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Littmann T, Göttle M, Reinartz MT, Kälble S, Wainer IW, Ozawa T, Seifert R. Recruitment of β-arrestin 1 and 2 to the β2-adrenoceptor: analysis of 65 ligands. J Pharmacol Exp Ther 2015; 355:183-90. [PMID: 26306764 DOI: 10.1124/jpet.115.227959] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 08/21/2015] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Beyond canonical signaling via Gαs and cAMP, the concept of functional selectivity at β2-adrenoceptors (β2ARs) describes the ability of adrenergic drugs to stabilize ligand-specific receptor conformations to initiate further signaling cascades comprising additional G-protein classes or β-arrestins (βarr). A set of 65 adrenergic ligands including 40 agonists and 25 antagonists in either racemic or enantiopure forms was used for βarr recruitment experiments based on a split-luciferase assay in a cellular system expressing β2AR. Many agonists showed only (weak) partial agonism regarding βarr recruitment. Potencies and/or efficacies increased depending on the number of chirality centers in (R) configuration; no (S)-configured distomer was more effective at inducing βarr recruitment other than the eutomer. βarr2 was recruited more effectively than βarr1. The analysis of antagonists revealed no significant effects on βarr recruitment. Several agonists showed preference for activation of Gαs GTPase relative to βarr recruitment, and no βarr-biased ligand was identified. IN CONCLUSION 1) agonists show strong bias for Gαs activation relative to βarr recruitment; 2) agonists recruit βarr1 and βarr2 with subtle differences; and 3) there is no evidence for βarr recruitment by antagonists.
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Affiliation(s)
- Timo Littmann
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Martin Göttle
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Michael T Reinartz
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Solveig Kälble
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Irving W Wainer
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Takeaki Ozawa
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
| | - Roland Seifert
- Institute of Pharmacology, Hannover Medical School, Hannover, Germany (T.L.; M.G.; M.T.R.; S.K., R.S.); Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, Maryland (I.W.W.); and Department of Chemistry, School of Science, The University of Tokyo, Tokyo, Japan (T.O.)
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Effects of (r,r)- and (r,r/s,s)-formoterol on airway relaxation and contraction in an experimental rat model. Curr Ther Res Clin Exp 2014; 68:249-61. [PMID: 24683215 DOI: 10.1016/j.curtheres.2007.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2007] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Racemic (R,R/S,S)-formoterol is a long-acting β-agonist composed of a 50:50 mixture of (R,R)- and (S,S)-enantiomers. OBJECTIVE The aim of this study was to determine whether (R,R)-formoterol and (R,R/S,S)-formoterol have differing effects on airway contraction and relaxation in vitro. METHODS Cylindrical airway segments 3-mm long were isolated from the mid-trachea of healthy Sprague-Dawley rats and placed in a modified Krebs-Henseleit solution. Dose-response curves of bethanechol-induced contraction (measured as milligrams of tension) and the concentration of bethanechol that elicited 50% to 75% of maximal contraction (EC50-75) were determined. The air-way cylinders were then precontracted with bethanechol at the EC50-75 and exposed to different concentrations of (R,R)-formoterol (0.0001-1.0 μM) or (R,R/S,S)-formoterol (0.0002-2.0 μM). Each concentration of the 2 formoterol formulations contained the same amount of (R,R)-enantiomer (eg, [R,R]-formoterol 0.0001 μM and [R,R/S,S]-formoterol 0.0002 1JM contained the same amount of [R,R]-enantiomer). The relaxation percentage in response to formoterol was calculated as a reduction in tension (in milligrams) in relation to baseline tension in the precontracted state, with each tracheal cylinder serving as its own control. To determine the effect of (R,R)-formoterol on airway contraction, tracheal cylinders were incubated with (R,R)- or (R,R/S,S)-formoterol before electrical field stimulation (EFS). RESULTS Tracheae from 56 three-week-old Sprague-Dawley rats were used in the study. The relaxation percentage of precontracted trachea was significantly greater after exposure to (R,R)-formoterol than to (R,R/S,S)-formoterol at a 2-fold higher concentration (P = 0.03; general linear model with repeated measures analysis comparing the 2 groups of animals). However, in a post hoc analysis, the mean (SE) relaxation percentage of precontracted trachea was significantly greater only after exposure to (R,R)-formoterol 0.01 μM than to (R,R/S,S)-formoterol 0.02 μM (15.6% [5.8%] vs 39.0% [5.6%]; P < 0.05, unpaired t test). EFS-induced airway contraction was significantly less in tracheal cylinders incubated in (R,R)-formoterol compared with those incubated in (R,R/S,S)-formoterol at a 2-fold higher concentration (P = 0.05; general linear model with repeated measures analysis comparing the 2 groups of animals). However, in the post hoc analysis, mean (SE) EFS-induced tracheal contraction was significantly less only in (R,R)-formoterol 0.01 μM compared with (R,R/S,S)-formoterol 0.02 μM at 10 V (1070 [55] mgvs 1225 [28] mg; P < 0.05, unpaired t test). CONCLUSION We found that (R,R)-formoterol may induce greater relaxation of precontracted airway smooth muscle cells than (R,R/S,S)-formoterol and that (R,R)-formoterol may have a greater inhibitory effect on the endogenous cholinergic and excitatory nonadrenergic, noncholinergic contractile airway responses than (R,R/S,S)-formoterol. We speculate that the presence of the (S,S)-enantiomer in (R,R/S,S)-formoterol may impair airway relaxation of pre-contracted trachea in rats.
