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Lee TI, Trang NN, Lee TW, Higa S, Kao YH, Chen YC, Chen YJ. Ketogenic Diet Regulates Cardiac Remodeling and Calcium Homeostasis in Diabetic Rat Cardiomyopathy. Int J Mol Sci 2023; 24:16142. [PMID: 38003332 PMCID: PMC10671812 DOI: 10.3390/ijms242216142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
A ketogenic diet (KD) might alleviate patients with diabetic cardiomyopathy. However, the underlying mechanism remains unclear. Myocardial function and arrhythmogenesis are closely linked to calcium (Ca2+) homeostasis. We investigated the effects of a KD on Ca2+ homeostasis and electrophysiology in diabetic cardiomyopathy. Male Wistar rats were created to have diabetes mellitus (DM) using streptozotocin (65 mg/kg, intraperitoneally), and subsequently treated for 6 weeks with either a normal diet (ND) or a KD. Our electrophysiological and Western blot analyses assessed myocardial Ca2+ homeostasis in ventricular preparations in vivo. Unlike those on the KD, DM rats treated with an ND exhibited a prolonged QTc interval and action potential duration. Compared to the control and DM rats on the KD, DM rats treated with an ND also showed lower intracellular Ca2+ transients, sarcoplasmic reticular Ca2+ content, sodium (Na+)-Ca2+ exchanger currents (reverse mode), L-type Ca2+ contents, sarcoplasmic reticulum ATPase contents, Cav1.2 contents. Furthermore, these rats exhibited elevated ratios of phosphorylated to total proteins across multiple Ca2+ handling proteins, including ryanodine receptor 2 (RyR2) at serine 2808, phospholamban (PLB)-Ser16, and calmodulin-dependent protein kinase II (CaMKII). Additionally, DM rats treated with an ND demonstrated a higher frequency and incidence of Ca2+ leak, cytosolic reactive oxygen species, Na+/hydrogen-exchanger currents, and late Na+ currents than the control and DM rats on the KD. KD treatment may attenuate the effects of DM-dysregulated Na+ and Ca2+ homeostasis, contributing to its cardioprotection in DM.
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Affiliation(s)
- Ting-I Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan; (T.-I.L.); (T.-W.L.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | | | - Ting-Wei Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan; (T.-I.L.); (T.-W.L.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Makiminato Urasoe City, Okinawa 901-2131, Japan;
| | - Yu-Hsun Kao
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei 11490, Taiwan
| | - Yi-Jen Chen
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Cardiovascular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei 11696, Taiwan
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2
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Huang SY, Lu YY, Lin YK, Chen YC, Chen YA, Chung CC, Lin WS, Chen SA, Chen YJ. Ceramide modulates electrophysiological characteristics and oxidative stress of pulmonary vein cardiomyocytes. Eur J Clin Invest 2022; 52:e13690. [PMID: 34662431 DOI: 10.1111/eci.13690] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Ceramide is involved in regulating metabolism and energy expenditure, and its abnormal myocardial accumulation may contribute to heart injury or lipotoxic cardiomyopathy. Whether ceramide can modulate the electrophysiology of pulmonary veins (PVs) remains unknown. MATERIALS AND METHODS We used conventional microelectrodes to measure the electrical activity of isolated rabbit PV tissue preparations before and after treatment with various concentrations of ceramide with or without H2 O2 (2 mM), MitoQ, wortmannin or 740 YP. A whole-cell patch clamp and fluorescence imaging were used to record the ionic currents, calcium (Ca2+ ) transients, and intracellular reactive oxygen species (ROS) and sodium (Na+ ) in isolated single PV cardiomyocytes before and after ceramide (1 μM) treatment. RESULTS Ceramide (0.1, 0.3, 1 and 3 μM) reduced the beating rate of PV tissues. Furthermore, ceramide (1 μM) suppressed the 2 mM H2 O2 -induced faster PV beating rate, triggered activities and burst firings, which were further reduced by MitoQ. In the presence of wortmannin, ceramide did not change the PV beating rate. The H2 O2 -induced faster PV beating rate could be counteracted by MitoQ or wortmannin with no additive effect from the ceramide. Ceramide inhibited pPI3K. Ceramide reduced Ca2+ transients, sarcoplasmic reticulum Ca2+ contents, L-type Ca2+ currents, Na+ currents, late Na+ currents, Na+ -hydrogen exchange currents, and intracellular ROS and Na+ in PV cardiomyocytes, but did not change Na+ -Ca2+ exchange currents. CONCLUSION C2 ceramide may exert the distinctive electrophysiological effect of modulating PV activities, which may be affected by PI3K pathway-mediated oxidative stress, and might play a role in the pathogenesis of PV arrhythmogenesis.
