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Grogan A, Lucero EY, Jiang H, Rockman HA. Pathophysiology and pharmacology of G protein-coupled receptors in the heart. Cardiovasc Res 2023; 119:1117-1129. [PMID: 36534965 PMCID: PMC10202650 DOI: 10.1093/cvr/cvac171] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/30/2022] [Accepted: 10/06/2022] [Indexed: 08/10/2023] Open
Abstract
G protein-coupled receptors (GPCRs), comprising the largest superfamily of cell surface receptors, serve as fundamental modulators of cardiac health and disease owing to their key roles in the regulation of heart rate, contractile dynamics, and cardiac function. Accordingly, GPCRs are heavily pursued as drug targets for a wide variety of cardiovascular diseases ranging from heart failure, cardiomyopathy, and arrhythmia to hypertension and coronary artery disease. Recent advancements in understanding the signalling mechanisms, regulation, and pharmacological properties of GPCRs have provided valuable insights that will guide the development of novel therapeutics. Herein, we review the cellular signalling mechanisms, pathophysiological roles, and pharmacological developments of the major GPCRs in the heart, highlighting the β-adrenergic, muscarinic, and angiotensin receptors as exemplar subfamilies.
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Affiliation(s)
- Alyssa Grogan
- Department of Medicine, Duke University Medical Center, DUMC 3104, 226 CARL Building, Durham, NC 27710, USA
| | - Emilio Y Lucero
- Department of Medicine, Duke University Medical Center, DUMC 3104, 226 CARL Building, Durham, NC 27710, USA
| | - Haoran Jiang
- Department of Medicine, Duke University Medical Center, DUMC 3104, 226 CARL Building, Durham, NC 27710, USA
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, DUMC 3104, 226 CARL Building, Durham, NC 27710, USA
- Cell Biology, Duke University Medical Center, DUMC 3104, 226 CARL Building, 12 Durham, NC 27710, USA
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Kaur G, Verma SK, Singh D, Singh NK. Role of G-Proteins and GPCRs in Cardiovascular Pathologies. Bioengineering (Basel) 2023; 10:bioengineering10010076. [PMID: 36671648 PMCID: PMC9854459 DOI: 10.3390/bioengineering10010076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 12/19/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
Cell signaling is a fundamental process that enables cells to survive under various ecological and environmental contexts and imparts tolerance towards stressful conditions. The basic machinery for cell signaling includes a receptor molecule that senses and receives the signal. The primary form of the signal might be a hormone, light, an antigen, an odorant, a neurotransmitter, etc. Similarly, heterotrimeric G-proteins principally provide communication from the plasma membrane G-protein-coupled receptors (GPCRs) to the inner compartments of the cells to control various biochemical activities. G-protein-coupled signaling regulates different physiological functions in the targeted cell types. This review article discusses G-proteins' signaling and regulation functions and their physiological relevance. In addition, we also elaborate on the role of G-proteins in several cardiovascular diseases, such as myocardial ischemia, hypertension, atherosclerosis, restenosis, stroke, and peripheral artery disease.
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Affiliation(s)
- Geetika Kaur
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
| | - Shailendra Kumar Verma
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
| | - Deepak Singh
- Lloyd Institute of Engineering and Technology, Greater Noida 201306, India
| | - Nikhlesh K. Singh
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA
- Department of Ophthalmology, Visual and Anatomical Sciences, School of Medicine, Wayne State University, Detroit, MI 48202, USA
- Correspondence:
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Muscarinic receptor activation reduces force and arrhythmias in human atria independent of IK,ACh. J Cardiovasc Pharmacol 2022; 79:678-686. [PMID: 35170489 DOI: 10.1097/fjc.0000000000001237] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 01/15/2022] [Indexed: 11/27/2022]
Abstract
ABSTRACT In human hearts, muscarinic receptors (M-R) are expressed in ventricular and atrial tissue, but the acetylcholine-activated potassium current (IK,ACh) is expressed mainly in the atrium. M-R activation decreases force and increases electrical stability in human atrium, but the impact of IK,ACh to both effects remains unclear. We employed a new selective blocker of IK,ACh to elaborate the contribution of IK,ACh to M-R activation-mediated effects in human atrium.Force and action potentials were measured in rat atria and in human right atrial trabeculae. Cumulative concentration-effect curves for norepinephrine-induced force and arrhythmias were measured in the presence of either carbachol (CCh;1µM) or CCh together with the IK,ACh -blocker XAF-1407 (1 µM) or in time-matched controls. To investigate the vulnerability to arrhythmias we performed some experiments also in the presence of cilostamide (0.3µM) and rolipram (1µM), inhibiting PDE3 and PDE4.In rat atria and human right atrial trabeculae, CCh shortened the action potential duration persistently. However, the direct negative inotropy of CCh was only transient in human, but stable in rat atria. In both rat and human atria, the negative inotropic effect was insensitive to blockage of IK,ACh by XAF-1407. In the presence of cilostamide and rolipram about 40% of trabeculae developed arrhythmias when exposed to norepinephrine. CCh prevented these concentration-dependent norepinephrine-induced arrhythmias, again insensitive to XAF-1407. Maximum catecholamine-induced force was not depressed by CCh.In human atrium, both the direct and the indirect negative inotropic effect of CCh are independent of IK,ACh. The same applies to the CCh-mediated suppression of norepinephrine/PDE-inhibition-induced arrhythmias.
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Schoeller C, Hoffmann S, Adolph S, Regenthal R, Abraham G. Expression of muscarinic acetylcholine receptors in turkey cardiac chambers. Res Vet Sci 2021; 136:602-608. [PMID: 33895569 DOI: 10.1016/j.rvsc.2021.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 10/21/2022]
Abstract
The aim of the present study was to characterize the specific binding sites for [N-methyl-3H]-scopolamine ([3H]-NMS), a radioligand for labeling muscarinic acetylcholine receptors (mAChRs), in membranes of four heart chambers obtained from adult male British United Turkey (BUT) Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys. MAChR subtypes were examined by inhibiting [3H]-NMS binding with subtype selective non-labelled receptor antagonists. In all left and right atria as well as left and right ventricles of both turkey breeds, the specific [3H]-NMS binding was saturable, reversible and of high affinity (KD range: 0.5-1.0 nM). The maximum receptor density (Bmax) was not significantly different between the four cardiac chambers of BUT Big 6 turkeys, but a significant difference was found between atria and ventricles of Cröllwitzer turkeys. Moreover, significant lower Bmax was found in the atria of Cröllwitzer turkeys than in the atria of BUT Big 6, while the ventricular Bmax was significantly higher. In all cardiac chambers, unlabeled mAChR antagonists competed for specific [3H]-NMS binding sites in a concentration-dependent manner, suggesting the presence of the M3 and M2 receptor subtypes, whereby the latter was the predominant subtype. The presence of the M1 subtype could not be excluded. In conclusion, there was a difference between BUT Big 6 ("meat-type") and Cröllwitzer ("wild-type") turkeys with regard to receptor density in heart chambers with dominant M2 and M3 receptor subtypes.
