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Baker JG, Summers RJ. Adrenoceptors: Receptors, Ligands and Their Clinical Uses, Molecular Pharmacology and Assays. Handb Exp Pharmacol 2024. [PMID: 38926158 DOI: 10.1007/164_2024_713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
The nine G protein-coupled adrenoceptor subtypes are where the endogenous catecholamines adrenaline and noradrenaline interact with cells. Since they are important therapeutic targets, over a century of effort has been put into developing drugs that modify their activity. This chapter provides an outline of how we have arrived at current knowledge of the receptors, their physiological roles and the methods used to develop ligands. Initial studies in vivo and in vitro with isolated organs and tissues progressed to cell-based techniques and the use of cloned adrenoceptor subtypes together with high-throughput assays that allow close examination of receptors and their signalling pathways. The crystal structures of many of the adrenoceptor subtypes have now been determined opening up new possibilities for drug development.
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Affiliation(s)
- Jillian G Baker
- Cell Signalling, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
- Department of Respiratory Medicine, Nottingham University Hospitals NHS Trust, Nottingham, UK.
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
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Jiménez-Sábado V, Casabella-Ramón S, Llach A, Gich I, Casellas S, Ciruela F, Chen SRW, Guerra JM, Ginel A, Benítez R, Cinca J, Tarifa C, Hove-Madsen L. Beta-blocker treatment of patients with atrial fibrillation attenuates spontaneous calcium release-induced electrical activity. Biomed Pharmacother 2023; 158:114169. [PMID: 36592495 DOI: 10.1016/j.biopha.2022.114169] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 12/21/2022] [Accepted: 12/28/2022] [Indexed: 01/01/2023] Open
Abstract
AIMS Atrial fibrillation (AF) has been associated with excessive spontaneous calcium release, linked to cyclic AMP (cAMP)-dependent phosphorylation of calcium regulatory proteins. Because β-blockers are expected to attenuate cAMP-dependent signaling, we aimed to examine whether the treatment of patients with β-blockers affected the incidence of spontaneous calcium release events or transient inward currents (ITI). METHODS The impact of treatment with commonly used β-blockers was analyzed in human atrial myocytes from 371 patients using patch-clamp technique, confocal calcium imaging or immunofluorescent labeling. Data were analyzed using multivariate regression analysis taking into account potentially confounding effects of relevant clinical factors RESULTS: The L-type calcium current (ICa) density was diminished significantly in patients with chronic but not paroxysmal AF and the treatment of patients with β-blockers did not affect ICa density in any group. By contrast, the ITI frequency was elevated in patients with either paroxysmal or chronic AF that did not receive treatment, and β-blocker treatment reduced the frequency to levels observed in patients without AF. Confocal calcium imaging showed that β-blocker treatment also reduced the calcium spark frequency in patients with AF to levels observed in those without AF. Furthermore, phosphorylation of the ryanodine receptor (RyR2) at Ser-2808 and phospholamban at Ser-16 was significantly lower in patients with AF that received β-blockers. CONCLUSION Together, our findings demonstrate that β-blocker treatment may be of therapeutic utility to prevent spontaneous calcium release-induced atrial electrical activity; especially in patients with a history of paroxysmal AF displaying preserved ICa density.
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Affiliation(s)
- Verónica Jiménez-Sábado
- CIBER Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain; IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Sergi Casabella-Ramón
- IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain; Department of Cell Biology, Physiology and Immunology and Neuroscience Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Anna Llach
- IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Ignasi Gich
- IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain
| | - Sandra Casellas
- Servicio de Cirugía Cardíaca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Francisco Ciruela
- Pharmacology Unit, Dept. Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, L'Hospitalet de Llobregat, Spain; Neuropharmacology and Pain Group, Neuroscience Program, Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Spain
| | - S R Wayne Chen
- Department of Physiology and Pharmacology, The Libin Cardiovascular Institute, University of Calgary, Canada
| | - José M Guerra
- CIBER Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain; IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Servicio de Cardiología and Univ. Autònoma de Barcelona, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Antonino Ginel
- Servicio de Cirugía Cardíaca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Raúl Benítez
- Dept. d'Enginyeria de Sistemes, Automàtica i Informàtica Industrial, Univ. Politècnica de Catalunya, Barcelona, Spain
| | - Juan Cinca
- Servicio de Cardiología and Univ. Autònoma de Barcelona, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Carmen Tarifa
- IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain
| | - Leif Hove-Madsen
- CIBER Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain; IIB Sant Pau, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Instituto de Investigaciones Biomédicas de Barcelona (IIBB-CSIC), Barcelona, Spain.
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Wołowiec Ł, Grześk G, Osiak J, Wijata A, Mędlewska M, Gaborek P, Banach J, Wołowiec A, Głowacka M. Beta-blockers in cardiac arrhythmias-Clinical pharmacologist's point of view. Front Pharmacol 2023; 13:1043714. [PMID: 36699057 PMCID: PMC9868422 DOI: 10.3389/fphar.2022.1043714] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/30/2022] [Indexed: 01/11/2023] Open
Abstract
β-blockers is a vast group of antiarrhythmic drugs which differ in their pharmacokinetic and chemical properties. Some of them block β-adrenergic receptors selectively while the others work non-selectively. Consequently, they reduce the influence of the sympathetic nervous system on the heart, acting negatively inotropic, chronotropic, bathmotropic and dromotropic. Although they have been present in medicine since the beginning of the 1960s, they still play a crucial role in the treatment of cardiac arrhythmias. They are also first-line group of drugs used to control the ventricular rate in patients with the most common arrhythmia-atrial fibrillation. Previous reports indicate that infection with SARS-CoV-2 virus may constitute an additional risk factor for arrhythmia. Due to the aging of the population in developed countries and the increase in the number of patients with cardiac burden, the number of people suffering from cardiac arrhythmias will increase in the upcoming years. As a result the role of above-mentioned beta-blockers will remain significant. Particularly noteworthy is propranolol-the oldest beta adrenergic antagonist, which in recent years has found additional applications due to its unique properties. In this article, we reviewed the accessible literature and summarized the current guidelines on the use of beta-blockers in the treatment of cardiac arrhythmias.
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Affiliation(s)
- Łukasz Wołowiec
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland,*Correspondence: Łukasz Wołowiec,
| | - Grzegorz Grześk
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Joanna Osiak
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Aleksandra Wijata
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Martyna Mędlewska
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Patryk Gaborek
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Joanna Banach
- Department of Cardiology and Clinical Pharmacology, Faculty of Health Sciences, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
| | - Anna Wołowiec
- Department of Geriatrics, Division of Biochemistry and Biogerontology, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Toruń, Poland
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Kubacka M, Szkaradek N, Mogilski S, Pańczyk K, Siwek A, Gryboś A, Filipek B, Żmudzki P, Marona H, Waszkielewicz AM. Design, synthesis and cardiovascular evaluation of some aminoisopropanoloxy derivatives of xanthone. Bioorg Med Chem 2018; 26:3773-3784. [PMID: 29706529 DOI: 10.1016/j.bmc.2018.04.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 04/10/2018] [Accepted: 04/16/2018] [Indexed: 12/21/2022]
Abstract
A series of aminoisopropanoloxy derivatives of xanthone has been synthesized and their pharmacological properties regarding the cardiovascular system has been evaluated. Radioligand binding and functional studies in isolated organs revealed that title compounds present high affinity and antagonistic potency for α1-(compound 2 and 8), β-(compounds 1, 3, 4, 7), α1/β-(compounds 5 and 6) adrenoceptors. Furthermore, compound 7, the structural analogue of verapamil, possesses calcium entry blocking activity. The title compounds showed hypotensive and antiarrhythmic properties due to their adrenoceptor blocking effect. Moreover, they did not affect QRS and QT intervals, and they did not have proarrhythmic potential at tested doses. In addition they exerted anti-aggregation effect. The results of this study suggest that new compounds with multidirectional activity in cardiovascular system might be found in the group of xanthone derivatives.
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Affiliation(s)
- M Kubacka
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - N Szkaradek
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland.
| | - S Mogilski
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - K Pańczyk
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - A Siwek
- Department of Pharmacobiology, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - A Gryboś
- Department of Pharmacobiology, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - B Filipek
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - P Żmudzki
- Department of Medicinal Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - H Marona
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
| | - A M Waszkielewicz
- Department of Bioorganic Chemistry, Chair of Organic Chemistry, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Krakow, Poland
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Bisoprolol protects myocardium cells against ischemia/reperfusion injury by attenuating unfolded protein response in rats. Sci Rep 2017; 7:11859. [PMID: 28928480 PMCID: PMC5605660 DOI: 10.1038/s41598-017-12366-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/07/2017] [Indexed: 01/02/2023] Open
Abstract
Bisoprolol (B) exerts potential cardioprotective effects against myocardial ischemia/reperfusion (I/R) injury. Unfolded protein response (UPR) attenuates I/R injury induced apoptosis by reducing oxidative damage and inflammation response. The current study investigated whether the protective effects of bisoprolol resulted from modulating UPR and anti-inflammatory during myocardial I/R condition and elucidated its potential mechanisms. Sprague-Dawley rats were treated with B in the absence or presence of the injected UPR activator dithiothreitol (DTT) and then subjected to myocardial I/R surgery. In vitro, cultured H9C2 cells were pretreated with B or DTT and then subjected to simulate ischemia reperfusion (SIR) operation. Bisoprolol conferred cardioprotective effects by improving postischemic cardiac function, decreasing infarct size, reducing apoptotic index, diminishing serum creatine kinase and lactate dehydrogenase levels, suppressing TNF-α and IL-6 secretion, inhibiting UPR signal pathways and downregulating caspase-12 and caspase-3 expressions. Consistently, B conferred similar antioxidative and anti-inflammatory effects against SIR injury in cultured H9C2 cardiomyocytes. Pretreatment with DTT or C/EBP homologous protein (CHOP) overexpression mediated by lentivirus administration both abolished these effects. In summary, our results demonstrate that Bisoprolol protects myocardium cells against ischemia/reperfusion injury partly by attenuating unfolded protein response.
