB. We also suggest that the CaMKIIδB-induced imbalance between NCX1 and SERCA2 is partially responsible for the disturbance of intracellular Ca2+ homeostasis and the pathological process of heart failure.
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Affiliation(s)
- Ying-Mei Lu
- Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Jiyun Huang
- Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, Zhejiang University, Hangzhou, China
| | - Norifumi Shioda
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Yasufumi Shirasaki
- Biological Research Laboratories, Daiichi-Sankyo Pharmaceutical Co., Ltd. Tokyo, Japan
| | - Xiao-ming Li
- Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Feng Han
- Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, Zhejiang University, Hangzhou, China
- * E-mail:
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Hudecova S, Sedlakova B, Kvetnansky R, Ondrias K, Krizanova O. Modulation of the sodium-calcium exchanger in the rat kidney by different sequential stressors. Stress 2010; 13:15-21. [PMID: 19658027 DOI: 10.3109/10253890902838835] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Stress, if exaggerated, modulates a variety of metabolic pathways and results in development of serious health consequences. The cell membrane sodium-calcium exchanger (NCX) is a major calcium extrusion system and is also modulated by stress. It has been shown previously that mRNA, protein levels and activity of the type 1 NCX (NCX1) in the left ventricle of the rat heart are increased by stressors, such as immobilization or hypoxia. In this study we investigated whether exposure to a subsequent different stressor can affect gene expression, protein level and activity of the NCX1 in rat kidney compared to exposure to only one type of stressor. In these experiments, we used immobilization and cold as the model stressors.We found that cold exposure at 4 degrees C for 24 h, when applied after immobilization repeated seven times, completely abolished the immobilization-induced increase in NCX mRNA level and after 7 days cold exposure the increases in NCX1 protein and activity in rat kidney were also abolished. Permanently increased NCX1 expression can result in imbalance of cellular calcium homeostasis and thus contribute to kidney dysfunction. Based on our results, we conclude that exposure to a cold stressor can have a protective effect on the kidney in rats exposed previously to repeated immobilization stress. This might be explained by differential stimulation of sympathetic neural and adrenal medullary responses by these different stressors.
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Affiliation(s)
- S Hudecova
- Institute ofMolecular Physiology and Genetics, Centre of Excellence for Cardiovascular Research, Slovak Academy of Sciences, Bratislava, Slovakia
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8
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Mani SK, Egan EA, Addy BK, Grimm M, Kasiganesan H, Thiyagarajan T, Renaud L, Brown JH, Kern CB, Menick DR. beta-Adrenergic receptor stimulated Ncx1 upregulation is mediated via a CaMKII/AP-1 signaling pathway in adult cardiomyocytes. J Mol Cell Cardiol 2009; 48:342-51. [PMID: 19945464 DOI: 10.1016/j.yjmcc.2009.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 11/18/2009] [Accepted: 11/18/2009] [Indexed: 10/20/2022]
Abstract
The Na(+)-Ca(2+) exchanger gene (Ncx1) is upregulated in hypertrophy and is often found elevated in end-stage heart failure. Studies have shown that the change in its expression contributes to contractile dysfunction. beta-Adrenergic receptor (beta-AR) signaling plays an important role in the regulation of calcium homeostasis in the cardiomyocyte, but chronic activation in periods of cardiac stress contributes to heart failure by mechanisms which include Ncx1 upregulation. Here, using a Ca(2+)/calmodulin-dependent protein kinase II (CaMKIIdelta(c)) null mouse, we demonstrate that beta-AR-stimulated Ncx1 upregulation is dependent on CaMKII. beta-AR-stimulated Ncx1 expression is mediated by activator protein 1 (AP-1) factors and is independent of cAMP-response element-binding protein (CREB) activation. The MAP kinases (ERK1/2, JNK and p38) are not required for AP-1 factor activation. Chromatin immunoprecipitation demonstrates that beta-AR stimulation activates the ordered recruitment of JunB homodimers, which then are replaced by c-Jun homodimers binding to the proximal AP-1 elements of the endogenous Ncx1 promoter. In conclusion, this work has provided insight into the intracellular signaling pathways and transcription factors regulating Ncx1 gene expression in a chronically beta-AR-stimulated heart.
