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Schröper T, Mehrkens D, Leiss V, Tellkamp F, Engelhardt S, Herzig S, Birnbaumer L, Nürnberg B, Matthes J. Protective effects of Gα i3 deficiency in a murine heart-failure model of β 1-adrenoceptor overexpression. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2024; 397:2401-2420. [PMID: 37843590 PMCID: PMC10933181 DOI: 10.1007/s00210-023-02751-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 09/26/2023] [Indexed: 10/17/2023]
Abstract
We have shown that in murine cardiomyopathy caused by overexpression of the β1-adrenoceptor, Gαi2-deficiency is detrimental. Given the growing evidence for isoform-specific Gαi-functions, we now examined the consequences of Gαi3 deficiency in the same heart-failure model. Mice overexpressing cardiac β1-adrenoceptors with (β1-tg) or without Gαi3-expression (β1-tg/Gαi3-/-) were compared to C57BL/6 wildtypes and global Gαi3-knockouts (Gαi3-/-). The life span of β1-tg mice was significantly shortened but improved when Gαi3 was lacking (95% CI: 592-655 vs. 644-747 days). At 300 days of age, left-ventricular function and survival rate were similar in all groups. At 550 days of age, β1-tg but not β1-tg/Gαi3-/- mice displayed impaired ejection fraction (35 ± 18% vs. 52 ± 16%) compared to wildtype (59 ± 4%) and Gαi3-/- mice (60 ± 5%). Diastolic dysfunction of β1-tg mice was prevented by Gαi3 deficiency, too. The increase of ANP mRNA levels and ventricular fibrosis observed in β1-tg hearts was significantly attenuated in β1-tg/Gαi3-/- mice. Transcript levels of phospholamban, ryanodine receptor 2, and cardiac troponin I were similar in all groups. However, Western blots and phospho-proteomic analyses showed that in β1-tg, but not β1-tg/Gαi3-/- ventricles, phospholamban protein was reduced while its phosphorylation increased. Here, we show that in mice overexpressing the cardiac β1-adrenoceptor, Gαi3 deficiency slows or even prevents cardiomyopathy and increases shortened life span. Previously, we found Gαi2 deficiency to aggravate cardiac dysfunction and mortality in the same heart-failure model. Our findings indicate isoform-specific interventions into Gi-dependent signaling to be promising cardio-protective strategies.
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Affiliation(s)
- Tobias Schröper
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany and Centre for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Dennis Mehrkens
- Department of Internal Medicine III, University Hospital of Cologne, Cologne, Germany and Centre for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Centre for Molecular Medicine Cologne, CMMC, University of Cologne, Cologne, Germany
| | - Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomics, and Interfaculty Centre for Pharmacogenomics and Drug Research, Eberhard Karls Universität, Tübingen, Germany
| | - Frederik Tellkamp
- CECAD Research Centre Institute for Genetics, University of Cologne, Cologne, Germany
| | - Stefan Engelhardt
- Institute of Pharmacology and Toxicology, Technische Universität München, Munich, Germany
| | - Stefan Herzig
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany
- TH Köln-University of Applied Sciences, Cologne, Germany
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, North Carolina, USA
- Institute of Biomedical Research, School of Medical Sciences, Catholic University of Buenos Aires, Buenos Aires, Argentina
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute for Experimental and Clinical Pharmacology and Pharmacogenomics, and Interfaculty Centre for Pharmacogenomics and Drug Research, Eberhard Karls Universität, Tübingen, Germany
| | - Jan Matthes
- Center of Pharmacology, Department II, University of Cologne and University Hospital Cologne, Cologne, Germany.
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Alegre KO, Paknejad N, Su M, Lou JS, Huang J, Jordan KD, Eng ET, Meyerson JR, Hite RK, Huang XY. Structural basis and mechanism of activation of two different families of G proteins by the same GPCR. Nat Struct Mol Biol 2021; 28:936-944. [PMID: 34759376 DOI: 10.1038/s41594-021-00679-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 09/30/2021] [Indexed: 01/14/2023]
Abstract
The β1-adrenergic receptor (β1-AR) can activate two families of G proteins. When coupled to Gs, β1-AR increases cardiac output, and coupling to Gi leads to decreased responsiveness in myocardial infarction. By comparative structural analysis of turkey β1-AR complexed with either Gi or Gs, we investigate how a single G-protein-coupled receptor simultaneously signals through two G proteins. We find that, although the critical receptor-interacting C-terminal α5-helices on Gαi and Gαs interact similarly with β1-AR, the overall interacting modes between β1-AR and G proteins vary substantially. Functional studies reveal the importance of the differing interactions and provide evidence that the activation efficacy of G proteins by β1-AR is determined by the entire three-dimensional interaction surface, including intracellular loops 2 and 4 (ICL2 and ICL4).
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Affiliation(s)
- Kamela O Alegre
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Navid Paknejad
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Minfei Su
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Jian-Shu Lou
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Jianyun Huang
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Kelsey D Jordan
- Simons Electron Microscopy Center, National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY, USA
| | - Edward T Eng
- Simons Electron Microscopy Center, National Resource for Automated Molecular Microscopy, New York Structural Biology Center, New York, NY, USA
| | - Joel R Meyerson
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | - Xin-Yun Huang
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA.
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Colombe AS, Pidoux G. Cardiac cAMP-PKA Signaling Compartmentalization in Myocardial Infarction. Cells 2021; 10:cells10040922. [PMID: 33923648 PMCID: PMC8073060 DOI: 10.3390/cells10040922] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/02/2021] [Accepted: 04/13/2021] [Indexed: 02/07/2023] Open
Abstract
Under physiological conditions, cAMP signaling plays a key role in the regulation of cardiac function. Activation of this intracellular signaling pathway mirrors cardiomyocyte adaptation to various extracellular stimuli. Extracellular ligand binding to seven-transmembrane receptors (also known as GPCRs) with G proteins and adenylyl cyclases (ACs) modulate the intracellular cAMP content. Subsequently, this second messenger triggers activation of specific intracellular downstream effectors that ensure a proper cellular response. Therefore, it is essential for the cell to keep the cAMP signaling highly regulated in space and time. The temporal regulation depends on the activity of ACs and phosphodiesterases. By scaffolding key components of the cAMP signaling machinery, A-kinase anchoring proteins (AKAPs) coordinate both the spatial and temporal regulation. Myocardial infarction is one of the major causes of death in industrialized countries and is characterized by a prolonged cardiac ischemia. This leads to irreversible cardiomyocyte death and impairs cardiac function. Regardless of its causes, a chronic activation of cardiac cAMP signaling is established to compensate this loss. While this adaptation is primarily beneficial for contractile function, it turns out, in the long run, to be deleterious. This review compiles current knowledge about cardiac cAMP compartmentalization under physiological conditions and post-myocardial infarction when it appears to be profoundly impaired.
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Xing G, Woo AYH, Pan L, Lin B, Cheng MS. Recent Advances in β 2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure. J Med Chem 2020; 63:15218-15242. [PMID: 33213146 DOI: 10.1021/acs.jmedchem.0c01195] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
β2-Adrenoceptor (β2-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β2-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β2-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β1-AR and the β2-AR on cardiomyocyte survival. Thus, β2-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β2-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β2-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.
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Affiliation(s)
- Gang Xing
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China.,Key Laboratory of Structure-Based Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Anthony Yiu-Ho Woo
- Department of Pharmacology, School of Life Sciences and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Li Pan
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China.,Key Laboratory of Structure-Based Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Bin Lin
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China.,Key Laboratory of Structure-Based Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Mao-Sheng Cheng
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China.,Key Laboratory of Structure-Based Drug Design and Discovery of Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, China
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Chowdhury A, Sarkar J, Kanti Pramanik P, Chakraborti T, Chakraborti S. Role of PKCζ-NADPH oxidase signaling axis in PKCα-mediated Giα2 phosphorylation for inhibition of adenylate cyclase activity by angiotensin II in pulmonary artery smooth muscle cells. Cell Biol Int 2020; 44:1142-1155. [PMID: 31965656 DOI: 10.1002/cbin.11311] [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: 09/03/2019] [Accepted: 01/21/2020] [Indexed: 11/10/2022]
Abstract
We sought to determine the mechanism by which angiotensin II (AngII) inhibits isoproterenol induced increase in adenylate cyclase (AC) activity and cyclic adenosine monophosphate (cAMP) production in bovine pulmonary artery smooth muscle cells (BPASMCs). Treatment with AngII stimulates protein kinase C-ζ (PKC-ζ), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and PKC-α activities, and also inhibits isoproterenol induced increase in AC activity and cAMP production in the cells. Pertussis toxin pretreatment eliminates AngII caused inhibition of isoproterenol induced increase in AC activity without a discernible change in PKC-ζ, NADPH oxidase, and PKC-α activities. Treatment of the cells with AngII increases α2 isoform of Gi (Giα2) phosphorylation; while pretreatment with chemical and genetic inhibitors of PKC-ζ and NADPH oxidase attenuate AngII induced increase in PKC-α activity and Giα2 phosphorylation, and also reverse AngII caused inhibition of isoproterenol induced increase in AC activity. Pretreatment of the cells with chemical and genetic inhibitors of PKC-α attenuate AngII induced increase in Giα2 phosphorylation and inhibits isoproterenol induced increase in AC activity without a discernible change in PKC-ζ and NADPH oxidase activities. Overall, PKCζ-NADPH oxidase-PKCα signaling axis plays a crucial role in Giα2 phosphorylation resulting in AngII-mediated inhibition of isoproterenol induced increase in AC activity in BPASMCs.