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Soave M, Stoddart LA, Brown A, Woolard J, Hill SJ. Use of a new proximity assay (NanoBRET) to investigate the ligand-binding characteristics of three fluorescent ligands to the human β1-adrenoceptor expressed in HEK-293 cells. Pharmacol Res Perspect 2016; 4:e00250. [PMID: 27588207 PMCID: PMC4988514 DOI: 10.1002/prp2.250] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 06/27/2016] [Accepted: 07/01/2016] [Indexed: 12/12/2022] Open
Abstract
Previous research has indicated that allosteric interactions across the dimer interface of β1‐adrenoceptors may be responsible for a secondary low affinity binding conformation. Here we have investigated the potential for probe dependence, in the determination of antagonist pKi values at the human β1‐adenoceptor, which may result from such allosterism interactions. Three fluorescent β1‐adrenoceptor ligands were used to investigate this using bioluminescence energy transfer (BRET) between the receptor‐bound fluorescent ligand and the N‐terminal NanoLuc tag of a human β1‐adrenoceptor expressed in HEK 293 cells (NanoBRET). This proximity assay showed high‐affinity‐specific binding to the NanoLuc‐ β1‐adrenoceptor with each of the three fluorescent ligands yielding KD values of 87.1 ± 10 nmol/L (n = 8), 38.1 ± 12 nmol/L (n = 7), 13.4 ± 2 nmol/L (n = 14) for propranolol‐Peg8‐BY630, propranolol‐ β(Ala‐Ala)‐BY630 and CGP‐12177‐TMR, respectively. Parallel radioligand‐binding studies with 3H‐CGP12177 and TIRF microscopy, to monitor NanoLuc bioluminescence, confirmed a high cell surface expression of the NanoLuc‐ β1‐adrenoceptor in HEK 293 cells (circa 1500 fmol.mg protein−1). Following a 1 h incubation with fluorescent ligands and β1‐adrenoceptor competing antagonists, there were significant differences (P < 0.001) in the pKi values obtained for CGP20712a and CGP 12177 with the different fluorescent ligands and 3H‐CGP 12177. However, increasing the incubation time to 2 h removed these significant differences. The data obtained show that the NanoBRET assay can be applied successfully to study ligand‐receptor interactions at the human β1‐adrenoceptor. However, the study also emphasizes the importance of ensuring that both the fluorescent and competing ligands are in true equilibrium before interpretations regarding probe dependence can be made.
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Affiliation(s)
- Mark Soave
- Cell Signalling and Pharmacology Research Group School of Life Sciences University of Nottingham Nottingham NG7 2UH United Kingdom
| | - Leigh A Stoddart
- Cell Signalling and Pharmacology Research Group School of Life Sciences University of Nottingham Nottingham NG7 2UH United Kingdom
| | - Alastair Brown
- Heptares Therapeutics Ltd. Bio Park Welwyn Garden City AL7 3AX United Kingdom
| | - Jeanette Woolard
- Cell Signalling and Pharmacology Research Group School of Life Sciences University of Nottingham Nottingham NG7 2UH United Kingdom
| | - Stephen J Hill
- Cell Signalling and Pharmacology Research Group School of Life Sciences University of Nottingham Nottingham NG7 2UH United Kingdom
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Gherbi K, Briddon SJ, Hill SJ. Detection of the secondary, low-affinity β1 -adrenoceptor site in living cells using the fluorescent CGP 12177 derivative BODIPY-TMR-CGP. Br J Pharmacol 2015; 171:5431-45. [PMID: 25052258 PMCID: PMC4261997 DOI: 10.1111/bph.12858] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/11/2014] [Accepted: 07/18/2014] [Indexed: 02/06/2023] Open
Abstract
Background and Purpose CGP 12177 not only inhibits agonist effects mediated through the catecholamine site of the β1-adrenoceptor with high affinity, but also exhibits agonist effects of its own at higher concentrations through a secondary, low-affinity β1-adrenoceptor site or conformation. β-blocker affinities for this ‘CGP 12177’ site of the human β1-adrenoceptor have thus far only been characterized in functional studies. Here, we used the fluorescent CGP 12177 analogue BODIPY-TMR-CGP to directly investigate receptor–ligand interactions at the secondary binding site of the β1-adrenoceptor. Experimental Approach The human β1-adrenoceptor was stably expressed in CHO cells containing a cAMP response element (CRE)-secreted placental alkaline phosphatase (SPAP) reporter gene construct. Functional responses of BODIPY-TMR-CGP were determined in the CRE-SPAP reporter gene assay, and manual and automated confocal microscopy platforms used to investigate the binding properties of BODIPY-TMR-CGP. Key Results BODIPY-TMR-CGP displayed a pharmacological profile similar to that of CGP 12177, retaining agonist activity at the secondary β1-adrenoceptor site. In confocal microscopy studies, specific BODIPY-TMR-CGP binding allowed clear visualization of β1-adrenoceptors in live cells. Using a wider concentration range of labelled ligand in a high-content fluorescence-based binding assay than is possible in radioligand binding assays, two-site inhibition binding curves of β-adrenoceptor antagonists were revealed in CHO cells expressing the human β1-adrenoceptor, but not the β2-adrenoceptor. Conclusions and Implications The fluorescent CGP 12177 analogue allowed the detection of the β1-adrenoceptor secondary site in both functional and binding studies. This suggests that BODIPY-TMR-CGP presents an important and novel fluorescent tool to investigate the nature of the secondary β1-adrenoceptor site.
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Affiliation(s)
- K Gherbi
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, UK
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Gherbi K, May LT, Baker JG, Briddon SJ, Hill SJ. Negative cooperativity across β1-adrenoceptor homodimers provides insights into the nature of the secondary low-affinity CGP 12177 β1-adrenoceptor binding conformation. FASEB J 2015; 29:2859-71. [PMID: 25837585 PMCID: PMC4478806 DOI: 10.1096/fj.14-265199] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/02/2015] [Indexed: 01/30/2023]
Abstract
At the β1-adrenoceptor, CGP 12177 potently antagonizes agonist responses at the primary high-affinity catecholamine conformation while also exerting agonist effects of its own through a secondary low-affinity conformation. A recent mutagenesis study identified transmembrane region (TM)4 of the β1-adrenoceptor as key for this low-affinity conformation. Others suggested that TM4 has a role in β1-adrenoceptor oligomerization. Here, assessment of the dissociation rate of a fluorescent analog of CGP 12177 [bordifluoropyrromethane-tetramethylrhodamine-(±)CGP 12177 (BODIPY-TMR-CGP)] at the human β1-adrenoceptor expressed in Chinese hamster ovary cells revealed negative cooperative interactions between 2 distinct β1-adrenoceptor conformations. The dissociation rate of 3 nM BODIPY-TMR-CGP was 0.09 ± 0.01 min−1 in the absence of competitor ligands, and this was enhanced 2.2- and 2.1-fold in the presence of 1 µM CGP 12177 and 1 µM propranolol, respectively. These effects on the BODIPY-TMR-CGP dissociation rate were markedly enhanced in β1-adrenoceptor homodimers constrained by bimolecular fluorescence complementation (9.8- and 9.9-fold for 1 µM CGP 12177 and 1 µM propranolol, respectively) and abolished in β1-adrenoceptors containing TM4 mutations vital for the second conformation pharmacology. This study suggests that negative cooperativity across a β1-adrenoceptor homodimer may be responsible for generating the low-affinity pharmacology of the secondary β1-adrenoceptor conformation.—Gherbi, K., May, L. T., Baker, J. G., Briddon, S. J., Hill, S. J. Negative cooperativity across β1-adrenoceptor homodimers provides insights into the nature of the secondary low-affinity CGP 12177 β1-adrenoceptor binding conformation.
