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Alsufyani HA, Daly C, Docherty JR. Interaction between α 1B - and other α 1 - and α 2 -adrenoceptors in producing contractions of mouse spleen. Basic Clin Pharmacol Toxicol 2021; 129:416-426. [PMID: 34383990 DOI: 10.1111/bcpt.13639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 07/24/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022]
Abstract
We have investigated the interaction of α1 - and α2 -adrenoceptor subtypes in producing isometric contractions to NA in mouse whole spleen. The α1 -adrenoceptor antagonist prazosin (10-8 M) or the α2 -adrenoceptor antagonist yohimbine (10-6 M) alone produced only small shifts in NA potency in wild type (WT) mice, but the combination produced a large shift in NA potency. In spleen from α1A/D -KO mice, the effects of prazosin and the combination of prazosin and yohimbine were similar to their effects in WT mice. Hence, in α1A/D -KO mice, in which the only α1 -adrenoceptor present is the α1B -adrenoceptor, prazosin still antagonized contractions to NA. The α1A -adrenoceptor antagonist RS100329 (3x10-9 M) produced significant shifts in the effects of higher concentrations of NA (EC50 and EC75 levels) and the α1D -adrenoceptor antagonist BMY7378 (3x10-8 M) produced significant shifts in the effects of lower concentrations of NA (EC25 and EC50 levels). The effects of BMY7378 and RS00329 demonstrate α1D -adrenoceptor and α1A -adrenoceptor components, and suggest that the α1B -adrenoceptor interacts with an α1D -adrenoceptor, and to a lesser extent an α1A -adrenoceptor, at low, and an α1A -adrenoceptor at high, NA concentrations. This study demonstrates the complex interaction between α1 - and α2 -adrenoceptor subtypes in producing contractions of mouse spleen and may have general implications for α-adrenoceptor mediated control of smooth muscle.
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Affiliation(s)
- Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Craig Daly
- School of Life Sciences, University of Glasgow, Glasgow, Scotland
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2
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Schranz D. Pharmacological Heart Failure Therapy in Children: Focus on Inotropic Support. Handb Exp Pharmacol 2020; 261:177-192. [PMID: 31707469 DOI: 10.1007/164_2019_267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Pediatric heart failure is a clinical syndrome, which needs to be distinctly defined and the pathophysiological consequences considered. Pharmacological treatment depends on the disease- and age-specific myocardial characteristics. Acute and chronic low cardiac output is the result of an inadequate heart rate (rhythm), myocardial contractility, preload and afterload, and also ventriculo-ventricular interaction, synchrony, atrio-ventricular and ventricular-arterial coupling. The treatment of choice is curing the cause of heart failure, if possible.Acute HF therapy is still based to the use of catecholamines and inodilators. The cornerstone of chronic HF treatment consists of blocking the endogenous, neuro-humoral axis, in particular the adrenergic and renin-angiotensin-aldosterone system.Before neprilysin inhibitors are used in young children, their potential side-effect for inducing Alzheimer disease needs to be clarified. The focus of the current review is put on the differential use of the inotropic drugs as epinephrine, norepinephrine, dopamine and dobutamine, and also the inodilators milrinone and levosimendan. Considering effects and side-effects of any cardiac stimulating treatment strategy, co-medication with ß-blockers, angiotensin converting inhibitors (ACEIs), angiotensin blockers (ARBs) and mineralocorticoid receptor antagonists (MRAs) is not a contradiction, but a senseful measure, even still during the acute inotropic treatment.Missing sophisticated clinical trials using accurate entry criteria and clinically relevant endpoints, there is especially in cardiovascular diagnosis and treatment of young children a compromise of evidence-based versus pathophysiology-based procedures. But based on the pharmacological and pathophysiological knowledge a hypothesis-driven individualized treatment is already currently possible and therefore indicated.
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Affiliation(s)
- Dietmar Schranz
- Pediatric Heart Center, Johann Wolfgang Goethe University Clinic, Frankfurt, Germany.
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3
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Karlsson JOG, Grundstrom N, Elwing H, Andersson RGG. The Fish Pigment Cell: An Alternative Model in Biomedical Research. Altern Lab Anim 2020. [DOI: 10.1177/026119299001800121.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Receptor-mediated pigment aggregation within pigment cells (chromatophores) of an isolated fish scale is an ideal model system for functional receptor studies. The superficial layer of the scale contains both dermal chromatophores and postganglionic sympathetic nerves. By means of stimulation of the nerves, or by addition of appropriate receptor agonists, it is possible to elicit pigment aggregation within the chromatophores. A single fish can contribute hundreds of scales, various pharmacological and biochemical experiments are easily carried out and the physiological response, i.e. pigment aggregation, is readily evaluated by the aid of a light microscope or a simple scale photometer.A denervation model, based on isolated scales, permits studies of factors involved in the sensitivity change, which typically takes place after experimental or pathological denervation.By using isolated fish scales it is quite simple to illustrate many biomedically important concepts, like receptor theory and nerve-effector cell communication. This makes the scale a very useful preparation in biomedical education.