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Affiliation(s)
- Shih-Yu Huang
- Division of Cardiac Electrophysiology, Cardiovascular Center, Cathay General Hospital, Taipei, Taiwan.,School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Yen-Yu Lu
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.,Division of Cardiology, Sijhih Cathay General Hospital, New Taipei City, Taiwan
| | - Yung-Kuo Lin
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan
| | - Yi-Ann Chen
- Division of Nephrology, Sijhih Cathay General Hospital, New Taipei City, Taiwan
| | - Cheng-Chih Chung
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Wei-Shiang Lin
- Division of Cardiology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Ann Chen
- Division of Cardiology, Department of Medicine, Heart Rhythm Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Yi-Jen Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Cardiovascular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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3
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Del Canto I, Santamaría L, Genovés P, Such-Miquel L, Arias-Mutis O, Zarzoso M, Soler C, Parra G, Tormos Á, Alberola A, Such L, Chorro FJ. Effects of the Inhibition of Late Sodium Current by GS967 on Stretch-Induced Changes in Cardiac Electrophysiology. Cardiovasc Drugs Ther 2019; 32:413-425. [PMID: 30173392 DOI: 10.1007/s10557-018-6822-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Mechanical stretch increases sodium and calcium entry into myocytes and activates the late sodium current. GS967, a triazolopyridine derivative, is a sodium channel blocker with preferential effects on the late sodium current. The present study evaluates whether GS967 inhibits or modulates the arrhythmogenic electrophysiological effects of myocardial stretch. METHODS Atrial and ventricular refractoriness and ventricular fibrillation modifications induced by acute stretch were studied in Langendorff-perfused rabbit hearts (n = 28) using epicardial multiple electrodes and high-resolution mapping techniques under control conditions and during the perfusion of GS967 at different concentrations (0.03, 0.1, and 0.3 μM). RESULTS On comparing ventricular refractoriness, conduction velocity and wavelength obtained before stretch had no significant changes under each GS967 concentration while atrial refractoriness increased under GS967 0.3 μM. Under GS967, the stretch-induced changes were attenuated, and no significant differences were observed between before and during stretch. GS967 0.3 μM diminished the normal stretch-induced changes resulting in longer (less shortened) atrial refractoriness (138 ± 26 ms vs 95 ± 9 ms; p < 0.01), ventricular refractoriness (155 ± 18 ms vs 124 ± 16 ms; p < 0.01) and increments in spectral concentration (23 ± 5% vs 17 ± 2%; p < 0.01), the fifth percentile of ventricular activation intervals (46 ± 8 ms vs 31 ± 3 ms; p < 0.05), and wavelength of ventricular fibrillation (2.5 ±0.5 cm vs 1.7 ± 0.3 cm; p < 0.05) during stretch. The stretch-induced increments in dominant frequency during ventricular fibrillation (control = 38%, 0.03 μM = 33%, 0.1 μM = 33%, 0.3 μM = 14%; p < 0.01) and the stretch-induced increments in arrhythmia complexity index (control = 62%, 0.03μM = 41%, 0.1 μM = 32%, 0.3 μM = 16%; p < 0.05) progressively decreased on increasing the GS967 concentration. CONCLUSIONS GS967 attenuates stretch-induced changes in cardiac electrophysiology.