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Affiliation(s)
- Caroline Schoeller
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, D-04103 Leipzig, Germany
| | - Sandra Hoffmann
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, D-04103 Leipzig, Germany
| | - Stephanie Adolph
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, D-04103 Leipzig, Germany
| | - Ralf Regenthal
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Clinical Pharmacology, Faculty of Medicine, University of Leipzig, Härtelstr. 16 -18, D-04107 Leipzig, Germany.
| | - Getu Abraham
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, D-04103 Leipzig, Germany.
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Lymperopoulos A, Cora N, Maning J, Brill AR, Sizova A. Signaling and function of cardiac autonomic nervous system receptors: Insights from the GPCR signalling universe. FEBS J 2021; 288:2645-2659. [PMID: 33599081 DOI: 10.1111/febs.15771] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 02/02/2021] [Accepted: 02/16/2021] [Indexed: 12/16/2022]
Abstract
The two branches of the autonomic nervous system (ANS), adrenergic and cholinergic, exert a multitude of effects on the human myocardium thanks to the activation of distinct G protein-coupled receptors (GPCRs) expressed on the plasma membranes of cardiac myocytes, cardiac fibroblasts, and coronary vascular endothelial cells. Norepinephrine (NE)/epinephrine (Epi) and acetylcholine (ACh) are released from cardiac ANS terminals and mediate the biological actions of the ANS on the heart via stimulation of cardiac adrenergic or muscarinic receptors, respectively. In addition, several other neurotransmitters/hormones act as facilitators of ANS neurotransmission in the heart, taking part in the so-called nonadrenergic noncholinergic (NANC) part of the ANS's control of cardiac function. These NANC mediators also use several different cell membrane-residing GPCRs to exert their effects in the myocardium. Cardiac ANS dysfunction and an imbalance between the activities of its two branches underlie a variety of cardiovascular diseases, from heart failure and hypertension to coronary artery disease, myocardial ischemia, and arrhythmias. In this review, we present the main well-established signaling modalities used by cardiac autonomic GPCRs, including receptors for salient NANC mediators, and we also highlight the latest developments pertaining to cardiac cell type-specific signal transduction, resulting in cell type-specific cardiac effects of each of these autonomic receptors.
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Affiliation(s)
- Anastasios Lymperopoulos
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Natalie Cora
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Jennifer Maning
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Ava R Brill
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
| | - Anastasiya Sizova
- Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
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Abstract
GPCRs (G-protein [guanine nucleotide-binding protein]-coupled receptors) play a central physiological role in the regulation of cardiac function in both health and disease and thus represent one of the largest class of surface receptors targeted by drugs. Several antagonists of GPCRs, such as βARs (β-adrenergic receptors) and Ang II (angiotensin II) receptors, are now considered standard of therapy for a wide range of cardiovascular disease, such as hypertension, coronary artery disease, and heart failure. Although the mechanism of action for GPCRs was thought to be largely worked out in the 80s and 90s, recent discoveries have brought to the fore new and previously unappreciated mechanisms for GPCR activation and subsequent downstream signaling. In this review, we focus on GPCRs most relevant to the cardiovascular system and discuss traditional components of GPCR signaling and highlight evolving concepts in the field, such as ligand bias, β-arrestin-mediated signaling, and conformational heterogeneity.
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Affiliation(s)
- Jialu Wang
- From the Department of Medicine (J.W., C.G., H.A.R.)
| | | | - Howard A Rockman
- From the Department of Medicine (J.W., C.G., H.A.R.).,Department of Cell Biology (H.A.R.).,Department of Molecular Genetics and Microbiology (H.A.R.), Duke University Medical Center, Durham, NC
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Garrott K, Dyavanapalli J, Cauley E, Dwyer MK, Kuzmiak-Glancy S, Wang X, Mendelowitz D, Kay MW. Chronic activation of hypothalamic oxytocin neurons improves cardiac function during left ventricular hypertrophy-induced heart failure. Cardiovasc Res 2018; 113:1318-1328. [PMID: 28472396 DOI: 10.1093/cvr/cvx084] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 04/28/2017] [Indexed: 01/07/2023] Open
Abstract
Aims A distinctive hallmark of heart failure (HF) is autonomic imbalance, consisting of increased sympathetic activity, and decreased parasympathetic tone. Recent work suggests that activation of hypothalamic oxytocin (OXT) neurons could improve autonomic balance during HF. We hypothesized that a novel method of chronic selective activation of hypothalamic OXT neurons will improve cardiac function and reduce inflammation and fibrosis in a rat model of HF. Methods and results Two groups of male Sprague-Dawley rats underwent trans-ascending aortic constriction (TAC) to induce left ventricular (LV) hypertrophy that progresses to HF. In one TAC group, OXT neurons in the paraventricular nucleus of the hypothalamus were chronically activated by selective expression and activation of excitatory DREADDs receptors with daily injections of clozapine N-oxide (CNO) (TAC + OXT). Two additional age-matched groups received either saline injections (Control) or CNO injections for excitatory DREADDs activation (OXT NORM). Heart rate (HR), LV developed pressure (LVDP), and coronary flow rate were measured in isolated heart experiments. Isoproterenol (0.01 nM-1.0 µM) was administered to evaluate β-adrenergic sensitivity. We found that increases in cellular hypertrophy and myocardial collagen density in TAC were blunted in TAC + OXT animals. Inflammatory cytokine IL-1β expression was more than twice higher in TAC than all other hearts. LVDP, rate pressure product (RPP), contractility, and relaxation were depressed in TAC compared with all other groups. The response of TAC and TAC + OXT hearts to isoproterenol was blunted, with no significant increase in RPP, contractility, or relaxation. However, HR in TAC + OXT animals increased to match Control at higher doses of isoproterenol. Conclusions Activation of hypothalamic OXT neurons to elevate parasympathetic tone reduced cellular hypertrophy, levels of IL-1β, and fibrosis during TAC-induced HF in rats. Cardiac contractility parameters were significantly higher in TAC + OXT compared with TAC animals. HR sensitivity, but not contractile sensitivity, to β-adrenergic stimulation was improved in TAC + OXT hearts.