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Affiliation(s)
| | - Nils Grundstrom
- Department of Pharmacology, University of Linköping, S-581 83 Linköping, Sweden
| | - Hans Elwing
- Laboratory of Applied Physics, University of Linköping, S-581 83 Linköping, Sweden
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Jankovic G, Marinko M, Milojevic P, Stojanovic I, Nenezic D, Kanjuh V, Yang Q, He GW, Novakovic A. Mechanisms of endothelium-dependent vasorelaxation induced by procyanidin B2 in venous bypass graft. J Pharmacol Sci 2019; 142:101-108. [PMID: 31874782 DOI: 10.1016/j.jphs.2019.11.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/22/2019] [Accepted: 11/13/2019] [Indexed: 10/25/2022] Open
Abstract
Cardioprotective abilities of procyanidins, might, at least in part, attribute to their vasodilator properties. The present study was undertaken to assess the vasorelaxant effect of procyanidin B2 on isolated human saphenous vein (HSV) and its underlying mechanisms. Procyanidin B2 relaxed phenylephrine-induced contraction of HSV rings in concentration-dependent manner. The relaxation was dependent on the presence of endothelium and was strongly affected by l-NAME, hydroxocobalamin or ODQ, the inhibitors of NO/cGMP pathway. Indomethacin significantly affected only the relaxation produced by the highest concentrations of procyanidin B2. Apamin and TRAM-34 combination, in the presence of l-NAME and indomethacin, did not additionally decreased procyanidin B2-induced relaxation. In the presence of K+ channel blockers, relaxation induced by procyanidin B2 was partially attenuated by 4-aminopyridine, significantly inhibited by glibenclamide and almost abolished by iberiotoxin. Procyanidin B2 also relaxed the contractions induced by phenylephrine or caffeine in Ca2+-free solution. Finally, nifedipine slightly, while thapsigargin strongly antagonized HSV relaxation. Our results indicate that procyanidin B2 induces endothelium-dependent relaxation of HSV, which results primarily from stimulation of NO production, as well K+ channels opening, especially BKCa, and partially KATP and KV. Regulation of the intracellular Ca2+ release and inhibition of Ca2+ influx probably contribute to procyanidin B2-induced relaxation.
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Affiliation(s)
- Goran Jankovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Marija Marinko
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Predrag Milojevic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Ivan Stojanovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Dragoslav Nenezic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | | | - Qin Yang
- TEDA International Cardiovascular Hospital, Tianjin, China
| | - Guo-Wei He
- TEDA International Cardiovascular Hospital, Tianjin, China
| | - Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
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5
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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: 35] [Impact Index Per Article: 7.0] [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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Marinko M, Jankovic G, Nenezic D, Milojevic P, Stojanovic I, Kanjuh V, Novakovic A. (-)-Epicatechin-induced relaxation of isolated human saphenous vein: Roles of K + and Ca 2+ channels. Phytother Res 2017; 32:267-275. [PMID: 29193528 DOI: 10.1002/ptr.5969] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 10/02/2017] [Accepted: 10/09/2017] [Indexed: 01/05/2023]
Abstract
In this study, we aimed to investigate relaxant effect of flavanol (-)-epicatechin on the isolated human saphenous vein (HSV), as a part of its cardioprotective action, and to define the mechanisms underlying this vasorelaxation. (-)-Epicatechin induced a concentration-dependent relaxation of HSV pre-contracted by phenylephrine. Among K+ channel blockers, 4-aminopyridine, margatoxin, and iberiotoxin significantly inhibited relaxation of HSV, while glibenclamide considerably reduced effects of the high concentrations of (-)-epicatechin. Additionally, (-)-epicatechin relaxed contraction induced by 80 mM K+ , whereas in the presence of nifedipine produced partial relaxation of HSV rings pre-contracted by phenylephrine. In Ca2+ -free solution, (-)-epicatechin relaxed contraction induced by phenylephrine, but had no effect on contraction induced by caffeine. A sarcoplasmic reticulum Ca2+ -ATPase inhibitor, thapsigargin, significantly reduced relaxation of HSV produced by (-)-epicatechin. These results demonstrate that (-)-epicatechin produces endothelium-independent relaxation of isolated HSV rings. Vasorelaxation to (-)-epicatechin probably involves activation of 4-aminopyridine- and margatoxin-sensitive KV channels, BKCa channels, and at least partly, KATP channels. In addition, not only the inhibition of extracellular Ca2+ influx, but regulation of the intracellular Ca2+ release, via inositol-trisphosphate receptors and reuptake into sarcoplasmic reticulum, via stimulation of Ca2+ -ATPase, as well, most likely participate in (-)-epicatechin-induced relaxation of HSV.
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Affiliation(s)
- Marija Marinko
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Goran Jankovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Dragoslav Nenezic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia.,Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Predrag Milojevic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia.,Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Ivan Stojanovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia.,Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | | | - Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
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7
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Novakovic A, Marinko M, Jankovic G, Stojanovic I, Milojevic P, Nenezic D, Kanjuh V, Yang Q, He GW. Endothelium-dependent vasorelaxant effect of procyanidin B2 on human internal mammary artery. Eur J Pharmacol 2017; 807:75-81. [DOI: 10.1016/j.ejphar.2017.04.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/31/2017] [Accepted: 04/12/2017] [Indexed: 02/05/2023]
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8
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Huang Z, Wu LL, Zhang YY, Gao Y, Yu GY. Functional α1-Adrenoceptor Subtypes in Human Submandibular Glands. J Dent Res 2016; 85:251-6. [PMID: 16498073 DOI: 10.1177/154405910608500309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
α1-Adrenoceptor has been discovered to exist in many human tissues and mediates important physiological functions. The purpose of this study was to detect the expression, distribution, and function of α1-adrenoceptor subtypes in human submandibular glands. α1A- and α1B-Adrenoceptor mRNAs were identified by reverse-transcription/polymerase chain-reaction (RT-PCR), and their proteins were detected by Western blotting. No expression of the α1D-adrenoceptor mRNA and protein was found. By in situ hybridization and immunohistochemistry, α1A- and α1B-adrenoceptor mRNAs and proteins were shown to be widespread in both ductal and acinar cells. By confocal microscopy, phenylephrine (stimulating both α1A- and α1B-adrenoceptors) or A61603 (α1A-selective agonist) induced an increase in intracellular calcium by 2.33 ± 0.18-fold and 1.81 ± 0.43-fold, respectively, while 5-methylurapidil (α1A-selective antagonist) partly blocked calcium mobility stimulated by phenylephrine. The results indicated that functional α1A- and α1B-adrenoceptors were expressed in human submandibular glands, and might contribute to the regulation of saliva synthesis and secretion.
