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Alsufyani HA, Docherty JR. Effects of RS17053 on α 1 -adrenoceptors in rat vas deferens and aorta. Fundam Clin Pharmacol 2023; 37:1170-1178. [PMID: 37392126 DOI: 10.1111/fcp.12930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/01/2023] [Accepted: 06/07/2023] [Indexed: 07/02/2023]
Abstract
BACKGROUND RS17053 is classed as an α1A -adrenoceptor selective antagonist. OBJECTIVES We have examined its profile of action at all subtypes of α1 -adrenoceptor. METHODS Noradrenaline (NA) evoked contractions of rat vas deferens involve α1D -adrenoceptors in phasic contractions and α1A -adrenoceptors in tonic contractions. Contractions of rat aorta to NA involve α1D - and α1B -adrenoceptors. RESULTS RS17053 (10-5 M) shifted NA potency and virtually abolished tonic contractions to NA, with little or limited effect on phasic contractions. The α1D -adrenoceptor antagonist BMY7378 (3 × 10-7 M) significantly inhibited the remaining phasic component of the contractions, and the α1A -adrenoceptor antagonist RS100329 (10-7 M) inhibited further the residual tonic contraction. Hence, RS17053 shows high selectivity for α1A -adrenoceptors over α1D -adrenoceptors in rat vas deferens. However, RS17053 (10-5 M) produced a large shift in the potency of NA in rat aorta, with a pKB of 6.82. Large shifts of NA potency in rat aorta involve α1B -adrenoceptor blockade. CONCLUSION Results in rat vas deferens demonstrate low potency of RS17053 at α1D -adrenoceptors, but results from rat aorta can only be explained as demonstrating α1B -adrenoceptor antagonism by RS17053. RS17053 may be a useful pharmacological tool when reclassified as a mainly α1A - and to a lesser extent α1B -adrenoceptor antagonist with little effect at α1D -adrenoceptors.
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Affiliation(s)
- Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
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2
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da Silva SB, Feitosa SGD, de L Alves SM, Santos RCA, Dos Anjos JV, Araújo AV. A Concise and Useful Guide to Understand How Alpha1 Adrenoceptor Antagonists Work. Mini Rev Med Chem 2022; 22:2383-2405. [PMID: 35507746 DOI: 10.2174/1389557522666220504141949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/23/2022] [Accepted: 03/16/2022] [Indexed: 11/22/2022]
Abstract
Adrenoceptors are the receptors for the catecholamines, adrenaline and noradrenaline. They are divided in α (α1 and α2) and β (β1, β2 and β3). α1-Adrenoceptors are subdivided in α1A, α1B and α1D. Most tissues express mixtures of α1-adrenoceptors subtypes, which appear to coexist in different densities and ratios, and in most cases their responses are probably due to the activation of more than one type. The three subtypes of α1-adrenoceptors are G-protein-coupled receptors (GPCR), specifically coupled to Gq/11. Additionally, the activation of these receptors may activate other signaling pathways or different components of these pathways, which leads to a great variety of possible cellular effects. The first clinically used α1 antagonist was Prazosin, for Systemic Arterial Hypertension (SAH). It was followed by its congeners, Terazosin and Doxazosin. Nowadays, there are many classes of α-adrenergic antagonists with different selectivity profiles. In addition to SAH, the α1-adrenoceptors are used for the treatment of Benign Prostatic Hyperplasia (BPH) and urolithiasis. This antagonism may be part of the mechanism of action of tricyclic antidepressants. Moreover, the activation of these receptors may lead to adverse effects such as orthostatic hypotension, similar to what happens with the antidepressants and with some antipsychotic. Structure-activity relationships can explain, in part, how antagonists work and how selective they can be for each one of the subtypes. However, it is necessary to develop new molecules which antagonize the α1-adrenoceptors or make chemical modifications in these molecules to improve the selectivity, pharmacokinetic profile and/or reduce the adverse effects of known drugs.
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Affiliation(s)
- Sidiane B da Silva
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Sidney G D Feitosa
- Departamento de Química Fundamental - Universidade Federal de Pernambuco. Av. Jornalista Aníbal Fernandes, s/n, Cidade Universitária - Recife, PE, 50740-560, Brazil
| | - Silvia M de L Alves
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Ruth C A Santos
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Janaína V Dos Anjos
- Departamento de Química Fundamental - Universidade Federal de Pernambuco. Av. Jornalista Aníbal Fernandes, s/n, Cidade Universitária - Recife, PE, 50740-560, Brazil
| | - Alice V Araújo
- Núcleo de Saúde Pública, Centro Acadêmico de Vitória - Universidade Federal de Pernambuco R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
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Alsufyani HA, Docherty JR. Roles for α 1-adrenoceptors during contractions by electrical field stimulation in mouse vas deferens. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY 2021; 25:525-532. [PMID: 34697263 PMCID: PMC8552829 DOI: 10.4196/kjpp.2021.25.6.525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 11/15/2022]
Abstract
We have investigated the relative roles of α1-adrenoceptors and purinoceptors in contractions to low and high frequency stimulation of the mouse vas deferens, in terms of the time course of responses. In separate experiments, isometric contractile responses were obtained to 10 pulses at 1 Hz and 40 pulses at 10 Hz. Responses to 1 Hz stimulation consisted of a series of discrete peaks. The α1A-adrenoceptor antagonist RS100329 (10–9M–10–7M) significantly reduced the response to the first pulse, the α1D-adrenoceptor antagonist BMY7378 (10–7M–10–6M) significantly reduced the response to the first two pulses, and the non-selective α1-adrenoceptor antagonist prazosin (10–8M) reduced the response to the first 4 pulses at 1 Hz. Responses to 10 Hz stimulation consisted of an early peak response and a maintained plateau response. RS100329 significantly reduced the peak response but did not significantly affect the plateau response. Prazosin, significantly reduced both the peak and plateau responses. The α1A-adrenoceptor antagonist RS17053 in high concentrations reduced mainly the plateau response leaving a clear early peak response. The plateau response of contraction was almost abolished by the purinoceptor antagonist suramin. These results suggest that there is a relatively minor early α1D-adrenoceptor and a larger early α1A-adrenoceptor component to stimulation-evoked contractions of mouse vas deferens, but the major α1-adrenoceptor component is revealed by prazosin to be α1B-adrenoceptor mediated. α1B-Adrenoceptor activation probably facilitates contractions mediated by other α1-adrenoceptors and by purinoceptors. These results suggest that combined non-selective α1-adrenoceptor blockade, particularly α1B-adrenoceptor blockade, in addition to P2X1-purinoceptor blockade is useful in reducing male fertility.
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Affiliation(s)
- Hadeel A. Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - James R. Docherty
- Department of Physiology, Royal College of Surgeons in Ireland (RCSI), Dublin D02 YN77, Ireland
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4
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Alsufyani HA, Docherty JR. Involvement of G proteins and Rho kinase in α 1-adrenoceptor mediated contractions of the rat portal vein. Can J Physiol Pharmacol 2020; 99:654-659. [PMID: 33096009 DOI: 10.1139/cjpp-2020-0347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Contractions of the rat portal vein in response to the α1-adrenoceptor agonist phenylephrine consist of phasic contractions at low concentrations, with tonic contractions superimposed at higher concentrations. The α1D-adrenoceptor antagonist BMY7378 (7.0, -log M) did not affect phasic or tonic contractions to phenylephrine. The relatively nonselective α1-adrenoceptor antagonist prazosin (7.5) shifted equally the potencies of phenylephrine at producing phasic and tonic contractions, with pKB values of 8.85 and 8.83 (-log M), respectively. The α1A-adrenoceptor antagonist RS100329 (8.5) produced a significantly greater shift in phenylephrine potency for phasic (pKB of 10.51) than tonic contractions (pKB of 9.78). Prazosin was less effective than RS100329 at reducing the effects of phenylephrine on frequency of phasic contractions. The Rho kinase inhibitor fasudil (5.0) did not affect phasic contractions to phenylephrine, but significantly reduced tonic contractions. It is concluded that there is no evidence for involvement of α1D-adrenoceptors in responses of the rat portal vein to phenylephrine, but phasic responses involve predominantly α1A-adrenoceptors. Tonic responses may involve predominantly α1B-adrenoceptors and are at least partly mediated by mechanisms involving Rho kinase sensitive to fasudil.
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Affiliation(s)
- Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
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Proudman RGW, Pupo AS, Baker JG. The affinity and selectivity of α-adrenoceptor antagonists, antidepressants, and antipsychotics for the human α1A, α1B, and α1D-adrenoceptors. Pharmacol Res Perspect 2020; 8:e00602. [PMID: 32608144 PMCID: PMC7327383 DOI: 10.1002/prp2.602] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 12/26/2022] Open
Abstract
α1-adrenoceptor antagonists are widely used for hypertension (eg, doxazosin) and benign prostatic hypertrophy (BPH, eg, tamsulosin). Some antidepressants and antipsychotics have been reported to have α1 affinity. This study examined 101 clinical drugs and laboratory compounds to build a comprehensive understanding of α1-adrenoceptor subtype affinity and selectivity. [3H]prazosin whole-cell binding was conducted in CHO cells stably expressing either the full-length human α1A, α1B, or α1D-adrenoceptor. As expected, doxazosin was a high-affinity nonselective α1-antagonist although other compounds (eg, cyclazosin, 3-MPPI, and ARC239) had higher affinities. Several highly α1A-selective antagonists were confirmed (SNAP5089 had over 1700-fold α1A selectivity). Despite all compounds demonstrating α1 affinity, only BMY7378 had α1D selectivity and no α1B-selective compounds were identified. Phenoxybenzamine (used in pheochromocytoma) and dibenamine had two-component-binding inhibition curves at all three receptors. Incubation with sodium thiosulfate abolished the high-affinity component suggesting this part is receptor mediated. Drugs used for hypertension and BPH had very similar α1A/α1B/α1D-adrenoceptor pharmacological profiles. Selective serotonin reuptake inhibitors (antidepressants) had poor α1-adrenoceptor affinity. Several tricyclic antidepressants (eg, amitriptyline) and antipsychotics (eg, chlorpromazine and risperidone) had high α1-adrenoceptor affinities, similar to, or higher than, α blockers prescribed for hypertension and BPH, whereas others had poor α1 affinity (eg, protriptyline, sulpiride, amisulpiride, and olanzapine). The addition of α blockers for the management of hypertension or BPH in people already taking tricyclic antidepressants and certain antipsychotics may not be beneficial. Awareness of the α-blocking potential of different antipsychotics may affect the choice of drug for those with delirium where additional hypotension (eg, in sepsis) may be detrimental.