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Affiliation(s)
- Karolina Gherbi
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Lauren T May
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jillian G Baker
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stephen J Briddon
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stephen J Hill
- Cell Signalling Research Group, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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Schlicker E, Pędzińska-Betiuk A, Kozłowska H, Szkaradek N, Żelaszczyk D, Baranowska-Kuczko M, Kieć-Kononowicz K, Marona H, Malinowska B. MH-3: evidence for non-competitive antagonism towards the low-affinity site of β1-adrenoceptors. Naunyn Schmiedebergs Arch Pharmacol 2014; 387:743-52. [DOI: 10.1007/s00210-014-0983-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 04/09/2014] [Indexed: 10/25/2022]
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Baker JG, Proudman RGW, Hill SJ. Identification of key residues in transmembrane 4 responsible for the secondary, low-affinity conformation of the human β1-adrenoceptor. Mol Pharmacol 2014; 85:811-29. [PMID: 24608857 DOI: 10.1124/mol.114.091587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The β1-adrenoceptor exists in two agonist conformations/states: 1) a high-affinity state where responses to catecholamines and other agonists (e.g., cimaterol) are potently inhibited by β1-adrenoceptor antagonists, and 2) a low-affinity secondary conformation where agonist responses, particularly CGP12177 [(-)-4-(3-tert-butylamino-2-hydroxypropoxy)-benzimidazol-2-one] are relatively resistant to inhibition by β1-adrenoceptor antagonists. Although both states have been demonstrated in many species (including human), the precise nature of the secondary state is unknown and does not occur in the closely related β2-adrenoceptor. Here, using site-directed mutagenesis and functional measurements of production of a cyclic AMP response element upstream of a secreted placental alkaline phosphatase reporter gene and accumulation of (3)H-cAMP, we examined the pharmacological consequences of swapping transmembrane (TM) regions of the human β1- and β2-adrenoceptors, followed by single point mutations, to determine the key residues involved in the β1-adrenoceptor secondary conformation. We found that TM4 (particularly amino acids L195 and W199) had a major role in the generation of the secondary β1-adrenoceptor conformation. Thus, unlike at the human β1-wild-type adrenoceptor, at β1-TM4 mutant receptors, cimaterol and CGP12177 responses were both potently inhibited by antagonists. CGP12177 acted as a simple partial agonist with similar KB and EC50 values in the β1-TM4 but not β1-wild-type receptors. Furthermore pindolol switched from a biphasic concentration response at human β1-wild-type adrenoceptors to a monophasic concentration response in the β1-TM4 mutant receptors. Mutation of these amino acids to those found in the β2-adrenoceptor (L195Q and W199Y), or mutation of a single residue (W199D) in the human β1-adrenoceptor thus abolished this secondary conformation and created a β1-adrenoceptor with only one high-affinity agonist conformation.
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Affiliation(s)
- Jillian G Baker
- Cell Signalling, School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
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Ali I, Hussain A, Saleem K. DETERMINATION OF STEREO-SELECTIVE BINDINGS OF RACEMIC PROPRANOLOL WITH β2-AD-GPCR IN HUMAN PLASMA. J LIQ CHROMATOGR R T 2013. [DOI: 10.1080/10826076.2012.673215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Imran Ali
- a Department of Chemistry , Jamia Millia Islamia (Central University) , New Delhi , India
| | - Afzal Hussain
- a Department of Chemistry , Jamia Millia Islamia (Central University) , New Delhi , India
| | - Kishwar Saleem
- a Department of Chemistry , Jamia Millia Islamia (Central University) , New Delhi , India
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Baker JG, Proudman RGW, Tate CG. The pharmacological effects of the thermostabilising (m23) mutations and intra and extracellular (β36) deletions essential for crystallisation of the turkey β-adrenoceptor. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2011; 384:71-91. [PMID: 21547538 PMCID: PMC3116118 DOI: 10.1007/s00210-011-0648-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 04/18/2011] [Indexed: 11/30/2022]
Abstract
The X-ray crystal structure of the turkey β-adrenoceptor has recently been determined. However, mutations were introduced into the native receptor that was essential for structure determination. These may cause alterations to the receptor pharmacology. It is therefore essential to understand the effects of these mutations on the pharmacological characteristics of the receptor. This study examined the pharmacological effects of both the m23 mutations and the β36 deletions, both alone and then in combination in the β36-m23 mutant used in the crystallisation and structure determination of the turkey β-adrenoceptor. Stable CHO-K1 cell lines were made of each of the receptor mutants and the affinity and efficacy of ligands assessed by (3)H-CGP 12177 whole cell ligand binding, (3)H-cAMP accumulation, and CRE-SPAP gene transcription assays. The m23 mutations reduced affinity for agonists, partial agonists and neutral antagonists by about tenfold whilst the β36 deletions alone had no effect on ligand affinity. Both sets of changes appeared to reduce the agonist activation of the receptor. Both the m23 and the β36 receptors retained two active agonist-induced receptor conformations similar to that of the original tβtrunc receptor. The combined β36-m23 receptor bound ligands with similar affinity to the m23 receptor; however, agonist activation was only observed with a few agonists including the catecholamines. Although the combination of mutations severely reduced the activation ability, the final crystallised receptor (β36-m23) was still a fully functional receptor capable of binding agonist and antagonist ligands and activating intracellular agonist responses.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, C Floor Medical School, University of Nottingham, Queen's Medical Centre, UK.
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Baker JG. A full pharmacological analysis of the three turkey β-adrenoceptors and comparison with the human β-adrenoceptors. PLoS One 2010; 5:e15487. [PMID: 21152092 PMCID: PMC2994877 DOI: 10.1371/journal.pone.0015487] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 10/01/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND There are three turkey β-adrenoceptors: the original turkey β-adrenoceptor from erythrocytes (tβtrunc, for which the X-ray crystal structure has recently been determined), tβ3C and tβ4C-receptors. This study examined the similarities and differences between these avian receptors and mammalian receptors with regards to binding characteristics and functional high and low affinity agonist conformations. METHODOLOGY/PRINCIPAL FINDINGS Stable cell lines were constructed with each of the turkey β-adrenoceptors and 3H-CGP12177 whole cell binding, CRE-SPAP production and (3)H-cAMP accumulation assays performed. It was confirmed that the three turkey β-adrenoceptors are distinct from each other in terms of amino acid sequence and binding characteristics. The greatest similarity of any of the turkey β-adrenoceptors to human β-adrenoceptors is between the turkey β3C-receptor and the human β2-adrenoceptor. There are pharmacologically distinct differences between the binding of ligands for the tβtrunc and tβ4C and the human β-adrenoceptors (e.g. with CGP20712A and ICI118551). The tβtrunc and tβ4C-adrenoceptors appear to exist in at least two different agonist conformations in a similar manner to that seen at both the human and rat β1-adrenoceptor and human β3-adrenoceptors. The tβ3C-receptor, similar to the human β2-adrenoceptor, does not, at least so far, appear to exist in more than one agonist conformation. CONCLUSIONS/SIGNIFICANCE There are several similarities, but also several important differences, between the recently crystallised turkey β-adrenoceptor and the human β-adrenoceptors. These findings are important for those the field of drug discovery using the recently structural information from crystallised receptors to aid drug design. Furthermore, comparison of the amino-acid sequence for the turkey and human adrenoceptors may therefore shed more light on the residues involved in the existence of the secondary β-adrenoceptor conformation.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, University of Nottingham, Nottingham, United Kingdom.
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Tuncay E, Seymen AA, Sam P, Gurdal H, Turan B. Effects of β-adrenergic receptor blockers on cardiac function: a comparative study in male versus female ratsThis article is one of a selection of papers from the NATO Advanced Research Workshop on Translational Knowledge for Heart Health (published in part 2 of a 2-part Special Issue). Can J Physiol Pharmacol 2009; 87:310-7. [DOI: 10.1139/y09-015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In heart disease, differences exist between women and men with respect to the impact of risk factors, symptoms, and therapeutic responses. The use of β-adrenergic receptor blockers is now well established in the treatment of mild and moderate systolic heart failure. Although there are significant differences among agents, their clinical effects are predictable. To address the question of sex disparities in the heart, however, we investigated the effect of treatment with the nonselective β-blockers timolol and propranolol on mechanical and electrical function of heart preparations from male and female rats. We examined the long-term effects of intragastric treatment with timolol (5 mg/kg per day) or propranolol (25 mg/kg per day) for 7 months on the hemodynamic and intracellular action potential parameters of the heart. Chronic administration of timolol but not propranolol produced a significant increase in the baseline activity of the left ventricular developed pressure (LVDP) in both male and female rats with no significant effect on the left ventricular end-diastolic pressure. Timolol or propranolol treatment of male rats and timolol but not propranolol treatment of female rats induced significant shortening in the repolarization phases of action potentials recorded from left ventricular papillary muscle strips of the hearts. The responses of LVDP to β-adrenergic stimulation were similar in timolol- or propranolol-treated or untreated male rats. On the other hand, timolol treatment markedly increased, and propranolol treatment significantly decreased, the responses of increase in LVDP in female rats. Our results suggest that although treatment with β-blockers for 7 months confirmed the role of the β-adrenergic pathway in heart function, there are marked differences in the effects of individual β-blockers on heart physiology. Sex differences should be taken into consideration when using β-blockers during experimental studies and clinical therapy.
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Affiliation(s)
- Erkan Tuncay
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Ali Aytac Seymen
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Pinar Sam
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Hakan Gurdal
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Ankara, Turkey
| | - Belma Turan
- Department of Biophysics, Faculty of Medicine, Ankara University, Ankara, Turkey
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Ankara, Turkey
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Galindo-Tovar A, Vargas ML, Kaumann AJ. Phosphodiesterases PDE3 and PDE4 jointly control the inotropic effects but not chronotropic effects of (-)-CGP12177 despite PDE4-evoked sinoatrial bradycardia in rat atrium. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2008; 379:379-84. [PMID: 19005642 DOI: 10.1007/s00210-008-0367-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 10/15/2008] [Indexed: 11/26/2022]
Abstract
Acting through a low-affinity site of the beta(1)-adrenoceptor (beta(1L)AR), CGP12177 causes sinoatrial tachycardia and positive inotropic effects in left atrium but not in the ventricle of the rat. However, inhibition of either PDE3 or PDE4 also uncovers positive inotropic effects of CGP12177 in ventricle, but whether these phosphodiesterases also control the atrial agonist effects of CGP12177 was unknown. We, therefore, investigated the effects of the PDE3-selective inhibitor cilostamide (300 nM) and PDE4 inhibitor rolipram (1 microM) on the (-)-CGP12177-evoked increases of sinoatrial beating rate and force of paced left atria of the rat. Rolipram (n = 8) increased basal sinoatrial rate by 27 +/- 5 bpm but cilostamide (n = 8) had no effect. The chronotropic potency of (-)-CGP12177 (-logEC(50)M = 7.5) was not changed by rolipram and cilostamide or their combination. (-)-CGP12177 increased left atrial force with intrinsic activity 0.25 compared to (-)-isoprenaline. Rolipram (n = 8) and cilostamide (n = 8) did not change basal force of left atria but concurrent rolipram + cilostamide (n = 8) increased force by 52 +/- 9% of the effect of 200 microM (-)-isoprenaline. Neither rolipram nor cilostamide affected the inotropic potency of (-)-CGP12177 (-logEC(50)M = 7.4) but concurrent rolipram + cilostamide caused potentiation (-logEC(50)M = 8.2) and converted (-)-CGP12177 into a full agonist compared to (-)-isoprenaline. Cyclic AMP appears to maintain sinoatrial rate and PDE4 elicits bradycardia through hydrolysis of cAMP in a compartment distinct from the beta(1L)AR-induced cAMP compartment through which (-)-CGP12177 causes tachycardia. In contrast to the (-)-CGP12177-evoked tachycardia, not controlled by PDE3 and PDE4, these isoenzymes jointly reduce (-)-CGP12177-evoked increases of left atrial contractility through beta(1L)AR.