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Affiliation(s)
- Z Huang
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Zhong Guan Cun South St. 22, 100081 Beijing, PRC
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Jiang M, Wan F, Wang F, Wu Q. Irisin relaxes mouse mesenteric arteries through endothelium-dependent and endothelium-independent mechanisms. Biochem Biophys Res Commun 2015; 468:832-6. [PMID: 26582714 DOI: 10.1016/j.bbrc.2015.11.040] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/08/2015] [Indexed: 02/07/2023]
Abstract
Irisin, a newly discovered myokine, has been shown to produce modest weight loss and improve glucose intolerance in mice. The purpose of this study was to investigate the effects of irisin on vascular activity and the mechanisms involved. Experiments were performed on mouse mesenteric arteries. We demonstrated that irisin induced relaxation in mesenteric arteries with or without endothelium in a concentration-dependent manner. It was further demonstrated that the irisin-induced vasorelaxation effects on endothelium-intact mesenteric arteries were reduced by pretreatment with Nω-nitro-L-arginine methyl ester (L-NAME) or 1H-[1, 2, 4] oxadizolo [4, 3-a] quinoxalin-1-one (ODQ). However, pretreatment with indomethacin (INDO), a nonselective cyclooxygenase inhibitor did not modulate irisin-induced relaxation. In addition, the contraction due to extracellular Ca(2+) influx and intracellular Ca(2+) release was also inhibited by irisin. In summary, these results suggested that the endothelium-dependent relaxation of irisin is mediated by the nitric oxide (NO)-guanosine 3', 5'-cyclic phosphate (cGMP)-dependent pathway but not the prostaglandin I2 (PGI2)-cyclic adenosine monophosphate (cAMP)-dependent mechanism. Endothelium-independent relaxation may be depend on inhibiting Ca(2+) influx through blocking VDCCs and intracellular Ca(2+) release through both IP3R and RyR channels.
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Affiliation(s)
- Miao Jiang
- Experimental Animal Center, The Second Hospital of Shandong University, Jinan 250012, PR China
| | - Fangzhu Wan
- Department of Clinical Medicine, School of Medicine, Shandong University, Jinan 250012, PR China
| | - Fang Wang
- Experimental Animal Center, The Second Hospital of Shandong University, Jinan 250012, PR China
| | - Qi Wu
- Department of Clinical Medicine, School of Medicine, Shandong University, Jinan 250012, PR China.
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10
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Jurkiewicz NH, Caricati-Neto A, Verde LF, Honda L, da Silva Junior ED, Reuter HR, Jurkiewicz A, Avellar MCW. Could α1-adrenoceptors and androgen receptors be modified by sexual maturation and testosterone in the rat testicular capsule? Life Sci 2015; 141:212-20. [DOI: 10.1016/j.lfs.2015.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 07/08/2015] [Accepted: 09/10/2015] [Indexed: 10/23/2022]
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11
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Novakovic A, Marinko M, Vranic A, Jankovic G, Milojevic P, Stojanovic I, Nenezic D, Ugresic N, Kanjuh V, Yang Q, He GW. Mechanisms underlying the vasorelaxation of human internal mammary artery induced by (-)-epicatechin. Eur J Pharmacol 2015; 762:306-12. [PMID: 26049011 DOI: 10.1016/j.ejphar.2015.05.066] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 05/03/2015] [Accepted: 05/21/2015] [Indexed: 02/05/2023]
Abstract
Evidences have suggested that flavanol compound (-)-epicatechin is associated with reduced risk of cardiovascular diseases. One of the mechanisms of its cardioprotective effect is vasodilation. However, the exact mechanisms by which (-)-epicatechin causes vasodilation are not yet clearly defined. The aims of the present study were to investigate relaxant effect of flavanol (-)-epicatechin on the isolated human internal mammary artery (HIMA) and to determine the mechanisms underlying its vasorelaxation. Our results showed that (-)-epicatechin induced a concentration-dependent relaxation of HIMA rings pre-contracted by phenylephrine. Among the K(+) channel blockers, 4-aminopyridine (4-AP) and margatoxin, blockers of voltage-gated K(+) (KV) channels, and glibenclamide, a selective ATP-sensitive K(+) (KATP) channels blocker, partly inhibited the (-)-epicatechin-induced relaxation of HIMA, while iberiotoxin, a most selective blocker of large conductance Ca(2+)-activated K(+) channels (BKCa), almost completely inhibited the relaxation. In rings pre-contracted by 80mM K(+), (-)-epicatechin induced partial relaxation of HIMA, whereas in Ca(2+)-free medium, (-)-epicatechin completely relaxed HIMA rings pre-contracted by phenylephrine and caffeine. Finally, thapsigargin, a sarcoplasmic reticulum Ca(2+)-ATPase inhibitor, slightly antagonized (-)-epicatechin-induced relaxation of HIMA pre-contracted by phenylephrine. These results suggest that (-)-epicatechin induces strong endothelium-independent relaxation of HIMA pre-contracted by phenylephrine whilst 4-AP- and margatoxin-sensitive KV channels, as well as BKCa and KATP channels, located in vascular smooth muscle, mediate this relaxation. In addition, it seems that (-)-epicatechin could inhibit influx of extracellular Ca(2+), interfere with intracellular Ca(2+) release and re-uptake by the sarcoplasmic reticulum.