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Affiliation(s)
- Animesh Chowdhury
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India
| | - Jaganmay Sarkar
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India
| | - Pijush Kanti Pramanik
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India
| | - Tapati Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India
| | - Sajal Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India
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Xu Z, Wu J, Xin J, Feng Y, Hu G, Shen J, Li M, Zhang Y, Xiao H, Wang L. β3-adrenergic receptor activation induces TGFβ1 expression in cardiomyocytes via the PKG/JNK/c-Jun pathway. Biochem Biophys Res Commun 2018; 503:146-151. [DOI: 10.1016/j.bbrc.2018.05.200] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 05/29/2018] [Indexed: 12/22/2022]
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Wang B, Xu M, Li W, Li X, Zheng Q, Niu X. Aerobic exercise protects against pressure overload-induced cardiac dysfunction and hypertrophy via β3-AR-nNOS-NO activation. PLoS One 2017. [PMID: 28622359 PMCID: PMC5473571 DOI: 10.1371/journal.pone.0179648] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aerobic exercise confers sustainable protection against cardiac hypertrophy and heart failure (HF). Nitric oxide synthase (NOS) and nitric oxide (NO) are known to play an important role in exercise-mediated cardioprotection, but the mechanism of NOS/NO stimulation during exercise remains unclear. The aim of this study is to determine the role of β3-adrenergic receptors (β3-ARs), NOS activation, and NO metabolites (nitrite and nitrosothiols) in the sustained cardioprotective effects of aerobic exercise. An HF model was constructed by transverse aortic constriction (TAC). Animals were treated with either moderate aerobic exercise by swimming for 9 weeks and/or the β3-AR-specific inhibitor SR59230A at 0.1 mg/kg/hour one day after TAC operation. Myocardial fibrosis, myocyte size, plasma catecholamine (CA) level, cardiac function and geometry were assessed using Masson’s trichrome staining, FITC-labeled wheat germ agglutinin staining, enzyme-linked immuno sorbent assay (ELISA) and echocardiography, respectively. Western blot analysis was performed to elucidate the expression of target proteins. The concentration of myocardial NO production was evaluated using the nitrate reductase method. Myocardial oxidative stress was assessed by detecting the concentration of myocardial super oxidative dismutase (SOD), malonyldialdehyde (MDA), and reactive oxygen species (ROS). Aerobic exercise training improved dilated left ventricular function and partially attenuated the degree of cardiac hypertrophy and fibrosis in TAC mice. Moreover, the increased expression of β3-AR, activation of neuronal NOS (nNOS), and production of NO were detected after aerobic exercise training in TAC mice. However, selective inhibition of β3-AR by SR59230A abolished the upregulation and activation of nNOS induced NO production. Furthermore, aerobic exercise training decreased the myocardial ROS and MDA contents and increased myocardial levels of SOD; both effects were partially attenuated by SR59230A. Our study suggested that aerobic exercise training could improve cardiac systolic function and alleviate LV chamber dilation, cardiac fibrosis and hypertrophy in HF mice. The mechanism responsible for the protective effects of aerobic exercise is associated with the activation of the β3-AR-nNOS-NO pathway.
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Affiliation(s)
- Bin Wang
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Ming Xu
- Department of Physiology, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Wenju Li
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Xiaoli Li
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Qiangsun Zheng
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
- Department of Cardiology, the Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
- * E-mail: (XN); (QZ)
| | - Xiaolin Niu
- Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
- * E-mail: (XN); (QZ)
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8
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Glasgow J, Koshman Y, Samarel AM, Tseng KY, Scrogin K. Myocardial infarction sensitizes medial prefrontal cortex to inhibitory effect of locus coeruleus stimulation in rats. Psychopharmacology (Berl) 2016; 233:2581-92. [PMID: 27150078 PMCID: PMC5715661 DOI: 10.1007/s00213-016-4305-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 04/20/2016] [Indexed: 12/13/2022]
Abstract
RATIONALE Anxiety is a common comorbidity that develops after myocardial infarction and is now an established independent risk factor for cardiovascular mortality. OBJECTIVE Here, we assessed anxiety and mapped neural activity of forebrain regions that regulate anxiety in a rat model of myocardial infarction in order to identify sites of dysregulation. METHODS Anxiety responses to novel (open field) or aversive stimuli (discriminative auditory fear conditioning) were assessed in rats subjected to coronary artery ligation (CAL) or sham ligation. Forebrain metabolic activity was measured by cytochrome oxidase (CO) histochemistry. Changes in CO activity and the incidence of ventricular arrhythmias were also assessed during modulation of fear circuitry induced by electrical stimulation of the locus coeruleus. RESULTS Coronary artery ligation had negligible effects on open-field behavior, but increased expression of learned fear and impaired fear cue discrimination. Cytochrome oxidase activity was increased in the medial prefrontal cortex and in the lateral amygdala after CAL. Locus coeruleus stimulation reduced CO activity in the infralimbic medial prefrontal cortex only in rats subjected to CAL. Stimulation of the LC also elicited new ventricular arrhythmias in rats subjected to CAL. CONCLUSION Coronary artery ligation sensitizes the infralimbic medial prefrontal cortex to the inhibitory effects of locus coeruleus stimulation. Suppression of infralimbic medial prefrontal cortical activity may impair the ability of rats subjected to CAL to discriminate between cues that signal aversive and neutral events which, in turn, may promote excessive sympathetic activation of the cardiovascular system in response to innocuous stimuli.
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Affiliation(s)
- Jaimee Glasgow
- Graduate Program in Cell Biology, Neurobiology, and Anatomy, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA
| | - Yevgeniya Koshman
- Cardiovascular Institute, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA
| | - Allen M Samarel
- Cardiovascular Institute, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA
| | - Kuei Y Tseng
- Department of Cellular and Molecular Pharmacology, The Chicago Medical School at Rosalind Franklin University, North Chicago, IL, USA
| | - Karie Scrogin
- Graduate Program in Cell Biology, Neurobiology, and Anatomy, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA.
- Cardiovascular Institute, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA.
- Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA.
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Singh A, Mallick BN. Targeting modulation of noradrenalin release in the brain for amelioration of REMS loss-associated effects. J Transl Int Med 2015; 3:8-16. [PMID: 27847879 PMCID: PMC4936468 DOI: 10.4103/2224-4018.154288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Rapid eye movement sleep (REMS) loss affects most of the physiological processes, and it has been proposed that REMS maintains normal physiological processes. Changes in cultural, social, personal traits and life-style severely affect the amount and pattern of sleep, including REMS, which then manifests symptoms in animals, including humans. The effects may vary from simple fatigue and irritability to severe patho-physiological and behavioral deficits such as cognitive and behavioral dysfunctions. It has been a challenge to identify a molecule(s) that may have a potential for treating REMS loss-associated symptoms, which are very diverse. For decades, the critical role of locus coeruleus neurons in regulating REMS has been known, which has further been supported by the fact that the noradrenalin (NA) level is elevated in the brain after REMS loss. In this review, we have collected evidence from the published literature, including those from this laboratory, and argue that factors that affect REMS and vice versa modulate the level of a common molecule, the NA. Further, NA is known to affect the physiological processes affected by REMS loss. Therefore, we propose that modulation of the level of NA in the brain may be targeted for treating REMS loss-related symptoms. Further, we also argue that among the various ways to affect the release of NA-level, targeting α2 adrenoceptor autoreceptor on the pre-synaptic terminal may be the better option for ameliorating REMS loss-associated symptoms.
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Affiliation(s)
- Abhishek Singh
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Melsom CB, Hussain RI, Ørstavik Ø, Aronsen JM, Sjaastad I, Skomedal T, Osnes JB, Levy FO, Krobert KA. Non-classical regulation of β1- and β 2-adrenoceptor-mediated inotropic responses in rat heart ventricle by the G protein Gi. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:1177-86. [PMID: 25216690 DOI: 10.1007/s00210-014-1036-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/05/2014] [Indexed: 01/08/2023]
Abstract
Studies suggest that increased activity of Gi contributes to the reduced β-adrenoceptor-mediated inotropic response (βAR-IR) in failing cardiomyocytes and that β2AR-IR but not β1AR-IR is blunted by dual coupling to Gs and Gi. We aimed to clarify the role of Gi upon the β1AR-IR and β2AR-IR in Sham and failing myocardium by directly measuring contractile force and cAMP accumulation. Contractility was measured ex vivo in left ventricular strips and cAMP accumulation in cardiomyocytes from rats with post-infarction heart failure (HF) or sham operates (Sham). The β2AR-IR in Sham and HF was small and was amplified by simultaneously inhibiting phosphodiesterases 3 and 4 (PDE3&4). In HF, the inotropic response and cAMP accumulation evoked by β1AR- or β2AR-stimulation were reduced. Inactivation of Gi with pertussis toxin (PTX) did not restore the β1AR-IR or β2AR-IR in HF to Sham levels but did enhance the maximal β2AR-IR. PTX increased both β1AR- and β2AR-evoked cAMP accumulation more in Sham than that in HF, and HF levels approached those in untreated Sham. The potency of agonists at β1 and at β2ARs (only under PDE3&4 inhibition) was increased in HF and by PTX in both HF and Sham. Without PDE3&4 inhibition, PTX increased only the maximal β2AR-IR, not potency. We conclude that Gi regulates both β1AR- and β2AR-IR independent of receptor coupling with Gi. Gi together with PDE3&4 tonically restrict the β2AR-IR. Gi inhibition did not restore the βAR-IR in HF despite increasing cAMP levels, suggesting that the mechanism of impairment resides downstream to cAMP signalling.