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Affiliation(s)
- Kara Garrott
- Department of Biomedical Engineering, The George Washington University, GWU Science and Engineering Hall, 800?22nd Street NW, Suite 5000, Washington, DC 20052, USA
| | - Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, Ross Hall, 2300 Eye St. NW, Suite 640, Washington, DC 20037, USA
| | - Edmund Cauley
- Department of Pharmacology and Physiology, The George Washington University, Ross Hall, 2300 Eye St. NW, Suite 640, Washington, DC 20037, USA
| | - Mary Kate Dwyer
- Department of Biomedical Engineering, The George Washington University, GWU Science and Engineering Hall, 800?22nd Street NW, Suite 5000, Washington, DC 20052, USA
| | - Sarah Kuzmiak-Glancy
- Department of Biomedical Engineering, The George Washington University, GWU Science and Engineering Hall, 800?22nd Street NW, Suite 5000, Washington, DC 20052, USA
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, Ross Hall, 2300 Eye St. NW, Suite 640, Washington, DC 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Ross Hall, 2300 Eye St. NW, Suite 640, Washington, DC 20037, USA
| | - Matthew W Kay
- Department of Biomedical Engineering, The George Washington University, GWU Science and Engineering Hall, 800?22nd Street NW, Suite 5000, Washington, DC 20052, USA
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Saternos HC, Almarghalani DA, Gibson HM, Meqdad MA, Antypas RB, Lingireddy A, AbouAlaiwi WA. Distribution and function of the muscarinic receptor subtypes in the cardiovascular system. Physiol Genomics 2017; 50:1-9. [PMID: 29093194 DOI: 10.1152/physiolgenomics.00062.2017] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Muscarinic acetylcholine receptors belong to the G protein-coupled receptor superfamily and are widely known to mediate numerous functions within the central and peripheral nervous system. Thus, they have become attractive therapeutic targets for various disorders. It has long been known that the parasympathetic system, governed by acetylcholine, plays an essential role in regulating cardiovascular function. Unfortunately, due to the lack of pharmacologic selectivity for any one muscarinic receptor, there was a minimal understanding of their distribution and function within this region. However, in recent years, advancements in research have led to the generation of knockout animal models, better antibodies, and more selective ligands enabling a more thorough understanding of the unique role muscarinic receptors play in the cardiovascular system. These advances have shown muscarinic receptor 2 is no longer the only functional subtype found within the heart and muscarinic receptors 1 and 3 mediate both dilation and constriction in the vasculature. Although muscarinic receptors 4 and 5 are still not well characterized in the cardiovascular system, the recent generation of knockout animal models will hopefully generate a better understanding of their function. This mini review aims to summarize recent findings and advances of muscarinic involvement in the cardiovascular system.
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Affiliation(s)
- Hannah C Saternos
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Daniyah A Almarghalani
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Hayley M Gibson
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Mahmood A Meqdad
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Raymond B Antypas
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Ajay Lingireddy
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Wissam A AbouAlaiwi
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
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Shimamoto K, Kawana M. Beta-Adrenergic Blockade Therapy for Autonomic Dysfunction is Less Effective for Elderly Patients with Heart Failure and Reduced Left Ventricular Ejection Fraction. JAPANESE CLINICAL MEDICINE 2015; 6:21-7. [PMID: 26483614 PMCID: PMC4603571 DOI: 10.4137/jcm.s30488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Heart rate variability (HRV) has been reported to be an independent predictor of all-cause and sudden cardiac death in patients with heart failure. In the aging heart, however, both autonomic and cardiac functions appear to be altered. We assessed the relationship between aging and responsiveness of HRV and ventricular remodeling to beta-adrenergic blockade therapy in patients with heart failure and reduced ejection fraction (HFREF). METHODS Twenty-eight clinically stable patients with chronic heart failure, sinus rhythm, and left ventricular ejection fraction <50% as confirmed by echocardiography were included. At baseline and after carvedilol treatment, 24-hour ambulatory Holter monitor recording was used to analyze HRV indices by the maximum entropy method. Changes in these parameters were compared among three age groups. RESULTS HR decreased in all groups after carvedilol treatment, but was still highest in the youngest group despite the same treatment doses. Time and frequency domain variables improved. The response of time domain variables (the standard deviation of all normal sinus to normal sinus [NN] intervals and the standard deviation of the averages of NN intervals in all 5-minute or 30-minute segments) to carvedilol therapy significantly decreased with increasing age. Ventricular reverse remodeling induced by carvedilol therapy significantly decreased with increasing age. Increases in time domain variables and a low-frequency domain moderately correlated with left ventricular reverse remodeling. CONCLUSION Beta-adrenergic blockade therapy improved HRV variables and ventricular remodeling in HFREF patients; however, the response tended to be milder in the elderly. HRV improvement was associated with ventricular reverse remodeling.