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Affiliation(s)
- Richard G. W. Proudman
- Cell Signalling Research GroupDivision of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesC Floor Medical SchoolQueen’s Medical CentreUniversity of NottinghamNottinghamUK
| | - Andre S. Pupo
- Department of PharmacologyInstitute of BiosciencesSão Paulo State UniversityBotucatu‐São PauloBrazil
| | - Jillian G. Baker
- Cell Signalling Research GroupDivision of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesC Floor Medical SchoolQueen’s Medical CentreUniversity of NottinghamNottinghamUK
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Kurahashi M, Kito Y, Hara M, Takeyama H, Sanders KM, Hashitani H. Norepinephrine Has Dual Effects on Human Colonic Contractions Through Distinct Subtypes of Alpha 1 Adrenoceptors. Cell Mol Gastroenterol Hepatol 2020; 10:658-671.e1. [PMID: 32376421 PMCID: PMC7474159 DOI: 10.1016/j.jcmgh.2020.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Colonic musculature contain smooth muscle cells (SMC), interstitial cells of Cajal (ICC), and platelet-derived growth factor receptor α+ cells (PDGFRα+ cells), which are electrically coupled and operate together as the SIP syncytium. PDGFRα+ cells have enriched expression of small conductance Ca2+-activated K+ (SK) channels. Purinergic enteric neural input activates SK channels in PDGFRα+ cells, hyperpolarizes SMC, and inhibits colonic contractions. Recently we discovered that PDGFRα+ cells in mouse colon have enriched expression of α1A adrenoceptors (ARs), which coupled to activation of SK channels and inhibited colonic motility, and α1A ARs were principal targets for sympathetic regulation of colonic motility. Here we investigated whether PDGFRα+ cells in human colon express α1A ARs and share the roles as targets for sympathetic regulation of colonic motility. METHODS Isometric tension recording, intracellular recording, and Ca2+ imaging were performed on muscles of the human colon. Responses to α1 ARs agonists or electric field stimulation with AR antagonists and neuroleptic reagents were studied. RESULTS Exogenous or endogenous norepinephrine released from nerve fibers inhibited colonic contractions through binding to α1A ARs or enhanced colonic contractions by acting on α1D ARs. Inhibitory responses were blocked by apamin, an antagonist of SK channels. Phenylephrine, α1 AR agonists, or norepinephrine increased intracellular [Ca2+] in PDGFRα+ cells, but not in ICC, and hyperpolarized SMCs by binding to α1 ARs expressed by PDGFRα+ cells. CONCLUSIONS Human colonic contractions are inhibited by α1A ARs expressed in PDGFRα+ cells and activated by α1D ARs expressed in SMC.
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Affiliation(s)
- Masaaki Kurahashi
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada.
| | - Yoshihiko Kito
- Department of Pharmacology, Saga University, Saga, Japan
| | - Masayasu Hara
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hiromitsu Takeyama
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada
| | - Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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Kurahashi M, Kito Y, Baker SA, Jennings LK, Dowers JGR, Koh SD, Sanders KM. A novel postsynaptic signal pathway of sympathetic neural regulation of murine colonic motility. FASEB J 2020; 34:5563-5577. [PMID: 32086857 DOI: 10.1096/fj.201903134r] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/04/2020] [Accepted: 02/13/2020] [Indexed: 01/14/2023]
Abstract
Transcriptome data revealed α1 adrenoceptors (ARs) expression in platelet-derived growth factor receptor α+ cells (PDGFRα+ cells) in murine colonic musculature. The role of PDGFRα+ cells in sympathetic neural regulation of murine colonic motility was investigated. Norepinephrine (NE), via α1A ARs, activated a small conductance Ca2+ -activated K+ (SK) conductance, evoked outward currents and hyperpolarized PDGFRα+ cells (the α1A AR-SK channel signal pathway). α1 AR agonists increased intracellular Ca2+ transients in PDGFRα+ cells and inhibited spontaneous phasic contractions (SPCs) of colonic muscle through activation of a SK conductance. Sympathetic nerve stimulation inhibited both contractions of distal colon and propulsive contractions represented by the colonic migrating motor complexes (CMMCs) via the α1A AR-SK channel signal pathway. Postsynaptic signaling through α1A ARs in PDGFRα+ cells is a novel mechanism that conveys part of stress responses in the colon. PDGFRα+ cells appear to be a primary effector of sympathetic neural regulation of murine colonic motility.
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Affiliation(s)
- Masaaki Kurahashi
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Yoshihiko Kito
- Department of Pharmacology, Saga University, Saga, Japan
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Libby K Jennings
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - James G R Dowers
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
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Docherty JR. The pharmacology of α 1-adrenoceptor subtypes. Eur J Pharmacol 2019; 855:305-320. [PMID: 31067439 DOI: 10.1016/j.ejphar.2019.04.047] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/17/2019] [Accepted: 04/29/2019] [Indexed: 01/30/2023]
Abstract
This review examines the functions of α1-adrenoceptor subtypes, particularly in terms of contraction of smooth muscle. There are 3 subtypes of α1-adrenoceptor, α1A- α1B- and α1D-adrenoceptors. Evidence is presented that the postulated α1L-adrenoceptor is simply the native α1A-adrenoceptor at which prazosin has low potency. In most isolated tissue studies, smooth muscle contractions to exogenous agonists are mediated particularly by α1A-, with a lesser role for α1D-adrenoceptors, but α1B-adrenoceptors are clearly involved in contractions of some tissues, for example, the spleen. However, nerve-evoked responses are the most crucial physiologically, so that these studies of exogenous agonists may overestimate the importance of α1A-adrenoceptors. The major α1-adrenoceptors involved in blood pressure control by sympathetic nerves are the α1D- and the α1A-adrenoceptors, mediating peripheral vasoconstrictor actions. As noradrenaline has high potency at α1D-adrenceptors, these receptors mediate the fastest response and seem to be targets for neurally released noradrenaline especially to low frequency stimulation, with α1A-adrenoceptors being more important at high frequencies of stimulation. This is true in rodent vas deferens and may be true in vasopressor nerves controlling peripheral resistance and tissue blood flow. The αlA-adrenoceptor may act mainly through Ca2+ entry through L-type channels, whereas the α1D-adrenoceptor may act mainly through T-type channels and exhaustable Ca2+ stores. α1-Adrenoceptors may also act through non-G-protein linked second messenger systems. In many tissues, multiple subtypes of α-adrenoceptor are present, and this may be regarded as the norm rather than exception, although one receptor subtype is usually predominant.
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
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Ishida H, Saito SY, Ishikawa T. α1A-Adrenoceptors, but not α1B- or α1D-adrenoceptors, contribute to enhanced contractile response to phenylephrine in cooling conditions in the rat tail artery. Eur J Pharmacol 2018; 838:120-128. [DOI: 10.1016/j.ejphar.2018.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/24/2018] [Accepted: 09/04/2018] [Indexed: 11/26/2022]
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Regional Heterogeneity in the Regulation of Vasoconstriction in Arteries and Its Role in Vascular Mechanics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:105-128. [PMID: 30315542 DOI: 10.1007/978-3-319-96445-4_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vasoconstriction and vasodilation play important roles in the circulatory system and can be regulated through different pathways that depend on myriad biomolecules. These different pathways reflect the various functions of smooth muscle cell (SMC) contractility within the different regions of the arterial tree and how they contribute to both the mechanics and the mechanobiology. Here, we review the primary regulatory pathways involved in SMC contractility and highlight their regional differences in elastic, muscular, and resistance arteries. In this way, one can begin to assess how these properties affect important biomechanical and mechanobiological functions in the circulatory system in health and disease.
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A lack of α1A-adrenergic receptor-mediated antidepressant-like effects of S-(+)-niguldipine and B8805-033 in the forced swim test. Behav Pharmacol 2016; 27:397-401. [DOI: 10.1097/fbp.0000000000000204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gallardo-Ortíz IA, Rodríguez-Hernández SN, López-Guerrero JJ, Del Valle-Mondragón L, López-Sánchez P, Touyz RM, Villalobos-Molina R. Role of α1D-adrenoceptors in vascular wall hypertrophy during angiotensin II-induced hypertension. ACTA ACUST UNITED AC 2016; 35:17-31. [DOI: 10.1111/aap.12035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/17/2015] [Accepted: 11/20/2015] [Indexed: 02/01/2023]
Affiliation(s)
- I. A. Gallardo-Ortíz
- Unidad de Biomedicina; Facultad de Estudios Superiores Iztacala; Universidad Nacional Autónoma de México; Tlalnepantla Mexico
| | - S. N. Rodríguez-Hernández
- Unidad de Biomedicina; Facultad de Estudios Superiores Iztacala; Universidad Nacional Autónoma de México; Tlalnepantla Mexico
| | - J. J. López-Guerrero
- Unidad de Biomedicina; Facultad de Estudios Superiores Iztacala; Universidad Nacional Autónoma de México; Tlalnepantla Mexico
| | - L. Del Valle-Mondragón
- Departamento de Farmacología; Instituto Nacional de Cardiología “Ignacio Chávez”; Mexico City Mexico
| | - P. López-Sánchez
- Seccion de Estudios de Posgrado e Investigacion; Escuela Superior de Medicina IPN; Mexico City Mexico
| | - R. M. Touyz
- Institute of Cardiovascular and Medical Sciences; BHF Glasgow Cardiovascular Research Centre; University of Glasgow; Glasgow UK
| | - R. Villalobos-Molina
- Unidad de Biomedicina; Facultad de Estudios Superiores Iztacala; Universidad Nacional Autónoma de México; Tlalnepantla Mexico
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Ge D, Yan X, Guo Y, Chen X, Guan R, Chen Y, Qiu D, Wang J. Activation of α1-adrenoceptors facilitates excitatory inputs to medullary airway vagal preganglionic neurons. J Appl Physiol (1985) 2015. [PMID: 26205539 DOI: 10.1152/japplphysiol.00045.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In mammals, the neural control of airway smooth muscle is dominated by a subset of airway vagal preganglionic neurons in the ventrolateral medulla. These neurons are physiologically modulated by adrenergic/noradrenergic projections, and weakened α₂-adrenergic inhibition of them is indicated to participate in the pathogenesis and exacerbation of asthma. This study tests whether these neurons are modulated by α₁-adrenoceptors, and if so, how. In anesthetized adult rats, microinjection of the α₁A-adrenoceptor agonist A61603 (1 pmol) unilaterally into the medullary region containing these neurons caused a significant increase in airway resistance, which was prevented by intraperitoneal atropine (0.5 mg/kg). In rhythmically firing medullary slices of newborn rats, A61603 (10 nM) caused depolarization in both the inspiratory-activated and inspiratory-inhibited airway vagal preganglionic neurons that were retrogradely labeled, and a significant increase in the spontaneous firing rate. Under voltage clamp, A61603 significantly enhanced the spontaneous excitatory inputs to both types of neurons and caused a tonic inward current in the inspiratory-activated neurons along with significantly increased peak amplitude of the inspiratory inward currents. The responses in vitro were prevented by α₁A-adrenoceptor antagonist RS100329 (1 μM), which alone significantly inhibited the spontaneous excitatory inputs to both types of the neurons. After pretreatment with tetrodotoxin (1 μM), A61603 (10 or 100 nM) had no effect on either type of neuron. We conclude that in rats, activation of α₁-adrenoceptors in the medullary region containing airway vagal preganglionic neurons increases airway vagal tone, and that this effect is primarily mediated by facilitation of the excitatory inputs to the preganglionic neurons.