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MESH Headings
- Adrenergic beta-1 Receptor Agonists
- Adrenergic beta-Agonists/pharmacology
- Animals
- Arrhythmia, Sinus/chemically induced
- Arrhythmia, Sinus/physiopathology
- Atrial Function, Left/drug effects
- Atrial Function, Left/physiology
- Atrial Function, Right/drug effects
- Atrial Function, Right/physiology
- Bradycardia/metabolism
- Cyclic Nucleotide Phosphodiesterases, Type 3/physiology
- Cyclic Nucleotide Phosphodiesterases, Type 4/physiology
- Drug Partial Agonism
- Female
- Heart Atria/drug effects
- Heart Atria/physiopathology
- Heart Rate/drug effects
- Heart Rate/physiology
- In Vitro Techniques
- Isoproterenol/pharmacology
- Male
- Myocardial Contraction/drug effects
- Myocardial Contraction/physiology
- Phosphodiesterase 3 Inhibitors
- Phosphodiesterase 4 Inhibitors
- Phosphodiesterase Inhibitors/pharmacology
- Propanolamines/pharmacology
- Quinolones/pharmacology
- Rats
- Rats, Sprague-Dawley
- Rolipram/pharmacology
- Stimulation, Chemical
- Tachycardia/chemically induced
- Tachycardia/physiopathology
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Affiliation(s)
- Alejandro Galindo-Tovar
- Department of Pharmacology, University of Murcia, University Hospital Virgen de la Arrixaca, Murcia, Spain
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Zacà V, Rastogi S, Mishra S, Wang M, Sharov VG, Gupta RC, Goldstein S, Sabbah HN. Atenolol is inferior to metoprolol in improving left ventricular function and preventing ventricular remodeling in dogs with heart failure. Cardiology 2008; 112:294-302. [PMID: 18832825 DOI: 10.1159/000159123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Accepted: 05/29/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVES beta-Blockers are standard therapy for patients with heart failure (HF). This study compared the effects of chronic monotherapy with 2 different beta(1)-selective adrenoceptor blockers, namely atenolol and metoprolol succinate, on left ventricular (LV) function and remodeling in dogs with coronary microembolization-induced HF [LV ejection fraction (EF) 30-40%]. METHODS Twenty HF dogs were randomized to 3 months of therapy with atenolol (50 mg once daily, n = 6), metoprolol succinate (100 mg, once daily, n = 7) or to no therapy (control, n = 7). LV EF and volumes were measured before initiating therapy and after 3 months of therapy. The change (Delta) in EF and volumes between measurements before and after therapy was calculated and compared among study groups. RESULTS In controls, EF decreased and end-systolic volume increased. Atenolol prevented the decrease in EF and the increase in ESV. In contrast, metoprolol succinate significantly increased EF and decreased end-systolic volume. DeltaEF was significantly higher and Deltaend-systolic volume significantly lower in metoprolol succinate-treated dogs compared to atenolol-treated dogs (EF: 6.0 +/- 0.86% vs. 0.8 +/- 0.85%, p < 0.05; end-systolic volume: -4.3 +/- 0.81 ml vs. -1 +/- 0.52 ml, p <0.05). CONCLUSIONS In HF dogs, chronic therapy with atenolol does not elicit the same LV function and remodeling benefits as those achieved with metoprolol succinate.
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Affiliation(s)
- Valerio Zacà
- Department of Medicine, Division of Cardiovascular Medicine, Henry Ford Heart and Vascular Institute, Detroit, MI 48202, USA
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17
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CGP12177-induced haemodynamic and vascular effects in normotensive and hypertensive rats. Eur J Pharmacol 2008; 591:196-202. [DOI: 10.1016/j.ejphar.2008.06.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 06/06/2008] [Accepted: 06/12/2008] [Indexed: 11/20/2022]
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18
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Comparison of the binding affinity of CGP-12177A at recombinant rat alpha(1D)-adrenoceptors expressed in BHK-21 cell membranes and alpha(1)-adrenoceptors present in rat cerebral cortex membranes. Eur J Pharmacol 2008; 590:303-9. [PMID: 18589413 DOI: 10.1016/j.ejphar.2008.05.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 05/07/2008] [Accepted: 05/30/2008] [Indexed: 11/24/2022]
Abstract
Recent in vitro studies, performed in rat aorta, mesenteric and intrapulmonary arteries, and human pulmonary artery, demonstrated that the beta-adrenoceptor ligand CGP-12177A (4-[3-[(1,1-dimethylethyl)amino]-2-hydroxypropoxy]-1,3-dihydro-2H-benzimidazol-2-one) is also provided with antagonist or partial agonist properties at alpha(1)-adrenoceptors. These observations were supported by estimates of CGP-12177A binding affinity at alpha(1)-adrenoceptors, which have been always performed in rat cerebral cortex membranes, as a surrogate of vascular tissue. Since alpha(1D)-adrenoceptors are predominant in both rat aorta and mesenteric artery, in the present study, we measured, for the first time, the binding affinity of CGP-12177A at recombinant rat alpha(1D)-adrenoceptors expressed in BHK-21 cell membranes. CGP-12177A binding affinity was also determined in rat cerebral cortex membranes, where various alpha(1)-adrenoceptor subtypes are present. By means of [(3)H]prazosin binding competition experiments, we found that CGP-12177A bound to alpha(1D)-adrenoceptor-expressing BHK-21 cell membranes, with a binding affinity (pK(i)=5.39+/-0.27) almost identical to that measured in cerebral membranes (pK(i)=5.44+/-0.07), indicating that it is a non-subtype selective alpha(1)-adrenoceptor ligand. Moreover, CGP-12177A binding affinity was very close to its functional affinity evaluated in rat aorta in terms of antagonist potency against phenylephrine-induced contraction (pK(B)=5.65+/-0.07). In conclusion, our results demonstrate that, in order to evaluate CGP-12177A binding affinity at aorta and mesenteric artery alpha(1)-adrenoceptors, estimates in rat cerebral membranes are as reliable as those in recombinant rat alpha(1D)-adrenoceptors, since both values are very close to CGP-12177A functional affinities in isolated vessels.