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Affiliation(s)
- Caroline Bull Melsom
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
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Chakraborti S, Roy S, Mandal A, Chowdhury A, Chakraborti T. Role of PKC-ζ in NADPH oxidase-PKCα-Giα axis dependent inhibition of β-adrenergic response by U46619 in pulmonary artery smooth muscle cells. Arch Biochem Biophys 2013; 540:133-44. [PMID: 24184446 DOI: 10.1016/j.abb.2013.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/02/2013] [Accepted: 10/23/2013] [Indexed: 02/04/2023]
Abstract
Treatment of bovine pulmonary artery smooth muscle cells (BPASMCs) with U46619 attenuated isoproterenol caused stimulation of adenyl cyclase activity and cAMP production. Pretreatment with SQ29548 (Tp receptor antagonist), apocynin (NADPH oxidase inhibitor) and Go6976 (PKC-α inhibitor) eliminated U46619 caused attenuation of isoproterenol stimulated adenyl cyclase activity. Pretreatment with SQ29548 and apocynin prevented U46619 induced increase in NADPH oxidase activity, PKC-α activity and Giα phosphorylation. However, pretreatment with CZI, a PKC-ζ inhibitor, markedly, but not completely, inhibited U46619 induced increase in NADPH oxidase activity, PKC-α activity, Giα phosphorylation and also significantly eliminated U46619 caused attenuation of isoproterenol stimulated adenyl cyclase activity. Pretreatment with Go6976 inhibited U46619 induced increase in Giα phosphorylation, but not PKC-ζ activity and NADPH oxidase activity. Pretreatment with pertussis toxin eliminated U46619 caused attenuation of isoproterenol stimulated adenyl cyclase activity without any discernible change in PKC-ζ, NADPH oxidase and PKC-α activities. Transfection of the cells with Tp, PKC-ζ and PKC-α siRNA duplexes corroborate the findings observed with their respective pharmacological inhibitors on the responses produced by U46619. Taken together, we suggest involvement of PKC-ζ in U46619 caused attenuation of isoproterenol stimulated β-adrenergic response, which is regulated by NADPH oxidase-PKCα-Giα axis in pulmonary artery smooth muscle cells.
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Affiliation(s)
- Sajal Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Nadia 741235, West Bengal, India.
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Hussain RI, Aronsen JM, Afzal F, Sjaastad I, Osnes JB, Skomedal T, Levy FO, Krobert KA. The functional activity of inhibitory G protein (G(i)) is not increased in failing heart ventricle. J Mol Cell Cardiol 2012; 56:129-38. [PMID: 23220156 DOI: 10.1016/j.yjmcc.2012.11.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 11/22/2012] [Accepted: 11/24/2012] [Indexed: 11/16/2022]
Abstract
Beta-adrenergic receptor (βAR) inotropic effects are attenuated and muscarinic receptor-mediated inhibition thereof is enhanced in heart failure. We investigated if increased G(i) activity contributes to attenuated βAR-inotropic effects and potentiates muscarinic accentuated antagonism in failing rat ventricle. Contractility was measured in ventricular strips and adenylyl cyclase (AC) activity in ventricular membranes from rats with post-infarction heart failure (HF) or Sham-operated controls (Sham). The maximal βAR-mediated inotropic effect of isoproterenol was reduced by ~70% and basal, βAR- & forskolin-stimulated AC activity was significantly lower in HF vs. Sham. Carbachol-evoked antagonism of the βAR-mediated inotropic response was complete only in HF despite a ~40% reduction in the ability of carbachol to inhibit βAR-stimulated AC. However, neither the relative efficacy (contractility decreased by ~46%) nor the potency of carbachol to inhibit the βAR inotropic response differed between Sham and HF ventricle. Pertussis toxin (PTX) inactivation of G(i) did not increase the maximal βAR inotropic effect or the attenuated basal, βAR- & forskolin-stimulated AC activity in HF, but increased the potency of isoproterenol only in Sham (~0.5 log unit). In HF ventricle pretreated with PTX, simultaneous inhibition of phosphodiesterases 3,4 (PDE3,4) alone produced a larger inotropic response than isoproterenol in ventricle untreated with PTX (84% and 48% above basal respectively). In the absence of PTX, PDE3,4 inhibition evoked negligible inotropic effects in HF. These data are not consistent with the hypothesis that increased G(i) activity contributes to the reduced βAR-mediated inotropic response and AC activity in failing ventricle. The data, however, support the hypothesis that G(i), through chronic receptor independent inhibition of AC, together with PDE3,4 activity, is necessary to maintain a low basal level of contractility.
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Affiliation(s)
- R I Hussain
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Oslo, Norway
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13
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Sun J, Fu L, Tang X, Han Y, Ma D, Cao J, Kang N, Ji H. Testosterone modulation of cardiac β-adrenergic signals in a rat model of heart failure. Gen Comp Endocrinol 2011; 172:518-25. [PMID: 21549119 DOI: 10.1016/j.ygcen.2011.04.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 03/16/2011] [Accepted: 04/20/2011] [Indexed: 01/08/2023]
Abstract
In this study, we examined the effects of castration and testosterone replacement on β-adrenoceptor and G protein expression in rats subjected to doxorubicin-induced heart failure. Five groups were included in this report: control, sham-castration with heart failure, castration with heart failure, castration+testosterone replacement with heart failure and castration+testosterone replacement and flutamide with heart failure. At 4 weeks post-treatment, echocardiography, hemodynamics and histopathology were assessed. Castration led to a further deterioration in myocardial performance, apoptosis and fibrosis, while testosterone replacement ameliorated these effects. Data obtained from Western blots revealed that testosterone upregulated the expression of β(2)-adrenoceptor, Gs, Gi(2) and bcl2 levels, downregulated the expression of β(3)-adrenoceptor, Gi(3) and GRK2 levels, and did not modify the expression of β(1)-adrenoceptor levels in the hearts of castrated rats subjected to doxorubicin-induced heart failure. Analyses of serum 17β-estradiol concentrations test confirmed that these effects of testosterone were exerted through the androgen pathway. Thus our findings suggest that testosterone may have beneficial effects for male heart failure patients with androgen deficiency and this protection involves modulation of the cardiac β-adrenergic system.
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Affiliation(s)
- Junfeng Sun
- Department of Cardiovascular Medicine, First Affiliated Hospital, Harbin Medical University, Harbin, China
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14
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Hussain RI, Afzal F, Mørk HK, Aronsen JM, Sjaastad I, Osnes JB, Skomedal T, Levy FO, Krobert KA. Cyclic AMP-dependent inotropic effects are differentially regulated by muscarinic G(i)-dependent constitutive inhibition of adenylyl cyclase in failing rat ventricle. Br J Pharmacol 2011; 162:908-16. [PMID: 21039419 DOI: 10.1111/j.1476-5381.2010.01097.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE β-Adrenoceptor (β-AR)-mediated inotropic effects are attenuated and G(i) proteins are up-regulated in heart failure (HF). Muscarinic receptors constitutively inhibit cAMP formation in normal rat cardiomyocytes. We determined whether constitutive activity of muscarinic receptors to inhibit adenylyl cyclase (AC) increases in HF and if so, whether it modifies the reduced β-AR- or emergent 5-HT₄-mediated cAMP-dependent inotropic effects. EXPERIMENTAL APPROACH Contractility and AC activity were measured and related to each other in rat ventricle with post-infarction HF and sham-operated (Sham) controls with or without blockade of muscarinic receptors by atropine and inactivation of G(i) protein by pertussis toxin (PTX). KEY RESULTS Isoprenaline-mediated inotropic effects were attenuated and basal, isoprenaline- and forskolin-stimulated AC activity was reduced in HF compared with Sham. Atropine or PTX pretreatment increased forskolin-stimulated AC activity in HF hearts. β-AR-stimulated AC and maximal inotropic response were unaffected by atropine in Sham and HF. In HF, the potency of serotonin (5-HT) to evoke an inotropic response was increased in the presence of atropine with no change in the maximal inotropic response. Interestingly, PTX pretreatment reduced the potency of 5-HT to evoke inotropic responses while increasing the maximal inotropic response. CONCLUSIONS AND IMPLICATIONS Although muscarinic constitutive inhibition of AC is increased in HF, it does not contribute to the reduced β-AR-mediated inotropic effects in rat ventricle in HF. The data support the hypothesis that there are differences in the functional compartmentation of 5-HT₄ and β-AR AC signalling in myocardium during HF.
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Affiliation(s)
- R I Hussain
- Department of Pharmacology, Faculty of Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
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15
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Afzal F, Aronsen JM, Moltzau LR, Sjaastad I, Levy FO, Skomedal T, Osnes JB, Qvigstad E. Differential regulation of β2 -adrenoceptor-mediated inotropic and lusitropic response by PDE3 and PDE4 in failing and non-failing rat cardiac ventricle. Br J Pharmacol 2011; 162:54-71. [PMID: 21133887 DOI: 10.1111/j.1476-5381.2010.00890.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE β-Adrenoceptors play a major role in regulating myocardial function through cAMP-dependent pathways. Different phosphodiesterases (PDEs) regulate intracellular cAMP-pools and thereby contribute to the compartmentalization of cAMP-dependent effects. We explored the involvement of PDEs in limiting the β(2) adrenoceptor-mediated positive inotropic (PIR) and lusitropic (LR) responses in sham-operated (Sham) and failing rat hearts. EXPERIMENTAL APPROACH Extensive myocardial infarctions were induced by coronary artery ligation in Wistar rats. Rats developing heart failure were studied 6 weeks after surgery. Contractility was measured in left ventricular strips from failing and Sham hearts. cAMP was quantified by RIA. KEY RESULTS In ventricular strips, stimulation of β(2) -adrenoceptors with (-)-adrenaline (300 nM CGP20712A present) exerted a small PIR and LR. In Sham hearts, β(2) -adrenoceptor-mediated as well as β(1) -adrenoceptor-mediated PIR and LR were increased by selective inhibition of either PDE3 (1 µM cilostamide) or PDE4 (10 µM rolipram). In failing rat hearts, PDE3 inhibition enhanced PIR and LR to both β(1) - and β(2) -adrenoceptor stimulation while PDE4 inhibition had no effect on these responses despite a significant increase in cAMP levels. Combined PDE3/4 inhibition further enhanced the PIR and LR of β(2) - and β(1) -adrenoceptor activation both in Sham and failing hearts, compared with PDE3 inhibition alone. PDE4 enzyme activity was reduced in failing hearts. CONCLUSIONS AND IMPLICATIONS Both PDE3 and PDE4 attenuated β(2) - and β(1) -adrenoceptor-mediated contractile responses in Sham hearts. In failing hearts, these responses are attenuated solely by PDE3 and thus even selective PDE3 inhibitors may provide a profound enhancement of β-adrenoceptor-mediated responses in heart failure.