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Affiliation(s)
- Dengyun Ge
- Department of Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xianxia Yan
- Department of Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Yuhong Guo
- Department of Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xingxin Chen
- Department of Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Ruijuan Guan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China; and
| | - Yonghua Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China; and
| | - Dongying Qiu
- Department of Gerontology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jijiang Wang
- Department of Neurobiology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China; and
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Owaki H, Sadahiro S, Takaki M. Characterizations of the α1-adrenoceptor subtypes mediating contractions of the human internal anal sphincter. J Pharmacol Sci 2015; 127:424-9. [DOI: 10.1016/j.jphs.2015.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/17/2015] [Accepted: 02/26/2015] [Indexed: 02/03/2023] Open
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Ribeiro CAS, Pupo AS. Involvement of α1B-adrenoceptors in the anti-immobility effect of imipramine in the tail suspension test. Eur J Pharmacol 2015; 750:39-42. [DOI: 10.1016/j.ejphar.2015.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 01/14/2015] [Accepted: 01/15/2015] [Indexed: 10/24/2022]
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16
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Copik AJ, Baldys A, Nguyen K, Sahdeo S, Ho H, Kosaka A, Dietrich PJ, Fitch B, Raymond JR, Ford APDW, Button D, Milla ME. Isoproterenol acts as a biased agonist of the alpha-1A-adrenoceptor that selectively activates the MAPK/ERK pathway. PLoS One 2015; 10:e0115701. [PMID: 25606852 PMCID: PMC4301629 DOI: 10.1371/journal.pone.0115701] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 11/26/2014] [Indexed: 11/24/2022] Open
Abstract
The α1A-AR is thought to couple predominantly to the Gαq/PLC pathway and lead to phosphoinositide hydrolysis and calcium mobilization, although certain agonists acting at this receptor have been reported to trigger activation of arachidonic acid formation and MAPK pathways. For several G protein-coupled receptors (GPCRs) agonists can manifest a bias for activation of particular effector signaling output, i.e. not all agonists of a given GPCR generate responses through utilization of the same signaling cascade(s). Previous work with Gαq coupling-defective variants of α1A-AR, as well as a combination of Ca2+ channel blockers, uncovered cross-talk between α1A-AR and β2-AR that leads to potentiation of a Gαq-independent signaling cascade in response to α1A-AR activation. We hypothesized that molecules exist that act as biased agonists to selectively activate this pathway. In this report, isoproterenol (Iso), typically viewed as β-AR-selective agonist, was examined with respect to activation of α1A-AR. α1A-AR selective antagonists were used to specifically block Iso evoked signaling in different cellular backgrounds and confirm its action at α1A-AR. Iso induced signaling at α1A-AR was further interrogated by probing steps along the Gαq /PLC, Gαs and MAPK/ERK pathways. In HEK-293/EBNA cells transiently transduced with α1A-AR, and CHO_α1A-AR stable cells, Iso evoked low potency ERK activity as well as Ca2+ mobilization that could be blocked by α1A-AR selective antagonists. The kinetics of Iso induced Ca2+ transients differed from typical Gαq- mediated Ca2+ mobilization, lacking both the fast IP3R mediated response and the sustained phase of Ca2+ re-entry. Moreover, no inositol phosphate (IP) accumulation could be detected in either cell line after stimulation with Iso, but activation was accompanied by receptor internalization. Data are presented that indicate that Iso represents a novel type of α1A-AR partial agonist with signaling bias toward MAPK/ERK signaling cascade that is likely independent of coupling to Gαq.
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Affiliation(s)
- Alicja. J. Copik
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Aleksander Baldys
- Nephrology Division, Department of Medicine, Medical University of South Carolina, and Medical and Research Services, Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425, United States of America
| | - Khanh Nguyen
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Sunil Sahdeo
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Hoangdung Ho
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Alan Kosaka
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Paul J. Dietrich
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Bill Fitch
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - John R. Raymond
- Nephrology Division, Department of Medicine, Medical University of South Carolina, and Medical and Research Services, Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425, United States of America
| | - Anthony P. D. W. Ford
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Donald Button
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Marcos E. Milla
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
- * E-mail:
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Effects of desipramine on prazosin potency at α1A- and α1D-adrenoceptors in rat vas deferens: Implications for the α1L-adrenoceptor subclassification. Eur J Pharmacol 2014; 744:183-9. [DOI: 10.1016/j.ejphar.2014.10.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/26/2014] [Accepted: 10/05/2014] [Indexed: 11/23/2022]
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Docherty JR. Prazosin has low potency at α1A-adrenoceptors and high potency at α1D-adrenoceptors in rat vas deferens. ACTA ACUST UNITED AC 2013; 33:49-57. [DOI: 10.1111/aap.12015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 08/19/2013] [Indexed: 11/27/2022]
Affiliation(s)
- J. R. Docherty
- Department of Physiology; Royal College of Surgeons in Ireland; 123 St. Stephen's Green Dublin Ireland
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20
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Zacharia J, Mauban JRH, Raina H, Fisher SA, Wier WG. High vascular tone of mouse femoral arteries in vivo is determined by sympathetic nerve activity via α1A- and α1D-adrenoceptor subtypes. PLoS One 2013; 8:e65969. [PMID: 23776582 PMCID: PMC3680395 DOI: 10.1371/journal.pone.0065969] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 05/02/2013] [Indexed: 02/04/2023] Open
Abstract
Background and purpose Determining the role of vascular receptors in vivo is difficult and not readily accomplished by systemic application of antagonists or genetic manipulations. Here we used intravital microscopy to measure the contributions of sympathetic receptors, particularly α1-adrenoceptor subtypes, to contractile activation of femoral artery in vivo. Experimental approach Diameter and intracellular calcium ([Ca2+]i) in femoral arteries were determined by intravital fluorescence microscopy in mice expressing a Myosin Light Chain Kinase (MLCK) based calcium-calmodulin biosensor. Pharmacological agents were applied locally to the femoral artery to determine the contributions of vascular receptors to tonic contraction and [Ca2+]i,. Key results In the anesthetized animal, femoral arteries were constricted to a diameter equal to 54% of their passive diameter (i.e. tone = 46%). Of this total basal tone, 16% was blocked by RS79948 (0.1 µM) and thus attributable to α2-adrenoceptors. A further 46% was blocked by prazosin (0.1 µM) and thus attributable to α1-adrenoceptors. Blockade of P2X and NPY1 receptors with suramin (0.5 mM) and BIBP3226 (1.0 µM) respectively, reduced tone by a further 22%, leaving 16% of basal tone unaffected at these concentrations of antagonists. Application of RS100329 (α1A-selective antagonist) and BMY7378 (α1D-selective) decreased tone by 29% and 26%, respectively, and reduced [Ca2+]i. Chloroethylclonidine (1 µM preferential for α1B-) had no effect. Abolition of sympathetic nerve activity (hexamethonium, i.p.) reduced basal tone by 90%. Conclusion and Implications Tone of mouse femoral arteries in vivo is almost entirely sympathetic in origin. Activation of α1A- and α1D-adrenoceptors elevates [Ca2+]i and accounts for at least 55% of the tone.
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Affiliation(s)
- Joseph Zacharia
- University of Maryland, School of Medicine, Baltimore, Maryland, United States of America.
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21
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Kitazawa T. Contractile signaling pathways in mouse prostate smooth muscle. Prostate 2013; 73:996-1006. [PMID: 23389830 DOI: 10.1002/pros.22647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 01/08/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND Prostate smooth muscle plays an important role in the physiological ejection of prostatic fluid and also in the pathogenesis of benign prostate hyperplasia. Although mouse is the best genetically engineered animal model to identify potential molecular targets for human diseases, only fragmentary information is available for basic mechanism of mouse prostate contraction. METHODS Small smooth muscle tubular rings were excised from four mouse prostate lobes to measure their isometric contractions. High K(+) , noradrenaline (NA), or acetylcholine (ACh) was applied with and without various antagonists and/or inhibitors to examine the contractile signaling pathways. RESULTS Maximum amplitude of agonist-induced contractions varied greatly with different lobes but not with different locations or orientations within each lobe. Both NA and ACh produced large contractions in ventral and dorsal rings, whereas only small contractions were elicited in lateral and anterior rings. Combination of alpha-1 and muscarinic antagonists suppressed K(+) depolarization-induced contraction potently in ventral rings, but slightly in anterior rings. Blocking of either Ca(2+) -release or Ca(2+) -influx reduced agonist-induced contraction of ventral rings, however, a considerable amount of contractility remained even with both blockers. Inhibitors of ROCK and PKC partially inhibited NA-induced contractions, whereas a combination of Ca(2+) -blockers and Ca(2+) -sensitization inhibitors strongly suppressed the contraction. CONCLUSIONS The ejection of prostatic fluid is differentially regulated in each prostate lobe. In ventral prostate smooth muscle, Ca(2+) -release, Ca(2+) -influx, and ROCK- and PKC-mediated Ca(2+) -sensitizations are all involved in NA-induced contractions. This finding is a useful step toward the understanding of the phenotypic changes in the smooth muscle of BPH prostate.
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Affiliation(s)
- Toshio Kitazawa
- Boston Biomedical Research Institute, Watertown, Massachusetts 02472, USA.