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19
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Carteolol, a non-conventional partial agonist of β1-adrenoceptors, relaxes phenylephrine-constricted rat aorta through antagonism at α1-adrenoceptors. Eur J Pharmacol 2008; 590:269-75. [DOI: 10.1016/j.ejphar.2008.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 04/24/2008] [Accepted: 05/19/2008] [Indexed: 11/21/2022]
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20
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Baker JG. Antagonist affinity measurements at the Gi-coupled human histamine H3 receptor expressed in CHO cells. BMC Pharmacol 2008; 8:9. [PMID: 18538007 PMCID: PMC2430196 DOI: 10.1186/1471-2210-8-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 06/06/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The H3 histamine receptor is a Gi-coupled GPCR that has been proven to exist in different agonist-induced states, including that defined by the protean agonist proxyfan. Several GPCRs are now known to exist in different states. For some of these, antagonist affinity measurement remain constant regardless of the state of the receptor, for others e.g. the beta-adrenoceptors, the antagonist affinity measurements vary considerably depending on which agonist-dependent state is being identified. The purpose of this study was to examine the antagonist affinity measurements at the Gi-coupling human H3 receptor, paying particular attention to measurements made in the presence of full agonists, partial agonists and the proxyfan protean agonist-induced state of the receptor. RESULTS CHO cells stably expressing the human histamine H3 receptor and a CRE-SPAP reporter were used. Measurements of CRE-gene transcription and 3H-cAMP accumulation were made. A range of ligands of different agonist efficacies were determined, including some partial agonists e.g. VUF 5681. Unlike other Gi-coupled receptors, no Gs-coupled state of the receptor was detected with these ligands. Antagonist affinity measurements were constant, whether the measurements were made in the presence of a full agonist, a partial agonist or the protean agonist proxyfan. CONCLUSION In contrast to all three subtypes of the beta-adrenoceptors, but in keeping with the traditional pharmacological dogma, antagonist affinity measurements remained constant at the human H3 receptor, including the medium-efficacy proxyfan-induced state of the receptor and the VUF5681-induced state of the receptor.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, Medical School, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
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21
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Kaumann AJ, Molenaar P. The low-affinity site of the β1-adrenoceptor and its relevance to cardiovascular pharmacology. Pharmacol Ther 2008; 118:303-36. [DOI: 10.1016/j.pharmthera.2008.03.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Accepted: 03/20/2008] [Indexed: 10/22/2022]
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22
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Cheong HI, Johnson J, Cormier M, Hosseini K. In vitro cytotoxicity of eight β-blockers in human corneal epithelial and retinal pigment epithelial cell lines: Comparison with epidermal keratinocytes and dermal fibroblasts. Toxicol In Vitro 2008; 22:1070-6. [DOI: 10.1016/j.tiv.2008.01.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 01/19/2008] [Accepted: 01/21/2008] [Indexed: 11/28/2022]
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Baker JG. A study of antagonist affinities for the human histamine H2 receptor. Br J Pharmacol 2007; 153:1011-21. [PMID: 18157166 DOI: 10.1038/sj.bjp.0707644] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Ligand affinity has been a fundamental concept in the field of pharmacology and has traditionally been considered to be constant for a given receptor-ligand interaction. Recent studies have demonstrated that this is not true for all three members of the G(s)-coupled beta-adrenoceptor family. This study evaluated antagonist affinity measurements at a different G(s)-coupled receptor, the histamine H(2) receptor, to determine whether antagonist affinity measurements made at a different family of GPCRs were constant. EXPERIMENTAL APPROACH CHO cells stably expressing the human histamine H(2) receptor and a CRE-SPAP reporter were used and antagonist affinity was assessed in short-term cAMP assays and longer term CRE gene transcription assays. KEY RESULTS Nine agonists and seven antagonists, of sufficient potency at the H(2) receptor to examine in detail, were identified. Measurements of antagonist affinity were the same regardless of the efficacy of the competing agonist, time of agonist incubation, cellular response measured or presence of a PDE inhibitor. CONCLUSIONS AND IMPLICATIONS Antagonist affinity at the G(s)-coupled histamine H(2) receptor obeys the accepted dogma for antagonism at GPCRs. This study further confirms that something unusual is indeed happening with the beta-adrenoceptors and is not an artefact related to the transfected cell system used. As the human histamine H(2) receptor does not behave in a similar manner to any of the human beta-adrenoceptors, it is clear that information gathered from one GPCR cannot be simply extrapolated to predict the behaviour of another GPCR. Each GPCR therefore requires careful and detailed evaluation on its own.
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Affiliation(s)
- J G Baker
- Institute of Cell Signalling, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
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24
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Molenaar P, Chen L, Semmler ABT, Parsonage WA, Kaumann AJ. HUMAN HEART ?-ADRENOCEPTORS: ?1-ADRENOCEPTOR DIVERSIFICATION THROUGH ?AFFINITY STATES? AND POLYMORPHISM. Clin Exp Pharmacol Physiol 2007; 34:1020-8. [PMID: 17714089 DOI: 10.1111/j.1440-1681.2007.04730.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. In atrium and ventricle from failing and non-failing human hearts, activation of beta(1)- or beta(2)-adrenoceptors causes increases in contractile force, hastening of relaxation, protein kinase A-catalysed phosphorylation of proteins implicated in the hastening of relaxation, phospholamban, troponin I and C-protein, consistent with coupling of both beta(1)- and beta(2)-adrenoceptors to stimulatory G(salpha)-protein but not inhibitory G(ialpha)-protein. 2. Two 'affinity states', namely beta(1H) and beta(1L), of the beta(1)-adrenoceptor exist. In human heart, noradrenaline elicits powerful increases in contractile force and hastening of relaxation. These effects are blocked with high affinity by beta-adenoceptor antagonists, including propranolol, (-)-pindolol, (-)-CGP 12177 and carvedilol. Some beta-blockers, typified by (-)-pindolol and (-)-CGP 12177, not only block the receptor, but also activate it, albeit at much higher concentrations (approximately 2 log units) than those required to antagonize the effects of catecholamines. In human heart, both (-)-CGP 12177 and (-)-pindolol increase contractile force and hasten relaxation. However, the involvement of the beta(1)-adrenoceptor was not immediately obvious because (-)-pindolol- and (-)-CGP 12177-evoked responses were relatively resistant to blockade by (-)-propranolol. Abrogation of cardiostimulant effects of (-)-CGP 12177 in beta(1)-/beta(2)-adrenoceptor double-knockout mice, but not beta(2)-adrenoceptor-knockout mice, revealed an obligatory role of the beta(1)-adrenoceptor. On the basis of these results, two 'affinity states' have been designated, the beta(1H)- and beta(1L)-adrenoceptor, where the beta(1H)-adrenoceptor is activated by noradrenaline and blocked with high affinity by beta-blockers and the beta(1L)-adrenoceptor is activated by drugs such as (-)-CGP 12177 and (-)-pindolol and blocked with low affinity by beta-blockers such as (-)-propranolol. The beta(1H)- and beta(1L)-adrenoceptor states are consistent with high- and low-affinity binding sites for (-)-[(3)H]-CGP 12177 radioligand binding found in cardiac muscle and recombinant beta(1)-adrenoceptors. 3. There are two common polymorphic locations of the beta(1)-adrenoceptor, at amino acids 49 (Ser/Gly) and 389 (Arg/Gly). Their existence has raised several questions, including their role in determining the effectiveness of heart failure treatment with beta-blockers. We have investigated the effect of long-term maximally tolerated carvedilol administration (> 1 year) on left ventricular ejection fraction (LVEF) in patients with non-ischaemic cardiomyopathy (mean left ventricular ejection fraction 23 +/- 7%; n = 135 patients). The administration of carvedilol improved LVEF to 37 +/- 13% (P < 0.005); however, the improvement was variable, with 32% of patients showing pound 5% improvement. Upon segregation of patients into Arg389Gly-beta(1)-adrenoceptors, it was found that carvedilol caused a greater increase in left ventricular ejection faction in patients carrying the Arg389 allele with Arg389Arg > Arg389Gly > Gly389Gly.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Adrenergic beta-Antagonists/pharmacology
- Animals
- Heart/drug effects
- Heart Atria/drug effects
- Heart Ventricles/drug effects
- Humans
- Myocardium/metabolism
- Polymorphism, Genetic/genetics
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/physiology
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/physiology
- Species Specificity
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Affiliation(s)
- P Molenaar
- Department of Medicine, The University of Queensland, The Prince Charles Hospital, Chermside, Queensland, Australia.
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25
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Baker JG, Hill SJ. Multiple GPCR conformations and signalling pathways: implications for antagonist affinity estimates. Trends Pharmacol Sci 2007; 28:374-81. [PMID: 17629959 PMCID: PMC2169386 DOI: 10.1016/j.tips.2007.06.011] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 05/22/2007] [Accepted: 06/26/2007] [Indexed: 01/27/2023]
Abstract
Antagonist affinity measurements have traditionally been considered important in characterizing the cell-surface receptors present in a particular cell or tissue. A central assumption has been that antagonist affinity is constant for a given receptor-antagonist interaction, regardless of the agonist used to stimulate that receptor or the downstream response that is measured. As a consequence, changes in antagonist affinity values have been taken as initial evidence for the presence of novel receptor subtypes. Emerging evidence suggests, however, that receptors can possess multiple binding sites and the same receptor can show different antagonist affinity measurements under distinct experimental conditions. Here, we discuss several mechanisms by which antagonists have different affinities for the same receptor as a consequence of allosterism, coupling to different G proteins, multiple (but non-interacting) receptor sites, and signal-pathway-dependent pharmacology (where the pharmacology observed varies depending on the signalling pathway measured).
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Vargas ML, Hernandez J, Kaumann AJ. Phosphodiesterase PDE3 blunts the positive inotropic and cyclic AMP enhancing effects of CGP12177 but not of noradrenaline in rat ventricle. Br J Pharmacol 2007; 147:158-63. [PMID: 16331293 PMCID: PMC1615855 DOI: 10.1038/sj.bjp.0706498] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
1.--The cardiostimulant effects of CGP12177, mediated through a beta(1)-adrenoceptor site with low affinity for (-)-propranolol, are potentiated by the nonselective PDE inhibitor IBMX but the role of PDE isoenzymes is unknown. We studied the effects of the PDE3-selective inhibitor cilostamide (300 nM) and PDE4-selective inhibitor rolipram (1 microM) on the positive inotropic and cyclic AMP-enhancing effects of CGP12177 and noradrenaline in right ventricular strips of rat. 2.--CGP12177 (under (-)-propranolol 200 nM) only increased contractile force in the presence of either cilostamide or rolipram with -logEC(50)M 6.7 (E(max)=23% over basal) and 7.1 (E(max)=50%) respectively. The combination of cilostamide and rolipram caused CGP12177 to enhance contractile force with -logEC(50)M=7.7 and E(max)=178%. 3.--The positive inotropic effects of noradrenaline (-logEC(50)M=6.9) were potentiated by rolipram (-logEC(50)M=7.4) but not by cilostamide (-logEC(50)M=7.0). 4.--In the presence of rolipram and (-)-propranolol, noradrenaline (2 microM) and CGP12177 (10 microM) produced matching inotropic effects but failed to increase cyclic AMP levels. 20 microM (-)-noradrenaline increased cyclic AMP levels, a response further enhanced by rolipram. 5.--Both PDE3 and PDE4 of rat ventricle appear to hydrolyse cyclic AMP generated through the low-affinity beta(1)-adrenoceptor site, thereby preventing inotropic responses of CGP12177. When (-)-noradrenaline interacts with the beta(1)-adrenoceptor, the generated cyclic AMP is hydrolysed only by PDE4, thereby reducing cardiostimulation.