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Dale PR, Cernecka H, Schmidt M, Dowling MR, Charlton SJ, Pieper MP, Michel MC. The pharmacological rationale for combining muscarinic receptor antagonists and β-adrenoceptor agonists in the treatment of airway and bladder disease. Curr Opin Pharmacol 2014; 16:31-42. [PMID: 24682092 PMCID: PMC4071415 DOI: 10.1016/j.coph.2014.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/03/2014] [Accepted: 03/04/2014] [Indexed: 02/07/2023]
Abstract
Muscarinic receptors increase smooth muscle tone in airways and urinary bladder. β-Adrenoceptors relax smooth muscle tone and oppose muscarinic contraction. Opposition involves transmitter release, signal transduction and receptor expression. This supports the combined use of muscarinic antagonists and β-adrenoceptor agonists.
Muscarinic receptor antagonists and β-adrenoceptor agonists are used in the treatment of obstructive airway disease and overactive bladder syndrome. Here we review the pharmacological rationale for their combination. Muscarinic receptors and β-adrenoceptors are physiological antagonists for smooth muscle tone in airways and bladder. Muscarinic agonism may attenuate β-adrenoceptor-mediated relaxation more than other contractile stimuli. Chronic treatment with one drug class may regulate expression of the target receptor but also that of the opposing receptor. Prejunctional β2-adrenoceptors can enhance neuronal acetylcholine release. Moreover, at least in the airways, muscarinic receptors and β-adrenoceptors are expressed in different locations, indicating that only a combined modulation of both systems may cause dilatation along the entire bronchial tree. While all of these factors contribute to a rationale for a combination of muscarinic receptor antagonists and β-adrenoceptor agonists, the full value of such combination as compared to monotherapy can only be determined in clinical studies.
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Affiliation(s)
- Philippa R Dale
- Department of Pharmacology, Cambridge University, Cambridge, UK
| | - Hana Cernecka
- University of Groningen, Department of Molecular Pharmacology, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Groningen Research Institute for Asthma and COPD, GRIAC, Groningen, The Netherlands
| | - Martina Schmidt
- University of Groningen, Department of Molecular Pharmacology, Groningen, The Netherlands; University of Groningen, University Medical Center Groningen, Groningen Research Institute for Asthma and COPD, GRIAC, Groningen, The Netherlands
| | - Mark R Dowling
- Department of Molecular Pharmacology, Respiratory Diseases, Novartis Institutes for Biomedical Research, Horsham, UK
| | - Steven J Charlton
- Department of Molecular Pharmacology, Respiratory Diseases, Novartis Institutes for Biomedical Research, Horsham, UK
| | - Michael P Pieper
- Respiratory Diseases Research and Department of Translational Medicine & Clinical Pharmacology, Boehringer Ingelheim Pharma GmbH, Ingelheim, Germany
| | - Martin C Michel
- Respiratory Diseases Research and Department of Translational Medicine & Clinical Pharmacology, Boehringer Ingelheim Pharma GmbH, Ingelheim, Germany; Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany.
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Abstract
Albuterol has been used for more than 40 years to treat acute asthma exacerbations as a racemic mixture of isomers: the active form, (R)-albuterol, or levalbuterol, and (S)-albuterol, classically considered inert. The single-isomer formulation, levalbuterol, has been synthesized recently and used therapeutically when the racemate is deemed less desirable. Basic investigations indicate that racemic albuterol and levalbuterol can produce effects that favor asthma remediation, including corticosteroid amplification and reduction of inflammatory mediators; in contrast, (S)-albuterol produces opposite effects. With inhalation of racemic albuterol, circulating (S)-albuterol persists 12 times longer than levalbuterol, suggesting potential for paradoxical effects observed clinically. Although mainly consistent with basic findings, clinical studies suggest no overwhelming superiority of levalbuterol over racemic albuterol; however, levalbuterol's effects may be greatest in moderate to severe asthma patients, especially with racemic albuterol overuse. Recent adoption of the hydrofluoroalkane formulation has narrowed the cost gap between levalbuterol and racemic albuterol metered-dose inhalers, but it remains for the nebulized formulations. Thus, physician selection of these drugs has remained dependent on experience, pharmaceutical knowledge, and established prescribing habits combined with cost factors, formulary structures, and availability, such that racemic albuterol is still used significantly compared with levalbuterol to treat acute asthma exacerbations.