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Affiliation(s)
- Aleksandra Novakovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia.
| | - Marija Marinko
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Aleksandra Vranic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Goran Jankovic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Predrag Milojevic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Ivan Stojanovic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Dragoslav Nenezic
- Faculty of Medicine, University of Belgrade, Belgrade, Serbia; Institute for Cardiovascular Diseases "Dedinje", Belgrade, Serbia
| | - Nenad Ugresic
- Department of Pharmacology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | | | - Qin Yang
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong; TEDA International Cardiovascular Hospital, Tianjin, China
| | - Guo-Wei He
- TEDA International Cardiovascular Hospital, Tianjin, China
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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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13
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Ferreira Verde L, Silva Lopes G, Miki Ihara SS, Hyppolito Jurkiewicz N, Jurkiewicz A. Acute treatment with alcohol affects calcium signaling and contraction associated with apoptosis in vas deferens of periadolescent rats. Eur J Pharmacol 2014; 735:211-8. [DOI: 10.1016/j.ejphar.2014.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 12/19/2022]
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14
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Chin JL, Aiden McCormick P, Docherty JR. Effects of portal hypertension on contractility of rat spleen. Eur J Pharmacol 2013; 721:1-4. [PMID: 24140433 DOI: 10.1016/j.ejphar.2013.09.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 09/11/2013] [Accepted: 09/22/2013] [Indexed: 11/19/2022]
Abstract
Portal hypertension induces changes in vascular responses to vasoconstrictors. However, the effects of portal hypertension on splenic contraction have not previously been investigated. In partial portal vein ligated (PVL) and sham-operated rats, we examined the splenic contractile responses to cumulative concentrations of noradrenaline and KCl. In PVL rats, the potency of noradrenaline in producing splenic contraction was significantly increased (pEC50 of 5.88 ± 0.08), as compared to sham (5.40 ± 0.06; p<0.001). In the presence of prazosin (10(-8)M), there was a significant rightward shift in the noradrenaline concentration response curve but the shift was greater for PVL, so that in the presence of prazosin there was no significant difference between PVL and sham animals in the potency of noradrenaline. Prazosin produced a significantly greater shift of noradrenaline potency in spleen from PVL (pKB of 8.88 ± 0.06) (n=6) than from sham animals (8.51 ± 0.08, n=6), demonstrating that the α1-adrenoceptor mediated component is greater in spleen from PVL. In the presence of prazosin (10(-8)M) the residual response is non-α1-adrenoceptor mediated, presumably α2-adrenoceptor mediated, and this response did not differ between sham and PVL. The maximum splenic contraction did not significantly differ between sham and PVL rats for either agonist. In conclusion, noradrenaline potency in contracting the rat spleen was significantly increased in tissues from PVL rats. The increased potency of prazosin suggests a greater predominance of α1-adrenoceptors in spleen of PVL rats, as prazosin has lower potency at α2-adrenoceptors.
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Affiliation(s)
- Jun Liong Chin
- Liver Unit, St. Vincent's University Hospital, University College Dublin, Elm Park, Dublin 4, Ireland; Department of Physiology, Royal College of Surgeons in Ireland, 123, St. Stephen's Green, Dublin 2, Ireland
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15
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Role of α1-adrenergic receptor subtypes in contractility of the rabbit abdominal aorta in vitro. ACTA VET BRNO 2013. [DOI: 10.2754/avb201382030331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Investigation of the effect of α1-adrenergic receptor subtypes on the contraction of the abdominal aorta will allow for more effective treatment of hypertension by use of selective antagonists. The aim of the study was to evaluate the participation of α1-adrenergic receptor subtypes in the contractility of the aortic smooth muscle cells in rabbits. The in vitro experiments were performed in isolated tissue preparations from 30 adult female New Zealand rabbits. The abdominal aortic sections were placed in organ bath chambers and contracted with increasing doses of non-selective α1-adrenergic receptor agonist phenylephrine without pre-incubation or after incubation in α1-adrenergic receptor subtype-selective or non-selective antagonists. Separate sections were incubated with increasing concentrations of antagonists. Phenylephrine caused maximal rise in arterial smooth muscle tone to 4.75 ± 0.47 mN. The most potent in blocking phenylephrine induced contraction was 5-metylurapidil (α1A-adrenergic receptor antagonist) followed by phentolamine and prazosin (non-selective α1-adrenergic receptor antagonists); BMY 7378 (α1D-adrenergic receptor antagonist), cyclazosin and L-765.314 (α1B-adrenergic receptor antagonists) were less effective. All antagonists, except BMY 7378 elicited relaxation of non-precontracted aorta in dose dependent manner. Our results indicate that postsynaptic α1A receptors are the most potent in producing rabbit abdominal aorta contraction, while α1B and α1D subtypes are less effective.
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16
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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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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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18
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Abstract
Adrenergic receptors form the interface between the sympathetic nervous system and the cardiovascular system. Genomic or cDNA clones for 8 types of mammalian adrenergic receptors have been obtained. Much has been learned about the structure and functional properties of the β(2)-adrenergic receptor. Less is known about the functional properties and the physiologic role of the other adrenergic receptors. Further progress in this field may lead to the development of more selective drugs to modify the physiologic processes controlled by these receptors.
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Affiliation(s)
- B Kobilka
- Howard Hughes Medical Institute and the Departments of Cardiology and Molecular and Cellular Physiology, Stanford University Medical Center, Stanford, CA 94305, USA
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Ramakrishna D, Subhash MN. Effect of amitriptyline on adrenergic receptor number and second messenger function in rat brain. Pak J Biol Sci 2012; 15:871-876. [PMID: 24205756 DOI: 10.3923/pjbs.2012.871.876] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Radioligand binding studies were done to investigate the effect of chronic administration of Amitriptyline on alpha1-adrenoceptor (alpha1-AR) receptor mediated response to inositol triphosphate (IP3) in rat brain. Our studies revealed a significant decrease in the densities of alpha1-ARs in cortex and cerebellum of rat brain after chronic administration of Amitriptyline (10 mg kg-1 b.wt.). However, there was no significant change in the affinity of [3H]prazosin to alpha1-ARs. Displacement studies showed that Amitriptyline has higher affinity for alpha1-AR with a Ki value of 182+/-16 nM. Significant change was observed in basal IP3 activity in cortex and cerebellum after Amitriptyline exposure. In cortex and cerebellum of experimental rats the NE (Norepinephrine) stimulated IP3 activity was significantly decreased (1460+/-102 DPM/g tissue; p<0.0001; 1188+/-112 DPM/g tissue; p<0.0001), when compared to NE stimulated IP3 activity (4152+/-286 and 3952+/-245 DPM/g tissue, respectively) in control rats. The decrease in NE stimulated IP3 activity in both regions may be due to the significant downregulation of alpha1-ARs in cortex after Amitriptyline exposure as these sites are positively coupled to IP3. The observed significant decrease in alphal-ARs with concomitant decrease in NE stimulated IP3 activity, after Amitriptyline treatment, suggests that Amitriptyline which has high affinity for these sites, acts by modulating the alpha1-AR receptor mediated response in brain.