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Affiliation(s)
- Santhosh K Mani
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, 114 Doughty Street, Box 250773, Charleston, SC 29425, USA
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9
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Xu L, Kappler CS, Mani SK, Shepherd NR, Renaud L, Snider P, Conway SJ, Menick DR. Chronic administration of KB-R7943 induces up-regulation of cardiac NCX1. J Biol Chem 2009; 284:27265-72. [PMID: 19661061 DOI: 10.1074/jbc.m109.022855] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NCX1 (sodium-calcium exchanger) is up-regulated in human heart failure and in many animal models of heart failure. The potential benefits and risks of therapeutically blocking NCX1 in heart failure and during ischemia-reperfusion are being actively investigated. In this study, we demonstrate that prolonged administration of the NCX1 inhibitor KB-R7943 resulted in the up-regulation of Ncx1 gene expression in both isolated adult cardiomyocytes and intact mouse hearts. Ncx1 up-regulation is mediated by the activation of p38. Importantly, p38 is not activated by KB-R7943 treatment in heart tubes from Ncx1(-/-) mice at 9.5 days postcoitum but is activated in heart tubes from Ncx1(+/+) mice. p38 activation does not appear to be in response to changes in cytosolic calcium concentration, [Ca(2+)](i). Interestingly, chronic KB-R7943 treatment in mice leads to the formation of an NCX1-p38 complex. Our study demonstrates for the first time that the electrogenic sarcolemma membrane cardiac NCX1 can act as a regulator of "activity-dependent signal transduction" leading to changes in gene expression.
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Affiliation(s)
- Lin Xu
- Department of Medicine, Gazes Cardiac Research Institute, Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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10
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Diedrichs H, Frank K, Schneider CA, Burst V, Hagemeister J, Zobel C, Müller-Ehmsen J. Increased functional importance of the Na,Ca-exchanger in contracting failing human myocardium but unchanged activity in isolated vesicles. Int Heart J 2008; 48:755-66. [PMID: 18160767 DOI: 10.1536/ihj.48.755] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The present study aimed to investigate the hypothesis that the function of the Na,Ca-exchanger (NCX) is of higher importance for contractility and Ca(2+)-homeostasis in left ventricle from terminally failing than from nonfailing human hearts. The effect of decreasing extracellular [Na](e) (140 to 25 mmol/L) on force of contraction in isolated left ventricular papillary muscle strips was studied as a reflection of NCX function in multicellular preparations (terminally failing, DCM, dilated cardiomyopathy, NYHA IV, n = 13; nonfailing, NF, donor hearts, n = 10). Decreasing [Na](e) has previously been shown to increase contractility in vitro secondary to a decreased Ca(2+)-extrusion by the NCX. In addition, the NCX activity was measured as Na(+)-dependent (45)Ca(2+)-uptake into isolated myocardial vesicles as a function of time and Ca(2+)-concentration (DCM n = 8, NF n = 8). Decreasing [Na](e) enhanced the contractility of papillary muscle strips in both DCM and NF, but the contractility of DCM was increased at smaller reductions of [Na](e) than NF. The NCX activity in isolated myocardial vesicles was unchanged as a function of time (T(1/2): DCM 2.4 +/- 0.3 s versus NF 2.5 +/- 0.3 s) and as a function of Ca(2+) (DCM 0.99 +/- 0.08 versus NF 0.96 +/- 0.07 nmol/mg protein x 3 s, K(1/2): DCM 39.2 microM versus NF 38.3 microM). These results demonstrate a higher sensitivity of the failing human myocardium towards Na,Ca-exchanger mediated positive inotropic effects, suggesting a higher significance of the Na,Ca-exchanger for the extrusion of Ca(2+)-ions in intact failing versus nonfailing human myocardium. Since the activity and the Ca (2+)-affinity of the Na,Ca-exchanger in isolated vesicles was unchanged, we propose that alterations in Ca(2+)-and Na(+)-homeostasis (due to impaired function of the sarcoplasmic reticulum and the Na(+), K(+)-ATPase) or the prolonged action potential are the reason for this observation.