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Affiliation(s)
- Faraz Afzal
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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16
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Ufer C, Germack R. Cross-regulation between beta 1- and beta 3-adrenoceptors following chronic beta-adrenergic stimulation in neonatal rat cardiomyocytes. Br J Pharmacol 2010; 158:300-13. [PMID: 19719783 DOI: 10.1111/j.1476-5381.2009.00328.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE We have previously shown that beta-adrenoceptors continuously stimulated with noradrenaline induces an increase in beta(3)-adrenoceptors (G alpha(i)PCRs) and a decrease in beta(1)-adrenoceptors (G alpha(s)PCRs) at functional, genomic and protein levels. This compensatory modification induced by noradrenaline is probably one of the consequences of cardiac depression observed in heart disease. Therefore, we investigated further the interaction between beta(1)- and beta(3)-adrenoceptors in neonatal rat cardiomyocytes. EXPERIMENTAL APPROACH Functional studies were performed by cyclic adenosine monophosphate (cAMP) accumulation assays in cells untreated or treated with dobutamine and ICI 118551 (beta(1)-adrenoceptor) or CL-3162436243 (beta(3)-adrenoceptor) for 24 h in the presence or absence of protein kinase inhibitors. Beta-adrenoceptor and protein kinase expression was monitored by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and by Western blotting, respectively. KEY RESULTS Chronic beta(1)- or beta(3)-adrenoceptor stimulation reduced beta(1)-adrenoceptor-mediated cAMP accumulation in association with a decrease in beta(1)-adrenoceptor mRNA and protein levels through protein kinase C (PKC), phosphoinositide 3-kinase (PI3K) and p38 mitogen-activated protein kinase (p38MAPK) activation. In contrast, both treatments induced an increase in beta(3)-adrenoceptor expression and beta(3)-adrenoceptor-inhibited forskolin response through PKC, extracellular-signal-regulated kinases 1 and 2 (ERK1/2) and p38MAPK phosphorylation, although no beta(3)-adrenoceptor response was observed in untreated cells. ERK1/2 and p38MAPK were activated by both treatments. The modulation of beta(1)- or beta(3)-adrenoceptor function did not require stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) although chronic beta(1)-adrenoceptor stimulation activated SAPK/JNK. Beta(3)-adrenoceptor treatment activated Akt although PI3K was not involved in beta(3)-adrenoceptor up-regulation. CONCLUSION AND IMPLICATIONS We show for the first time that chronic beta(1)- or beta(3)-adrenoceptor stimulation leads to the modulation of beta(1)- and beta(3)-adrenoceptors by a cross-regulation involving PKC, PI3K p38MAPK and MEK/ERK1/2 pathway, and through protein kinase A when beta(1)-adrenoceptors are chronically activated.
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Affiliation(s)
- Christoph Ufer
- Institute of Biochemistry, University Medecine Berlin-Charité, Berlin, Germany; Biomedical Research Centre, School of Biomedical and Natural Sciences, Nottingham Trent University, Nottingham, UK
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17
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Ziolkowski N, Grover AK. Functional linkage as a direction for studies in oxidative stress: α-adrenergic receptorsThis review is one of a selection of papers published in a Special Issue on Oxidative Stress in Health and Disease. Can J Physiol Pharmacol 2010; 88:220-32. [PMID: 20393587 DOI: 10.1139/y10-013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The α-adrenergic receptors (adrenoceptors) are activated by the endogenous agonists epinephrine and norepinephrine. They are G protein-coupled receptors that may be broadly classified into α1 (subclasses α1A, α1B, α1D) and α2 (subclasses α2A, α2B, α2C). The α1-adrenoceptors act by binding to Gαq subunits of the G proteins, causing activation of phospholipase C (PLC). PLC converts phosphatidylinositol 4,5-bisphosphate into inositol trisphosphate (IP3) and diacylglycerol (DAG), which have downstream effects on cytosolic Ca2+ concentration. The α2-adrenoceptors bind to Gαi thus inhibiting adenylyl cyclase and decreasing cAMP levels. DAG alters protein kinase C activity and cAMP activates protein kinase A. The downstream pathways of the two receptors may also interact. Activation of α1- and α2-adrenoceptors in vascular smooth muscle results in vasoconstriction. However, the densities of individual receptor subclasses vary between vessel beds or between vessels of various sizes within the same bed. In vasculature, the densities of adrenoceptor subclasses differ between conduit arteries and arterioles. These differences, along with differences in coupling mechanisms, allow for fine regulation of arterial blood flow. This diversity is enhanced by interactions resulting from homo- and heterodimer formation of the receptors, metabolic pathways, and kinases. Reactive oxygen species generated in pathologies may alter α1- and α2-adrenoceptor cascades, change vascular contractility, or cause remodeling of blood vessels. This review emphasizes the need for understanding the functional linkage between α-adrenoceptor subtypes, coupling, cross talk, and oxidative stress in cardiovascular pathologies.
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Affiliation(s)
- Natalia Ziolkowski
- Departments of Medicine and Biology, McMaster University, 1200 Main Street West, Hamilton, ON L8N 3Z5, Canada
| | - Ashok K. Grover
- Departments of Medicine and Biology, McMaster University, 1200 Main Street West, Hamilton, ON L8N 3Z5, Canada
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18
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Chakir K, Daya SK, Aiba T, Tunin RS, Dimaano VL, Abraham TP, Jaques-Robinson KM, Jacques K, Lai EW, Pacak K, Zhu WZ, Xiao RP, Tomaselli GF, Kass DA. Mechanisms of enhanced beta-adrenergic reserve from cardiac resynchronization therapy. Circulation 2009; 119:1231-40. [PMID: 19237665 DOI: 10.1161/circulationaha.108.774752] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Cardiac resynchronization therapy (CRT) is the first clinical heart failure treatment that improves chamber systolic function in both the short-term and long-term yet also reduces mortality. The mechanical impact of CRT is immediate and well documented, yet its long-term influences on myocyte function and adrenergic modulation that may contribute to its sustained benefits are largely unknown. METHODS AND RESULTS We used a canine model of dyssynchronous heart failure (DHF; left bundle ablation, atrial tachypacing for 6 weeks) and CRT (DHF for 3 weeks, biventricular tachypacing for subsequent 3 weeks), contrasting both to nonfailing controls. CRT restored contractile synchrony and improved systolic function compared with DHF. Myocyte sarcomere shortening and calcium transients were markedly depressed at rest and after isoproterenol stimulation in DHF (both anterior and lateral walls), and CRT substantially improved both. In addition, beta(1) and beta(2) stimulation was enhanced, coupled to increased beta(1) receptor abundance but no change in binding affinity. CRT also augmented adenylate cyclase activity over DHF. Inhibitory G-protein (Galpha(i)) suppression of beta-adrenergic stimulation was greater in DHF and reversed by CRT. Galpha(i) expression itself was unaltered; however, expression of negative regulators of Galpha(i) signaling (particularly RGS3) rose uniquely with CRT over DHF and controls. CRT blunted elevated myocardial catecholamines in DHF, restoring levels toward control. CONCLUSIONS CRT improves rest and beta-adrenergic-stimulated myocyte function and calcium handling, upregulating beta(1) receptors and adenylate cyclase activity and suppressing G(i)-coupled signaling associated with novel RGS upregulation. The result is greater rest and sympathetic reserve despite reduced myocardial neurostimulation as components underlying its net benefit.
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Affiliation(s)
- Khalid Chakir
- Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA
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19
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Blumer JB, Lord K, Saunders TL, Pacchioni A, Black C, Lazartigues E, Varner KJ, Gettys TW, Lanier SM. Activator of G protein signaling 3 null mice: I. Unexpected alterations in metabolic and cardiovascular function. Endocrinology 2008; 149:3842-9. [PMID: 18450958 PMCID: PMC2488243 DOI: 10.1210/en.2008-0050] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Activator of G protein signaling (AGS)-3 plays functional roles in cell division, synaptic plasticity, addictive behavior, and neuronal development. As part of a broad effort to define the extent of functional diversity of AGS3-regulated-events in vivo, we generated AGS3 null mice. Surprisingly, AGS3 null adult mice exhibited unexpected alterations in cardiovascular and metabolic functions without any obvious changes in motor skills, basic behavioral traits, and brain morphology. AGS3 null mice exhibited a lean phenotype, reduced fat mass, and increased nocturnal energy expenditure. AGS3 null mice also exhibited altered blood pressure control mechanisms. These studies expand the functional repertoire for AGS3 and other G protein regulatory proteins providing unexpected mechanisms by which G protein systems may be targeted to influence obesity and cardiovascular function.