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Affiliation(s)
| | - Jesus Hernandez
- Department of Pharmacology, University of Murcia, Murcia, Spain
| | - Alberto J Kaumann
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG
- Author for correspondence:
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Abstract
Most modern theories about stress recognize that although stress is not a disease, it may be the trigger for the majority of diseases when allostatic overload has been generated. During stress, the glucocorticoids and catecholamines play a key role in the regulation of physiological parameters and homeostasis during stress. In the heart, positive chronotropic, inotropic, and lusitropic responses to catecholamines are mediated by various subtypes of adrenergic receptors (beta-ARs), mainly beta1- and beta2-adrenergic receptors. beta-ARs also control cardiomyocyte growth and death, thus contributing to cardiac remodelling. The structural basis of each beta-AR subtype, as well as their signalling pathways, and adaptive responses to stress are discussed. The participation of beta3- and putative beta4-ARs in the control of cardiac function is also discussed, with emphasis on low affinity beta-AR isoforms and the role they play in the response to the catecholamines under stress. The changes in beta-AR signalling under pathogenic conditions as well as under stress are reviewed.
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Affiliation(s)
- Iraídes N Santos
- Institute of Biology, State University of Campinas (UNICAMP), Department of Physiology and Biophysics, Campinas, SP, Brazil
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Zakrzeska A, Schlicker E, Kwolek G, Kozłowska H, Malinowska B. Positive inotropic and lusitropic effects mediated via the low-affinity state of beta1-adrenoceptors in pithed rats. Br J Pharmacol 2006; 146:760-8. [PMID: 16151438 PMCID: PMC1751196 DOI: 10.1038/sj.bjp.0706382] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 Activation by CGP 12177 and cyanopindolol of the human and rat low-affinity state of beta(1)-adrenoceptors increases frequency and contractile force and hastens relaxation in isolated cardiac tissues, and probably relaxes isolated vessels. In order to identify the positive inotropic, positive lusitropic and vasodilator effects of both agonists also in vivo, we have determined their effects on the left ventricular systolic pressure (LVSP), the rate of intraventricular pressure rise (+dP dt(-1)(max)) and decline (-dP dt(-1)(max)), the diastolic blood pressure (DBP) and the mesenteric blood flow (MBF) in pithed and vagotomized rats. 2 CGP 12177 (0.1-100 nmol kg(-1)) and cyanopindolol (1-1000 nmol kg(-1)) dose-dependently enhanced all cardiac parameters. The nonselective beta-adrenoceptor antagonist bupranolol 10 micromol kg(-1) diminished the CGP 12177 (100 nmol kg(-1))-stimulated increases in LVSP from 26.3+/-8.2 to 13.1+/-1.8 mmHg (P<0.05), +dP dt(-1)(max) from 5287+/-290 to 2439+/-296 mmHg s(-1) (P<0.001) and -dP dt(-1)(max) from -3836+/-301 to -2187+/-443 mmHg s(-1) (P<0.05), respectively. The beta(1)-adrenoceptor antagonist CGP 20712A 10 micromol kg(-1) (known to block the low-affinity state of beta(1)-adrenoceptors at high doses) inhibited increases in +/-dP dt(-1)(max) elicited by the highest dose of CGP 12177. 3 The highest doses of CGP 12177 and cyanopindolol increased DBP by about 10 mmHg and MBF by 1.4+/-0.3 and 0.6+/-0.3 ml min(-1), respectively. The vascular effects of CGP 12177 were not affected by bupranolol and CGP 20712A. 4 In conclusion, activation of the low-affinity state of beta(1)-adrenoceptors by CGP 12177 and cyanopindolol in pithed rats causes a positive inotropic and lusitropic effect. By contrast, the vascular effects of CGP 12177 and cyanopindolol are not mediated by these receptors and have only marginal influence under in vivo conditions.
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Affiliation(s)
- Agnieszka Zakrzeska
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-089 Białystok, Poland
| | - Eberhard Schlicker
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Grzegorz Kwolek
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-089 Białystok, Poland
| | - Hanna Kozłowska
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-089 Białystok, Poland
| | - Barbara Malinowska
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-089 Białystok, Poland
- Author for correspondence:
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Floreani M, Froldi G, Cavalli M, Bova S, Giron MC, Varani K, Gessi S, Borea PA, Dorigo MT, Dorigo P. Characterization of intrinsic sympathomimetic activity of carteolol in rat cardiovascular preparations. J Pharmacol Sci 2005; 95:115-23. [PMID: 15153658 DOI: 10.1254/jphs.95.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
We evaluated in vitro, in myocardial and vascular preparations isolated from reserpine-treated rats, the intrinsic sympathomimetic activity (ISA) of carteolol, a beta(1)/beta(2)-adrenoceptor blocking agent used in cardiovascular and non-cardiovascular diseases. In spontaneously beating atria, carteolol, at low concentrations (0.01 and 0.1 microM), antagonized the positive inotropic effect of isoprenaline, whereas at higher concentrations (1 microM to 1 mM), it caused an increase in the force of contraction (EC(50): 4.6 +/- 0.1 microM, E(max): 17.1 +/- 1.1%, with respect to the maximum isoprenaline response) and a slight increase (7.8 +/- 1.9% over basal values) in the heart rate. The positive inotropic effect of carteolol was abolished by concentrations of propranolol or timolol (10 microM) much higher than those blocking isoprenaline effects in the same preparations. A similar positive inotropic effect was also observed in electrically driven left atrium and in Langendorff perfused hearts. Functional and biochemical evidences supported the involvement of cAMP in the cardiac action of carteolol. In peripheral arteries (femoral and tail) pre-contracted with phenylephrine, carteolol exerted ISA-related relaxing effects, independent of the presence of endothelium and sensitive to high concentrations (10 microM) of conventional beta-blockers. On the basis of these results, we propose to categorize carteolol as a non-conventional partial agonist of both cardiac and vascular beta-adrenoceptors.
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Affiliation(s)
- Maura Floreani
- Department of Pharmacology and Anaesthesiology, Pharmacology Section, University of Padova, Italy
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Barbuti A, Gravante B, Riolfo M, Milanesi R, Terragni B, DiFrancesco D. Localization of pacemaker channels in lipid rafts regulates channel kinetics. Circ Res 2004; 94:1325-31. [PMID: 15073040 DOI: 10.1161/01.res.0000127621.54132.ae] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lipid rafts are discrete membrane subdomains rich in sphingolipids and cholesterol. In ventricular myocytes a function of caveolae, a type of lipid rafts, is to concentrate in close proximity several proteins of the beta-adrenergic transduction pathway. We have investigated the subcellular localization of HCN4 channels expressed in HEK cells and studied the effects of such localization on the properties of pacemaker channels in HEK and rabbit sinoatrial (SAN) cells. We used a discontinuous sucrose gradient and Western blot analysis to detect HCN4 proteins in HEK and in SAN cells, and found that HCN4 proteins localize to low-density membrane fractions together with flotillin (HEK) or caveolin-3 (SAN), structural proteins of caveolae. Lipid raft disruption by cell incubation with methyl-beta-cyclodextrin (MbetaCD) impaired specific HCN4 localization. It also shifted the midpoint of activation of the HCN4 current in HEK cells and of I(f) in SAN cells to the positive direction by 11.9 and 10.4 mV, respectively. These latter effects were not due to elevation of basal cyclic nucleotide levels because the cholesterol-depletion treatment did not alter the current response to cyclic nucleotides. In accordance with an increased I(f), MbetaCD-treated SAN cells showed large increases of diastolic depolarization slope (87%) and rate (58%). We also found that the kinetics of HCN4- and native f-channel deactivation were slower after lipid raft disorganization. In conclusion, our work indicates that pacemaker channels localize to lipid rafts and that disruption of lipid rafts causes channels to redistribute within the membrane and modifies their kinetic properties.
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Affiliation(s)
- Andrea Barbuti
- Department of Biomolecular Sciences and Biotechnology, Laboratory of Molecular Physiology and Neurobiology, University of Milano, Milano, Italy
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Joseph SS, Lynham JA, Colledge WH, Kaumann AJ. Binding of (-)-[3H]-CGP12177 at two sites in recombinant human beta 1-adrenoceptors and interaction with beta-blockers. Naunyn Schmiedebergs Arch Pharmacol 2004; 369:525-32. [PMID: 15060759 DOI: 10.1007/s00210-004-0884-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Accepted: 02/06/2004] [Indexed: 12/18/2022]
Abstract
To verify the hypothesis that the non-conventional partial agonist (-)-CGP12177 binds at two beta(1)-adrenoceptor sites, human beta(1)-adrenoceptors, expressed in CHO cells, were labelled with (-)-[(3)H]-CGP12177. We compared the binding affinity and antagonist potency of 12 clinically used beta-blockers against the cyclic AMP-enhancing effects of (-)-isoprenaline and (-)-CGP12177.(-)-[(3)H]-CGP12177 bound to a high affinity site (H; K(H)=0.47 nM) and low affinity site (L); K(L)=235 nM). (-)-[(3)H]-CGP12177 dissociated from the beta(1)-adrenoceptors with a fast component (k(off)=0.45 min(-1)), consistent with the L-site, and a slow component (k(off)=0.017-0.033 min(-1)), consistent with the H-site. (-)-Isoprenaline and (-)-CGP12177 caused 96-fold and 12-fold maximal increases in cyclic AMP levels with -logEC(50)M of 8.2 and 7.6. (-)-CGP12177 antagonised the effects of (-)-isoprenaline with a pK(B) of 9.9. The beta-blockers antagonised the effects of (-)-isoprenaline more than the effects of (-)-CGP12177 with potency ratios: (-)-atenolol 1,000, (+/-)-metropolol 676, (-)-pindolol 631, (-)-timolol 589, (+/-)-carvedilol 204, (+/-)-oxprenolol 138, (+/-)-sotalol 132, (-)-propranolol 120, (+/-)-bisoprolol 95, (+/-)-alprenolol 81, (+/-)-nadolol 68 and (-)-bupranolol 56. In intact cells the binding constants of beta-blockers, estimated from competition with 3-5 nM (-)-[(3)H]-CGP12177 (binding to the H-site), correlated with the corresponding affinities estimated from antagonism of the (-)-isoprenaline effects. We conclude that (-)-[(3)H]-CGP12177 binds at two sites in the recombinant beta(1)-adrenoceptor. (-)-CGP12177 is an antagonist of catecholamine effects through the H-site and a non-conventional partial agonist through the L-site. beta-blockers are more potent antagonists through the H-site than the L-site.