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Kinami J, Tsuchihashi H, Baba S, Mano F, Maruyama K, Nagatomo T. α1-Adrenoceptor Subtypes in the Rat Ventricular Muscle. J Pharm Pharmacol 2011; 44:97-100. [PMID: 1352824 DOI: 10.1111/j.2042-7158.1992.tb03569.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Abstract
Scatchard analyses of [3H]prazosin binding in rat ventricular muscle membranes showed biphasic curves, which identified α1High- and α1Low-affinity sites. The α1High-affinity site was completely inhibited by 1 μm phenoxybenzamine. The displacement potencies of α1-adrenergic antagonists were characterized by [3H]prazosin binding to α1High. and α1Low-affinity sites in the absence and presence of 1 μm phenoxybenzamine. The affinities of most chemicals for α1Low-affinity sites were significantly lower than those for α1High-affinity sites, but WB-4101 (2-(2,6-dimethoxy-phenoxyethyl)aminomethyl-1,4-benzodioxane), arotinolol, cinanserin, nifedipine, and p-aminoclonidine had the same affinities for both α1Low- and α1High-affinity sites. These results show that two α1-adrenoceptor subtypes, α1High- and α1Low-affinity, are present in the rat heart, and that there are physical variations in α1-adrenoceptor binding sites, based on their selectivity to antagonists.
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Affiliation(s)
- J Kinami
- Department of Pharmacology, Niigata College of Pharmacy, Japan
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22
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Abstract
Abstract
The object of this study was to examine the existence and characteristics of α1-adrenoceptor subtypes in the bovine prostate using the radioligand binding assay method. [3H]Prazosin was used as the radioligand and its binding sites in bovine prostate were classified into two subtypes. One subtype showed a high affinity (α1High, Kd: 101·1 Pm and Bmax: 11·8 fmol (mg protein)−1) and the other had a low affinity (α1Low, Kd: 3371·4 Pm and Bmax: 50·5 fmol (mg protein)−1). Although the same pKi values of clorethylclonidine, p-aminoclonidine, benoxathian and dibenamine to both α1High and α1 Low binding sites in bovine prostate tissue were observed, other α1 antagonists used in this study had different pKi values for the two α1-adrenoceptor subtypes. The existence and binding characteristics of α1-adrenoceptor subtypes in bovine prostate were clarified. It is possible that agents selective for one site may contribute to the development of better drugs for the treatment of bladder outlet obstructions of men with benign prostatic hyperplasia.
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Affiliation(s)
- K Maruyama
- Department of Pharmacology, Niigata College of Pharmacy, Japan
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23
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Göçmez SS, Utkan T, Ulak G, Gacar N, Erden F. Effects of long-term treatment with fluoxetine and venlafaxine on rat isolated vas deferens. ACTA ACUST UNITED AC 2010; 30:197-202. [DOI: 10.1111/j.1474-8673.2010.00456.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Goyal R, Mittal A, Chu N, Zhang L, Longo LD. alpha(1)-Adrenergic receptor subtype function in fetal and adult cerebral arteries. Am J Physiol Heart Circ Physiol 2010; 298:H1797-806. [PMID: 20348219 PMCID: PMC2886655 DOI: 10.1152/ajpheart.00112.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 03/24/2010] [Indexed: 11/22/2022]
Abstract
In the developing fetus, cerebral artery (CA) contractility demonstrates significant functional differences from that of the adult. This may be a consequence of differential activities of alpha(1)-adrenergic receptor (alpha(1)-AR) subtypes. Thus we tested the hypothesis that maturational differences in adrenergic-mediated CA contractility are, in part, a consequence of differential expression and/or activities of alpha(1)-AR subtypes. In CA from fetal ( approximately 140 days) and nonpregnant adult sheep, we used wire myography and imaging, with simultaneous measurement of tension and intracellular Ca(2+) concentration ([Ca(2+)](i)), radioimmunoassay, and Western immunoblots to examine phenylephrine (Phe)-induced contractile responses. The alpha(1A)-AR antagonists (5-MU and WB-4101) completely inhibited Phe-induced contraction in adult but not fetal CA; however, [Ca(2+)](i) increase was reduced significantly in both age groups. The alpha(1D)-AR antagonist (BMY-7378) blocked both Phe-induced contractions and Ca(2+) responses to a significantly greater extent in adult compared with fetal CA. In both age groups, inhibition of alpha(1A)-AR and alpha(1B)-AR, but not alpha(1D)-AR, significantly reduced inositol 1,4,5-trisphosphate responses to Phe. Western immunoblots demonstrated that the alpha(1)-AR subtype expression was only approximately 20% in fetal CA compared with the adult. Moreover, in fetal CA, the alpha(1D)-AR was expressed significantly greater than the other two subtypes. Also, in fetal but not adult CA, Phe induced a significant increase in activated ERK1/2; this increase in phosphorylated ERK was blocked by alpha(1B)-AR (CEC) and alpha(1D)-AR (BMY-7378) inhibitors, but not by alpha(1A)-AR inhibitors (5-MU or WB-4101). In conclusion, in the fetal CA, alpha(1B)-AR and alpha(1D)-AR subtypes play a key role in contractile response as well as in ERK activation. We speculate that in fetal CA alpha(1B)-AR and alpha(1D)-AR subtypes may be a critical factor associated with cerebrovascular growth and function.