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Affiliation(s)
- Ken Shimamoto
- Department of Cardiology, Tokyo Women's Medical University Aoyama Hospital, Tokyo, Japan
| | - Masatoshi Kawana
- Department of Cardiology, Tokyo Women's Medical University Aoyama Hospital, Tokyo, Japan
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Li Y, Xuan YH, Liu SS, Dong J, Luo JY, Sun ZJ. Short‑term vagal nerve stimulation improves left ventricular function following chronic heart failure in rats. Mol Med Rep 2015; 12:1709-16. [PMID: 25873055 PMCID: PMC4464404 DOI: 10.3892/mmr.2015.3597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 03/10/2015] [Indexed: 01/01/2023] Open
Abstract
Increasing numbers of animal and clinical investigations have demonstrated the effectiveness of long-term electrical vagal nerve stimulation (VNS) on chronic heart failure (CHF). The present study investigated the effects of short-term VNS on the hemodynamics of cardiac remodeling and cardiac excitation-contraction coupling (ECP) in an animal model of CHF following a large myocardial infarction. At 3 weeks subsequent to ligation of the left coronary artery, the surviving rats were randomized into vagal and sham-stimulated groups. The right vagal nerve of the CHF rats was stimulated for 72 h. The vagal nerve was stimulated with rectangular pulses of 40 ms duration at 1 Hz, 5 V. The treated rats, compared with the untreated rats, had significantly higher left ventricular ejection fraction (54.86±9.73, vs. 45.60±5.51%; P=0.025) and left ventricular fractional shortening (25.31±6.30, vs. 15.42±8.49%; P=0.013), and lower levels of brain natriuretic peptide (10.07±2.63, vs. 19.95±5.22 ng/ml; P=0.001). The improvement in cardiac pumping function was accompanied by a decrease in left ventricular end diastolic volume (1.11±0.50, vs. 1.54±0.57 cm3; P=0.032) and left ventricular end systolic volume (0.50±0.28, vs. 0.87±0.36 cm3; P=0.007). Furthermore, the expression levels of ryanodine receptor type 2 (RyR2) and sarcoplasmic reticulum calcium adenosine triphosphatase (SERCA2) were significantly higher in the treated rats compared with the untreated rats (P=0.011 and P=0.001 for RyR2 and SERCA2, respectively). Therefore, VNS was beneficial to the CHF rats through the prevention of cardiac remodeling and improvement of cardiac ECP.
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Affiliation(s)
- Yan Li
- Department of Geriatrics, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Yan-Hua Xuan
- Department of Cardiology Medicine, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Shuang-Shuang Liu
- Department of Cardiology Medicine, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Jing Dong
- Department of Cardiology Medicine, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Jia-Ying Luo
- Department of Cardiology Medicine, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Zhi-Jun Sun
- Department of Cardiology Medicine, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
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Comparison of the Intrinsic Vasorelaxant and Inotropic Effects of the Antiarrhythmic Agents Vernakalant and Flecainide in Human Isolated Vascular and Cardiac Tissues. J Cardiovasc Pharmacol 2013. [DOI: 10.1097/fjc.0b013e31827afd29] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dysfunctional nucleus tractus solitarius: its crucial role in promoting neuropathogenetic cascade of Alzheimer's dementia--a novel hypothesis. Neurochem Res 2012; 37:846-68. [PMID: 22219130 DOI: 10.1007/s11064-011-0680-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/16/2011] [Accepted: 12/15/2011] [Indexed: 12/22/2022]
Abstract
The pathophysiological mechanism(s) underlying Alzheimer's disease (AD) still remain unclear, and no disease-modifying or prophylactic therapies are currently available. Unraveling the fundamental neuropathogenesis of AD is an important challenge. Several studies on AD have suggested lesions in a number of CNS areas including the basal forebrain, hippocampus, entorhinal cortex, amygdale/insula, and the locus coeruleus. However, plausible unifying studies on the upstream factors that involve these heterogeneous regions and herald the onset of AD pathogenesis are not available. The current article presents a novel nucleus tractus solitarius (NTS) vector hypothesis that underpins several disparate biological mechanisms and neural circuits, and identifies relevant hallmarks of major presumptive causative factor(s) linked to the NTS, in older/aging individuals. Aging, obesity, infection, sleep apnea, smoking, neuropsychological states, and hypothermia-all activate inflammatory cytokines and oxidative stress. The synergistic impact of systemic proinflammatory mediators activates microglia and promotes neuroinflammation. Acutely, the innate immune response is protective defending against pathogens/toxins; however, when chronic, it causes neuroinflammation and neuronal dysfunction, particularly in brainstem and neocortex. The NTS in the brainstem is an essential multiple signaling hub, and an extremely important central integration site of baroreceptor, chemoreceptor, and a multitude of sensory afferents from gustatory, gastrointestinal, cardiac, pulmonary, and upper airway systems. Owing to persistent neuroinflammation, the dysfunctional NTS exerts deleterious impact on nucleus ambiguus, dorsal motor nucleus of vagus, hypoglossal, parabrachial, locus coeruleus and many key nuclei in the brainstem, and the hippocampus, entorhinal cortex, prefrontal cortex, amygdala, insula, and basal forebrain in the neocortex. The neuronal and synaptic dysfunction emanating from the inflamed NTS may affect its interconnected pathways impacting almost the entire CNS--which is already primed by neuroinflammation, thus promoting cognitive and neuropsychiatric symptoms. The upstream factors discussed here may underpin the neuropathopgenesis of AD. AD pathology is multifactorial; the current perspective underscores the value of attenuating disparate upstream factors--in conjunction with anticholinesterase, anti-inflammatory, immunosuppressive, and anti-oxidant pharmacotherapy. Amelioration of the NTS pathology may be of central importance in countering the neuropathological cascade of AD. The NTS, therefore, may be a potential target of novel therapeutic strategies.
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Hussain RI, Qvigstad E, Birkeland JAK, Eikemo H, Glende A, Sjaastad I, Skomedal T, Osnes JB, Levy FO, Krobert KA. Activation of muscarinic receptors elicits inotropic responses in ventricular muscle from rats with heart failure through myosin light chain phosphorylation. Br J Pharmacol 2009. [PMID: 19159405 DOI: 10.1111/j.1476-5381.2009.00016.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Muscarinic stimulation increases myofilament Ca(2+) sensitivity with no apparent inotropic response in normal rat myocardium. Increased myofilament Ca(2+) sensitivity is a molecular mechanism promoting increased contractility in failing cardiac tissue. Thus, muscarinic receptor activation could elicit inotropic responses in ventricular myocardium from rats with heart failure, through increasing phosphorylation of myosin light chain (MLC). EXPERIMENTAL APPROACH Contractile force was measured in left ventricular papillary muscles from male Wistar rats, 6 weeks after left coronary artery ligation or sham surgery. Muscles were also frozen, and MLC-2 phosphorylation level was quantified. KEY RESULTS Carbachol (10 micromol.L(-1)) evoked a positive inotropic response only in muscles from rats with heart failure approximating 36% of that elicited by 1 micromol.L(-1) isoproterenol (20 +/- 1.5% and 56 +/- 6.1% above basal respectively). Carbachol-evoked inotropic responses did not correlate with infarction size but did correlate with increased left ventricular end diastolic pressure, heart weight/body weight ratio and lung weight, primary indicators of the severity of heart failure. Only muscarinic receptor antagonists selective for M(2) receptors antagonized carbachol-mediated inotropic effects with the expected potency. Carbachol-evoked inotropic responses and increase in phosphorylated MLC-2 were attenuated by MLC kinase (ML-9) and Rho-kinase inhibition (Y-27632), and inotropic responses were abolished by Pertussis toxin pretreatment. CONCLUSION AND IMPLICATIONS In failing ventricular muscle, muscarinic receptor activation, most likely via M(2) receptors, provides inotropic support by increasing MLC phosphorylation and consequently, myofilament Ca(2+) sensitivity. Enhancement of myofilament Ca(2+) sensitivity, representing a less energy-demanding mechanism of inotropic support may be particularly advantageous in failing hearts.