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Affiliation(s)
- Joe B Blumer
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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20
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Ding YF, Brower GL, Zhong Q, Murray D, Holland M, Janicki JS, Zhong J. Defective intracellular Ca2+ homeostasis contributes to myocyte dysfunction during ventricular remodelling induced by chronic volume overload in rats. Clin Exp Pharmacol Physiol 2008; 35:827-35. [PMID: 18346170 DOI: 10.1111/j.1440-1681.2008.04923.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]
Abstract
1. Previous studies have demonstrated progressive ventricular hypertrophy, dilatation and contractile depression in response to chronic volume overload. Whether this decompensation was related to intrinsic myocyte dysfunction was not clear. The present study evaluated ventricular myocyte function at critical times during the progression of ventricular remodelling induced by volume overload. 2. Chronic volume overload was induced with an infrarenal aortocaval fistula in rats. Myocyte contraction and intracellular Ca(2+) concentrations ([Ca(2+)](i)) were evaluated using a fura-2 fluorescence and edge detection system. Protein levels of sarcoplasmic reticulum (SR) Ca(2+) transporters were determined by western blots. Progressive ventricular dilatation developed following creation of the fistula. Although myocyte function in 5 week fistula rats was comparable to that of the control group, myocytes from rats 10 weeks post-fistula demonstrated significant depression of cell shortening and peak [Ca(2+)](i). Application of isoproterenol (0.1 micromol/L) was not able to compensate for the functional deficiency in myocytes from 10 week fistula rats. Caffeine (10 mmol/L) induced SR Ca(2+) release, as well as protein expression of SR Ca(2+)-ATPase, and ryanodine receptors were reduced in myocytes obtained from the same group of 10 week fistula rats. 3. These data indicate that the transition to heart failure secondary to chronic volume overload is related to depressed myocyte contractility secondary to altered intracellular Ca(2+) homeostasis.
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Affiliation(s)
- Yan-Feng Ding
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849, USA
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21
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Zheng M, Zhu W, Han Q, Xiao RP. Emerging concepts and therapeutic implications of β-adrenergic receptor subtype signaling. Pharmacol Ther 2005; 108:257-68. [PMID: 15979723 DOI: 10.1016/j.pharmthera.2005.04.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Accepted: 04/20/2005] [Indexed: 12/31/2022]
Abstract
The stimulation of beta-adrenergic receptor (betaAR) plays a pivotal role in regulating myocardial function and morphology in the normal and failing heart. Three genetically and pharmacologically distinct betaAR subtypes, beta1AR, beta2AR, and beta3AR, are identified in various types of cells. While both beta1AR and beta2AR, the predominant betaAR subtypes expressed in the heart of many mammalian species including human, are coupled to the Gs-adenylyl cyclase-cAMP-PKA pathway, beta2AR dually activates pertussis toxin-sensitive Gi proteins. During acute stimulation, beta2AR-Gi coupling partially inhibits the Gs-mediated positive contractile and relaxant effects via a Gi-Gbetagamma-phosphoinositide 3-kinase (PI3K)-dependent mechanism in adult rodent cardiomyocytes. More importantly, persistent beta1AR stimulation evokes a multitude of cardiac toxic effects, including myocyte apoptosis and hypertrophy, via a calmodulin-dependent protein kinase II (CaMKII)-, rather than cAMP-PKA-, dependent mechanism in rodent heart in vivo and cultured cardiomyocytes. In contrast, persistent beta2AR activation protects myocardium by a cell survival pathway involving Gi, PI3K, and Akt. In this review, we attempt to highlight the distinct functionalities and signaling mechanisms of these betaAR subtypes and discuss how these subtype-specific properties of betaARs might affect the pathogenesis of congestive heart failure (CHF) and the therapeutic effectiveness of certain beta-blockers in the treatment of congestive heart failure.
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Affiliation(s)
- Ming Zheng
- Institute of Cardiovascular Sciences, Peking University, Beijing 100083, People's Republic of China
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22
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Zhu W, Zeng X, Zheng M, Xiao RP. The enigma of beta2-adrenergic receptor Gi signaling in the heart: the good, the bad, and the ugly. Circ Res 2005; 97:507-9. [PMID: 16166560 DOI: 10.1161/01.res.0000184615.56822.bd] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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He JQ, Balijepalli RC, Haworth RA, Kamp TJ. Crosstalk of β-Adrenergic Receptor Subtypes Through G
i
Blunts β-Adrenergic Stimulation of L-Type Ca
2+
Channels in Canine Heart Failure. Circ Res 2005; 97:566-73. [PMID: 16100050 DOI: 10.1161/01.res.0000181160.31851.05] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The mechanisms underlying the blunted contractile response to β-adrenergic receptor (β-AR) stimulation in heart failure (HF) are incompletely understood, especially with regard to β-AR subtype–specific regulation of L-type Ca
2+
channels. We evaluated the impact of HF induced by pacing tachycardia on β-AR regulation of L-type Ca
2+
channels in a canine model. To evaluate changes in the relative subcellular distribution of β-AR subtypes, left ventricular membranes enriched in surface sarcolemma and T-tubular sarcolemma were prepared. Radioligand binding using [
125
I]cyanopindolol revealed that HF resulted in a comparable decrease in the density of β
1
-ARs in both surface and T-tubule sarcolemma (55±4%, n=7,
P
<0.001; and 45±10%, n=7,
P
<0.01, respectively), but no significant change in β
2
-AR density was observed. Whole-cell patch clamp studies demonstrated a markedly blunted increase in
I
Ca,L
in response to saturating concentrations of the nonselective β-AR agonist isoproterenol (0.1 μmol/L) in failing myocytes compared with control (129±20%, n=11, versus 332±35%, n=7;
P
<0.001). Experiments testing β
1
-AR– and β
2
-AR–selective stimulation showed that the major component of the blunted response to nonselective β-AR stimulation in HF was caused by β
2
-AR activation, resulting in a pertussis toxin–sensitive, G
i
-mediated inhibition of the β
1
-AR–induced increase in
I
Ca,L
. In conclusion, canine HF results in the following: (1) a uniform reduction in β
1
-AR density in surface and T-tubule membrane fractions without a change in β
2
-AR density; and (2) the emergence of distinct G
i
-coupling to β
2
-ARs resulting in accentuated antagonism of β
1
-AR–mediated stimulation of
I
Ca,L
. These results have implications for optimizing the use of β-AR drugs in HF.
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MESH Headings
- Albuterol/pharmacology
- Animals
- Calcium Channels, L-Type/physiology
- Dogs
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Heart Failure/physiopathology
- Isoproterenol/pharmacology
- Pertussis Toxin/pharmacology
- Propanolamines/pharmacology
- Receptors, Adrenergic, beta-1/analysis
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/analysis
- Receptors, Adrenergic, beta-2/physiology
- Sarcolemma/chemistry
- Signal Transduction/physiology
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Affiliation(s)
- Jia-Qiang He
- Department of Physiology, University of Wisconsin, Madison, WI 53792, USA
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24
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Qvigstad E, Sjaastad I, Bøkenes J, Schiander I, Solberg L, Sejersted OM, Osnes JB, Skomedal T. Carvedilol blockade of alpha1- and beta-adrenoceptor induced inotropic responses in rats with congestive heart failure. Eur J Pharmacol 2005; 516:51-9. [PMID: 15916756 DOI: 10.1016/j.ejphar.2005.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Accepted: 04/15/2005] [Indexed: 11/23/2022]
Abstract
Carvedilol is a combined alpha(1)- and beta-adrenoceptor antagonist. We investigated the ability of carvedilol to antagonize functional effects mediated through myocardial alpha(1)-adrenoceptors in failing vs. non-failing (sham-operated) control hearts and compared such antagonisms to those of myocardial beta-adrenoceptors. Congestive heart failure was induced in Wistar rats by coronary artery ligation. Papillary muscles experiments were performed. Carvedilol antagonized inotropic effects mediated through myocardial alpha(1)-adrenoceptors with similar potencies in failing (pK(i)=7.7 (95%, CI; 7.4-8.0)) and sham-operated hearts (pK(i)=7.9 (95%, CI; 7.6-8.1)). The potency for the alpha(1)-adrenoceptors was 10-30-fold lower than that for the beta-adrenoceptors. In failing hearts, the alpha(1)-adrenoceptor mediated response was similar in size to the attenuated beta-adrenoceptor mediated inotropic response. The beta-adrenoceptor mediated lusitropic effects were not, however, attenuated in failing compared to sham-operated hearts. A low degree of alpha(1)-adrenoceptor blockade in the myocardium may contribute to the beneficial effects of carvedilol in heart failure.
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Affiliation(s)
- Eirik Qvigstad
- Department of Pharmacology, University of Oslo, P.O. Box 1057 Blindern, N-0316 Oslo, Norway.