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Affiliation(s)
- Irene Del Canto
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Electronics, Universitat Politècnica de València, Valencia, Spain
| | - Laura Santamaría
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | | | - Luis Such-Miquel
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiotherapy, Valencia University - Estudi General, Valencia, Spain
| | | | - Manuel Zarzoso
- Department of Physiotherapy, Valencia University - Estudi General, Valencia, Spain
| | - Carlos Soler
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Germán Parra
- Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Álvaro Tormos
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Electronics, Universitat Politècnica de València, Valencia, Spain
| | - Antonio Alberola
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Luis Such
- CIBER CV. Carlos III Health Institute, Madrid, Spain.,Department of Physiology, Valencia University - Estudi General, Valencia, Spain
| | - Francisco J Chorro
- CIBER CV. Carlos III Health Institute, Madrid, Spain. .,Service of Cardiology, Valencia University Clinic Hospital, INCLIVA, Valencia, Spain. .,Department of Medicine, Valencia University - Estudi General, Valencia, Spain. .,Servicio de Cardiología, Hospital Clínico Universitario, Avda. Blasco Ibañez 17, 46010, Valencia, Spain.
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4
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Empagliflozin Attenuates Myocardial Sodium and Calcium Dysregulation and Reverses Cardiac Remodeling in Streptozotocin-Induced Diabetic Rats. Int J Mol Sci 2019; 20:ijms20071680. [PMID: 30987285 PMCID: PMC6479313 DOI: 10.3390/ijms20071680] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 03/30/2019] [Accepted: 04/02/2019] [Indexed: 12/18/2022] Open
Abstract
Diabetes mellitus (DM) has significant effects on cardiac calcium (Ca2+) and sodium (Na+) regulation. Clinical studies have shown that empagliflozin (Jardiance™) has cardiovascular benefits, however the mechanisms have not been fully elucidated. This study aimed to investigate whether empagliflozin modulates cardiac electrical activity as well as Ca2+/Na+ homeostasis in DM cardiomyopathy. Electrocardiography, echocardiography, whole-cell patch-clamp, confocal microscopic examinations, and Western blot, were performed in the ventricular myocytes of control and streptozotocin-induced DM rats, with or without empagliflozin (10 mg/kg for 4 weeks). The results showed that the control and empagliflozin-treated DM rats had smaller left ventricular end-diastolic diameters and shorter QT intervals than the DM rats. In addition, the prolonged action potential duration in the DM rats was attenuated in the empagliflozin-treated DM rats. Moreover, the DM rats had smaller sarcoplasmic reticular Ca2+ contents, intracellular Ca2+ transients, L-type Ca2+, reverse mode Na+-Ca2+exchanger currents, lower protein expressions of sarcoplasmic reticulum ATPase, ryanodine receptor 2 (RyR2), but higher protein expressions of phosphorylated RyR2 at serine 2808 than the control and empagliflozin-treated DM rats. The incidence and frequency of Ca2+ sparks, cytosolic and mitochondrial reactive oxygen species, and late Na+ current and Na+/hydrogen-exchanger currents were greater in the DM rats than in the control and empagliflozin-treated DM rats. Empagliflozin significantly changed Ca2+ regulation, late Na+ and Na+/hydrogen-exchanger currents and electrophysiological characteristics in DM cardiomyopathy, which may contribute to its cardioprotective benefits in DM patients.