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Affiliation(s)
- R I Hussain
- Department of Pharmacology, University of Oslo, Oslo, Norway
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14
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Hussain RI, Qvigstad E, Birkeland JAK, Eikemo H, Glende A, Sjaastad I, Skomedal T, Osnes JB, Levy FO, Krobert KA. Activation of muscarinic receptors elicits inotropic responses in ventricular muscle from rats with heart failure through myosin light chain phosphorylation. Br J Pharmacol 2009; 156:575-86. [PMID: 19159405 DOI: 10.1111/j.1750-3639.2009.00016.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Muscarinic stimulation increases myofilament Ca(2+) sensitivity with no apparent inotropic response in normal rat myocardium. Increased myofilament Ca(2+) sensitivity is a molecular mechanism promoting increased contractility in failing cardiac tissue. Thus, muscarinic receptor activation could elicit inotropic responses in ventricular myocardium from rats with heart failure, through increasing phosphorylation of myosin light chain (MLC). EXPERIMENTAL APPROACH Contractile force was measured in left ventricular papillary muscles from male Wistar rats, 6 weeks after left coronary artery ligation or sham surgery. Muscles were also frozen, and MLC-2 phosphorylation level was quantified. KEY RESULTS Carbachol (10 micromol.L(-1)) evoked a positive inotropic response only in muscles from rats with heart failure approximating 36% of that elicited by 1 micromol.L(-1) isoproterenol (20 +/- 1.5% and 56 +/- 6.1% above basal respectively). Carbachol-evoked inotropic responses did not correlate with infarction size but did correlate with increased left ventricular end diastolic pressure, heart weight/body weight ratio and lung weight, primary indicators of the severity of heart failure. Only muscarinic receptor antagonists selective for M(2) receptors antagonized carbachol-mediated inotropic effects with the expected potency. Carbachol-evoked inotropic responses and increase in phosphorylated MLC-2 were attenuated by MLC kinase (ML-9) and Rho-kinase inhibition (Y-27632), and inotropic responses were abolished by Pertussis toxin pretreatment. CONCLUSION AND IMPLICATIONS In failing ventricular muscle, muscarinic receptor activation, most likely via M(2) receptors, provides inotropic support by increasing MLC phosphorylation and consequently, myofilament Ca(2+) sensitivity. Enhancement of myofilament Ca(2+) sensitivity, representing a less energy-demanding mechanism of inotropic support may be particularly advantageous in failing hearts.
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Affiliation(s)
- R I Hussain
- Department of Pharmacology, University of Oslo, Oslo, Norway
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15
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Zhang GQ, Zhang W. Heart rate, lifespan, and mortality risk. Ageing Res Rev 2009; 8:52-60. [PMID: 19022405 DOI: 10.1016/j.arr.2008.10.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 10/06/2008] [Accepted: 10/21/2008] [Indexed: 11/28/2022]
Abstract
An increasing body of scientific research and observational evidence indicates that resting heart rate (HR) is inversely related to the lifespan among homeothermic mammals and within individual species. In numerous human studies with patients stratified by resting HR, increased HR is universally associated with greater risk of death. The correlation between HR and maximum lifespan seems to be due to both basal metabolic rate and cardiovascular-related mortality risk. Both intrinsic and extrinsic factors are already postulated to determine how the biological clock works, through regulating and modulating the processes such as protein oxidation, free radical production, inflammation and telomere shortening. Given the remarkable correlation between HR and lifespan, resting HR should be seriously considered as another possible cap on maximum lifespan. Future research is needed to determine whether deliberate cardiac slowing, through methods like lifestyle modification, pharmacological intervention, or medical devices, can decelerate biological clock of aging, reduce cardiovascular mortality and increase maximum lifespan in humans in general.
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Affiliation(s)
- Gus Q Zhang
- The University of Texas Southwestern Medical School, Dallas, TX 75390, USA
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16
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Brattelid T, Tveit K, Birkeland JAK, Sjaastad I, Qvigstad E, Krobert KA, Hussain RI, Skomedal T, Osnes JB, Levy FO. Expression of mRNA encoding G protein-coupled receptors involved in congestive heart failure--a quantitative RT-PCR study and the question of normalisation. Basic Res Cardiol 2007; 102:198-208. [PMID: 17370034 DOI: 10.1007/s00395-007-0648-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 02/20/2007] [Accepted: 02/21/2007] [Indexed: 10/23/2022]
Abstract
Congestive heart failure (CHF) induces changes in the neurohumoral system and gene expression in viable myocardium. Several of these genes encode G protein-coupled receptors (GPCRs) involved in mechanisms which compensate for impaired myocardial function. We used real-time quantitative RT-PCR (Q-RT-PCR) to investigate the expression of mRNA encoding 15 different GPCRs possibly involved in CHF, and the effect of normalisation to GAPDH mRNA (GAPDH) or 18S rRNA (18S). CHF was induced in rats by coronary artery ligation, with sham-operated controls (Sham). After 6 weeks, mRNA expression in viable left ventricular myocardium was determined using both 18S and GAPDH as the normalisation standard. An apparent 30% reduction in GAPDH mRNA levels vs. 18S in CHF compared to Sham, although not significant in itself, influenced the interpretation of regulation of other genes.Thus, levels of mRNA encoding receptors for angiotensin II (AT(1)), endothelin (ET(A), ET(B)) and the muscarinic acetylcholine (mACh) receptor M(1) increased significantly in CHF only when normalised to GAPDH. Levels of mRNA encoding the mACh receptors M(3) and M(4) and the serotonin receptors 5-HT(2A) and 5-HT(4) increased, whereas alpha(1D)-adrenoceptor mRNA decreased in CHF irrespective of the normalisation standard. No significant change was detected for M2 and M5 mACh receptors or alpha(1A)-, alpha(1B)-, beta(1)- or beta(2)-adrenoceptors. Q-RT-PCR is a sensitive and powerful method to monitor changes in GPCR mRNA expression in CHF. However, the normalisation standard used is important for the interpretation of mRNA regulation.