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Affiliation(s)
- Holger Diedrichs
- Clinic III for Internal Medicine, University of Cologne, Cologne, Germany
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Menick DR, Renaud L, Buchholz A, Müller JG, Zhou H, Kappler CS, Kubalak SW, Conway SJ, Xu L. Regulation of Ncx1 gene expression in the normal and hypertrophic heart. Ann N Y Acad Sci 2007; 1099:195-203. [PMID: 17446459 PMCID: PMC3096001 DOI: 10.1196/annals.1387.058] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The Na+/Ca2+ exchanger (NCX1) is crucial in the regulation of [Ca2+]i in the cardiac myocyte. The exchanger is upregulated in cardiac hypertrophy, ischemia, and failure. This upregulation can have an effect on Ca2+ transients and possibly contribute to diastolic dysfunction and an increased risk of arrhythmias. Studies from both in vivo and in vitro model systems have provided an initial skeleton of the potential signaling pathways that regulate the exchanger during development, growth, and hypertrophy. The Ncx1 gene is upregulated in response to alpha-adrenergic stimulation. We have shown that this is via p38alpha activation of transcription factors binding to the Ncx1 promotor at the -80 CArG element. Interestingly, most of the elements, including the CArG element, which we have demonstrated to be important for regulation of Ncx1 expression are in the proximal 184 bp of the promotor. Using a transgenic mouse, we have shown that the proximal 184 bp is sufficient for expression of reporter genes in adult cardiomyocytes and for the correct spatiotemporal pattern of Ncx1 expression in development but not for upregulation in response to pressure overload.
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Affiliation(s)
- Donald R Menick
- Division of Cardiology, Department of Medicine, Gazes Cardiac Research Institute, Medical University of South Carolina, 114 Doughty St., Charleston, SC 29425, USA.
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12
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He LP, Cleemann L, Soldatov NM, Morad M. Molecular determinants of cAMP-mediated regulation of the Na+-Ca2+ exchanger expressed in human cell lines. J Physiol 2003; 548:677-89. [PMID: 12626672 PMCID: PMC2342879 DOI: 10.1113/jphysiol.2002.036426] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The cardiac Na+-Ca2+ exchanger (NCX1) is one of the major sarcolemmal Ca2+ transporters of cardiomyocytes. Structure-function studies suggest that beta-adrenergic inhibition of NCX1, as reported for frog, but not mammalian hearts, may be associated with a unique splice variant of frog cardiac NCX1 where insertion of an extra exon completes the coding of a nucleotide binding P-loop. To test the involvement of the P-loop in cAMP-mediated regulation of NCX1 we used four stably transfected human cell lines (a previously established line of baby hamster kidney (BHK) cells and three new lines of human embryonic kidney (HEK) cells) expressing: (1) wild-type dog NCX1 (dog NCX1); (2) wild-type frog NCX1 (frog NCX1); (3) chimeric frog-dog NCX1 incorporating the completed P-loop from the frog NCX1 into the dog NCX1 sequence (frog/dog NCX1); and (4) a mutated frog NCX1 where a putative protein kinase A (PKA) site was disrupted by substitution of a single serine residue with glycine (S374G frog NCX1). Structural expression of these NCX1 constructs was confirmed using Western blot analysis of extracted proteins and immunofluorescence imaging. The NCX1-generated current (INa-Ca) was reliably measured in cells expressing dog (2.0 +/- 0.15 pA pF-1), frog (0.6 +/- 0.1 pA pF-1) and frog/dog (0.6 +/- 0.1 pA pF-1) NCX1, but less so in those expressing S374G frog NCX1 (0.3 +/- 0.1 pA pF-1). Addition of 100 microM 8-bromoadenosine 3',5' cyclic monophosphate (8-Br-cAMP) suppressed INa-Ca of frog and frog/dog NCX1 by 60-80 %. The suppression of INa-Ca was smaller and transient in cells expressing S374G frog NCX1, and absent in cells expressing dog NCX1. Intracellular Ca2+ (Ca2+i)-transients, activated by rapid withdrawal of Na+, were also downregulated in the frog and frog/dog NCX1 and to a smaller and transient extent in S374G frog NCX1. Our findings suggest that the suppressive effect of beta-adrenergic agonists requires the presence of the P-loop domain of the frog NCX1, and provide evidence that the putative PKA site, present in both dog and frog NCX1, might also be critical in the cAMP-mediated regulation of the exchanger.