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Joca HC, Coleman AK, Ward CW, Williams GSB. Quantitative tests reveal that microtubules tune the healthy heart but underlie arrhythmias in pathology. J Physiol 2019; 598:1327-1338. [PMID: 30582750 PMCID: PMC7432954 DOI: 10.1113/jp277083] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 12/14/2018] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Our group previously discovered and characterized the microtubule mechanotransduction pathway linking diastolic stretch to NADPH oxidase 2-derived reactive oxygen species signals that regulate calcium sparks and calcium influx pathways. Here we used focused experimental tests to constrain and expand our existing computational models of calcium signalling in heart. Mechanistic and quantitative modelling revealed new insights in disease including: changes in microtubule network density and properties, elevated NOX2 expression, altered calcium release dynamics, how NADPH oxidase 2 is activated by and responds to stretch, and finally the degree to which normalizing mechano-activated reactive oxygen species signals can prevent calcium-dependent arrhythmias. ABSTRACT Microtubule (MT) mechanotransduction links diastolic stretch to generation of NADPH oxidase 2 (NOX2)-dependent reactive oxygen species (ROS), signals we term X-ROS. While stretch-elicited X-ROS primes intracellular calcium (Ca2+ ) channels for synchronized activation in the healthy heart, the dysregulated excess in this pathway underscores asynchronous Ca2+ release and arrhythmia. Here, we expanded our existing computational models of Ca2+ signalling in heart to include MT-dependent mechanotransduction through X-ROS. Informed by new focused experimental tests to properly constrain our model, we quantify the role of X-ROS on excitation-contraction coupling in healthy and pathological conditions. This approach allowed for a mechanistic investigation that revealed new insights into X-ROS signalling in disease including changes in MT network density and post-translational modifications (PTMs), elevated NOX2 expression, altered Ca2+ release dynamics (i.e. Ca2+ sparks and Ca2+ waves), how NOX2 is activated by and responds to stretch, and finally the degree to which normalizing X-ROS can prevent Ca2+ -dependent arrhythmias.
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Affiliation(s)
- Humberto C Joca
- Centre for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrew K Coleman
- Centre for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Chris W Ward
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - George S B Williams
- Centre for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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6
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Chorro FJ, Canto ID, Brines L, Such-Miquel L, Calvo C, Soler C, Zarzoso M, Trapero I, Tormos Á, Such L. Estudio experimental de los efectos de EIPA, losartán y BQ-123 sobre las modificaciones electrofisiológicas inducidas por el estiramiento miocárdico. Rev Esp Cardiol 2015. [DOI: 10.1016/j.recesp.2014.12.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Chorro FJ, Canto ID, Brines L, Such-Miquel L, Calvo C, Soler C, Zarzoso M, Trapero I, Tormos Á, Such L. Experimental Study of the Effects of EIPA, Losartan, and BQ-123 on Electrophysiological Changes Induced by Myocardial Stretch. ACTA ACUST UNITED AC 2015; 68:1101-10. [PMID: 25985899 DOI: 10.1016/j.rec.2014.12.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/12/2014] [Indexed: 11/26/2022]
Abstract
INTRODUCTION AND OBJECTIVES Mechanical response to myocardial stretch has been explained by various mechanisms, which include Na(+)/H(+) exchanger activation by autocrine-paracrine system activity. Drug-induced changes were analyzed to investigate the role of these mechanisms in the electrophysiological responses to acute myocardial stretch. METHODS Multiple epicardial electrodes and mapping techniques were used to analyze changes in ventricular fibrillation induced by acute myocardial stretch in isolated perfused rabbit hearts. Four series were studied: control (n = 9); during perfusion with the angiotensin receptor blocker losartan (1 μM, n = 8); during perfusion with the endothelin A receptor blocker BQ-123 (0.1 μM, n = 9), and during perfusion with the Na(+)/H(+) exchanger inhibitor EIPA (5-[N-ethyl-N-isopropyl]-amiloride) (1 μM, n = 9). RESULTS EIPA attenuated the increase in the dominant frequency of stretch-induced fibrillation (control=40.4%; losartan=36% [not significant]; BQ-123=46% [not significant]; and EIPA=22% [P<.001]). During stretch, the activation maps were less complex (P<.0001) and the spectral concentration of the arrhythmia was greater (greater regularity) in the EIPA series: control=18 (3%); EIPA = 26 (9%) (P < .02); losartan=18 (5%) (not significant); and BQ-123=18 (4%) (not significant). CONCLUSIONS The Na(+)/H(+) exchanger inhibitor EIPA attenuated the electrophysiological effects responsible for the acceleration and increased complexity of ventricular fibrillation induced by acute myocardial stretch. The angiotensin II receptor antagonist losartan and the endothelin A receptor blocker BQ-123 did not modify these effects.