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Affiliation(s)
- Ravi Goyal
- Center for Perinatal Biology, Department of Physiology and Pharmacology, Loma Linda Univ., School of Medicine, Loma Linda, CA 92350, USA
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25
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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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26
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Zhang Y, Hong X, Liu H, Huo Y, Xu X. Arg347Cys polymorphism of alpha1A-adrenoceptor gene is associated with blood pressure response to nifedipine GITS in Chinese hypertensive patients. J Hum Genet 2009; 54:360-4. [PMID: 19444285 DOI: 10.1038/jhg.2009.42] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our objectives were to evaluate whether polymorphisms in the alpha1A- and beta2-adrenoceptor genes influence blood pressure response to nifedipine gastrointestinal therapeutic system (GITS). Hypertensive patients received daily treatment with an oral dosage of 30 mg nifedipine GITS for 16 days. Genotypes of the Arg347Cys polymorphism in the alpha1A-adrenoceptor gene and the Arg16Gly and Gln27Glu polymorphisms in the beta2-adrenoceptor gene were determined by TaqMan single-nucleotide polymorphism genotyping assay. The sixteenth-day steady-state plasma concentration of nifedipine was measured using HPLC with UV detection. Multivariate linear regression was performed in a total of 447 patients to evaluate the effects of these polymorphisms on blood pressure response to nifedipine GITS. Patients carrying the Cys347 allele of the alpha1A-adrenoceptor gene had a greater systolic blood pressure reduction than did those carrying two Arg347 alleles of the alpha1A-adrenoceptor gene (32.5+/-14.0 versus 27.3+/-15.5 mm Hg, respectively, P=0.006). However, diastolic blood pressure reduction was not associated with the Arg347Cys polymorphism in the alpha1A-adrenoceptor gene. In addition, no significant associations were observed between blood pressure reduction and two polymorphisms in the beta2-adrenoceptor gene. Our data suggest that the Arg347Cys polymorphism in the alpha1A-adrenoceptor gene may be used to predict blood pressure response to nifedipine GITS in Chinese hypertensive patients.
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Affiliation(s)
- Yan Zhang
- Department of Cardiology, Peking University First Hospital, Beijing, China
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27
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Sanbe A, Tanaka Y, Fujiwara Y, Miyauchi N, Mizutani R, Yamauchi J, Cotecchia S, Koike K, Tsujimoto G, Tanoue A. Enhanced vascular contractility in alpha1-adrenergic receptor-deficient mice. Life Sci 2009; 84:713-8. [DOI: 10.1016/j.lfs.2009.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 01/28/2009] [Accepted: 02/12/2009] [Indexed: 11/24/2022]
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KASEDA SHUNICHI, ZIPES DOUGLASP. Effects of Alpha Adrenergic Stimulation and Blockade on Early Afterdepolarizations Induced by Cesium in Canine Cardiac Purkinje Fibers. J Cardiovasc Electrophysiol 2008. [DOI: 10.1111/j.1540-8167.1990.tb01046.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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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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30
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Kerchove CM, Luna MSA, Zablith MB, Lazari MFM, Smaili SS, Yamanouye N. Alpha1-adrenoceptors trigger the snake venom production cycle in secretory cells by activating phosphatidylinositol 4,5-bisphosphate hydrolysis and ERK signaling pathway. Comp Biochem Physiol A Mol Integr Physiol 2008; 150:431-7. [PMID: 18555716 DOI: 10.1016/j.cbpa.2008.04.607] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 04/30/2008] [Accepted: 04/30/2008] [Indexed: 11/26/2022]
Abstract
Loss of venom from the venom gland after biting or manual extraction leads to morphological changes in venom secreting cells and the start of a cycle of production of new venom. We have previously shown that stimulation of both alpha- and beta-adrenoceptors in the secretory cells of the venom gland is essential for the onset of the venom production cycle in Bothrops jararaca. We investigated the signaling pathway by which the alpha-adrenoceptor initiates the venom production cycle. Our results show that the alpha(1)-adrenoceptor subtype is present in venom gland of the snake. In quiescent cells, stimulation of alpha(1)-adrenoceptor with phenylephrine increased the total inositol phosphate concentration, and this effect was blocked by the phospholipase C inhibitor U73122. Phenylephrine mobilized Ca(2+) from thapsigargin-sensitive stores and increased protein kinase C activity. In addition, alpha(1)-adrenoceptor stimulation increased the activity of ERK 1/2, partially via protein kinase C. Using RT-PCR approach we obtained a partial sequence of a snake alpha(1)-adrenoceptor (260 bp) with higher identity with alpha(1D) and alpha(1B)-adrenoceptors from different species. These results suggest that alpha(1)-adrenoceptors in the venom secreting cells are probably coupled to a G(q) protein and trigger the venom production cycle by activating the phosphatidylinositol 4,5-bisphosphate and ERK signaling pathway.
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Affiliation(s)
- Celine M Kerchove
- Laboratório de Farmacologia, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900, São Paulo, SP, Brazil
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Khan AH, Sattar MA, Abdullah NA, Johns EJ. Influence of cisplatin-induced renal failure on the α1-adrenoceptor subtype causing vasoconstriction in the kidney of the rat. Eur J Pharmacol 2007; 569:110-8. [PMID: 17559832 DOI: 10.1016/j.ejphar.2007.04.063] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 04/17/2007] [Accepted: 04/20/2007] [Indexed: 10/23/2022]
Abstract
This study investigated whether the alpha(1)-adrenoceptor subtype(s) mediating the vasoconstrictor actions of the renal sympathetic nerves were altered in rats with cisplatin-induced renal failure. Male Wistar Kyoto rats were used and half received cisplatin (5 mg/kg i.p.) to induce renal failure and were taken for study 7 days later. The renal blood flow reductions caused by electrical renal nerve stimulation and close intra-renal administration of noradrenaline, phenylephrine and methoxamine were determined before and after amlodopine (AMP), 5-methylurapidil (MeU), chloroethylclonidine (CEC) or BMY 7378. Water intake and creatinine clearance were decreased (P<0.05) by 40-50% while fractional excretion of sodium was increased two-fold in the cisplatin treated rats. Mean arterial pressure was higher, 110+/-2 versus 102+/-3 mmHg and renal blood flow was lower, 10.7+/-0.9 versus 18.9+/-0.1 ml/min/kg in the renal failure rats (both P<0.05). AMP, MeU and BMY 7378 decreased (all P<0.05) the adrenergically induced renal vasoconstrictor responses in the renal failure groups by 30 to 50% and in normal rats by 20 to 40%. In the presence of CEC, renal nerve stimulation and noradrenaline and methoxamine induced renal vasoconstrictor responses were enhanced (all P<0.05) in the renal failure but not in the normal rats. These data showed that alpha(1A)- and alpha(1D)-adrenoceptors were the major subtypes in mediating adrenergically induced renal vasoconstriction but there was no substantial shift in subtype in renal failure. The contribution of alpha(1B)-adrenoceptor subtypes either pre- or post-synaptic appeared to be raised in the renal failure rats.