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Affiliation(s)
- Li-Ping He
- Georgetown University, 4000 Reservoir Road NW, Washington, DC 20007, USA
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Miyamoto S, Zhu BM, Kamiya K, Nagasawa Y, Hashimoto K. KB-R7943, a Na+/Ca2+ exchange inhibitor, does not suppress ischemia/reperfusion arrhythmias nor digitalis arrhythmias in dogs. JAPANESE JOURNAL OF PHARMACOLOGY 2002; 90:229-35. [PMID: 12499577 DOI: 10.1254/jjp.90.229] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate) has been used as a pharmacological tool to block the Ca(2+) influx-mode of the Na(+)/Ca(2+) exchanger, which is thought to contribute to ischemia/reperfusion and digitalis arrhythmias. We examined effects of KB-R7943 on ischemia/reperfusion arrhythmias in beagle dogs anesthetized with sodium pentobarbital. Lead II ECG and BP were measured. KB-R7943 or the solvent (10% DMSO) was injected i.v. as a bolus, and 5 min later, the left anterior descending coronary artery was occluded for 30 min followed by reperfusion. KB-R7943 at 5 or 10 mg/kg increased BP without changing ECG parameters including the heart rate. Although 5 mg/kg KB-R7943 deceased the number of arrhythmic beats during the ischemic period, mortality due to ischemia/reperfusion was not decreased by KB-R7943 (5 and 10 mg/kg). KB-R7943 at 5 mg/kg also did not suppress the ouabain-induced arrhythmias. These negative results suggest that Na(+)/Ca(2+) exchange inhibition may not be a useful strategy of suppressing arrhythmias.
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Affiliation(s)
- Shigeki Miyamoto
- Department of Pharmacology, University of Yamanashi, Faculty of Medicine, Nakakoma-gun, Yamanashi, Japan
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14
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Menick DR, Xu L, Kappler C, Jiang W, Withers P, Shepherd N, Conway SJ, Müller JG. Pathways regulating Na+/Ca2+ exchanger expression in the heart. Ann N Y Acad Sci 2002; 976:237-47. [PMID: 12502566 DOI: 10.1111/j.1749-6632.2002.tb04746.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Na(+)/Ca(2+) exchanger (NCX1) is regulated at the transcriptional level in cardiac hypertrophy, ischemia, and failure. Following pressure overload, activation of MAPKs coincides with the kinetics of NCX1 gene upregulation in adult cardiocytes. Using adenoviral gene delivery, we begin to identify the molecular pathways responsible for upregulation of the exchanger gene. Inhibition of ERK with the MEK inhibitor UO126, the ERK protein phosphatase MKP-3, inhibited ERK activation, but only inhibited alpha-adrenergic-induced NCX1 upregulation by 30%. Overexpression of DN-JNK lowered basal NCX1 expression. Overexpression of activated MKK-3 was sufficient for alpha-adrenergic-stimulated upregulation of the reporter gene. Together, this data indicates that (1) JNK mediates basal cardiac expression of the NCX1 gene, (2) ERK and p38 play a role in alpha-adrenergic-stimulated NCX1 upregulation, and (3) p38 activation alone is sufficient for NCX1 upregulation.