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22
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Moro C, Tajouri L, Chess-Williams R. Adrenoceptor Function and Expression in Bladder Urothelium and Lamina Propria. Urology 2013. [DOI: 10.1016/j.urology.2012.09.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Kitazawa T, Kitazawa K. Size-dependent heterogeneity of contractile Ca2+ sensitization in rat arterial smooth muscle. J Physiol 2012; 590:5401-23. [PMID: 22930267 DOI: 10.1113/jphysiol.2012.241315] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Each segment along arterial vessels adapts to different circumstances, including blood pressure and sympathetic innervation. PKC and Rho-associated kinase (ROCK) Ca(2+)-sensitizing pathways leading to myosin phosphatase inhibition are critically involved in α(1)-adrenoceptor-mediated vascular smooth muscle contraction in distinctive time-dependent manners. We tested whether the amplitude and time course of each pathway varies dynamically between arterial segments. Using pharmacological approaches, we determined the time-dependent roles of Ca(2+) release, Ca(2+) influx, PKC and ROCK in α(1)-agonist-induced contraction and phosphorylation of key proteins in denuded rat small mesenteric artery, midsized caudal artery and thoracic aorta. SR Ca(2+) release and voltage-dependent Ca(2+) influx were essential for the initial rising and late sustained phases, respectively, of phenylephrine-induced contraction, regardless of arterial size. In small mesenteric arteries, α(1A)-subtype-specific antagonists and inhibitors of PKC, but not ROCK, markedly reduced the initial and late phases of contraction in a non-additive manner and suppressed phosphorylation of myosin light chain (MLC) and CPI-17, but not myosin targeting subunit of myosin light chain phosphatase (MYPT1). In aorta, an α(1D)-specific antagonist reduced both the initial and late phases of contraction with a significant decrease in MLC but not CPI-17 or MYPT1 phosphorylation. ROCK inhibitors, but not PKC inhibitors, suppressed the sustained phase of contraction with a decrease in MLC and MYPT1 phosphorylation in the aorta. The effect of ROCK inhibitors was additive with the α(1D)-antagonist. The results for midsized arteries were intermediate. Thus, the PKC-CPI-17 Ca(2+)-sensitizing pathway, which is dependent on PKC subtype and a Ca(2+)-handling mechanism, and is downstream of α(1A) receptors, plays a major role in α(1)-agonist-induced contraction of small resistance arteries in the splanchnic vascular beds. The effect of PKC and ROCK increases and decreases, respectively, with decreasing arterial size.
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Affiliation(s)
- Toshio Kitazawa
- Boston Biomedical Research Institute, 64 Grove Street, Watertown, MA 02472, USA.
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24
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Näreoja K, Kukkonen JP, Rondinelli S, Toivola DM, Meriluoto J, Näsman J. Adrenoceptor activity of muscarinic toxins identified from mamba venoms. Br J Pharmacol 2012; 164:538-50. [PMID: 21557730 DOI: 10.1111/j.1476-5381.2011.01468.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Muscarinic toxins (MTs) are snake venom peptides named for their ability to interfere with ligand binding to muscarinic acetylcholine receptors (mAChRs). Recent data infer that these toxins may have other G-protein-coupled receptor targets than the mAChRs. The purpose of this study was to systematically investigate the interactions of MTs with the adrenoceptor family members. EXPERIMENTAL APPROACH We studied the interaction of four common MTs, MT1, MT3, MT7 and MTα, with cloned receptors expressed in insect cells by radioligand binding. Toxins showing modest to high-affinity interactions with adrenoceptors were additionally tested for effects on functional receptor responses by way of inhibition of agonist-induced Ca²⁺ increases. KEY RESULTS All MTs behaved non-competitively in radioligand displacement binding. MT1 displayed higher binding affinity for the human α(2B)-adrenoceptor (IC₅₀ = 2.3 nM) as compared with muscarinic receptors (IC₅₀ ≥ 100 nM). MT3 appeared to have a broad spectrum of targets showing high-affinity binding (IC₅₀ = 1-10 nM) to M₄ mAChR, α(1A)-, α(1D)- and α(2A)-adrenoceptors and lower affinity binding (IC₅₀ ≥ 25 nM) to α(1B)- and α(2C)-adrenoceptors and M₁ mAChR. MT7 did not detectably bind to other receptors than M₁, and MTα was specific for the α(2B)-adrenoceptor. None of the toxins showed effects on β₁- or β₂-adrenoceptors. CONCLUSIONS AND IMPLICATIONS Some of the MTs previously found to interact predominantly with mAChRs were shown to bind with high affinity to selected adrenoceptor subtypes. This renders these peptide toxins useful for engineering selective ligands to target various adrenoceptors.
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Affiliation(s)
- K Näreoja
- Department of Biosciences, Biochemistry, Åbo Akademi University, Turku, Finland
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25
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Yohimbine antagonises α1A- and α1D-adrenoceptor mediated components in addition to the α2A-adrenoceptor component to pressor responses in the pithed rat. Eur J Pharmacol 2012; 679:90-4. [DOI: 10.1016/j.ejphar.2012.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 11/20/2011] [Accepted: 01/10/2012] [Indexed: 11/20/2022]
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Nishimune A, Yoshiki H, Uwada J, Anisuzzaman ASM, Umada H, Muramatsu I. Phenotype pharmacology of lower urinary tract α(1)-adrenoceptors. Br J Pharmacol 2012; 165:1226-34. [PMID: 21745191 PMCID: PMC3372711 DOI: 10.1111/j.1476-5381.2011.01591.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 06/20/2011] [Accepted: 06/28/2011] [Indexed: 12/01/2022] Open
Abstract
α(1)-Adrenoceptors are involved in numerous physiological functions, including micturition. However, the pharmacological profile of the α(1)-adrenoceptor subtypes remains controversial. Here, we review the literature regarding α(1)-adrenoceptors in the lower urinary tract from the standpoint of α(1L) phenotype pharmacology. Among three α(1)-adrenoceptor subtypes (α(1A), α(1B) and α(1D)), α(1a)-adrenoceptor mRNA is the most abundantly transcribed in the prostate, urethra and bladder neck of many species, including humans. In prostate homogenates or membrane preparations, α(1A)-adrenoceptors with high affinity for prazosin have been detected as radioligand binding sites. Functional α(1)-adrenoceptors in the prostate, urethra and bladder neck have low affinity for prazosin, suggesting the presence of an atypical α(1)-adrenoceptor phenotype (designated as α(1L)). The α(1L)-adrenoceptor occurs as a distinct binding entity from the α(1A)-adrenoceptor in intact segments of variety of tissues including prostate. Both the α(1L)- and α(1A)-adrenoceptors are specifically absent from Adra1A (α(1a)) gene-knockout mice. Transfection of α(1a)-adrenoceptor cDNA predominantly expresses α(1A)-phenotype in several cultured cell lines. However, in CHO cells, such transfection expresses α(1L)- and α(1A)-phenotypes. Under intact cell conditions, the α(1L)-phenotype is predominant when co-expressed with the receptor interacting protein, CRELD1α. In summary, recent pharmacological studies reveal that two distinct α(1)-adrenoceptor phenotypes (α(1A) and α(1L)) originate from a single Adra1A (α(1a)-adrenoceptor) gene, but adrenergic contractions in the lower urinary tract are predominantly mediated via the α(1L)-adrenoceptor. From the standpoint of phenotype pharmacology, it is likely that phenotype-based subtypes such as the α(1L)-adrenoceptor will become new targets for drug development and pharmacotherapy.
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Affiliation(s)
- A Nishimune
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, Organization for Life Science Advancement Programs, and Child Development Research Center, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
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Martínez-Salas SG, Campos-Peralta JM, Pardo JP, Hernández-Muñoz R, Ibarra M, Tanoue A, Tsujimoto G, Villalobos-Molina R. α(1D)-Adrenoceptor regulates the vasopressor action of α(1A)-adrenoceptor in mesenteric vascular bed of α(1D)-adrenoceptor knockout mice. ACTA ACUST UNITED AC 2012; 31:64-71. [PMID: 21951586 DOI: 10.1111/j.1474-8673.2011.00468.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1 The pressor action of the α(1A)-adrenoceptor (α(1A)-AR) agonist A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) and the α(1)-ARs agonist phenylephrine and their blockade by selective α(1)-ARs antagonists in the isolated mesenteric vascular bed of wild-type (WT) mice and α(1D)-AR knockout (KO α(1D)-AR) mice were evaluated. 2 The apparent potency of A61603 to increase the perfusion pressure in the mesenteric vascular bed of WT and KO α(1D)-AR mice is 86 and 138 times the affinity of phenylephrine, respectively. 3 A61603 also enhanced the perfusion pressure by ≈1.7 fold in the mesenteric vascular bed of WT mice compared with KO α(1D)-AR mice. 4 Because of its high affinity, low concentrations of the α(1A)-AR selective antagonist RS100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy) phenyl]-1-piperazinyl] propyl]-2,4-(1H)-pyrimidinedione) shifted the agonist concentration-response curves to the right in the mesenteric vascular bed of WT and KO α(1D)-AR mice. 5 The α(1D)-AR selective antagonist BMY7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione) did not modify the A61603 or the phenylephrine-induced pressor effect. 6 The α(1B/D)-ARs alkylating antagonist chloroethylclonidine (CEC) shifted the agonist concentration-response curves to the right and decreased the maximum phenylephrine-induced vascular contraction in KO α(1D)-AR mice when compared to WT mice; however, CEC only slightly modified the contraction induced by A61603. 7 The results indicate that the isolated mesenteric vascular bed of WT and KO α(1D)-AR mice expresses α(1A)-AR, that the pressor action of α(1A)-AR is up-regulated for α(1D)-AR in WT mice and suggest an important role of α(1B)-AR in the vascular pressure evoked by phenylephrine in KO α(1D)-AR mice.
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Affiliation(s)
- S G Martínez-Salas
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México (UNAM) Escuela Militar de Graduados de Sanidad, Universidad del Ejército y Fuerza Aérea, Mexico
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López-Islas I, López-Sánchez P, Ibarra M, Gallardo-Ortiz IA, Terrón JA. Effect of inter-renal aortic coarctation-induced hypertension on function and expression of vascular α(1A)- and α(1D)-adrenoceptors. Can J Physiol Pharmacol 2011; 90:1-12. [PMID: 22149309 DOI: 10.1139/y11-099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the effect of inter-renal aortic coarctation on the function and expression of vascular α(1A)- and α(1D)-adrenoceptors and plasma angiotensin II (ATII) in rats. Male Wistar rats, either sham operated (SO), or with aortic coarctation for 7 (AC7) and 14 days (AC14) were used for agonist-induced pressor responses in vehicle (physiological saline)- and antagonist-treated anesthetized animals, immunoblot analysis (α(1A)- and α(1D)-adrenoceptor in aorta and caudal arteries), and immunoassay (plasma ATII). The α(1D)-adrenoceptor antagonist, BMY-7378 (BMY) blocked noradrenaline-induced responses in the order SO > AC7 ≫ AC14; in contrast, the α(1A)-adrenoceptor antagonist RS-100329 (RS), produced a marginal shift to the right of the dose-response curve to noradrenaline, along with a strong decrease of the maximum pressor effect in the order SO > AC7 = AC14. The potency of the α(1A)-adrenoceptor agonist A-61603 increased in rats with AC14, and responses were inhibited by RS in the order AC14 > AC7 > SO. In aorta, α(1D)-adrenoceptor protein increased in AC7 and decreased in AC14; α(1A)-adrenoreceptor protein increased in the caudal artery of AC7 and returned to control values in AC14. Plasma ATII increased in AC7 and AC14, compared with SO rats. These results suggest an early and direct relationship between ATII and α(1D)-adrenoreceptors in the development of hypertension in this experimental model.