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Affiliation(s)
- Francisco J Chorro
- Servicio de Cardiología, Hospital Clínico Universitario de Valencia, INCLIVA, Valencia, Spain; Departamento de Medicina, Universidad de Valencia-Estudi General, Valencia, Spain.
| | - Irene Del Canto
- Departamento de Medicina, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Laia Brines
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Luis Such-Miquel
- Departamento de Fisioterapia, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Conrado Calvo
- Departamento de Electrónica, Universidad Politécnica de Valencia, Valencia, Spain
| | - Carlos Soler
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Manuel Zarzoso
- Departamento de Fisioterapia, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Isabel Trapero
- Departamento de Enfermería, Universidad de Valencia-Estudi General, Valencia, Spain
| | - Álvaro Tormos
- Departamento de Electrónica, Universidad Politécnica de Valencia, Valencia, Spain
| | - Luis Such
- Departamento de Fisiología, Universidad de Valencia-Estudi General, Valencia, Spain
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Abstract
Myocardial stretch elicits a rapid increase in developed force, which is mainly caused by an increase in myofilament calcium sensitivity (Frank-Starling mechanism). Over the ensuing 10-15 min, a second gradual increase in force takes place. This slow force response to stretch is known to be the result of an increase in the calcium transient amplitude and constitutes the in vitro equivalent of the Anrep effect described 100 years ago in the intact heart. In the present review, we will update and discuss what is known about the Anrep effect as the mechanical counterpart of autocrine/paracrine mechanisms involved in its genesis. The chain of events triggered by myocardial stretch comprises 1) release of angiotensin II, 2) release of endothelin, 3) activation of the mineralocorticoid receptor, 4) transactivation of the epidermal growth factor receptor, 5) increased formation of mitochondria reactive oxygen species, 6) activation of redox-sensitive kinases upstream myocardial Na(+)/H(+) exchanger (NHE1), 7) NHE1 activation, 8) increase in intracellular Na(+) concentration, and 9) increase in Ca(2+) transient amplitude through the Na(+)/Ca(2+) exchanger. We will present the experimental evidence supporting each of the signaling steps leading to the Anrep effect and its blunting by silencing NHE1 expression with a specific small hairpin interference RNA injected into the ventricular wall.
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Affiliation(s)
- Horacio E Cingolani
- Centro de Investigaciones Cardiovasculares, Universidad Nacional de La Plata, La Plata, Argentina.
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9
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Brines L, Such-Miquel L, Gallego D, Trapero I, del Canto I, Zarzoso M, Soler C, Pelechano F, Cánoves J, Alberola A, Such L, Chorro FJ. Modifications of mechanoelectric feedback induced by 2,3-butanedione monoxime and Blebbistatin in Langendorff-perfused rabbit hearts. Acta Physiol (Oxf) 2012; 206:29-41. [PMID: 22497862 DOI: 10.1111/j.1748-1716.2012.02441.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/16/2011] [Accepted: 03/26/2012] [Indexed: 11/30/2022]
Abstract
AIM Myocardial stretching is an arrhythmogenic factor. Optical techniques and mechanical uncouplers are used to study the mechanoelectric feedback. The aim of this study is to determine whether the mechanical uncouplers 2,3-butanedione monoxime and Blebbistatin hinder or modify the electrophysiological effects of acute mechanical stretch. METHODS The ventricular fibrillation (VF) modifications induced by acute mechanical stretch were studied in 27 Langendorff-perfused rabbit hearts using epicardial multiple electrodes and mapping techniques under control conditions (n = 9) and during the perfusion of 2,3-butanedione monoxime (15 mM) (n = 9) or Blebbistatin (10 μm) (n = 9). RESULTS In the control series, myocardial stretch increased the complexity of the activation maps and the dominant frequency (DF) of VF from 13.1 ± 2.0 Hz to 19.1 ± 3.1 Hz (P < 0.001, 46% increment). At baseline, the activation maps showed less complexity in both the 2,3-butanedione monoxime and Blebbistatin series, and the DF was lower in the 2,3-butanedione monoxime series (11.4 ± 1.2 Hz; P < 0.05). The accelerating effect of mechanical stretch was abolished under 2,3-butanedione monoxime (maximum DF = 11.7 ± 2.4 Hz, 5% increment, ns vs baseline, P < 0.0001 vs. control series) and reduced under Blebbistatin (maximum DF = 12.9 ± 0.7 Hz, 8% increment, P < 0.01 vs. baseline, P < 0.0001 vs. control series). The variations in complexity of the activation maps under stretch were not significant in the 2,3-butanedione monoxime series and were significantly attenuated under Blebbistatin. CONCLUSION The accelerating effect and increased complexity of myocardial activation during VF induced by acute mechanical stretch are abolished under the action of 2,3-butanedione monoxime and reduced under the action of Blebbistatin.