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25
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Heijink IH, van den Berge M, Vellenga E, de Monchy JGR, Postma DS, Kauffman HF. Altered beta2-adrenergic regulation of T cell activity after allergen challenge in asthma. Clin Exp Allergy 2005; 34:1356-63. [PMID: 15347367 DOI: 10.1111/j.1365-2222.2004.02037.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Airway inflammation in asthma is orchestrated by recruitment of T helper (Th)2 lymphocytes to the lung and subsequent production of Th2-like cytokines upon allergen challenge. OBJECTIVE To examine whether allergen-induced dysfunction of the beta2-adrenergic receptor (beta2-AR) contributes to the enhanced T(h2) cell activity in asthma. METHODS Beta2-adrenergic regulation of cytokine mRNA expression was studied in alpha-CD3/alpha-CD28-activated peripheral blood lymphocytes from seven asthma patients before and 6 h after allergen challenge, in conjunction with the effects of beta2-agonist fenoterol on T cell chemotaxis and signalling pathways. RESULTS A complete loss of beta2-AR control over expression of the Th2 cytokines IL-4, IL-5 and IL-13, but not of the Th1 cytokine IFN-gamma, was observed after allergen challenge. Furthermore, we found impaired beta2-AR regulation of T cell migration as well as signal transduction pathways, i.e. the phosphorylation of cyclic adenosine monophosphate-responsive element binding protein and the inhibition of the mitogen-activated protein kinase pathway. The loss of beta2-AR control was associated with increased beta-adrenergic receptor kinase expression, which might be involved in beta2-AR desensitization. In addition, we demonstrate for the first time that T cells exposed to the chemokine thymus and activation-regulated chemokine show hyporesponsiveness to fenoterol. CONCLUSION Our results suggest that allergen-induced loss of beta2-AR control, possibly mediated by chemokine release, plays an important role in enhanced Th2-like activity in asthma.
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Affiliation(s)
- I H Heijink
- Department of Allergology, University Hospital Groningen, Groningen, The Netherlands
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26
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Xiao RP, Zhu W, Zheng M, Chakir K, Bond R, Lakatta EG, Cheng H. Subtype-specific beta-adrenoceptor signaling pathways in the heart and their potential clinical implications. Trends Pharmacol Sci 2004; 25:358-65. [PMID: 15219978 DOI: 10.1016/j.tips.2004.05.007] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Rui-Ping Xiao
- Laboratory of Cardiovascular Science, National Institute on Aging/NIH, Baltimore, MD 21224, USA.
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27
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Daneshtalab N, Lewanczuk RZ, Russell A, Jamali F. Rheumatoid arthritis does not reduce the pharmacodynamic response to valsartan. J Clin Pharmacol 2004; 44:245-52. [PMID: 14973301 DOI: 10.1177/0091270003262951] [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] [Indexed: 11/17/2022]
Abstract
Inflammatory conditions decrease the cardiovascular response to calcium channel and beta-adrenergics blockers due, likely, to down-regulation of the receptors mediated by pro-inflammatory mediators such as C-reactive protein (CRP), nitric oxide (NO), and tumor necrosis factor. The purpose of this investigation was to determine whether down-regulation is also evident in angiotensin II type 1 receptors (AT(1)R) during varying inflammatory states. Normotensive subjects were divided into three groups according to the severity of disease: 14 with active rheumatoid arthritis, 12 with controlled rheumatoid arthritis, and 12 healthy control subjects. The AT(1)R antagonist valsartan (160 mg) was given to all the subjects, and blood samples were taken for pharmacokinetic analysis. The systolic, diastolic, and mean arterial pressures were determined at all blood collection times. The degree of inflammation was measured using joint swelling, NO, and CRP. Plasma valsartan concentration was measured using high-performance liquid chromatography (HPLC). Patients with active disease had significantly higher joint swelling, NO, and CRP than other groups. Plasma valsartan concentration-time curves were remarkably similar in all groups. No reduced response was noticed. Our preliminary observation suggests a need for further studies to examine the possibility of AT(1)R antagonists as alternatives to other cardiovascular drugs so that their potency may be reduced by inflammation.
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Affiliation(s)
- Noriko Daneshtalab
- Faculty of Pharmacy and Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2N8
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Nickerson JG, Dugan SG, Drouin G, Perry SF, Moon TW. Activity of the unique beta-adrenergic Na+/H+ exchanger in trout erythrocytes is controlled by a novel beta3-AR subtype. Am J Physiol Regul Integr Comp Physiol 2003; 285:R526-35. [PMID: 12775554 DOI: 10.1152/ajpregu.00146.2003] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
beta-Adrenoceptors (beta-ARs) are seven-transmembrane domain, G protein-coupled receptors that transduce the cellular effects of epinephrine and norepinephrine and play a pivotal role in the vertebrate stress response. This study reports the cloning and characterization of two previously unreported beta-ARs from the rainbow trout (Oncorhynchus mykiss). Phylogenetic analysis of amino acid sequences indicates that both beta-ARs are homologs of the mammalian beta3-AR. Analysis of tissue expression patterns indicates that one of these trout beta3-adrenoceptors (beta3a-AR) is highly expressed in gill and heart, whereas the second (beta3b-AR) is highly expressed by red blood cells (RBC). Expression of the beta3b-AR in the RBC coupled with the finding of a single category of beta-AR binding sites on RBC membranes provides strong evidence for the control of the trout RBC beta-AR Na+/H+ exchanger (beta-NHE) activity by signaling through this beta3b-subtype and not through a beta1-subtype as previously proposed. The RBC-specific trout beta3b-AR exhibits binding characteristics that distinguish this receptor from each of the three pharmacologically defined categories of mammalian beta-ARs (beta1-, beta2-, and beta3-AR). This study is the first to report the presence of a beta3-AR subtype in a fish species, and the proposal that the beta3b-AR controls RBC beta-NHE activity represents a novel role for the beta3-AR subtype in vertebrates.
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Affiliation(s)
- James G Nickerson
- Dept. of Biology, Univ. of Ottawa, 150 Louis Pasteur, PO Box 450, Station A Ottawa, Ontario, Canada K1N 6N5
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Saraiva RM, Chedid NGB, Quintero H CC, Díaz G LE, Masuda MO. Impaired beta-adrenergic response and decreased L-type calcium current of hypertrophied left ventricular myocytes in postinfarction heart failure. Braz J Med Biol Res 2003; 36:635-48. [PMID: 12715084 DOI: 10.1590/s0100-879x2003000500012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Infarct-induced heart failure is usually associated with cardiac hypertrophy and decreased -adrenergic responsiveness. However, conflicting results have been reported concerning the density of L-type calcium current (I Ca(L)), and the mechanisms underlying the decreased -adrenergic inotropic response. We determined I Ca(L) density, cytoplasmic calcium ([Ca2+]i) transients, and the effects of -adrenergic stimulation (isoproterenol) in a model of postinfarction heart failure in rats. Left ventricular myocytes were obtained by enzymatic digestion 8-10 weeks after infarction. Electrophysiological recordings were obtained using the patch-clamp technique. [Ca2+]i transients were investigated via fura-2 fluorescence. -Adrenergic receptor density was determined by [ H]-dihydroalprenolol binding to left ventricle homogenates. Postinfarction myocytes showed a significant 25% reduction in mean I Ca(L) density (5.7 0.28 vs 7.6 0.32 pA/pF) and a 19% reduction in mean peak [Ca2+]i transients (0.13 0.007 vs 0.16 0.009) compared to sham myocytes. The isoproterenol-stimulated increase in I Ca(L) was significantly smaller in postinfarction myocytes (Emax: 63.6 4.3 vs 123.3 0.9% in sham myocytes), but EC50 was not altered. The isoproterenol-stimulated peak amplitude of [Ca2+]i transients was also blunted in postinfarction myocytes. Adenylate cyclase activation through forskolin produced similar I Ca(L) increases in both groups. -Adrenergic receptor density was significantly reduced in homogenates from infarcted hearts (Bmax: 93.89 20.22 vs 271.5 31.43 fmol/mg protein in sham myocytes), while Kd values were similar. We conclude that postinfarction myocytes from large infarcts display reduced I Ca(L) density and peak [Ca2+]i transients. The response to -adrenergic stimulation was also reduced and was probably related to -adrenergic receptor down-regulation and not to changes in adenylate cyclase activity.
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MESH Headings
- Adenylyl Cyclases/drug effects
- Adrenergic beta-Agonists/pharmacology
- Animals
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/metabolism
- Colforsin/pharmacology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Electrophysiologic Techniques, Cardiac
- Female
- Heart Failure/etiology
- Heart Failure/metabolism
- Hypertrophy, Left Ventricular/pathology
- Isoproterenol/pharmacology
- Male
- Myocardial Infarction/complications
- Myocardial Infarction/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Rats
- Rats, Wistar
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/metabolism
- Time Factors
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Affiliation(s)
- R M Saraiva
- Departamento de Cardiologia, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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Sjaastad I, Schiander I, Sjetnan A, Qvigstad E, Bøkenes J, Sandnes D, Osnes JB, Sejersted OM, Skomedal T. Increased contribution of alpha 1- vs. beta-adrenoceptor-mediated inotropic response in rats with congestive heart failure. ACTA PHYSIOLOGICA SCANDINAVICA 2003; 177:449-58. [PMID: 12648162 DOI: 10.1046/j.1365-201x.2003.01063.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM In failing myocardium the mechanical response to beta-adrenoceptor stimulation is attenuated. Alternative signalling systems might provide inotropic support when the beta-adrenoceptor system is dysfunctioning. Accordingly, the inotropic responses to alpha 1- and beta-adrenoceptor stimulation by the endogenous adrenoceptor agonist noradrenaline in non-failing and failing rat hearts were compared. METHODS Chronic heart failure was induced in male Wistar rats by coronary artery ligation. Corresponding sham groups were prepared. After 6 weeks, papillary muscles from non-failing and failing hearts were isolated. Receptor binding studies were performed in the corresponding myocardium. The alpha 1-adrenoceptor-mediated inotropic response was not changed while the beta-adrenoceptor-mediated response was substantially reduced in failing compared with non-failing myocardium. RESULTS No change in potency for the agonists was observed at the alpha 1-adrenoceptors, while an increased potency for the agonists at the beta-adrenoceptors was found during heart failure. The lusitropic response to beta-adrenoceptor stimulation was intact during heart failure. No over all change in affinity or number of either adrenoceptor type was observed in receptor binding studies. The alpha 1-adrenoceptor-mediated inotropic response became dominating compared with the beta-adrenoceptor-mediated one in failing rat myocardium in contrast to the dominating role of the latter in non-failing myocardium. The attenuation of the beta-adrenoceptor-mediated inotropic response in rat failing myocardium was not because of a reduced number of receptors. CONCLUSION Increasing contractility through stimulation of alpha 1-adrenoceptors in situ by the endogenous agonist may be an alternative way of inotropic support during heart failure and even more so during beta-adrenoceptor blockade.