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Affiliation(s)
- Trond Brattelid
- Dept. of Pharmacology, University of Oslo, 1057, Blindern, 0316 Oslo, Norway
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17
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Xu XL, Zang WJ, Lu J, Kang XQ, Li M, Yu XJ. Effects of carvedilol on M2 receptors and cholinesterase-positive nerves in adriamycin-induced rat failing heart. Auton Neurosci 2006; 130:6-16. [PMID: 16798104 DOI: 10.1016/j.autneu.2006.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Revised: 04/10/2006] [Accepted: 04/19/2006] [Indexed: 11/26/2022]
Abstract
Heart failure is correlated with attenuation of parasympathetic nervous function and enhanced sympathetic activity. Carvedilol, a third-generation beta-blocker, may improve the prognosis of heart failure better than selective beta(1)-blockers. Not all of its effects, however, can be explained by direct actions on the sympathetic nervous system. This study was therefore performed to investigate the possible alterations of muscarinic cholinergic (M)(2) receptors and cholinesterase-positive nerves in different regions of the adriamycin-induced failing rat heart, and the potential effects of carvedilol on these M(2) receptors and cholinesterase-positive nerves. Karnovsky-Roots histochemical staining combined with point counting methods, and immunochemical streptavidin-biotin complex staining and image analysis were used to test the distribution of cholinesterase-positive nerves and the expression of M(2) receptors, respectively. Our results show that the cholinesterase-positive nerve system was downregulated in the adriamycin-induced failing heart group, while the density of M(2) receptors was increased in the carvedilol 3- and 10-mg/kg body weight groups, especially in the endocardial tissues of the left-ventricular free wall. It is concluded that upregulation of M(2) receptors may be one of the potential mechanisms by which carvedilol exert its action on heart failure.
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Affiliation(s)
- Xiao-Li Xu
- Division of Cardiovascular Physiology and Pharmacology, School of Medicine, Xi'an Jiaotong University, Xi'an, China
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18
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Soares PPDS, Porto CS, Abdalla FMF, De La Fuente RN, Moreira ED, Krieger EM, Irigoyen MC. Effects of rat sinoaortic denervation on the vagal responsiveness and expression of muscarinic acetylcholine receptors. J Cardiovasc Pharmacol 2006; 47:331-6. [PMID: 16633073 DOI: 10.1097/01.fjc.0000205982.67653.26] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We studied heart rate (HR) responses to vagal electrical stimulation (VES) and the expression of muscarinic acetylcholine receptors (mAChRs) in the rat atria 1 day (SADa) and 20 days (SADc) after sinoaortic denervation (SAD). Arterial blood pressure (BP) was recorded in conscious, unrestrained rats and during vagal electrical stimulation of the vagus nerve. In the acute phase, SADa rats had hypertension, tachycardia, and increased blood pressure lability. In the chronic phase, heart rate and blood pressure in SADc rats returned to normal whereas blood pressure lability remained increased. VES produced a frequency-dependent bradycardia that was higher in SADa and SADc groups. Binding experiments with [H] N-methylscopolamine showed that in the chronic phase of SAD mAChRs density (SADc = 412.2 +/- 28.64, SADa = 273.38 +/- 48.37 and CTR = 241.5 +/- 25.35 fmol/mg of protein, P < 0.05) and affinity increased in SADc rats (reduced dissociation constant: SADc = 0.45 +/- 0.05, SADa = 1.01+/-0.26, and CTR = 0.98 +/- 0.12 mM, P < 0.05). Our study provides evidence that vagal hyperresponsiveness coexists with increased sympathetic activity in SADa rats without a concomitant increase in mAChRs density or affinity, suggesting that complex mechanisms might modulate the "accentuated antagonism" observed in the acute SAD phase. However, SADc rats had increased bradycardia to VES, increased affinity, and upregulation of mAChRs in the atria. Our results show that, 20 days after SAD in the rat, functional and cellular adaptations occur in the cardiac parasympathetic efferent pathway that may contribute to other regulatory mechanisms to compensate for cardiovascular changes provoked by baroreceptor arch disruption.
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Affiliation(s)
- Pedro Paulo da Silva Soares
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil, Department of Physiology and Pharmacology, Fluminense Federal University, Rio de Janeiro, Brazil.
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19
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Bonnemeier H, Schäfer U. Neurocardiology: Antifibrillatory effects of heart-brain interactions after myocardial reperfusion*. Crit Care Med 2005; 33:2708-9. [PMID: 16276215 DOI: 10.1097/01.ccm.0000186888.38583.67] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Vasconcelos CML, Araújo MS, Silva BA, Conde-Garcia EA. Negative inotropic and chronotropic effects on the guinea pig atrium of extracts obtained from Averrhoa carambola L. leaves. Braz J Med Biol Res 2005; 38:1113-22. [PMID: 16007283 DOI: 10.1590/s0100-879x2005000700015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
It has been reported that star fruit can lead to a fatal outcome in uremic patients. The intoxication syndrome consists of hiccups, mental confusion, dizziness, and vomiting. On the other hand, folk medicine uses teas and infusions of carambola leaves to treat headache, vomiting, cough, insomnia, and diabetes. This motivated us to determine if Averrhoa carambola can act on the contractility and automaticity of the guinea pig heart. We measured the atrial isometric force in stimulated left atria and determined the chronotropic changes in spontaneously beating right atria. The carambola leaf extracts (1.5 mg/ml) abolished the contractile force in a concentration-dependent manner. Among the crude, methanolic, ethanolic, aqueous, and acetic extracts, the aqueous one was the most potent (EC50 = 520 +/- 94 microg/ml; flavonoids and tannins are the main constituents; Na+ and K+ contents in 1.0 mg/ml of aqueous extract were 0.12 +/- 0.016 and 1.19 +/- 0.15 mM, respectively). The aqueous extract abolished the positive Bowditch staircase phenomenon and reduced the inotropic response to CaCl2 (0.17-8.22 mM), events that are dependent on the cellular Ca2+ inward current. The adrenergic, muscarinic or opioid membrane receptors do not seem to participate in the mechanism of action of the cardioactive substance(s). In spontaneously beating atria, the aqueous extract promoted a negative chronotropic effect that was antagonized by 0.1 microM isoproterenol bitartrate. With this agonist, the EC50 of the aqueous extract increased from 133 +/- 58 to 650 +/- 100 microg/ml. These data regarding the effect of A. carambola on guinea pig atrial contractility and automaticity indicate an L-type Ca2+ channel blockade.