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Affiliation(s)
- Abdul H Khan
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
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32
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Sanbe A, Tanaka Y, Fujiwara Y, Tsumura H, Yamauchi J, Cotecchia S, Koike K, Tsujimoto G, Tanoue A. Alpha1-adrenoceptors are required for normal male sexual function. Br J Pharmacol 2007; 152:332-40. [PMID: 17603545 PMCID: PMC2042949 DOI: 10.1038/sj.bjp.0707366] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Alpha(1)-adrenoceptor antagonists are extensively used in the treatment of hypertension and lower urinary tract symptoms associated with benign prostatic hyperplasia. Among the side effects, ejaculatory dysfunction occurs more frequently with drugs that are relatively selective for alpha(1A)-adrenoceptors compared with other drugs of this class. This suggests that alpha(1A)-adrenoceptors may contribute to ejaculation. However, this has not been studied at the molecular level. EXPERIMENTAL APPROACH The physiological contribution of each alpha(1)-adrenoceptor subtype was characterized using alpha(1)-adrenoceptor subtype-selective knockout (KO) mice (alpha(1A)-, alpha(1B)- and alpha(1D)-AR KO mice) since the subtype-specific drugs available are only moderately selective. We analysed the role of alpha(1)-adrenoceptors in the blood pressure and vascular response as well as ejaculation by determining these variables in alpha(1)-adrenoceptor subtype-selective KO mice and in mice with all their alpha(1)-adrenoceptor subtypes deleted (alpha(1)-AR triple-KO mice). KEY RESULTS The pregnancy rate was reduced by 50% in alpha(1A)-adrenoceptor KO mice, and this reduction was dramatically enhanced in alpha(1)-adrenoceptor triple-KO mice. Contractile tension of the vas deferens in response to noradrenaline was markedly decreased in alpha(1A)-adrenoceptor KO mice, and this contraction was completely abolished in alpha(1)-adrenoceptor triple-KO mice. This attenuation of contractility was also observed in the electrically stimulated vas deferens. CONCLUSIONS AND IMPLICATIONS These results demonstrate that alpha(1)-adrenoceptors, particularly alpha(1A)-adrenoceptors, are required for normal contractility of the vas deferens and consequent sperm ejaculation as well as having a function in fertility.
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Affiliation(s)
- A Sanbe
- Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo, Japan.
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33
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Schach C, Xu M, Platoshyn O, Keller SH, Yuan JXJ. Thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels. Am J Physiol Lung Cell Mol Physiol 2006; 292:L685-98. [PMID: 17098807 DOI: 10.1152/ajplung.00276.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Cellular redox change regulates pulmonary vascular tone by affecting function of membrane and cytoplasmic proteins, enzymes, and second messengers. This study was designed to test the hypothesis that functional modulation of ion channels by thiol oxidation contributes to regulation of excitation-contraction coupling in isolated pulmonary artery (PA) rings. Acute treatment with the thiol oxidant diamide produced a dose-dependent relaxation in PA rings; the IC50 was 335 and 58 microM for 40 mM K+ - and 2 microM phenylephrine-induced PA contraction, respectively. The diamide-mediated pulmonary vasodilation was affected by neither functional removal of endothelium nor 8-bromoguanosine-3'-5'-cyclic monophosphate (50 microM) and HA-1004 (30 microM). A rise in extracellular K+ concentration (from 20 to 80 mM) attenuated the thiol oxidant-induced PA relaxation. Passive store depletion by cyclopiazonic acid (50 microM) and active store depletion by phenylephrine (in the absence of external Ca2+ both induced PA contraction due to capacitative Ca2+ entry. Thiol oxidation by diamide significantly attenuated capacitative Ca2+ entry-induced PA contraction due to active and passive store depletion. The PA rings isolated from left and right PA branches appeared to respond differently to store depletion. Although the active tension induced by passive store depletion was comparable, the active tension induced by active store depletion was 3.5-fold greater in right branches than in left branches. These data indicate that thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels, which subsequently attenuate Ca2+ influx and decrease cytosolic free Ca2+ concentration in pulmonary artery smooth muscle cells. The mechanisms involved in thiol oxidation-mediated pulmonary vasodilation or activation of K+ channels and inhibition of store-operated Ca2+ channels appear to be independent of functional endothelium and of the cGMP-dependent protein kinase pathway.
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Affiliation(s)
- Christian Schach
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0725, La Jolla, CA 92093-0725, USA
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Koshimizu TA, Tanoue A, Tsujimoto G. Clinical implications from studies of alpha1 adrenergic receptor knockout mice. Biochem Pharmacol 2006; 73:1107-12. [PMID: 17141736 DOI: 10.1016/j.bcp.2006.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 10/27/2006] [Accepted: 11/02/2006] [Indexed: 11/18/2022]
Abstract
alpha1-Adrenergic receptors (alpha1-ARs) modulate a large number of physiological functions in cardiovascular and noncardiovascular tissues. Because individual members of the alpha1-AR family (alpha1A-, alpha1B-, and alpha1D-ARs) have overlapping expression profiles in most tissues, elucidation of the precise physiological roles of individual alpha1-AR subtypes remains a challenging task. To alleviate this constraint, a gene targeting approach has been employed to generate mutant mice lacking one or two alpha1-AR genes. Recent studies on these mutant mouse strains are discussed in this article, with an emphasis on the role of alpha1-AR in the central nervous system and lower urinary tracts. These are two major tissues of particular interest for the development of new therapeutic strategies targeted to the alpha1-ARs. By combining gene targeting techniques with pharmacological tools, the specific roles of alpha1-AR subtypes could be delineated.