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Affiliation(s)
- Inés López-Islas
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, Apartado postal 14-740, Zacatenco 07000, México DF, Mexico
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29
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Mori A, Hanada M, Sakamoto K, Nakahara T, Ishii K. Noradrenaline contracts rat retinal arterioles via stimulation of α(1A)- and α(1D)-adrenoceptors. Eur J Pharmacol 2011; 673:65-9. [PMID: 22040923 DOI: 10.1016/j.ejphar.2011.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 09/29/2011] [Accepted: 10/08/2011] [Indexed: 10/16/2022]
Abstract
The aim of this study was to characterize the α₁-adrenoceptor subtype(s) involved in the noradrenaline-induced contraction of retinal arterioles in rats. In vivo ocular fundus images were captured with a digital camera equipped with a special objective lens. By measuring changes in diameter of retinal arterioles in the fundus images, retinal vascular response was assessed. The systemic blood pressure and heart rate in the animals were also continuously recorded. Following blockade of β₁/β₂-adrenoceptors with propranolol, noradrenaline (0.03-3 μg/kg/min, i.v.) decreased the diameter of retinal arterioles and increased the mean blood pressure in a dose-dependent manner. The highest dose (3 μg/kg/min, i.v.) of noradrenaline caused a small increase in heart rate. The α(1A)-adrenoceptor antagonist RS100329 (0.1 mg/kg, i.v.) and the α(1D)-adrenoceptor antagonist BMY 7378 (1 mg/kg, i.v.) significantly prevented noradrenaline-induced contraction of retinal arterioles and pressor responses whereas the α(1B)-adrenoceptor antagonist L-765314 (1 mg/kg, i.v.) did not. The α(1A)-adrenoceptor agonist, A 61603 (0.03-0.3 μg/kg/min, i.v.), also caused contractile responses of retinal arterioles and pressor responses. These responses were almost completely prevented by RS100329 (0.1 mg/kg, i.v.), but not by BMY 7378 (1 mg/kg, i.v.). These results suggest that the contractile effects of noradrenaline on retinal arterioles and peripheral resistance vessels are, at least in part, mediated by stimulation of α(1A)- and α(1D)-adrenoceptors. Furthermore, it is likely that the α₁-adrenoceptor subtype(s) involved in rat vascular responses are similar in both retinal and peripheral circulation.
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Affiliation(s)
- Asami Mori
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
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[From lab to clinical activity: adrenergic receptors and human uro-genital tissues]. Urologia 2011; 78:153-60. [PMID: 21786233 DOI: 10.5301/ru.2011.8540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2011] [Indexed: 11/20/2022]
Abstract
BACKGROUND Nowadays translational medicine is acquiring a more and more important role in connecting laboratory experimental results on human tissues to clinical findings and drug employment. We want to underline the importance of in vitro studies, which have been extensively performed on animal organs, but few studies have been performed on human tissues. Nevertheless, a more accurate result when compared to the in vivo use of drugs can be given only by testing the very same human tissues in a lab. We related clinical treatments of different pathologies with the results obtained in laboratory studying in vitro fragments of human organs extracted during surgery exposed to different mediators and drugs. METHODS Fragments of urethers, bladder (detrusorial muscle and bladder neck muscle fibers), corpora cavernosa, and vas deferens were extracted during demolitive surgery trying not to traumatize the tissue, in order to keep it alive and not to ruin its contractile fibers. The fragments were then put into polisaline solution and, once in the laboratory, fixed on suitable isolated organ support, fixed at one side of the thermostatic pool and on the other side connected to a digital monitoring system. The contractility was then studied after adding different mediators. RESULTS The urethers have shown a stronger response to NE and PGF2a, with a different contractility in their distal part due to a major concentration of alpha-receptors; the bladder neck has also shown a strong contractile response to NE and PGF2a, and is inhibited by alpha-blockers; the bladder detrusor, instead, responds to ACH (acetylcholine) and PGF2a; the vas deferens shows a different type of contractility in the prostatic part compared to the epididimary part when stimulated with noradrenaline and PGF2a; the corpora cavernosa respond to NE and PGF2a. CONCLUSIONS The results obtained after stimulating the fragments can explain and prove the receptorial activity of inner mediators and of commonly used drugs which have, for years, been used empirically; the simplicity and repetitivity of the method can be considered and used not only to research the physiological functioning of different organs, but also the functioning of new drugs before testing them on patients, being more reliable and accurate than tests on animal tissues. This experimental work has shown that using human tissues in testing specific mediators is the most reliable laboratory method.
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Vasopressor nerve responses in the pithed rat, previously identified as α2-adrenoceptor mediated, may be α1D-adrenoceptor mediated. Eur J Pharmacol 2011; 658:182-6. [PMID: 21376031 DOI: 10.1016/j.ejphar.2011.02.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 01/20/2011] [Accepted: 02/05/2011] [Indexed: 11/21/2022]
Abstract
Responses to pressor nerve stimulation in the pithed rat have been variously described as mediated, at least in part, by α(2)-adrenoceptors and by α(1A) and α(1D)-adrenoceptors. We have examined the subtypes of α-adrenoceptor involved in rises in diastolic blood pressure in the pithed rat preparation produced by vasopressor nerve stimulation with 10 pulses at 1 Hz or 20 pulses at 5 Hz. Vasopressor nerve responses to 1 Hz stimulation were markedly inhibited by the α(1A)-adrenoceptor antagonist RS 100329 (0.1mg/kg) and by the α(1D-)adrenoceptor antagonist BMY 7378 (0.1mg/kg). The α(2)-adrenoceptor antagonist yohimbine (0.1mg/kg) significantly increased pressor nerve responses to 1 Hz stimulation, but yohimbine (1mg/kg) significantly reduced pressor nerve responses. However, following BMY 7378 (0.1mg/kg), yohimbine (1mg/kg) did not produce any further inhibition of pressor nerve responses to 1 Hz stimulation. The α(2A)-adrenoceptor antagonist BRL 44408 (1mg/kg) did not reduce pressor responses to 1 Hz stimulation. BMY 7378 produced much less inhibition of pressor nerve responses to 5 Hz stimulation, whereas RS 100329 produced similar inhibition of 1 Hz and 5 Hz responses. Yohimbine (0.1 and 1mg/kg) did not significantly affect pressor nerve responses to 5 Hz stimulation. In conclusion, pressor nerve responses in the pithed rat involve both α(1A) and α(1D)-adrenoceptor, but there is no clear evidence for the involvement of α(2)-adrenoceptors.
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Rayment SJ, Eames T, Simpson JAD, Dashwood MR, Henry Y, Gruss H, Acheson AG, Scholefield JH, Wilson VG. Investigation of the distribution and function of alpha-adrenoceptors in the sheep isolated internal anal sphincter. Br J Pharmacol 2010; 160:1727-40. [PMID: 20649575 DOI: 10.1111/j.1476-5381.2010.00842.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE We have investigated the distribution of alpha-adrenoceptors in sheep internal anal sphincter (IAS), as a model for the human tissue, and evaluated various imidazoline derivatives for potential treatment of faecal incontinence. EXPERIMENTAL APPROACH Saturation and competition binding with (3)H-prazosin and (3)H-RX821002 were used to confirm the presence and density of alpha-adrenoceptors in sheep IAS, and the affinity of imidazoline compounds at these receptors. A combination of in vitro receptor autoradiography and immunohistochemistry was used to investigate the regional distribution of binding sites. Contractile activity of imidazoline-based compounds on sheep IAS was assessed by isometric tension recording. KEY RESULTS Saturation binding confirmed the presence of both alpha(1)- and alpha(2)-adrenoceptors, and subsequent characterization with sub-type-selective agents, identified them as alpha(1A)- and alpha(2D)-adrenoceptor sub-types. Autoradiographic studies with (3)H-prazosin showed a positive association of alpha(1)-adrenoceptors with immunohistochemically identified smooth muscle fibres. Anti-alpha(1)-adrenoceptor immunohistochemistry revealed similar distributions of the receptor in sheep and human IAS. The imidazoline compounds caused concentration-dependent contractions of the anal sphincter, but the maximum responses were less than those elicited by l-erythro-methoxamine, a standard non-imidazoline alpha(1)-adrenoceptor agonist. Prazosin (selective alpha(1)-adrenoceptor antagonist) significantly reduced the magnitude of contraction to l-erythro-methoxamine at the highest concentration used. Both prazosin and RX811059 (a selective alpha(2)-adrenoceptor antagonist) reduced the potency (pEC(50)) of clonidine. CONCLUSIONS AND IMPLICATIONS This study shows that both alpha(1)- and alpha(2)-adrenoceptors are expressed in the sheep IAS, and contribute (perhaps synergistically) to contractions elicited by various imidazoline derivatives. These agents may prove useful in the treatment of faecal incontinence.
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Affiliation(s)
- S J Rayment
- Centre for Integrated Systems Biology and Medicine, Department of Surgery, The University of Nottingham Medical School, Queen's Medical Centre, Clifton Boulevard, Nottingham, UK
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Zwier JM, Roux T, Cottet M, Durroux T, Douzon S, Bdioui S, Gregor N, Bourrier E, Oueslati N, Nicolas L, Tinel N, Boisseau C, Yverneau P, Charrier-Savournin F, Fink M, Trinquet E. A fluorescent ligand-binding alternative using Tag-lite® technology. ACTA ACUST UNITED AC 2010; 15:1248-59. [PMID: 20974902 DOI: 10.1177/1087057110384611] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
G-protein-coupled receptors (GPCRs) are crucial cell surface receptors that transmit signals from a wide range of extracellular ligands. Indeed, 40% to 50% of all marketed drugs are thought to modulate GPCR activity, making them the major class of targets in the drug discovery process. Binding assays are widely used to identify high-affinity, selective, and potent GPCR drugs. In this field, the use of radiolabeled ligands has remained so far the gold-standard method. Here the authors report a less hazardous alternative for high-throughput screening (HTS) applications by the setup of a nonradioactive fluorescence-based technology named Tag-lite(®). Selective binding of various fluorescent ligands, either peptidic or not, covering a large panel of GPCRs from different classes is illustrated, particularly for chemokine (CXCR4), opioid (δ, µ, and κ), and cholecystokinin (CCK1 and CCK2) receptors. Affinity constants of well-known pharmacological agents of numerous GPCRs are in line with values published in the literature. The authors clearly demonstrate that the Tag-lite binding assay format can be successfully and reproducibly applied by using different cellular materials such as transient or stable recombinant cells lines expressing SNAP-tagged GPCR. Such fluorescent-based binding assays can be performed with adherent cells or cells in suspension, in 96- or 384-well plates. Altogether, this new technology offers great advantages in terms of flexibility, rapidity, and user-friendliness; allows easy miniaturization; and makes it completely suitable for HTS applications.