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Affiliation(s)
- C M L Vasconcelos
- Laboratório de Biofísica do Coração, Departamento de Fisiologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe, Aracaju, SE, Brasil
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21
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Brodde OE, Leineweber K. Autonomic receptor systems in the failing and aging human heart: similarities and differences. Eur J Pharmacol 2004; 500:167-76. [PMID: 15464030 DOI: 10.1016/j.ejphar.2004.07.022] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2004] [Indexed: 11/21/2022]
Abstract
Changes in autonomic receptor systems (alpha- and beta-adrenoceptors and muscarinic receptors) were compared in the aging and failing human heart. In both settings responsiveness of beta-adrenoceptors and all other receptor systems that evoke their effects via cyclic AMP accumulation was diminished. Muscarinic receptor function, on the other hand, was decreased in the aging, but unchanged in the failing heart; in contrast, G protein-coupled receptor kinase activity was increased in the failing, but unchanged in the aging heart. alpha-Adrenoceptor function was unchanged or slightly decreased in the failing heart. However, nothing is known on alpha-adrenoceptor changes in the aging heart. These results indicate that in the failing human heart all autonomic receptor systems appear to be altered in the direction to attenuate beta-adrenoceptor responses to sympathetic (over)stimulation while in the aging human heart autonomic receptor systems appear to be altered in a direction that protects the heart against too pronounced reduction in beta-adrenoceptor responsiveness.
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Affiliation(s)
- Otto-Erich Brodde
- Departments of Pathophysiology and Nephrology, University of Essen School of Medicine, IG I., 9.OG, Hufelandstr. 55, D-45147 Essen, Germany.
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22
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Wang Z, Shi H, Wang H. Functional M3 muscarinic acetylcholine receptors in mammalian hearts. Br J Pharmacol 2004; 142:395-408. [PMID: 15148264 PMCID: PMC1574958 DOI: 10.1038/sj.bjp.0705787] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2004] [Revised: 03/08/2004] [Accepted: 03/10/2004] [Indexed: 11/08/2022] Open
Abstract
In contrast to most peripheral tissues where multiple subtypes of muscarinic acetylcholine receptor (mAChR) coexist, with each of them playing its part in the orchestra of parasympathetic innervation, the myocardium has been traditionally considered to possess a single mAChR subtype. Although there is much evidence to support the notion that one receptor subtype (M2) orchestrates myocardial muscarinic transduction, there is emerging evidence that M1 and M3 receptors are also expressed and are of potential physiological, pathophysiological and pharmacological relevance. Clarifying this issue has a profound impact on our thinking about the cholinergic control of the heart function and disease and approaches to new drug development for the treatment of heart disease associated with parasympathetic dysfunction. This review article presents evidence for the presence of the M3 receptor subtype in the heart, and analyzes the controversial data from published pharmacological, functional and molecular studies. The potential roles of the M3 receptors, in parasympathetic control of heart function under normal physiological conditions and in heart failure, myocardial ischemia and arrhythmias, are discussed. On the basis of these considerations, we have made some proposals concerning the future of myocardial M3 receptor research.
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Affiliation(s)
- Zhiguo Wang
- Research Center, Montreal Heart Institute, University of Montreal, Montreal, Quebec, Canada.
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23
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Li M, Zheng C, Sato T, Kawada T, Sugimachi M, Sunagawa K. Vagal Nerve Stimulation Markedly Improves Long-Term Survival After Chronic Heart Failure in Rats. Circulation 2004; 109:120-4. [PMID: 14662714 DOI: 10.1161/01.cir.0000105721.71640.da] [Citation(s) in RCA: 450] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Diminished cardiac vagal activity and higher heart rate predict a high mortality rate of chronic heart failure (CHF) after myocardial infarction. We investigated the effects of chronic electrical stimulation of the vagus nerve on cardiac remodeling and long-term survival in an animal model of CHF after large myocardial infarction.
Methods and Results—
Two weeks after the ligation of the left coronary artery, surviving rats were randomized to vagal- and sham-stimulated groups. Using an implantable miniature radio-controlled electrical stimulator, we stimulated the right vagal nerve of CHF rats for 6 weeks. The intensity of electrical stimulation was adjusted for each rat, so that the heart rate was lowered by 20 to 30 beats per minute. The treated rats had significantly lower left ventricular end-diastolic pressure (17.1±5.9 versus 23.5±4.2 mm Hg,
P
<0.05) and higher maximum dp/dt of left ventricular pressure (4152±237 versus 2987±192 mm Hg/s,
P
<0.05) than the untreated rats. Improvement of cardiac pumping function was accompanied by a decrease in normalized biventricular weight (2.75±0.25 versus 3.14±0.22 g/kg,
P
<0.01). Although the 140-day survival of the untreated group was only half, vagal stimulation markedly improved the survival rate (86% versus 50%,
P
=0.008). Vagal stimulation therapy achieved a 73% reduction in a relative risk ratio of death.
Conclusions—
Vagal nerve stimulation markedly improved the long-term survival of CHF rats through the prevention of pumping failure and cardiac remodeling.