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Affiliation(s)
- Donald R Menick
- Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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15
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Müller JG, Isomatsu Y, Koushik SV, O'Quinn M, Xu L, Kappler CS, Hapke E, Zile MR, Conway SJ, Menick DR. Cardiac-specific expression and hypertrophic upregulation of the feline Na(+)-Ca(2+) exchanger gene H1-promoter in a transgenic mouse model. Circ Res 2002; 90:158-64. [PMID: 11834708 DOI: 10.1161/hh0202.103231] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The NCX1 gene contains three promoters (H1, K1, and Br1), and as a result of alternative promoter usage and alternative splicing, there are multiple tissue-specific variants of the Na(+)-Ca(2+) exchanger. We have proposed that for NCX1, the H1 promoter regulates expression in the heart, the K1 promoter regulates expression in the kidney, and the Br1 promoter regulates expression in the brain as well as low-level ubiquitous expression. Here, using a transgenic mouse model, we test the role of the DNA region including -1831 to 67 bp of intron 1, encompassing exon H1 of the feline NCX1 gene (NCX1H1). The NCX1H1 promoter was sufficient for driving the normal spatiotemporal pattern of NCX1 expression in cardiac development. The luciferase reporter gene was expressed in a heart-restricted pattern both in early embryos (embryonic days 8 to 14) and in later embryos (after embryonic day 14), when NCX1 is also expressed in other tissues. In the adult, no luciferase activity was detected in the kidney, liver, spleen, uterus, or skeletal muscle; minimal activity was detected in the brain; and very high levels of luciferase expression were detected in the heart. Transverse aortic constriction-operated mice showed significantly increased left ventricular mass after 7 days. In addition, there was a 2-fold upregulation of NCX1H1 promoter activity in the left ventricle in animals after 7 days of pressure overload compared with both control and sham-operated animals. This work demonstrates that the NCX1H1 promoter directs cardiac-specific expression of the exchanger in both the embryo and adult and is also sufficient for the upregulation of NCX1 in response to pressure overload.
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Affiliation(s)
- Joachim G Müller
- Gazes Cardiac Research Institute and Division of Cardiology, Medical University of South Carolina, Ralph H. Johnson Department of Veterans Affairs, Charleston, SC 29425, USA
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16
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Boateng SY, Naqvi RU, Koban MU, Yacoub MH, MacLeod KT, Boheler KR. Low-dose ramipril treatment improves relaxation and calcium cycling after established cardiac hypertrophy. Am J Physiol Heart Circ Physiol 2001; 280:H1029-38. [PMID: 11179044 DOI: 10.1152/ajpheart.2001.280.3.h1029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rapid cooling contractures were used in this study to test whether low-dose ramipril improves sarcoplasmic reticulum (SR) Ca(2+) uptake and Na(+)/Ca(2+) exchanger function in isolated hypertrophied rat myocytes. Compensated cardiac hypertrophy was induced by abdominal aortic constriction for 5 wk followed by administration of ramipril (50 microg x kg(-1) x day(-1)) or vehicle for 4 wk. Myocyte cell length and cell width were significantly (P < 0.05) increased in both hypertrophied groups (+/-ramipril). Myocytes were loaded with indo 1, and relaxation was investigated after rapid cooling. Hypertrophied myocyte relaxation in Na(+)-free/Ca(2+)-free solution was 63% slower (P < 0.01) and the fall in intracellular Ca(2+) was 60% slower (P < 0.05) than the relaxation of control cells. After ramipril treatment both relaxation and the decline in intracellular Ca(2+) returned to control rates through improved SR Ca(2+)-ATPase function. Relaxation in caffeine showed no change after hypertrophy; however, after ramipril treatment the time to 50% relaxation in caffeine decreased by 30% (P < 0.05). The improvement in Ca(2+) extrusion across the sarcolemmal membrane occurred independently of changes in Na(+)/Ca(2+) exchanger mRNA and protein abundance. These data demonstrate that ramipril improves both SR-dependent and non-SR-dependent calcium cycling after established cardiac hypertrophy. However, the improvements in function are independent of transcriptional activation and likely to involve altered intracellular ion concentrations.