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Methven L, Simpson PC, McGrath JC. Alpha1A/B-knockout mice explain the native alpha1D-adrenoceptor's role in vasoconstriction and show that its location is independent of the other alpha1-subtypes. Br J Pharmacol 2010; 158:1663-75. [PMID: 19888965 DOI: 10.1111/j.1476-5381.2009.00462.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE Theoretically, three alpha(1)-adrenoceptor subtypes can interact at the signalling level to alter vascular contraction or at the molecular level to alter each other's cellular location. The alpha(1A/B)-adrenoceptor knockout mouse (alpha(1A/B)-KO) was used to study the isolated alpha(1D)-adrenoceptor to consider these potential interactions in native tissue. EXPERIMENTAL APPROACH Pharmacological analysis of carotid and mesenteric arteries employed wire myography and fluorescent ligand binding (alpha(1)-adrenoceptor ligand BODIPY FL-prazosin, QAPB). KEY RESULTS alpha(1A/B)-KO carotid had clear alpha(1D)-adrenoceptor-induced contractions. In WT carotid alpha(1D)-adrenoceptor dominated but all three alpha(1)-subtypes participated. alpha(1A/B)-KO mesenteric had alpha(1D)-adrenoceptor responses with high sensitivity and small maximum, explaining how alpha(1D)-adrenoceptor could determine agonist sensitivity in WT. In both arteries alpha(1A/B)-KO fluorescence levels were reduced but pharmacologically more consistent with 'pure'alpha(1D)-adrenoceptors. alpha(1D)-Adrenoceptor binding in alpha(1A/B)-KO was observed on the cell surface and intracellularly and was present in a high proportion of smooth-muscle cells in both strains, regardless of artery type. CONCLUSIONS AND IMPLICATIONS 'Pure'alpha(1D)-adrenoceptor pharmacology in alpha(1A/B)-KO provides a quantitative standard. Functionally, the alpha(1D)- and alpha(1A)-adrenoceptors produce additive responses and do not significantly compensate for each other. alpha(1D)-Adrenoceptor contributes to sensitivity even in resistance arteries. In alpha(1A/B)-KO, the loss of alpha(1A)- and alpha(1B)-adrenoceptors is reflected by a general decrease in fluorescence, but similar binding distribution to WT indicates that the alpha(1D)-adrenoceptor location in native smooth-muscle cells is not influenced by other alpha(1)-adrenoceptors. Equivalent levels of receptors did not correspond to equivalent responses. In conclusion, alpha(1)-subtypes do not interact but provide independent alternative signals for vascular regulation.
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Affiliation(s)
- L Methven
- Integrative and Systems Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
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Docherty JR. Subtypes of functional alpha1-adrenoceptor. Cell Mol Life Sci 2010; 67:405-17. [PMID: 19862476 PMCID: PMC11115521 DOI: 10.1007/s00018-009-0174-4] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 09/11/2009] [Accepted: 10/05/2009] [Indexed: 11/29/2022]
Abstract
In this review, subtypes of functional alpha1-adrenoceptor are discussed. These are cell membrane receptors, belonging to the seven-transmembrane-spanning G-protein-linked family of receptors, which respond to the physiological agonist noradrenaline. alpha1-Adrenoceptors can be divided into alpha1A-, alpha1B- and alpha1D-adrenoceptors, all of which mediate contractile responses involving Gq/11 and inositol phosphate turnover. A fourth alpha1-adrenoceptor, the alpha1L-, represents a functional phenotype of the alpha1A-adrenoceptor. alpha1-Adrenoceptor subtype knock-out mice have refined our knowledge of the functions of alpha-adrenoceptor subtypes, particuarly as subtype-selective agonists and antagonists are not available for all subtypes. alpha1-Adrenoceptors function as stimulatory receptors involved particularly in smooth muscle contraction, especially contraction of vascular smooth muscle, both in local vasoconstriction and in the control of blood pressure and temperature, and contraction of the prostate and bladder neck. Central actions are now being elucidated.
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MESH Headings
- Animals
- Blood Pressure/physiology
- Body Temperature Regulation
- Drug Inverse Agonism
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Inositol Phosphates/metabolism
- Mice
- Mice, Knockout
- Muscle, Smooth/physiology
- Muscle, Smooth, Vascular/physiology
- Receptors, Adrenergic, alpha-1/classification
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-1/physiology
- Second Messenger Systems/physiology
- Vasoconstriction/physiology
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123, St. Stephen's Green, Dublin 2, Ireland.
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Methven L, McBride M, Wallace GA, McGrath JC. The alpha 1B/D-adrenoceptor knockout mouse permits isolation of the vascular alpha 1A-adrenoceptor and elucidates its relationship to the other subtypes. Br J Pharmacol 2009; 158:209-24. [PMID: 19572943 PMCID: PMC2795267 DOI: 10.1111/j.1476-5381.2009.00269.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 01/30/2009] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Mesenteric and carotid arteries from the alpha(1B/D)-adrenoceptor knockout (alpha(1B/D)-KO) were employed to isolate alpha(1A)-adrenoceptor pharmacology and location and to reveal these features in the wild-type (WT) mouse. EXPERIMENTAL APPROACH Functional pharmacology by wire myography and receptor localization by confocal microscopy, using the fluorescent alpha(1)-adrenoceptor ligand BODIPY FL-Prazosin (QAPB), on mesenteric (an 'alpha(1A)-adrenoceptor' tissue) and carotid (an 'alpha(1D)-adrenoceptor' tissue) arteries. KEY RESULTS Alpha(1B/D)-KO mesenteric arteries showed straightforward alpha(1A)-adrenoceptor agonist/antagonist pharmacology. WT had complex pharmacology with alpha(1A)- and alpha(1D)-adrenoceptor components. alpha(1B/D)-KO had a larger alpha(1A)-adrenoceptor response suggesting compensatory up-regulation: no increase in fluorescent ligand binding suggests up-regulation of signalling. alpha(1B/D)-KO carotid arteries had low efficacy alpha(1A)-adrenoceptor responses. WT had complex pharmacology consistent with co-activation of all three subtypes. Fluorescent binding had straightforward alpha(1A)-adrenoceptor characteristics in both arteries of alpha(1B/D)-KO. Fluorescent binding varied between cells in relative intracellular and surface distribution. Total fluorescence was reduced in the alpha(1B/D)-KO due to fewer smooth muscle cells showing fluorescent binding. WT binding was greater and sensitive to alpha(1A)- and alpha(1D)-adrenoceptor antagonists. CONCLUSIONS AND IMPLICATIONS The straightforward pharmacology and fluorescent binding in the alpha(1B/D)-KO was used to interpret the properties of the alpha(1A)-adrenoceptor in the WT. Reduced total fluorescence in alpha(1B/D)-KO arteries, despite a clear difference in the functionally dominant subtype, indicates that measurement of receptor protein is unlikely to correlate with function. Fewer cells bound QAPB in the alpha(1B/D)-KO suggesting different cellular phenotypes of alpha(1A)-adrenoceptor exist. The alpha(1B/D)-KO provides robust assays for the alpha(1A)-adrenoceptor and takes us closer to understanding multi-receptor subtype interactions.
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MESH Headings
- Adrenergic Agonists/pharmacology
- Adrenergic Antagonists/pharmacology
- Adrenergic alpha-1 Receptor Agonists
- Animals
- Carotid Arteries/drug effects
- Carotid Arteries/physiology
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Protein Subunits/classification
- Protein Subunits/physiology
- Receptors, Adrenergic, alpha-1/classification
- Receptors, Adrenergic, alpha-1/deficiency
- Receptors, Adrenergic, alpha-1/physiology
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Affiliation(s)
- L Methven
- Integrative and Systems Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
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Gómez-Zamudio JH, Villalobos-Molina R. Adventitia removal does not modify the α1D-adrenoceptors response in aorta during hypertension and ageing. ACTA ACUST UNITED AC 2009; 29:117-33. [DOI: 10.1111/j.1474-8673.2009.00432.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Copik AJ, Ma C, Kosaka A, Sahdeo S, Trane A, Ho H, Dietrich PS, Yu H, Ford APDW, Button D, Milla ME. Facilitatory interplay in alpha 1a and beta 2 adrenoceptor function reveals a non-Gq signaling mode: implications for diversification of intracellular signal transduction. Mol Pharmacol 2008; 75:713-28. [PMID: 19109357 DOI: 10.1124/mol.108.050765] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Agonist occupied alpha(1)-adrenoceptors (alpha(1)-ARs) engage several signaling pathways, including phosphatidylinositol hydrolysis, calcium mobilization, arachidonic acid release, mitogen-activated protein (MAP) kinase activation, and cAMP accumulation. The natural agonist norepinephrine (NE) activates with variable affinity and intrinsic efficacy all adrenoceptors, and in cells that coexpress alpha(1)- and beta-AR subtypes, such as cardiomyocytes, this leads to coactivation of multiple downstream pathways. This may result in pathway cross-talk with significant consequences to heart physiology and pathologic state. To dissect signaling components involved specifically in alpha(1A)- and beta(2)-AR signal interplay, we have developed a recombinant model system that mimics the levels of receptor expression observed in native cells. We followed intracellular Ca(2+) mobilization to monitor in real time the activation of both G(q) and G(s) pathways. We found that coactivation of alpha(1A)- and beta(2)-AR by the nonselective agonist NE or via a combination of the highly selective alpha(1A)-AR agonist A61603 and the beta-selective agonist isoproterenol led to increases in Ca(2+) influx from the extracellular compartment relative to stimulation with A61603 alone, with no effect on the associated transient release of Ca(2+) from intracellular stores. This effect became more evident upon examination of an alpha(1A)-AR variant exhibiting a partial defect in coupling to G(q), and we attribute it to potentiation of a non G(q)-pathway, uncovered by application of a combination of xestospongin C, an endoplasmic reticulum inositol 1,4,5-triphosphate receptor blocker, and 2-aminoethoxydiphenyl borate, a nonselective storeoperated Ca(2+) entry channel blocker. We also found that stimulation with A61603 of a second alpha(1A)-AR variant entirely unable to signal induced no Ca(2+) unless beta(2)-AR was concomitantly activated. These results may be accounted for by the presence of alpha(1A)/beta(2)-AR heterodimers or alternatively by specific adrenoceptor signal cross-talk resulting in distinct pharmacological behavior. Finally, our findings provide a new conceptual framework to rationalize outcomes from clinical studies targeting alpha- and beta-adrenoceptors.