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Affiliation(s)
- Shirin S Joseph
- Department of Physiology, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
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Joseph SS, Lynham JA, Grace AA, Colledge WH, Kaumann AJ. Markedly reduced effects of (-)-isoprenaline but not of (-)-CGP12177 and unchanged affinity of beta-blockers at Gly389-beta1-adrenoceptors compared to Arg389-beta1-adrenoceptors. Br J Pharmacol 2004; 142:51-6. [PMID: 15037517 PMCID: PMC1574932 DOI: 10.1038/sj.bjp.0705753] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Substitution of arginine by glycine at position 389, a frequent beta(1)-adrenoceptor polymorphism, reduces adenylyl cyclase stimulation by (-)-isoprenaline. beta(1)-Adrenoceptors mediate the effects of catecholamines and nonconventional partial agonists ((-)-CGP12177) through different sites. We investigated the influence of the 389 polymorphism on beta blocker affinity, as well as on the responses to (-)-isoprenaline and the nonconventional partial agonist (-)-CGP12177 on cyclic AMP levels in CHO cells expressing recombinant Arg389-beta(1)-adrenoceptors (101 fmol mg(-1) protein) or Gly389-beta(1)-adrenoceptors (94 fmol mg(-1)). 2. The affinity of beta-blockers and partial agonists, estimated from competition binding with (-)-[(125)I]-cyanopindolol, was not different for Arg389-beta(1)-adrenoceptors and Gly389-beta(1)-adrenoceptors. 3. The maximum cAMP increases by (-)-isoprenaline and (-)-CGP12177 at Gly389-beta(1)-adrenoceptors were reduced by 97 and 46%, but the potencies enhanced 2 and 0.5 log units, respectively, compared to Arg389-beta(1)-adrenoceptors. The intrinsic activity of (-)-CGP12177 with respect to the (-)-isoprenaline was 0.057 at Arg389-beta(1)-adrenoceptors and 1.05 at Gly389-beta(1)-adrenoceptors. 4. We confirm in intact CHO cells that responses to (-)-isoprenaline are markedly reduced at Gly389-beta(1)-adrenoceptors compared to Arg389-beta(1)-adrenoceptors. However, the 389 polymorphism reduces considerably less the agonist responses to (-)-CGP12177, indicating that coupling to G(s) protein is different for beta(1)-adrenoceptors activated by catecholamines than for receptors activated by nonconventional partial agonists. The affinity of beta-blockers is conserved across the Arg389Gly polymorphism.
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Affiliation(s)
- S S Joseph
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG
| | - J A Lynham
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG
| | - A A Grace
- Papworth Hospital, NHS Trust, Papworth Everard, Cambridge, CB3 8ARE
| | - W H Colledge
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG
| | - A J Kaumann
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG
- Author for correspondence:
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Lewis CJ, Gong H, Brown MJ, Harding SE. Overexpression of beta 1-adrenoceptors in adult rat ventricular myocytes enhances CGP 12177A cardiostimulation: implications for 'putative' beta 4-adrenoceptor pharmacology. Br J Pharmacol 2004; 141:813-24. [PMID: 14757703 PMCID: PMC1574257 DOI: 10.1038/sj.bjp.0705668] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. CGP 12177A mediates cardiostimulation by activation of the 'putative' beta(4)-adrenoceptor; however, it has recently been reported that disruption of the beta(1)-adrenoceptor gene abolishes this effect. We have adenovirally overexpressed beta(1)-adrenoceptors in isolated, cultured adult rat ventricular cardiomyocytes and observed the inotropic potency of isoprenaline and CGP 12177A (in the presence of 1 microm propranolol). 2. Isoprenaline was a full inotropic agonist at rat ventricular myocytes (pD(2) 7.69+/-0.12). CGP 12177A was a nonconventional partial agonist (pD(2) 6.34+/-0.09), increasing inotropy and lusitropy, with an intrinsic activity of 0.34 and antagonised by bupranolol. 3. beta(1)-adrenoceptor overexpression enhanced the inotropic potency of isoprenaline by 11.7-fold (pD(2) 8.76+/-0.14) and CGP 12177A by 5.9-fold (7.11+/-0.10), respectively. Green fluorescent protein (GFP) overexpression did not alter the potency of isoprenaline or CGP 12177A (pD(2) 7.41+/-0.24 and pD(2) 6.60+/-0.50, respectively). 4. The cardiostimulant effects of CGP 12177A were enhanced by IBMX (phosphodiesterase inhibitor) and decreased by Rp-cAMPS (cAMP antagonist). CGP 12177A also increased cAMP levels. CGP 12177A but not isoprenaline initiated arrhythmias at lower concentrations following beta(1)-adrenoceptor overexpression. 5. (125)I-Cyanopindolol saturation binding in Adv.beta(1) myocytes demonstrated approximately 18-fold increase in beta(1)-adrenoceptors. (3)H-CGP 12177A saturation binding, in the presence of propranolol, increased approximately 5-fold following overexpression of beta(1)-adrenoceptors. 6. This study demonstrates enhanced cardiostimulation by CGP 12177A (in the presence of propranolol) in rat ventricular myocytes overexpressing beta(1)-adrenoceptors, mediated by a Gs/cAMP signalling pathway. 'Putative' beta(4)-adrenoceptor pharmacology appears to be mediated by activation of a novel affinity state of the beta(1)-adrenoceptor.
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Affiliation(s)
- Clive J Lewis
- Clinical Pharmacology Unit, Department of Medicine, Cambridge University, Cambridge.
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Malinowska B, Kieć-Kononowicz K, Flau K, Godlewski G, Kozłowska H, Kathmann M, Schlicker E. Atypical cardiostimulant beta-adrenoceptor in the rat heart: stereoselective antagonism by bupranolol but lack of effect by some bupranolol analogues. Br J Pharmacol 2003; 139:1548-54. [PMID: 12922943 PMCID: PMC1573984 DOI: 10.1038/sj.bjp.0705390] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Atypical beta-adrenoceptors resistant to propranolol, but blocked by bupranolol, increase contractile force and/or frequency of the heart in humans and rats. We compared the potencies of the enantiomers of bupranolol and examined the possible effects of seven bupranolol analogues including bevantolol (BEV) at this receptor in pithed and vagotomized rats. 2. CGP 12177, an agonist of the atypical beta-adrenoceptor, increased heart rate dose-dependently. Its dose-response curve was shifted to the right by S-(-)-bupranolol 10 micro mol kg(-1) by a factor of 8.4, but not affected by the same dose of R-(+)-bupranolol. 3. Desmethylbupranolol and compounds BK-21, BK-22, BK-23 and BK-25 also increased heart rate dose-dependently. The beta(1)-adrenoceptor antagonist CGP 20712 given in combination with the beta(2)-adrenoceptor antagonist ICI 118,551 (0.1 micro mol kg(-1) each) reduced the positive chronotropic action of the five bupranolol analogues without affecting that of CGP 12177. The potencies of the bupranolol analogues to increase heart rate were correlated (r=0.91, P<0.05) with their affinities for beta(1)-adrenoceptor binding sites in rat brain cortex membranes labelled with [(3)H]CGP 12177 (in the presence of ICI 118,551). 4. BK-26 and BEV, 10 micro mol kg(-1) each, had only minor effects on heart rate by themselves and did not antagonize the effect of CGP 12177. However, at 1 micro mol kg(-1), they antagonized the increase in heart rate elicited by the beta(1)-adrenoceptor agonist prenalterol. 5. In conclusion, bupranolol is a stereoselective antagonist at the atypical cardiostimulant beta-adrenoceptor. The effects of the bupranolol analogues are related to the activation or blockade of beta(1)-adrenoceptors, but not of atypical beta-adrenoceptors.