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Affiliation(s)
- S Y Boateng
- Department of Cardiothoracic Surgery, National Heart and Lung Institute, Imperial College School of Medicine, London SW3 6LY, United Kingdom
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17
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Espinosa L, Chouabe C, Morales A, Lachuer J, Georges B, Fatemi M, Terrenoire C, Tourneur Y, Bonvallet R. Increased sodium-calcium exchange current in right ventricular cell hypertrophy induced by simulated high altitude in adult rats. J Mol Cell Cardiol 2000; 32:639-53. [PMID: 10756120 DOI: 10.1006/jmcc.2000.1106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ventricular hypertrophy is associated with an increase in action potential (AP) duration which is potentially arrhythmogenic. The implication of the Na-Ca exchange current (I(Na-Ca)) in the lengthening of the AP is controversial. The role of this current in the increased duration of the low plateau of the AP in hypertrophied adult rat ventricular myocytes by simulated chronic high-altitude exposure ( approximately 4500 m) was evaluated. Electrophysiological experiments were carried out on isolated right ventricular myocytes from exposed and control rats with the perforated patch or the conventional whole-cell technique in current or in voltage clamp condition. With the two techniques, a significant increase of the low plateau duration was observed in hypertrophied myocytes as compared to controls. The low plateau in hypertrophied myocytes was depressed when Na was replaced by Li and was no longer recorded when intracellular Ca was buffered with EGTA. Inward tail currents, evoked either on repolarization to -80 mV following a depolarizing pulse to +10 mV or by interrupted AP technique, were greater in hypertrophied than in control myocytes and were abolished when Na was replaced by Li or when intracellular Ca was buffered with EGTA, indicating an increased Na-Ca exchange activity. The Li-sensitive current-voltage curves, obtained by a voltage clamp ramp protocol with an intracellular calcium buffered solution, were not significantly different in both hypertrophied and control myocytes, suggesting no modification in the density of the Na-Ca exchange protein. This was corroborated by the lack of difference in NCX1 mRNA levels between right ventricles from control and exposed rats. We conclude that increased duration of the low plateau of rat ventricular AP in altitude cardiac hypertrophy may be attributed to an increase of the inward I(Na-Ca). This augmented I(Na-Ca)may result from a modification in the intracellular Ca homeostasis.
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Affiliation(s)
- L Espinosa
- UMR CNRS 5578, Physiologie des Régulations Energétiques, Cellulaires et Moléculaires, Campus La Doua, Villeurbanne, 69622, France
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18
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Anderson SE, Gray SD, Atherley R, Cala PM. Na-dependent changes in intracellular Ca in spontaneously hypertensive rat hearts. Comp Biochem Physiol A Mol Integr Physiol 1999; 123:299-309. [PMID: 10501022 DOI: 10.1016/s1095-6433(99)00071-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
To determine whether Na/Ca exchange is altered in primary hypertension, Na-dependent changes in intracellular Ca, ([Ca]i), were measured in isolated perfused hearts from Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Intracellular Na, (Nai, mEq/kg dry wt), and [Ca]i were measured by NMR spectroscopy. Control [Ca]i was less in WKY than SHR (176 +/- 18 vs 253 +/- 21 nmol/l; mean +/- S.E., P < 0.05), whereas Nai was not significantly different. One explanation for this is that net Na/Ca exchange flux is decreased in SHR. If this hypothesis is correct, the rate of Ca uptake in SHR should be less than WKY when Na/Ca exchange is reversed by decreasing the transmembrane Na gradient. The Na gradient was reduced by decreasing extracellular Na, ([Na]o) and/or by increasing [Na]i. To increase [Na]i, Na uptake was stimulated by acidification while Na extrusion by Na/K ATPase was inhibited by K-free perfusion. Seventeen minutes after acidification, Nai had increased but was not significantly different in SHR and WKY (18.0 +/- 2.3 to 57.4 +/- 7.6 vs 20.3 +/- 0.6 to 66.5 +/- 4.8 mEq/kg dry wt, respectively). Yet [Ca]i was greater in WKY than SHR (1768 +/- 142 vs 1201 +/- 90 nmol/l; P < 0.05). [Ca]i was also measured after decreasing [Na]o from 141 to 30 mmol/l. Fifteen minutes after reducing [Na]o, [Ca]i was greater in WKY than SHR (833 +/- 119 vs 425 +/- 94 nmol/l; P < 0.05). Thus for both protocols, decreasing the transmembrane Na gradient led to increased [Ca]i in both SHR and WKY, but less increase in SHR. The results are consistent with the hypothesis that Na/Ca exchange activity is less in SHR than WKY myocardium.