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Affiliation(s)
- Alicja J Copik
- Inflammation Discovery, Roche Palo Alto, Palo Alto, California, USA
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Bexis S, Cleary L, McGrath JC, Tanoue A, Tsujimoto G, Docherty JR. Alpha(1D)-adrenoceptors mediate nerve and agonist-evoked contractions in mouse vas deferens: evidence obtained from knockout technology. ACTA ACUST UNITED AC 2008; 28:81-5. [PMID: 18598289 DOI: 10.1111/j.1474-8673.2008.00420.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1 It has been demonstrated that nerve-evoked contractions of the rat vas deferens involve alpha(1D)-adrenoceptors. Definitive evidence for a similar alpha(1D)-adrenoceptor-mediated response in mouse vas deferens has been more difficult to obtain. In this study, we have used alpha(1D)-adrenoceptor knockout (alpha(1D)-KO) mice to aid in the pharmacological characterization. 2 Mouse whole vas deferens was stimulated with a single pulse every 5 min. Once a stable response had been obtained, vehicle or antagonist was administered cumulatively at 5-min intervals and a response to stimulation obtained 5 min later. Cumulative concentration-response curves were also obtained for noradrenaline. 3 In vas deferens from alpha(1D)-KO mice, the contractile response to low concentrations of noradrenaline and the contractile response to a single stimulus were significantly reduced as compared to wild type (WT). 4 The alpha(1D)-adrenoceptor selective antagonist, BMY 7378, produced a concentration-dependent inhibition of single pulse-evoked contractions of vas deferens from WT and alpha(1D)-KO mice. BMY 7378 was significantly less potent in inhibiting stimulation-evoked contractions in vas deferens from alpha(1D)-KO mice. 5 It is concluded that alpha(1D)-adrenoceptors mediate a component of nerve- and agonist-evoked contractions of the vas deferens of WT mice.
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Affiliation(s)
- S Bexis
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
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Mills KA, Hausman N, Chess-Williams R. Characterization of the alpha1-adrenoceptor subtype mediating contractions of the pig internal anal sphincter. Br J Pharmacol 2008; 155:110-7. [PMID: 18516067 PMCID: PMC2527848 DOI: 10.1038/bjp.2008.217] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 01/07/2008] [Accepted: 04/15/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND AND PURPOSE The internal anal sphincter has been shown to contract in response to alpha1-adrenoceptor stimulation and therefore alpha1-adrenoceptor agonists may be useful in treating faecal incontinence. This study characterizes the alpha1-adrenoceptor subtype responsible for mediating contraction of the internal anal sphincter of the pig. EXPERIMENTAL APPROACH The potency of agonists and the affinities of several receptor subtype selective antagonists were determined on smooth muscle strips for the pig internal anal sphincter. Cumulative concentration-response curves were performed using phenylephrine and noradrenaline. KEY RESULTS The potency of the alpha1A-adrenoceptor selective agonist A61603 (pEC50=7.79+/-0.04) was 158-fold greater than that for noradrenaline (pEC50=5.59+/-0.02). Phenylephrine (pEC50=5.99+/-0.05) was 2.5-fold more potent than noradrenaline. The alpha1D-adrenoceptor selective antagonist BMY7378 caused rightward shifts of the concentration-response curves to phenylephrine and noradrenaline, yielding low affinity estimates of 6.59+/-0.15 and 6.33+/-0.13, respectively. Relatively high affinity estimates were obtained for the alpha1A-adrenoceptor selective antagonists, RS100329 (9.01+/-0.14 and 9.06+/-0.22 with phenylephrine and noradrenaline, respectively) and 5-methylurapidil (8.51+/-0.10 and 8.31+/-0.10, respectively). Prazosin antagonized responses of the sphincter to phenylephrine and noradrenaline, yielding mean affinity estimates of 8.58+/-0.10 and 8.15+/-0.08, respectively. The Schild slope for prazosin with phenylephrine was equal to unity (1.01+/-0.24), however the Schild slope using noradrenaline was significantly less than unity (0.50+/-0.11, P<0.05). CONCLUSION AND IMPLICATIONS The results suggest that contraction of circular smooth muscle from the pig internal anal sphincter is mediated via a population of adrenoceptors with the pharmacological characteristics of the alpha1A/L-adrenoceptor, most probably the alpha1L-adrenoceptor form of this receptor.
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Affiliation(s)
- K A Mills
- Faculty of Health Sciences and Medicine, Bond University Gold Coast, Australia
| | - N Hausman
- Department of Medicine, Manchester University Manchester, UK
| | - R Chess-Williams
- Faculty of Health Sciences and Medicine, Bond University Gold Coast, Australia
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Role of alpha1-adrenoceptor subtypes in the effects of methylenedioxy methamphetamine (MDMA) on body temperature in the mouse. Br J Pharmacol 2007; 153:591-7. [PMID: 18037913 DOI: 10.1038/sj.bjp.0707590] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE We have investigated the ability of alpha(1)-adrenoceptor antagonists to affect the hyperthermia produced by methylenedioxy methamphetamine (MDMA) in conscious mice. EXPERIMENTAL APPROACH Mice were implanted with temperature probes under ether anaesthesia and allowed 2 weeks recovery. MDMA (20 mg kg(-1)) was administered subcutaneously 30 min after vehicle or test antagonist or combination of antagonists and effects on body temperature monitored. KEY RESULTS Following vehicle, MDMA produced a hyperthermia, reaching a maximum increase of 1.8 degrees C at 140 min. Prazosin (0.1 mg kg(-1)) revealed an early significant hypothermia to MDMA of -1.94 degrees C. The alpha(1A)-adrenoceptor antagonist RS 100329 (0.1 mg kg(-1)), or the alpha(1D)-adrenoceptor antagonist BMY 7378 (0.5 mg kg(-1)) given alone, did not reveal a hypothermia to MDMA, but the combination of the two antagonists revealed a significant hypothermia to MDMA. The putative alpha(1B)-adrenoceptor antagonist cyclazosin (1 mg kg(-1)) also revealed a significant hypothermia to MDMA, but actions of cyclazosin at the other alpha(1)-adrenoceptor subtypes cannot be excluded. CONCLUSIONS AND IMPLICATIONS More than one subtype of alpha(1)-adrenoceptor is involved in a component of the hyperthermic response to MDMA in mouse, probably both alpha(1A)- and alpha(1D)-adrenoceptors, and removal of this alpha(1)-adrenoceptor-mediated component reveals an initial hypothermia.
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Martínez-Salas SG, Campos-Peralta JM, Pares-Hipolito J, Gallardo-Ortíz IA, Ibarra M, Villalobos-Molina R. Alpha1A-adrenoceptors predominate in the control of blood pressure in mouse mesenteric vascular bed. ACTA ACUST UNITED AC 2007; 27:137-42. [PMID: 17584443 DOI: 10.1111/j.1474-8673.2007.00403.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1 The pressor action of the alpha1A-adrenoceptor agonist, A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) or the alpha1-adrenoceptor agonist phenylephrine, and their blockade by selective alpha1-adrenoceptor antagonists in the mouse isolated mesenteric vascular bed were evaluated. 2 A61603 showed a approximately 235-fold higher potency in elevating perfusion pressure in mesenteric bed compared to phenylephrine. 3 The alpha1A-adrenoceptor selective antagonist RS 100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy) phenyl]-1-piperazinyl] propyl]-2,4-(1H)-pyrimidinedione), displaced with high affinity agonist concentration-response curves to the right in a concentration-dependent manner. 4 The alpha1D-adrenoceptor selective antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione), did not displace A61603 nor did it block the phenylephrine-induced pressor response. 5 The alpha1B/D-adrenoceptor alkylating antagonist chloroethylclonidine (CEC), caused a rightward shift of the phenylephrine concentration-response curve and reduced its maximum response; however, CEC only slightly modified A61603 evoked contraction. 6 The results indicate that the isolated mouse mesenteric vascular bed expresses alpha1A-adrenoceptors and suggest a very discrete role for 1B-adrenoceptors.
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Affiliation(s)
- S G Martínez-Salas
- Escuela Militar de Graduados de Sanidad, Universidad del Ejército y Fuerza Aérea, Secretaría de la Defensa Nacional, México, D.F
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43
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Nelson CP, Challiss RAJ. “Phenotypic” pharmacology: The influence of cellular environment on G protein-coupled receptor antagonist and inverse agonist pharmacology. Biochem Pharmacol 2007; 73:737-51. [PMID: 17046719 DOI: 10.1016/j.bcp.2006.09.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 08/31/2006] [Accepted: 09/06/2006] [Indexed: 11/25/2022]
Abstract
A central dogma of G protein-coupled receptor (GPCR) pharmacology has been the concept that unlike agonists, antagonist ligands display equivalent affinities for a given receptor, regardless of the cellular environment in which the affinity is assayed. Indeed, the widespread use of antagonist pharmacology in the classification of receptor expression profiles in vivo has relied upon this 'antagonist assumption'. However, emerging evidence suggests that the same gene-product may exhibit different antagonist pharmacological profiles, depending upon the cellular context in which it is expressed-so-called 'phenotypic' profiles. In this commentary, we review the evidence relating to some specific examples, focusing on adrenergic and muscarinic acetylcholine receptor systems, where GPCR antagonist/inverse agonist pharmacology has been demonstrated to be cell- or tissue-dependent, before going on to examine some of the ways in which the cellular environment might modulate receptor pharmacology. In the majority of cases, the cellular factors responsible for generating phenotypic profiles are unknown, but there is substantial evidence that factors, including post-transcriptional modifications, receptor oligomerization and constitutive receptor activity, can influence GPCR pharmacology and these concepts are discussed in relation to antagonist phenotypic profiles. A better molecular understanding of the impact of cell background on GPCR antagonist pharmacology is likely to provide previously unrealized opportunities to achieve greater specificity in new drug discovery candidates.
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Affiliation(s)
- Carl P Nelson
- Department of Cell Physiology & Pharmacology, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester LE1 9HN, UK.
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Michel MC, Vrydag W. Alpha1-, alpha2- and beta-adrenoceptors in the urinary bladder, urethra and prostate. Br J Pharmacol 2006; 147 Suppl 2:S88-119. [PMID: 16465187 PMCID: PMC1751487 DOI: 10.1038/sj.bjp.0706619] [Citation(s) in RCA: 338] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 We have systematically reviewed the presence, functional responses and regulation of alpha(1)-, alpha(2)- and beta-adrenoceptors in the bladder, urethra and prostate, with special emphasis on human tissues and receptor subtypes. 2 Alpha(1)-adrenoceptors are only poorly expressed and play a limited functional role in the detrusor. Alpha(1)-adrenoceptors, particularly their alpha(1A)-subtype, show a more pronounced expression and promote contraction of the bladder neck, urethra and prostate to enhance bladder outlet resistance, particularly in elderly men with enlarged prostates. Alpha(1)-adrenoceptor agonists are important in the treatment of symptoms of benign prostatic hyperplasia, but their beneficial effects may involve receptors within and outside the prostate. 3 Alpha(2)-adrenoceptors, mainly their alpha(2A)-subtype, are expressed in bladder, urethra and prostate. They mediate pre-junctional inhibition of neurotransmitter release and also a weak contractile effect in the urethra of some species, but not humans. Their overall post-junctional function in the lower urinary tract remains largely unclear. 4 Beta-adrenoceptors mediate relaxation of smooth muscle in the bladder, urethra and prostate. The available tools have limited the unequivocal identification of receptor subtypes at the protein and functional levels, but it appears that the beta(3)- and beta(2)-subtypes are important in the human bladder and urethra, respectively. Beta(3)-adrenoceptor agonists are promising drug candidates for the treatment of the overactive bladder. 5 We propose that the overall function of adrenoceptors in the lower urinary tract is to promote urinary continence. Further elucidation of the functional roles of their subtypes will help a better understanding of voiding dysfunction and its treatment.