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Affiliation(s)
- Barbara Malinowska
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-230 Białystok 8, Poland
| | - Katarzyna Kieć-Kononowicz
- Zakład Technologii Chemicznej Środków Leczniczych, Uniwersytet Jagielloński, Collegium Medicum, ul. Medyczna 9, 30-688 Kraków, Poland
| | - Karsten Flau
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Grzegorz Godlewski
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-230 Białystok 8, Poland
| | - Hanna Kozłowska
- Zakład Fizjologii Doświadczalnej, Akademia Medyczna w Białymstoku, ul. Mickiewicza 2A, 15-230 Białystok 8, Poland
| | - Markus Kathmann
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
| | - Eberhard Schlicker
- Institut für Pharmakologie und Toxikologie, Universität Bonn, Reuterstrasse 2b, 53113 Bonn, Germany
- Author for correspondence:
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Baker JG, Hall IP, Hill SJ. Pharmacology and direct visualisation of BODIPY-TMR-CGP: a long-acting fluorescent beta2-adrenoceptor agonist. Br J Pharmacol 2003; 139:232-42. [PMID: 12770928 PMCID: PMC1573863 DOI: 10.1038/sj.bjp.0705287] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2003] [Revised: 03/03/2003] [Accepted: 03/18/2003] [Indexed: 11/09/2022] Open
Abstract
1 Fluorescence techniques offer a way to circumvent several problems associated with many radioligand binding and functional assays and the need for large numbers of cells. Fluorescent ligands also offer the advantage of allowing real time direct visualisation of ligand - receptors interactions. A fluorescent analogue of CGP 12177 (BODIPY-TMR-CGP) has thus been evaluated as a beta(2)-adrenoceptor ligand in CHO-K1 cells expressing the human beta(2)-adrenoceptor. 2 Studies of (3)H-cAMP accumulation showed that BODIPY-TMR-CGP stimulated an increase in cAMP accumulation and cyclic AMP response element (CRE)-mediated gene transcription with an EC(50) of 21-28 nM. Both of these responses were antagonised by the selective beta(2)-adrenoceptor antagonist ICI 118551. 3 Binding studies with (3)H-CGP 12177, and functional studies of CRE-regulated gene transcription showed that the BODIPY-TMR-CGP interaction with the human beta(2)-adrenoceptor is of very long duration. 4 Visualisation of the binding of BODIPY-TMR-CGP to single living mammalian cells was clearly demonstrated by confocal microscopy and showed that this ligand was able to selectively label cell surface beta(2)-adrenoceptors in living CHO-K1 cells transfected with the human beta(2)-adrenoceptor with an apparent K(D) of 27 nM. Studies with cells expressing a beta(2)-adrenoceptor-green fluorescent protein (GFP) fusion protein provided further strong evidence that BODIPY-TMR-CGP was binding to the beta(2)-adrenoceptor. 5 BODIPY-TMR-CGP is therefore a long-acting fluorescent beta(2)-adrenoceptor agonist that can be used to label beta(2)-adrenoceptors in the plasma membrane of living cells.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, C Floor, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, U.K
| | - Ian P Hall
- Institute of Cell Signalling, C Floor, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, U.K
| | - Stephen J Hill
- Institute of Cell Signalling, C Floor, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, U.K
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Baker JG, Hall IP, Hill SJ. Pharmacological characterization of CGP 12177 at the human beta(2)-adrenoceptor. Br J Pharmacol 2002; 137:400-8. [PMID: 12237261 PMCID: PMC1573492 DOI: 10.1038/sj.bjp.0704855] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Revised: 05/27/2002] [Accepted: 06/24/2002] [Indexed: 11/09/2022] Open
Abstract
1 It has recently been reported that CGP 12177 can act as an agonist at a novel secondary site within the human beta(1)-adrenoceptor. The aim of this study was to undertake a detailed pharmacological study of the effects of CGP 12177 on the human beta(2)-adrenoceptor. 2 CGP 12177 acted as a potent partial agonist of (3)H-cyclic AMP accumulation (log EC(50)-8.90+/-0.06) and CRE-mediated reporter gene transcription (log EC(50)-9.66+/-0.04) in CHO-K1 cells expressing the human beta(2)-adrenoceptor. These CGP-induced responses were antagonized by the beta(2)-selective antagonist ICI 118551 (apparent log K(D) values of -8.84+/-0.15 and -9.51+/-0.02 for the cyclic AMP and reporter gene responses respectively). 3 CGP 12177 was also able to antagonize both cyclic AMP and reporter gene responses to more efficacious beta(2)-agonists with similar log K(D) values (e.g. -9.57+/-0.15 and -10.04+/-0.096 respectively with salbutamol as agonist). 4 (3)H-CGP 12177 binding to beta(2)-adrenoceptors in intact CHO-beta(2) cells yielded a log K(D) value of -9.84+/-0.06, but indicated that the ligand dissociates very slowly from the receptor (t(1/2) for dissociation=65 min). However, studies with a Green Fluorescent Protein (GFP)-tagged beta(2)-adrenoceptor indicated that CGP 12177 does not stimulate beta(2)-adrenoceptor internalization. 5 This study demonstrates that CGP 12177 is a high affinity partial agonist of both cAMP accumulation and CRE-mediated gene transcription at the human beta(2)-adrenoceptor. It provides no evidence that CGP 12177 can discriminate a secondary site on the beta(2)-adrenoceptor analogous to that observed for the human beta(1)-adrenoceptor. However, despite its very weak actions on cAMP accumulation, the potent agonist effects of CGP 12177 on CRE-mediated gene transcription at the human beta(2)-adrenoceptor, coupled with its long duration of action, offers a potential lead for drug development for the treatment of chronic inflammatory airway diseases.
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Affiliation(s)
- Jillian G Baker
- Institute of Cell Signalling, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH
| | - Ian P Hall
- Institute of Cell Signalling, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH
| | - Stephen J Hill
- Institute of Cell Signalling, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH
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Heubach JF, Rau T, Eschenhagen T, Ravens U, Kaumann AJ. Physiological antagonism between ventricular beta 1-adrenoceptors and alpha 1-adrenoceptors but no evidence for beta 2- and beta 3-adrenoceptor function in murine heart. Br J Pharmacol 2002; 136:217-29. [PMID: 12010770 PMCID: PMC1573340 DOI: 10.1038/sj.bjp.0704700] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2001] [Revised: 02/13/2002] [Accepted: 02/27/2002] [Indexed: 11/08/2022] Open
Abstract
1. Murine left atrium lacks inotropic beta(2)-adrenoceptor function. We investigated whether beta(2)-adrenoceptors are involved in the cardiostimulant effects of (-)-adrenaline on spontaneously beating right atria and paced right ventricular myocardium of C57BL6 mice. We also studied a negative inotropic effect of (-)-adrenaline. 2. Sinoatrial tachycardia, evoked by (-)-adrenaline was resistant to blockade by beta(2)-selective ICI 118,551 (50 nM) but antagonized by beta(1)-selective CGP 20712A (300 nM). This pattern was unaffected by pretreatment with pertussis toxin (PTX, 600 microg kg(-1) i.p. 24 h) which reversed carbachol-evoked bradycardia to tachycardia. 3. Increases of ventricular force by (-)-adrenaline and (-)-noradrenaline were not blocked by ICI 118,551 but antagonized by CGP 20712A. 4. Under blockade of beta-adrenoceptors, (-)-adrenaline and (-)-noradrenaline depressed ventricular force (-logIC(50)M=7.7 and 6.9). The cardiodepressant effects of (-)-adrenaline were antagonized by phentolamine (1 microM) and prazosin (1 microM) but not by (-)-bupranolol (1 microM). Prazosin potentiated the positive inotropic effects of (-)-adrenaline (in the absence of beta-blockers) from -logEC(50)M=6.2 - 6.8. 5. PTX-treatment reduced carbachol-evoked depression of ventricular force in the presence of high catecholamine concentrations. Inhibition of ventricular function of G(i) protein was verified by 82% reduction of in vitro ADP-ribosylation. PTX-treatment tended to increase the positive inotropic potency of (-)-adrenaline under all conditions investigated, including the presence of ICI 118,551. 6. (-)-Adrenaline causes murine cardiostimulation through beta(1)-adrenoceptors but not through beta(2)-adrenoceptors. The negative inotropic effects of (-)-adrenaline are mediated through ventricular alpha(1)-adrenoceptors but not through beta(3)-adrenoceptors. Both G(i) protein and alpha(1)-adrenoceptors restrain (-)-adrenaline-evoked increases in right ventricular force mediated through beta(1)-adrenoceptors.
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MESH Headings
- Adrenergic alpha-1 Receptor Agonists
- Adrenergic alpha-1 Receptor Antagonists
- Adrenergic beta-1 Receptor Agonists
- Adrenergic beta-1 Receptor Antagonists
- Adrenergic beta-2 Receptor Agonists
- Adrenergic beta-2 Receptor Antagonists
- Adrenergic beta-3 Receptor Agonists
- Adrenergic beta-3 Receptor Antagonists
- Animals
- Dose-Response Relationship, Drug
- Heart Ventricles/drug effects
- In Vitro Techniques
- Male
- Mice
- Mice, Inbred C57BL
- Myocardial Contraction/drug effects
- Myocardial Contraction/physiology
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/physiology
- Receptors, Adrenergic, beta-3/physiology
- Sinoatrial Node/drug effects
- Sinoatrial Node/physiology
- Ventricular Function
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Affiliation(s)
- Jürgen F Heubach
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät Carl Gustav Carus der TU Dresden, D-01307 Dresden, Germany
| | - Thomas Rau
- Institut für Experimentelle und Klinische Pharmakologie, Friedrich-Alexander Universität Erlangen, Germany
| | - Thomas Eschenhagen
- Institut für Experimentelle und Klinische Pharmakologie, Friedrich-Alexander Universität Erlangen, Germany
| | - Ursula Ravens
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät Carl Gustav Carus der TU Dresden, D-01307 Dresden, Germany
| | - Alberto J Kaumann
- Department of Physiology, University of Cambridge, Cambridge CB2 3EG, U.K
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