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Affiliation(s)
- S E Anderson
- Department of Human Physiology, University of California, Davis 95616-8644, USA.
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Cheng G, Hagen TP, Dawson ML, Barnes KV, Menick DR. The role of GATA, CArG, E-box, and a novel element in the regulation of cardiac expression of the Na+-Ca2+ exchanger gene. J Biol Chem 1999; 274:12819-26. [PMID: 10212268 DOI: 10.1074/jbc.274.18.12819] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cardiac Na+-Ca2+ exchanger (NCX1) is the principal Ca2+ efflux mechanism in cardiocytes. The exchanger is up-regulated in both cardiac hypertrophy and failure. In this report, we identify the cis-acting elements that control cardiac expression and alpha-adrenergic up-regulation of the exchanger gene. Deletion analysis revealed that a minimal cardiac promoter fragment from -184 to +172 is sufficient for cardiac expression and alpha-adrenergic stimulation. Mutational analysis revealed that both the CArG element at -80 and the GATA element at -50 were required for cardiac expression. Gel mobility shift assay supershift analysis demonstrated that the serum response factor binds to the CArG element and GATA-4 binds to the GATA element. Point mutations in the -172 E-box demonstrated that it was required for alpha-adrenergic induction. In addition, deletion analysis revealed one or more enhancer elements in the first intron (+103 to +134) that are essential for phenylephrine up-regulation but bear no homology to any known transcription element. Therefore, this work demonstrates that SRF and GATA-4 are critical for NCX1 expression in neonatal cardiomyocytes and that the -172 E-box in addition to a novel enhancer element(s) are required for phenylephrine up-regulation of NCX1 and may mediate its hypertrophic up-regulation.
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Affiliation(s)
- G Cheng
- Cardiology Division, Department of Medicine, and the Gazes Cardiac Research Institute, Medical University of South Carolina, Charleston, South Carolina, 29425-2221, USA
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20
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Lu HR, Yang P, Remeysen P, Saels A, Dai DZ, De Clerck F. Ischemia/reperfusion-induced arrhythmias in anaesthetized rats: a role of Na+ and Ca2+ influx. Eur J Pharmacol 1999; 365:233-9. [PMID: 9988107 DOI: 10.1016/s0014-2999(98)00878-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We hypothesized that by limiting the Na+ and Ca2+ loading by a blocker/inhibitor of the Na+ channel (lidocaine), Na+ overload (R56865: N-[1-[4-(4-fluorophenoxy)butyl]-4-piperidinyl]-N-methyl-2-benzothiazo lamine), Ca2+ channel (verapamil), Na+ -H+ exchange (ethylisobutyl amiloride) or of Na+ -Ca2+ exchange (No. 7943: 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulfonate), it should be possible to reduce ischemia/reperfusion-induced arrhythmias. To test this hypothesis, we used anaesthetized rats subjected to 5 min of coronary artery occlusion followed by 10 min of reperfusion to study antiarrhythmic effects of above compounds on reperfusion-induced ventricular premature beats, ventricular tachycardia, and reversible and irreversible ventricular fibrillation. Compound or saline was administered as an intravenous bolus injection at 5 min before ischemia. Pretreatment with lidocaine (5 mg/kg), verapamil (0.63 mg/kg), R56865 (0.63 mg/kg) or ethylisobutyl amiloride (1.25 mg/kg) significantly reduced or abolished all types of ventricular arrhythmias. However, pretreatment with verapamil was associated with second or third degree heart block in 3 out of 12 animals. Pretreatment with No. 7943 did not significantly influence the ischemia/reperfusion-induced ventricular arrhythmias. The present results suggest that both intracellular Na+ -and Ca2+ -loading play important roles in reperfusion-induced ventricular arrhythmias and the inhibition of Na+ -Ca2+ exchange to limit Ca2+ loading probably does not play any important role in ischemia/reperfusion-induced arrhythmias in anaesthetized rats.