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MESH Headings
- Adrenergic Agonists/pharmacology
- Animals
- Gene Expression Regulation
- Humans
- Male
- Muscle Contraction
- Muscle, Smooth/metabolism
- Prostate/drug effects
- Prostate/metabolism
- Receptors, Adrenergic/drug effects
- Receptors, Adrenergic/genetics
- Receptors, Adrenergic/metabolism
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Adrenergic, beta/metabolism
- Urethra/drug effects
- Urethra/metabolism
- Urinary Bladder/drug effects
- Urinary Bladder/metabolism
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Affiliation(s)
- Martin C Michel
- Department of Pharmacology & Pharmacotherapy, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
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45
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Morton JS, Daly CJ, Jackson VM, McGrath JC. Alpha(1A)-adrenoceptors mediate contractions to phenylephrine in rabbit penile arteries. Br J Pharmacol 2006; 150:112-20. [PMID: 17115072 PMCID: PMC2013850 DOI: 10.1038/sj.bjp.0706956] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Maintained penile erection depends on the absence of alpha-adrenoceptor (alpha-AR) activation and so can be facilitated by alpha-blockers. This study seeks the alpha(1)-AR subtypes involved in order to inform the pro-erectile consequences of subtype selective blockade. EXPERIMENTAL APPROACH Wire myography was used with dorsal (nutritional supply) and cavernous (erectile inflow) penile arteries; standard alpha-AR-selective agonists and antagonists were employed to classify responses. KEY RESULTS In both penile arteries noradrenaline (NA) and phenylephrine (PE, alpha(1)-AR agonist) caused concentration-dependent contractions. Sensitivity to NA was increased by NA uptake blockers, cocaine (3 microM) and corticosterone (30 microM). PE responses were antagonised by phentolamine (non-selective alpha-AR: dorsal pK(B) 8.00, cavernous 8.33), prazosin (non-subtype-selective alpha(1)-AR: dorsal 8.60, cavernous 8.41) and RS100329 (alpha(1A)-AR selective: dorsal 9.03, cavernous 8.80) but not by BMY7378 (alpha(1D)-AR selective: no effect at 1-100 nM) or Rec15/2615 (alpha(1B)-AR selective: no effect at 1-100 nM). Schild analysis was straightforward in cavernous artery, indicating that PE activates only alpha(1A)-AR. In dorsal artery Schild slopes were low, though alpha(1A)-AR was still indicated. Analysis using UK 14,304 and rauwolscine indicated an alpha(2)-AR component in dorsal artery that may account for low slopes to alpha(1)-AR antagonists. CONCLUSIONS AND IMPLICATIONS Penile arteries have a predominant, functional alpha(1A)-AR population with little evidence of other alpha(1)-AR subtypes. Dorsal arteries (nutritional supply) also have alpha(2)-ARs. Thus, alpha-AR blockers with affinity for alpha(1A)-AR or alpha(2)-AR would potentially have pro-erectile properties; the combination of these perhaps being most effective. This should inform the design of drugs to assist/avoid penile erection.
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Affiliation(s)
- J S Morton
- Autonomic Physiology Unit, Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, Glasgow, UK
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Jaime-Figueroa S, Zamilpa A, Guzmán A, Morgans DJ. N-3-ALKYLATION OF URACIL AND DERIVATIVES VIA N-1-BOC PROTECTION. SYNTHETIC COMMUN 2006. [DOI: 10.1081/scc-100108223] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Alejandro Zamilpa
- a Roche Bioscience , 3401 Hillview Ave., Palo Alto, CA, 94304, U.S.A
| | - Angel Guzmán
- a Roche Bioscience , 3401 Hillview Ave., Palo Alto, CA, 94304, U.S.A
| | - David J. Morgans
- a Roche Bioscience , 3401 Hillview Ave., Palo Alto, CA, 94304, U.S.A
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Bagot K, Chess-Williams R. Alpha1A/L-adrenoceptors mediate contraction of the circular smooth muscle of the pig urethra. ACTA ACUST UNITED AC 2006; 26:345-53. [PMID: 16968473 DOI: 10.1111/j.1474-8673.2006.00374.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sympathetically mediated urethral tone is essential for the maintenance of continence and involves the activation of postjunctional alpha(1)-adrenoceptors. This study characterizes the alpha(1)-adrenoceptor subtypes responsible for mediating contraction of the urethral circular smooth muscle of the pig. The potency order of a number of agonists and the affinities of several receptor selective antagonists were determined on pig-isolated circular smooth muscle strips in the presence of cocaine (1 microm) and corticosterone (10 microm) to inhibit amine uptake and propranolol (1 microm) to antagonize beta-adrenoceptors. The potency order for agonists was N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A61603) > noradrenaline = phenylephrine = M6434 > methoxamine with pEC(50) values of 7.3, 5.8, 5.7, 5.6 and 5.0 respectively. 4 The alpha(1D)-adrenoceptor-selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione (BMY7378) caused rightward shifts of the concentration-response curves to noradrenaline, yielding a low affinity estimate (6.6) for the urethral receptor. The alpha(1A)-adrenoceptor-selective antagonists, RS100329 and 5-methylurapidil, gave relatively high affinity estimates (9.6 and 8.8 respectively) for this receptor. All three antagonists produced Schild plots with slopes close to unity but did reduce maximum responses at higher concentrations. Prazosin antagonized responses of the urethra to noradrenaline, yielding a mean affinity estimate of 9.0. Although the Schild plot for prazosin again had a slope of unity, this drug also reduced maximum responses to noradrenaline at all concentrations examined (10-100 nm). N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamide (RS17053), which discriminates between responses mediated via alpha(1A) (high affinity) and alpha(1L)-adrenoceptors (low affinity) at concentrations up to 3 microm, failed to antagonize responses of the urethra. 5 These results suggest that contraction of urethral circular smooth muscle in the pig is mediated via a single population of adrenoceptors with the pharmacological characteristics of the alpha(1A/L)-adrenoceptor, most probably the alpha(1L)-adrenoceptor.
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Affiliation(s)
- K Bagot
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
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48
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Parés-Hipólito J, Gómez-Zamudio JH, Gallardo-Ortiz IA, López-Guerrero JJ, Santamaría-Ortiz J, Ibarra M, Villalobos-Molina R. Selective agonists reveal ?1A- and ?1B-adrenoceptor subtypes in caudal artery of the young rat. ACTA ACUST UNITED AC 2006; 26:371-8. [PMID: 16968476 DOI: 10.1111/j.1474-8673.2006.00380.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Multiple alpha(1)-adrenoceptors were evaluated in caudal artery of the young Wistar rat using selective agonists and antagonists. Arteries were exposed to the selective alpha(1A)-adrenoceptor agonist, A-61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) or to phenylephrine and to prazosin (alpha(1)-adrenoceptor antagonist), or the selective alpha(1A)-adrenoceptor antagonists 5-methylurapidil, RS 100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy)phenyl]-1-piperazinyl]propyl]-2,4-(1H)-pyrimidinedione), RS 17053 (N-[2(2-cyclopropylmethoxy) ethyl]-5-chloro-alpha, alpha-dimethyl-1H-indole-3-ethanamide), and the selective alpha(1D)-adrenoceptor antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione). Results showed a 100-fold higher potency of A-61603 for the alpha(1)-adrenoceptor present in the artery, compared with phenylephrine. Prazosin displaced both agonists with high affinity, whereas 5-methylurapidil, RS 100329 and RS 17053 displaced A-61603 with high affinity, indicating the presence of alpha(1A)-adrenoceptors. The selective alpha(1A)-adrenoceptor antagonists blocked phenylephrine responses with low affinity, suggesting that phenylephrine activated a second receptor population in caudal artery. BMY 7378 antagonized with low affinity both A-61603 and phenylephrine-induced contractions, indicating absence of alpha(1D)-adrenoceptors in the vessel. The results suggest that functional alpha(1B)-adrenoceptors are present in caudal arteries of the young Wistar rat.
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Affiliation(s)
- J Parés-Hipólito
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Sede Sur, Mexico, D.F
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Kinsella GK, Watson GW, Rozas I. Theoretical proton affinities of α1 adrenoceptor ligands. Bioorg Med Chem 2006; 14:1580-7. [PMID: 16256353 DOI: 10.1016/j.bmc.2005.10.007] [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] [Received: 04/05/2005] [Revised: 10/06/2005] [Accepted: 10/06/2005] [Indexed: 10/25/2022]
Abstract
A systematic study has been performed of the proton affinity of a large family of agonists and antagonists of the alpha1-adrenoceptor at the B3LYP/6-31G* level of theory. After a conformational search, all the N atoms were considered as protonation sites and protonation energy values were determined. The inclusion of solvation by means of the Onsager model yielded stabilization in the proton affinity values obtained. In addition, a good correlation was found between the proton affinity values corresponding to the first protonation in gas phase of some of the compounds and their corresponding experimental affinity constants K(i) for the alpha1A adrenergic receptor.
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Affiliation(s)
- Gemma K Kinsella
- Department of Chemistry, University of Dublin, Trinity College, Ireland
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Kinsella GK, Rozas I, Watson GW. Computational Study of Antagonist/α1A Adrenoceptor ComplexesObservations of Conformational Variations on the Formation of Ligand/Receptor Complexes. J Med Chem 2005; 49:501-10. [PMID: 16420037 DOI: 10.1021/jm0503751] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As selective antagonist inhibition may relieve the symptoms of benign prostatic hyperplasia, we have examined the interactions of antagonists including quinazoline and imidazolidinium/guanidinium compounds complexed with a homology model of the alpha(1A) adrenoceptor. Our approach involves docking of ligands of various structural classes followed by molecular dynamics simulations of antagonist/receptor complexes, which demonstrates that different structural classes of antagonist induce different receptor conformations upon binding with particular variations noted in the conformation of TM-V. Subsequently, we examined the interactions and the conformational flexibility of alpha(1) and alpha(1A) adrenoceptor antagonists, with the ligand-induced receptor conformers. This study indicated that a receptor conformation induced by one structural class of antagonist is not suitable for direct screening of another class. Our analysis indicates that computational high-throughput screening is likely to give inaccurate data on binding and selectivity and such studies need to consider conformational changes in the receptor.
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Affiliation(s)
- Gemma K Kinsella
- School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland
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