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Affiliation(s)
- L. Brines
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - L. Such-Miquel
- Department of Physiotherapy; Valencia University, Estudi General; Valencia; Spain
| | - D. Gallego
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - I. Trapero
- Department of Infirmary; Valencia University, Estudi General; Valencia; Spain
| | - I. del Canto
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - M. Zarzoso
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - C. Soler
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - F. Pelechano
- Department of Medicine; Valencia University, Estudi General; Valencia; Spain
| | - J. Cánoves
- Service of Cardiology; Valencia University Clinic Hospital; INCLIVA, Valencia; Spain
| | - A. Alberola
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
| | - L. Such
- Department of Physiology; Valencia University, Estudi General; Valencia; Spain
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10
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Abstract
AbstractPreload-induced changes of active tension and [Ca2+]i are “dissociated” in mammalian myocardium. This study aimed to describe the distinct effects of preload at low and physiological [Ca2+]o. Rat RV papillary muscles were studied in isometric conditions at 25‡C and 0.33 Hz at 1 mM (hypo-Ca group) and 2.5 mM [Ca2+]o (normal-Ca group). [Ca2+]i was monitored with fura-2/AM. Increase of preload caused a rise of active tension in hypo-Ca and normal-Ca groups whereas peak fluorescence rose significantly only at low [Ca2+]o. End-diastolic tension, end-diastolic level of fluorescence, time-to-peak tension, but not time-to-peak of Ca2+ transient, progressively increased with preload. Mechanical relaxation decelerated with preload while Ca2+ transient decay time decreased in the initial phase and increased in the late phase, resulting in a prominent “bump” configuration. The “bump” was assessed as a ratio of its area to the fluorescence trace area. It was a new finding that the preload-induced rise of this ratio was twice as large in hypo-Ca. Our results indicate that preload-induced changes in active tension and [Ca2+]i are “dissociated” in rat myocardium, with relatively higher expression at low [Ca2+]o. Ca-dependence of Ca-TnC association/dissociation kinetics is thought to be a main contributor to these preload-induced effects.
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11
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Pérez NG, Nolly MB, Roldan MC, Villa-Abrille MC, Cingolani E, Portiansky EL, Álvarez BV, Ennis IL, Cingolani HE. Silencing of NHE-1 blunts the slow force response to myocardial stretch. J Appl Physiol (1985) 2011; 111:874-80. [DOI: 10.1152/japplphysiol.01344.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Myocardial stretch induces a biphasic force response: a first abrupt increase followed by a slow force response (SFR), believed to be the in vitro manifestation of the Anrep effect. The SFR is due to an increase in Ca2+ transient of unclear mechanism. We proposed that Na+/H+ exchanger (NHE-1) activation is a key factor in determining the contractile response, but recent reports challenged our findings. We aimed to specifically test the role of the NHE-1 in the SFR. To this purpose small hairpin interference RNA capable of mediating specific NHE-1 knockdown was incorporated into a lentiviral vector (l-shNHE1) and injected into the left ventricular wall of Wistar rats. Injection of a lentiviral vector expressing a nonsilencing sequence (scramble) served as control. Myocardial NHE-1 protein expression and function (the latter evaluated by the recovery of pHi after an acidic load and the SFR) were evaluated. Animals transduced with l-shNHE1 showed reduced NHE-1 expression (45 ± 8% of controls; P < 0.05), and the presence of the lentivirus in the left ventricular myocardium, far from the site of injection, was evidenced by confocal microscopy. These findings correlated with depressed basal pHi recovery after acidosis [maxdpHi/d t 0.055 ± 0.008 (scramble) vs. 0.009 ± 0.004 (l-shNHE1) pH units/min, P < 0.05], leftward shift of the relationship between JH+ (H+ efflux corrected by the intrinsic buffer capacity), and abolishment of SFR (124 ± 2 vs. 101 ± 2% of rapid phase; P < 0.05) despite preserved ERK1/2 phosphorylation [247 ± 12 (stretch) and 263 ± 23 (stretch l-shNHE1) % of control; P < 0.05 vs. nonstretched control], well-known NHE-1 activators. Our results provide strong evidence to propose NHE-1 activation as key factor in determining the SFR to stretch.