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Delmotte P, Sanderson MJ. Effects of albuterol isomers on the contraction and Ca2+ signaling of small airways in mouse lung slices. Am J Respir Cell Mol Biol 2007; 38:524-31. [PMID: 18063837 DOI: 10.1165/rcmb.2007-0214oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The beta(2)-adrenergic agonist, albuterol, is used as a bronchodilator by patients with asthma and consists of a racemic mixture of (R)- and (S)-albuterol. However, the action of the individual enantiomers is poorly understood. Consequently, we investigated the effects of (R)-, (S)- and racemic-albuterol on airway smooth muscle cell (SMC) contraction and Ca(2+) signaling in mouse lung slices with phase-contrast and confocal microscopy. (R)-albuterol relaxed airways contracted with methacholine (MCh) in a dose-dependent manner. By contrast, (S)-albuterol had no effect on airways. (R)-albuterol had a greater relaxant effect than a double concentration of racemic albuterol. Because MCh-induced contraction of airway SMCs is mediated by Ca(2+) oscillations and an increase in Ca(2+) sensitivity, the effects of albuterol on these responses were examined. Both (R)- and racemic albuterol decreased the frequency of the MCh-induced Ca(2+) oscillations by a similar amount. However, (R)-albuterol was more effective than racemic albuterol in decreasing the Ca(2+) sensitivity of the airway SMCs in "model" lung slices with a clamped [Ca(2+)](i). In contrast, (S)-albuterol had no effect on the Ca(2+) oscillations or the Ca(2+) sensitivity. In conclusion, (R)-albuterol consistently induced a greater airway relaxation than racemic albuterol, and (S)-albuterol appears to be responsible for this reduced efficacy.
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Affiliation(s)
- Philippe Delmotte
- Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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Chávez J, Segura P, Vargas MH, Arreola JL, Flores-Soto E, Montaño LM. Paradoxical effect of salbutamol in a model of acute organophosphates intoxication in guinea pigs: role of substance P release. Am J Physiol Lung Cell Mol Physiol 2007; 292:L915-23. [PMID: 17158603 DOI: 10.1152/ajplung.00253.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Organophosphates induce bronchoobstruction in guinea pigs, and salbutamol only transiently reverses this effect, suggesting that it triggers additional obstructive mechanisms. To further explore this phenomenon, in vivo (barometric plethysmography) and in vitro (organ baths, including ACh and substance P concentration measurement by HPLC and immunoassay, respectively; intracellular Ca2+measurement in single myocytes) experiments were performed. In in vivo experiments, parathion caused a progressive bronchoobstruction until a plateau was reached. Administration of salbutamol during this plateau decreased bronchoobstruction up to 22% in the first 5 min, but thereafter airway obstruction rose again as to reach the same intensity as before salbutamol. Aminophylline caused a sustained decrement (71%) of the parathion-induced bronchoobstruction. In in vitro studies, paraoxon produced a sustained contraction of tracheal rings, which was fully blocked by atropine but not by TTX, ω-conotoxin (CTX), or epithelium removal. During the paraoxon-induced contraction, salbutamol caused a temporary relaxation of ∼50%, followed by a partial recontraction. This paradoxical recontraction was avoided by the M2- or neurokinin-1 (NK1)-receptor antagonists (methoctramine or AF-DX 116, and L-732138, respectively), accompanied by a long-lasting relaxation. Forskolin caused full relaxation of the paraoxon response. Substance P and, to a lesser extent, ACh released from tracheal rings during 60-min incubation with paraoxon or physostigmine, respectively, were significantly increased when salbutamol was administered in the second half of this period. In myocytes, paraoxon did not produce any change in the intracellular Ca2+basal levels. Our results suggested that: 1) organophosphates caused smooth muscle contraction by accumulation of ACh released through a TTX- and CTX-resistant mechanism; 2) during such contraction, salbutamol relaxation is functionally antagonized by the stimulation of M2receptors; and 3) after this transient salbutamol-induced relaxation, a paradoxical contraction ensues due to the subsequent release of substance P.
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Affiliation(s)
- Jaime Chávez
- Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, Universidad Nacional Autónoma de México, México DF, México
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