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Affiliation(s)
- I Sjaastad
- Institute for Experimental Medical Research, University of Oslo, Ullevaal University Hospital, Norway
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31
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Kompa AR, Samuel CS, Summers RJ. Inotropic responses to human gene 2 (B29) relaxin in a rat model of myocardial infarction (MI): effect of pertussis toxin. Br J Pharmacol 2002; 137:710-8. [PMID: 12381685 PMCID: PMC1573542 DOI: 10.1038/sj.bjp.0704922] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Relaxin produces powerful inotropic and chronotropic responses in isolated atria. The effect of relaxin has been examined in a rat model of cardiac failure, induced by myocardial infarction (MI). Maximum inotropic responses to isoprenaline (sham 5.4+/-0.3 mN; MI 2.6+/-0.3 mN; P<0.001) and relaxin (sham 5.1+/-0.6 mN; MI 2.8+/-0.5 mN; P=0.013) were reduced in left atria following MI. No change in chronotropic responsiveness was observed in right atria. Pertussis toxin (PTX) treatment restored inotropic responses to isoprenaline (sham 5.5+/-1.3 mN; MI 5.8+/-1.0 mN; P=0.850) but not to relaxin. Instead, PTX reduced inotropic responses to relaxin in sham animals to the same level seen in the MI group (sham 3.2+/-1.7 mN; MI 2.8+/-0.6 mN; P=0.847). In right atria, PTX treatment did not affect the maximum chronotropic response to isoprenaline, but reduced responses to relaxin in both sham and MI animals. R3 relaxin and relaxin receptor (LGR7) mRNA was present in atria and left ventricle (LV) from sham and MI animals. R3 relaxin mRNA expression was increased in atria but not LV from MI animals. LGR7 mRNA expression was reduced in atria and LV from MI animals. PTX treatment in unoperated rats increased chronotropic responses (vehicle 184.3+/-5.3 beats min(-1); PTX 211.3+/-9.5 beats min(-1); P=0.029) and produced a rightward shift in the concentration-response curve to isoprenaline in left atria. PTX reduced inotropic (vehicle 3.3+/-0.7 mN; PTX 0.8+/-0.2 mN; P=0.005) and chronotropic (vehicle 130.2+/-8.1 beats min(-1); PTX 90.6+/-11.1 beats min(-1); P=0.012) responses to relaxin. 6 In left atria, relaxin produced a small increase in cAMP compared to those produced by isoprenaline and forskolin. However, PTX treatment significantly reduced relaxin-, isoprenaline- and forskolin-stimulated cAMP accumulation. Cardiac failure in MI animals caused a reduced inotropic response to both relaxin and (-)-isoprenaline. In non-MI animals, PTX treatment also reduced inotropic responses to relaxin. Differences between responses to (-)-isoprenaline and relaxin can be explained by changes in coupling efficiency occurring at the level of adenylate cyclase.
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Affiliation(s)
- Andrew R Kompa
- Department of Pharmacology, Monash University, Victoria, 3800, Australia
| | - Chrishan S Samuel
- Howard Florey Institute, University of Melbourne, Victoria, 3010, Australia
| | - Roger J Summers
- Department of Pharmacology, Monash University, Victoria, 3800, Australia
- Author for correspondence:
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Doggrell SA. Effects of BDF 9198 on left ventricular contractility in advanced spontaneously hypertensive rats with heart failure. J Pharm Pharmacol 2002; 54:1097-102. [PMID: 12195824 DOI: 10.1211/002235702320266253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
In the first part of this study, we characterized 24-month-old Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs), their heart weights, and the responses of the isolated left ventricles to electrical stimulation. In the main part of the study, we tested whether the positive inotropic effects of BDF 9198, which prevents the closure of the cardiac sodium channel, were present in senescence and heart failure. Thus, we studied the effects of BDF 9198 on the left ventricle strips of 24-month-old WKy rats (senescence) and SHRs using contractility methods. In comparison with WKY rats, the left ventricles of 24-month-old SHRs were hypertrophied and had prolonged times to peak contraction. BDF 9198 (10(-8) to 10(-6) M) was a positive inotrope on the left ventricles of WKY rats, with a maximum augmenting effect of 122% with BDF 9198 at 10(-7) M. The magnitude of the augmenting effects of BDF 9198 were reduced in SHR heart failure, with a maximum augmenting effect of 26% at 10(-7) M. BDF 9198 at 10(-6) M attenuated the responses of the SHR left ventricle to electrical stimulation. In conclusion, the potential of drugs that prevent closure of the sodium channel as positive inotropes in the treatment of heart failure should be further considered.
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Affiliation(s)
- Sheila A Doggrell
- Faculty of Medicine and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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Xiao RP. Beta-adrenergic signaling in the heart: dual coupling of the beta2-adrenergic receptor to G(s) and G(i) proteins. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2001; 2001:re15. [PMID: 11604549 DOI: 10.1126/stke.2001.104.re15] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Beta-adrenergic receptor (AR) subtypes are archetypical members of the G protein-coupled receptor (GPCR) superfamily. Whereas both beta1AR and beta2AR stimulate the classic G(s)-adenylyl cyclase-3',5'-adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling cascade, beta2AR couples to both G(s) and G(i) proteins, activating bifurcated signaling pathways. In the heart, dual coupling of the beta2AR to G(s) and G(i) results in compartmentalization of the G(s)-stimulated cAMP signal, thus selectively affecting plasma membrane effectors (such as L-type Ca(2+) channels) and bypassing cytoplasmic target proteins (such as phospholamban and myofilament contractile proteins). More important, the beta2AR-to-G(i) branch delivers a powerful cell survival signal that counters apoptosis induced by the concurrent G(s)-mediated signal or by a wide range of assaulting factors. This survival pathway sequentially involves G(i), G(beta)(gamma), phosphoinositide 3-kinase, and Akt. Furthermore, cardiac-specific transgenic overexpression of betaAR subtypes in mice results in distinctly different phenotypes in terms of the likelihood of cardiac hypertrophy and heart failure. These findings indicate that stimulation of the two betaAR subtypes activates overlapping, but different, sets of signal transduction mechanisms, and fulfills distinct or even opposing physiological and pathophysiological roles. Because of these differences, selective activation of cardiac beta2AR may provide catecholamine-dependent inotropic support without cardiotoxic consequences, which might have beneficial effects in the failing heart.
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Affiliation(s)
- R P Xiao
- Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224, USA.
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Xiao RP. -Adrenergic Signaling in the Heart: Dual Coupling of the 2-Adrenergic Receptor to Gs and Gi Proteins. Sci Signal 2001. [DOI: 10.1126/scisignal.1042001re15] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Michelotti GA, Price DT, Schwinn DA. Alpha 1-adrenergic receptor regulation: basic science and clinical implications. Pharmacol Ther 2000; 88:281-309. [PMID: 11337028 DOI: 10.1016/s0163-7258(00)00092-9] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Adrenergic receptors (ARs) are members of the G-protein-coupled receptor family, which includes alpha 1ARs, alpha 2ARs, beta 1ARs, beta 2ARs, beta 3ARs, adenosine, muscarinic, angiotensin, endothelin receptors, and many others that are responsible for a large variety of physiologic effects through G-protein coupling. This review focuses on alpha 1ARs and their regulation at both the mRNA and protein levels. Currently, three alpha 1AR subtypes have been characterized both pharmacologically and at the gene level: alpha 1aAR, alpha 1bAR, and alpha 1dAR. These are expressed in a species- and tissue-dependent manner. Mutagenesis approaches have been extremely valuable in the identification of key residues that govern alpha 1AR ligand binding and signaling. These studies reveal that alpha 1ARs have evolved an exquisitely sensitive regulation of their activity in which any disruption of the native structure has profound effects on subsequent function and effector coupling. Significant advances have also been made in the elucidation of signaling pathway components, resulting in the identification of novel pathways that can lead to pathologic conditions. Specific topics include mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and G-protein-coupled receptor cross-talk pathways. Within this context, recent studies identifying underlying transcriptional mechanisms involved in the regulation of the alpha 1AR subtypes are also discussed. Finally, given the potentially important role of alpha 1ARs in the vasculature, as well as in the pathology of many diseases, such as myocardial hypertrophy and benign prostatic hyperplasia, the clinical relevance of alpha 1AR distribution, pharmacology, and therapeutic intervention is reviewed.