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Affiliation(s)
- H R Lu
- Department of Cardiovascular and Pulmonary Pharmacology, Janssen Research Foundation, Beerse, Belgium
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21
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Scheller T, Kraev A, Skinner S, Carafoli E. Cloning of the multipartite promoter of the sodium-calcium exchanger gene NCX1 and characterization of its activity in vascular smooth muscle cells. J Biol Chem 1998; 273:7643-9. [PMID: 9516469 DOI: 10.1074/jbc.273.13.7643] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sodium-calcium exchange activity is mediated by proteins encoded in a small gene family, of which the gene NCX1 is ubiquitously expressed in mammalian tissues. In this study, the multipartite promoter of this gene was analyzed in the human and rat genomes by means of DNA cloning, reverse transcriptase-polymerase chain reaction, and transient transfection of fusion constructs with the firefly luciferase gene into cultured rat aortic smooth muscle cells. The gene-proximal promoter, located 30 kilobase pairs (kb) away from the first coding exon 2, has features of a GC-rich housekeeping promoter and is apparently always active; in specific tissues, however, it is augmented by one or two additional promoters, located either within 1.5 kb upstream of it, or 35 kb upstream. The gene proximal promoter shows the highest activity in aortic smooth muscle cells. In mammalian species transcripts from all three promoters undergo splicing via an intermediate, containing two noncoding exons, of which the downstream one is normally not present in the terminal splicing product.
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Affiliation(s)
- T Scheller
- Institute of Biochemistry, Swiss Federal Institute of Technology (ETH), 8092 Zürich, Switzerland
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22
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Nicholas SB, Yang W, Lee SL, Zhu H, Philipson KD, Lytton J. Alternative promoters and cardiac muscle cell-specific expression of the Na+/Ca2+ exchanger gene. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:H217-32. [PMID: 9458871 DOI: 10.1152/ajpheart.1998.274.1.h217] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Many studies have investigated the regulation of the Na+/ Ca2+ exchanger, NCX1, but limited data exist on transcriptional regulation of the NCX1 gene. We have identified the transcription start sites of three tissue-specific alternative promoters of NCX1 transcripts from rat heart, kidney, and brain. We have characterized the cardiac NCX1 promoter, from which the most abundant quantities of NCX1 transcripts are expressed. Transfection of primary cardiac myocytes, CHO cells, and COS-7 cells with overlapping genomic DNA fragments spanning the NCX1 cardiac transcription start site has uncovered a cardiac cell-specific minimum promoter from -137 to +85. The cardiac NCX1 promoter is TATA-less but has putative binding sites for cardiac-specific GATA factors, an E box, and an Inr as well as multiple active enhancers. The kidney NCX1 promoter has a typical TATA box and binding sites for several tissue-specific factors. The brain NCX1 promoter is very GC-rich and possesses several Sp-1 binding sites consistent with its ubiquitous expression.
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Affiliation(s)
- S B Nicholas
- Department of Physiology, University of California, School of Medicine, Los Angeles 90095-1760, USA
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23
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Barnes KV, Cheng G, Dawson MM, Menick DR. Cloning of Cardiac, Kidney, and Brain Promoters of the Feline ncx1 Gene. J Biol Chem 1997. [DOI: 10.1074/jbc.272.17.11510] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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