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Affiliation(s)
- Néstor G. Pérez
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Mariela B. Nolly
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Mirian C. Roldan
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - María C. Villa-Abrille
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Eugenio Cingolani
- Cedars Sinai Heart Institute, Cedars Sinai Medical Center, Los Angeles, California; and
| | - Enrique L. Portiansky
- Instituto de Patología. Facultad de Cs. Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina
| | - Bernardo V. Álvarez
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Irene L. Ennis
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Horacio E. Cingolani
- Centro de Investigaciones Cardiovasculares, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
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Cingolani HE, Ennis IL, Aiello EA, Pérez NG. Role of autocrine/paracrine mechanisms in response to myocardial strain. Pflugers Arch 2011; 462:29-38. [DOI: 10.1007/s00424-011-0930-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/19/2011] [Accepted: 01/19/2011] [Indexed: 10/18/2022]
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13
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Chorro FJ, Trapero I, Such-Miquel L, Pelechano F, Mainar L, Cánoves J, Tormos Á, Alberola A, Hove-Madsen L, Cinca J, Such L. Pharmacological modifications of the stretch-induced effects on ventricular fibrillation in perfused rabbit hearts. Am J Physiol Heart Circ Physiol 2009; 297:H1860-9. [DOI: 10.1152/ajpheart.00144.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Stretch induces modifications in myocardial electrical and mechanical activity. Besides the effects of substances that block the stretch-activated channels, other substances could modulate the effects of stretch through different mechanisms that affect Ca2+ handling by myocytes. Thirty-six Langendorff-perfused rabbit hearts were used to analyze the effects of the Na+/Ca2+ exchanger blocker KB-R7943, propranolol, and the adenosine A2 receptor antagonist SCH-58261 on the acceleration of ventricular fibrillation (VF) produced by acute myocardial stretching. VF recordings were obtained with two epicardial multiple electrodes before, during, and after local stretching in four experimental series: control ( n = 9), KB-R7943 (1 μM, n = 9), propranolol (1 μM, n = 9), and SCH-58261 (1 μM, n = 9). Both the Na+/Ca2+ exchanger blocker KB-R7943 and propranolol induced a significant reduction ( P < 0.001 and P < 0.05, respectively) in the dominant frequency increments produced by stretching with respect to the control and SCH-58261 series (control = 49.9%, SCH-58261 = 52.1%, KB-R7943 = 9.5%, and propranolol = 12.5%). The median of the activation intervals, the functional refractory period, and the wavelength of the activation process during VF decreased significantly under stretch in the control and SCH-58261 series, whereas no significant variations were observed in the propranolol and KB-R7943 series, with the exception of a slight but significant decrease in the median of the fibrillation intervals in the KB-R7943 series. KB-R7943 and propranolol induced a significant reduction in the activation maps complexity increment produced by stretch with respect to the control and SCH-58261 series. In conclusion, the electrophysiological effects responsible for stretch-induced VF acceleration in the rabbit heart are reduced by the Na+/Ca2+ exchanger blocker KB-R7943 and by propranolol but not by the adenosine A2 receptor antagonist SCH-58261.