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Affiliation(s)
- Meihua Li
- Department of Cardiovascular Dynamics, Cardiovascular Center Research Institute, Suita, Japan
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24
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Abstract
In the mammalian heart, cardiac function is under the control of the sympathetic and parasympathetic nervous system. All regions of the mammalian heart are innervated by parasympathetic (vagal) nerves, although the supraventricular tissues are more densely innervated than the ventricles. Vagal activation causes stimulation of cardiac muscarinic acetylcholine receptors (M-ChR) that modulate pacemaker activity via I(f) and I(K.ACh), atrioventricular conduction, and directly (in atrium) or indirectly (in ventricles) force of contraction. However, the functional response elicited by M-ChR-activation depends on species, age, anatomic structure investigated, and M-ChR-agonist concentration used. Among the five M-ChR-subtypes M(2)-ChR is the predominant isoform present in the mammalian heart, while in the coronary circulation M(3)-ChR have been identified. In addition, evidence for a possible existence of an additional, not M(2)-ChR in the heart has been presented. M-ChR are subject to regulation by G-protein-coupled-receptor kinase. Alterations of cardiac M(2)-ChR in age and various kinds of disease are discussed.
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Affiliation(s)
- S Dhein
- Institute of Pharmacology, University of Halle-Wittenberg, Germany.
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25
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Abstract
Angiotensin II interacts with specific cell surface angiotensin AT1 and AT2 receptors and, in some vertebrates, with an atypical angiotensin AT receptor. This study was designed to characterize the angiotensin receptor in the heart of Bothrops jararaca snake. A specific and saturable angiotensin II binding site was detected in cardiac membranes and yielded Kd=7.34+/-1.41 nM and B(max)=72.49+/-18 fmol/mg protein. Competition-binding studies showed an angiotensin receptor with low affinity to both angiotensin receptor antagonists, losartan (2-n-butyl-4-chloro-5-hydroxymethyl-1-[(2'-(1H-tetrazol-5-yl)biphenyl-4-yl)methyl]imidazole) and PD123319 ((s)-1-(4-[dimethylamino]-3-methylphenyl)methyl-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylate). Studies on the intracellular signaling pathways showed that phospholipase C/inositol phosphate breakdown and adenylylcyclase/cyclic AMP generation were not coupled with this angiotensin receptor. An adenylylcyclase enzyme sensitive to forskolin was detected. The results indicate the presence of an angiotensin receptor in the heart of B. jararaca snake pharmacologically distinct from angiotensin AT1 and AT2 receptors. It seems to belong to a new class of angiotensin receptors, like some other atypical angiotensin AT receptors that have already been described.
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Affiliation(s)
- M C Breno
- Laboratory of Pharmacology, Instituto Butantan, SP, São Paulo, Brazil
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26
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Seyfarth T, Gerbershagen HP, Giessler C, Leineweber K, Heinroth-Hoffmann I, Pönicke K, Brodde OE. The cardiac beta-adrenoceptor-G-protein(s)-adenylyl cyclase system in monocrotaline-treated rats. J Mol Cell Cardiol 2000; 32:2315-26. [PMID: 11113007 DOI: 10.1006/jmcc.2000.1262] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In rats, injection of the alkaloid monocrotaline (MCT) causes right ventricular hypertrophy and cardiac failure. In order to study whether, in MCT-treated rats, changes in the cardiac beta -adrenoceptor-G-protein(s)-adenylyl cyclase system might be comparable to those found in human primary pulmonary hypertension, we assessed in right and left ventricles from MCT-treated rats the components of the beta -adrenoceptor system: the receptor number and subtype distribution (by (-)-[(125)I]iodocyanopindolol binding), the G-proteins (by quantitative Western blotting), and the activity of adenylyl cyclase. A single injection of 60 mg/kg i.p. MCT caused in rats right ventricular hypertrophy (RVH); part of the rats developed cardiac failure (RVF). In these rats the cardiac beta -adrenoceptor-G-protein(s)-adenylyl cyclase system was markedly changed beta -adrenoceptors were desensitized due to a decrease in receptor number, an uncoupling of the receptor from the G(s)-adenylyl cyclase system, a decrease in G(s)and a decrease in the activity of the catalytic unit of adenylyl cyclase. In general, these changes were more pronounced in right ventricles v left ventricles, and in rats with RVF v rats with RVH. On the other hand, cardiac muscarinic receptors and G(i)appeared not to be altered. We conclude that in MCT-treated rats changes in the cardiac beta -adrenoceptor-G-protein(s)-adenylyl cyclase system occur that resemble those observed in human primary pulmonary hypertension. Thus, MCT-treated rat appears to be a suitable animal model to study in more detail the pathophysiology of the development of right heart failure, and to identify new therapeutic possibilities.
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Affiliation(s)
- T Seyfarth
- Institute of Pharmacology, Martin-Luther-University of Halle-Wittenberg, Halle, D-06097, Germany
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27
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Dhein S, Giessler C, Wangemann T, Silber RE, Zerkowski HR, Brodde OE. Differential pattern of endothelin-1-induced inotropic effects in right atria and left ventricles of the human heart. J Cardiovasc Pharmacol 2000; 36:564-9. [PMID: 11065215 DOI: 10.1097/00005344-200011000-00004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In human right atrium, endothelin A (ET(A)) receptors couple to both inositol phosphate formation and inhibition of adenylylcyclase, whereas in human left ventricle, ET(A) receptors couple only to inositol phosphate formation. To find out whether this might be of functional relevance, we studied, in right atria obtained from 32 patients undergoing coronary bypass grafting without apparent heart failure, and in right atria and left ventricles from eight patients with end-stage heart failure (NYHA IV) undergoing heart transplantation, the effects of endothelin-1 (ET-1) on basal force of contraction or on force of contraction increased by 1 microM forskolin. ET-1 (0.1 microM) exerted a positive inotropic effect in atrial and ventricular tissue; this could be antagonized by the ET(A)-receptor antagonist BQ 123, but not by the ET(B)-receptor antagonist BQ 788. In atrial, but not in ventricular tissue, this positive inotropic effect was preceded by a transient negative inotropic effect. This negative inotropic effect was inhibited by BQ 123, but not by BQ 788. It was significantly prolonged in forskolin-prestimulated atria, and was significantly larger in atria from failing hearts. We conclude that, because ET-1 inhibits adenylylcyclase and causes negative inotropic effects in atria but not in ventricles, adenylylcyclase inhibition might be responsible for the transient negative inotropic effect of ET-1.
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Affiliation(s)
- S Dhein
- Department of Pharmacology, University of Halle, Germany.
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