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Affiliation(s)
- G A Michelotti
- Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC 27710, USA
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36
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37
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Prahash AJ, Gupta S, Anand IS. Myocyte response to beta-adrenergic stimulation is preserved in the noninfarcted myocardium of globally dysfunctional rat hearts after myocardial infarction. Circulation 2000; 102:1840-6. [PMID: 11023941 DOI: 10.1161/01.cir.102.15.1840] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cellular mechanisms underlying the diminished inotropic response of remodeled hearts after myocardial infarction (MI) remain unclear. METHODS AND RESULTS Left ventricular (LV) remodeling and function were assessed by 2D echocardiography and isolated perfused heart studies in 6-week post-MI and sham-operated rats. LV myocytes from sham and noninfarcted MI hearts were used for morphometric and functional studies. Beta-adrenergic receptor (beta-AR) agonist isoproterenol (ISO)-induced contractile response was measured in isolated hearts. The effects of ISO and forskolin on contractile function and calcium transients of isolated myocytes were recorded. ISO-induced cAMP generation was compared in sham and MI myocytes. beta-AR density was measured by radioligand binding. MI hearts were remodeled (LV diameter 8.5+/-0.3 versus 5.7+/-0.3 mm, P:<0.001) and showed global (% fractional shortening 19.1+/-2.5 versus 55.3+/-2.2, P:<0.01) and regional contractile dysfunction of noninfarcted myocardium (% systolic posterior wall thickening 37+/-4 versus 62+/-10, P:<0.01). Isolated heart function (LV developed pressure 58+/-2 versus 72+/-3 mm Hg, P:=0.004) and ISO concentration response were reduced in MI hearts. Myocytes from the noninfarcted LV were structurally remodeled (32% longer and 18% wider), but their contractile response and intracellular calcium kinetics to ISO and forskolin were not diminished. beta-AR receptor density (B(max) 24+/-1.5 versus 22.4+/-1.6 fmol/mg protein) and beta-AR agonist-stimulated cAMP were similar in both groups. CONCLUSIONS Isolated myocytes from the remodeled and dysfunctional myocardium are structurally modified but contract normally under basal conditions and in response to beta-AR stimulation. beta-AR density is preserved in remodeled myocytes. Nonmyocyte factors may be more important in the genesis of contractile dysfunction in the remodeled rat heart up to 6 weeks after MI.
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Affiliation(s)
- A J Prahash
- Department of Medicine and Division of Cardiology, University of Minnesota and VA Medical Center, Minneapolis, MN 55417, USA
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Kompa AR, Summers RJ. Lidocaine and surgical modification reduces mortality in a rat model of cardiac failure induced by coronary artery ligation. J Pharmacol Toxicol Methods 2000; 43:199-203. [PMID: 11257484 DOI: 10.1016/s1056-8719(00)00103-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Coronary artery ligation in the rat provides a useful experimental model of cardiac failure; however, this procedure carries with it a high mortality rate (50%). In this study, we used lidocaine (10 mg/kg, i.m.) before coronary artery ligation and 2 h after surgery to minimise the incidence of ventricular fibrillation (VF) that leads to sudden death in this model. We found that coronary artery ligation, using lidocaine in conjunction with a modified surgical procedure, had a mortality rate of 15%, much lower than reported in previous studies using this model. These modifications allow for the production of larger infarcts with 29% of animals having an infarct size > 50% of the epicardial surface. Infarct size in our myocardial infarction (MI) group varied between 5% and 75% of the left ventricular (LV) surface area resulting in a mean infarct size of 41.3 +/- 1.3% for the epicardial surface and 40.0 +/- 1.3% for the endocardial surface.
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Affiliation(s)
- A R Kompa
- Department of Pharmacology, Monash University, Victoria 3800, Australia.
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Kompa AR, Summers RJ. Desensitization and resensitization of beta 1- and putative beta 4-adrenoceptor mediated responses occur in parallel in a rat model of cardiac failure. Br J Pharmacol 1999; 128:1399-406. [PMID: 10602318 PMCID: PMC1571772 DOI: 10.1038/sj.bjp.0702920] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Cardiostimulant effects of the non-conventional partial agonist, CGP 12177A, are mediated by a receptor distinct from the beta3-adrenoceptor and termed the putative beta4-adrenoceptor. Using a rat model of cardiac failure, induced by myocardial infarction (MI), we compared the desensitization and resensitization of responses to CGP 12177A with those to isoprenaline and RO 363 in left (LA) and right atria (RA). We also examined the ability of beta-adrenoceptor antagonists to block responses to CGP 12177A. 2. MI reduced the maximum inotropic response to isoprenaline by 48% (sham 4.1+/-0.6 mN, n=10; MI 2.1+/-0.4 mN, n=8, P<0.02), RO 363 by 61% (sham 4.2+/-0.5 mN, n=10; MI 1.8+/-0.3 mN, n=8, P<0.005) and CGP 12177A by 49% (sham 1.4+/-0.1 mN, n=5; MI 0.7+/-0.2 mN, n=7, P<0.05) in electrically stimulated LA. MI also reduced the sensitivity to isoprenaline (pEC50: sham 8.79+/-0.08, n=10; MI 8.30+/-0.10, n=8; P=0.001) and RO 363 (pEC50: sham 8.69+/-0.07, n=10; MI 8.33+/-0.10, n=8; P<0.01). The maximum chronotropic responses to isoprenaline, RO 363 and CGP 12177A in RA were unaffected. 3. Pertussis toxin treatment (10 microg kg-1, i.p.) restored the maximum inotropic response and sensitivity to isoprenaline (sham 3.5+/-0.5 mN, n=9; MI 3.2+/-0.6 mN, n=11, P=0.702) and CGP 12177A (sham 1.6+/-0.3 mN, n=6; MI 1.9+/-0.4 mN, n=7, P=0.537) in MI animals to levels similar to those in the sham group. 4. CGP 20712A (pKB: LA 6.7+/-0.2, n=6; RA 7. 1+/-0.1, n=4), ICI 118,551 (pKB: LA 6.4+/-0.1, n=5; RA 6.3+/-0.1, n=6), propranolol (pKB: LA 6.6+/-0.1, n=5; RA 6.8+/-0.1, n=6) and bupranolol (pKB: LA 7.2+/-0.1, n=6; RA 7.7+/-0.1, n=8), showed moderate affinity for the putative beta4-adrenoceptor. 5. Desensitization after MI and resensitization (after pertussis toxin treatment) to isoprenaline and CGP 12177A therefore occur in parallel, suggesting that the beta1- and putative beta4-adrenoceptor use the same signalling pathway. Antagonist affinity studies confirmed that drugs acting at beta1-adrenoceptors also interact with putative beta4-adrenoceptors with approximately 100 times lower affinity. We suggest that CGP 12177A produces its cardiac effects by interacting with a low affinity state of the beta1-adrenoceptor.
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MESH Headings
- Animals
- Disease Models, Animal
- Heart Failure/metabolism
- Heart Failure/physiopathology
- Kinetics
- Myocardial Contraction/drug effects
- Myocardial Contraction/physiology
- Myocardial Infarction/metabolism
- Myocardial Infarction/physiopathology
- Pertussis Toxin
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, beta/metabolism
- Receptors, Adrenergic, beta/physiology
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-1/physiology
- Virulence Factors, Bordetella/pharmacology
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Affiliation(s)
- Andrew R Kompa
- Department of Pharmacology, Monash University, Wellington Road, Clayton, Victoria, 3168, Australia
| | - Roger J Summers
- Department of Pharmacology, Monash University, Wellington Road, Clayton, Victoria, 3168, Australia
- Author for correspondence:
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Huang B, Wang S, Qin D, Boutjdir M, El-Sherif N. Diminished basal phosphorylation level of phospholamban in the postinfarction remodeled rat ventricle: role of beta-adrenergic pathway, G(i) protein, phosphodiesterase, and phosphatases. Circ Res 1999; 85:848-55. [PMID: 10532953 DOI: 10.1161/01.res.85.9.848] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Three weeks after myocardial infarction (MI) in the rat, remodeled hypertrophy of noninfarcted myocardium is at its maximum and the heart is in a compensated stage with no evidence of heart failure. Our hemodynamic measurements at this stage showed a slight but insignificant decrease of +dP/dt but a significantly higher left ventricular end-diastolic pressure. To investigate the basis of the diastolic dysfunction, we explored possible defects in the beta-adrenergic receptor-G(s/i) protein-adenylyl cyclase-cAMP-protein kinase A-phosphatase pathway, as well as molecular or functional alterations of sarcoplasmic reticulum Ca(2+)-ATPase and phospholamban (PLB). We found no significant difference in both mRNA and protein levels of sarcoplasmic reticulum Ca(2+)-ATPase and PLB in post-MI left ventricle compared with control. However, the basal levels of both the protein kinase A-phosphorylated site (Ser16) of PLB (p16-PLB) and the calcium/calmodulin-dependent protein kinase-phosphorylated site (Thr17) of PLB (p17-PLB) were decreased by 76% and 51% in post-MI myocytes (P<0.05), respectively. No change was found in the beta-adrenoceptor density, G(salpha) protein level, or adenylyl cyclase activity. Inhibition of phosphodiesterase and G(i) protein by Ro-20-1724 and pertussis toxin, respectively, did not correct the decreased p16-PLB or p17-PLB levels. Stimulation of beta-adrenoceptor or adenylyl cyclase increased both p16-PLB and p17-PLB in post-MI myocytes to the same levels as in sham myocytes, suggesting that decreased p16-PLB and p17-PLB in post-MI myocytes is not due to a decrease in the generation of p16-PLB or p17-PLB. We found that type 1 phosphatase activity was increased by 32% (P<0.05) with no change in phosphatase 2A activity. Okadaic acid, a protein phosphatase inhibitor, significantly increased p16-PLB and p17-PLB levels in post-MI myocytes and partially corrected the prolonged relaxation of the [Ca(2+)](i) transient. In summary, prolonged relaxation of post-MI remodeled myocardium could be explained, in part, by altered basal levels of p16-PLB and p17-PLB caused by increased protein phosphatase 1 activity.
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Affiliation(s)
- B Huang
- Cardiology Division, Department of Medicine, State University of New York Health Science Center and Veterans Affairs Medical Center, Brooklyn, NY 11203, USA
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