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Affiliation(s)
- Francisco J. Chorro
- Service of Cardiology, Valencia University Clinic Hospital, Valencia
- Departments of 2Medicine,
| | | | | | | | - Luis Mainar
- Service of Cardiology, Valencia University Clinic Hospital, Valencia
| | - Joaquín Cánoves
- Service of Cardiology, Valencia University Clinic Hospital, Valencia
| | - Álvaro Tormos
- Department of Electronics, Valencia Polytechnic University, Valencia; and
| | | | - Leif Hove-Madsen
- Cardiology Department, Santa Creu i Sant Pau Hospital, Barcelona, Spain
| | - Juan Cinca
- Cardiology Department, Santa Creu i Sant Pau Hospital, Barcelona, Spain
| | - Luis Such
- Physiology, Valencia University, Valencia
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14
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Wilhelm J, Kondratev D, Christ A, Gallitelli MF. Stretch induced accumulation of total Ca and Na in cytosol and nucleus: a comparison between cardiac trabeculae and isolated myocytes. Can J Physiol Pharmacol 2006; 84:487-98. [PMID: 16902594 DOI: 10.1139/y05-134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
By means of electron probe microanalysis (EPMA), we quantified changes in total sodium [Na] and calcium [Ca] concentration owing to the following: (i) local axial stretch (LAS) of isolated rat myocytes and (ii) end-to-end stretch (ETES) of rat ventricular trabeculae. For LAS, the distance between patch pipette and a cell-attached stylus was increased by maximally 20%; this activated a nonselective cationic current I(SAC) of approximately -0.5 nA, which was blocked by streptomycin. Trabeculae were stretched end-to-end from 85% L(max) to L(max). Stretch increased cytosolic [Na](total) by 34% in isolated myocytes (p < 0.001) and by 43% in trabeculae (p < 0.001). The increment in nuclear [Na](total) was 21% in myocytes (p < 0.01) and 20% in trabeculae (p < 0.001). Stretch increased [Ca](total) in isolated myocytes, in both cytosol (from 0.63 +/- 0.09 to 1.09 +/- 0.20 mmol/L, p < 0.05) and nucleus (from 0.33 +/- 0.05 to 0.64 +/- 0.13 mmol/L, p < 0.05). In trabeculae, the stretch-induced increment of 51% in cytosolic [Ca](total) remained nonsignificant (p < 0.15). In the nucleus, [Ca](total) did not change. We interpret the difference of stretch on nuclear calcium in myocytes vs. trabeculae with the assumption that LAS, but not ETES, produces shear-stress components that translate the mechanical stimulus deeply into the cell where it may modulate [Ca](total) by signals independent of I(SAC).
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Affiliation(s)
- J Wilhelm
- Julius Bernstein Institute of Physiology, University of Halle, Germany
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15
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Park HS, Lee BK, Park S, Kim SU, Lee SH, Baik EJ, Lee S, Yi KY, Yoo SE, Moon CH, Jung YS. Effects of sabiporide, a specific Na+/H+ exchanger inhibitor, on neuronal cell death and brain ischemia. Brain Res 2005; 1061:67-71. [PMID: 16225853 DOI: 10.1016/j.brainres.2005.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 08/30/2005] [Accepted: 09/01/2005] [Indexed: 12/31/2022]
Abstract
We investigated the effects of an Na(+)/H(+) exchanger inhibitor, sabiporide, on excitotoxicity in cultured neuronal cells and in vivo. Sabiporide attenuated glutamate- or NMDA (N-methyl-d-aspartic acid)-induced neuronal cell death. Sabiporide also reduced glutamate or NMDA-induced increase in [Ca(2+)](i). In in vivo brain ischemia model, sabiporide produced protective effects, decreasing the infarct size and edema volume. Our results suggest that sabiporide elicits neuroprotective effect both in vitro and in vivo.
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Affiliation(s)
- Hye-Seong Park
- Department of Physiology, School of Medicine, Ajou University, Suwon, Kyungkido 442-749, Republic of Korea
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