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Affiliation(s)
- Taka-aki Koshimizu
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Hein P, Michel MC. Signal transduction and regulation: are all alpha1-adrenergic receptor subtypes created equal? Biochem Pharmacol 2006; 73:1097-106. [PMID: 17141737 DOI: 10.1016/j.bcp.2006.11.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 10/30/2006] [Accepted: 11/01/2006] [Indexed: 02/06/2023]
Abstract
The current manuscript reviews the evidence whether and how subtypes of alpha(1)-adrenergic receptors, i.e. alpha(1A)-, alpha(1B)- and alpha(1D)-adrenergic receptors, differentially couple to signal transduction pathways and exhibit differential susceptibility to regulation. In both regards studies in tissues or cells natively expressing the subtypes are hampered because the relative expression of the subtypes is poorly controlled and the observed effects may be cell-type specific. An alternative approach, i.e. transfection of multiple subtypes into the same host cell line overcomes this limitation, but it often remains unclear whether results in such artificial systems are representative for the physiological situation. The overall evidence suggests that indeed subtype-intrinsic and cell type-specific factors interact to direct alpha(1)-adrenergic receptor signaling and regulation. This may explain why so many apparently controversial findings have been reported from various tissues and cells. One of the few consistent themes is that alpha(1D)-adrenergic receptors signal less effectively upon agonist stimulation than the other subtypes, most likely because they exhibit spontaneous internalization.
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Affiliation(s)
- Peter Hein
- Department of Pharmacology, University of Würzburg, Würzburg, Germany
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36
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Ambrosio SR, Tirapelli CR, da Costa FB, de Oliveira AM. Kaurane and pimarane-type diterpenes from the Viguiera species inhibit vascular smooth muscle contractility. Life Sci 2006; 79:925-33. [PMID: 16780894 DOI: 10.1016/j.lfs.2006.05.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 04/10/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
The research, development and use of natural products as therapeutic agents, especially those derived from plants, have been increasing in recent years. Despite the fact that plants provide a rich source of novel biologically active compounds, only a small percentage have been phytochemically investigated and studied for their medical potential. Viguiera is a genus that belongs to the family Asteraceae and to the sunflower tribe Heliantheae, which is widespread mostly in Mexico and in other areas of the Andes and upland areas of Brazil. A review on the secondary metabolites pointed out that sesquiterpene lactones and diterpenes, of the kaurane and pimarane-type, are the main compounds produced by these plants. Some reports have shown that kaurane- and pimarane-type diterpenes exert several biological activities such as anti-inflammatory action, antimicrobial and antispasmodic activities. Kaurenoic and pimaradienoic acids, which are the main secondary metabolites isolated by our research group from the roots of Viguiera robusta and V. arenaria, respectively, have been evaluated on vascular smooth muscle contractility. We showed that these diterpenoids are able to inhibit the vascular contractility mainly by blocking extracellular Ca(2+) influx. Additionally, in this review we discuss the structure-activity relationship of the diterpenes regarding their inhibitory activity on vascular contractility.
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Affiliation(s)
- Sergio R Ambrosio
- Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto - Universidade de São Paulo (USP), Ribeirão Preto, Brazil
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Jurkiewicz NH, Caricati-Neto A, Verde LF, Avellar MCW, Reuter HR, Jurkiewicz A. Sympathetic neurotransmission in the rat testicular capsule: functional characterization and identification of mRNA encoding alpha1-adrenoceptor subtypes. Eur J Pharmacol 2006; 543:141-50. [PMID: 16822496 DOI: 10.1016/j.ejphar.2006.05.045] [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: 03/02/2006] [Revised: 05/11/2006] [Accepted: 05/19/2006] [Indexed: 12/01/2022]
Abstract
The rat testicular capsule is a thin tissue surrounding the testis, whose precise function is still unknown. We have studied the contractile effects of electrical field stimulation, noradrenaline, and the blockade by antagonists of adrenergic receptors, in order to characterize sympathetic neurotransmission, and adrenoceptor subtypes. In addition, reverse transcription polymerase chain reaction (RT-PCR) assays were made to check for the expression of the three known subtypes of alpha(1)-adrenoceptors. The effects of electrical field stimulation (2 to 20 Hz, 1 ms, 60 V) were almost totally abolished by depletion of neuronal noradrenaline storage with reserpine (10 mg/Kg), but not by the purinergic receptor antagonist suramin (10(-5) M), indicating that noradrenaline, but not ATP, was involved in contractions. The selective alpha(1)-adrenoceptor antagonist prazosin (10(-7) M) was more effective than the selective alpha(2)-adrenoceptor antagonist idazoxan (10(-7) M) to inhibit contractions induced by electrical field stimulation, pointing out a major involvement of alpha(1)-adrenoceptor. When noradrenaline was used instead of electrical field stimulation, it showed a high potency (pD(2)=7.9). Noradrenaline-induced contractions were competitively blocked by the selective alpha(1A)-adrenoceptor antagonists WB 4101 (pA(2)=8.88), phentolamine (pA(2)=8.39) and by the alpha(1B)-adrenoceptor antagonist spiperone (pA(2)=8.57), indicating the presence of functional alpha(1A)- and alpha(1B)-adrenoceptors. In addition, contractions were not blocked by the selective alpha(1D)-adrenoceptor antagonist BMY 7378 (up to 10(-6) M), while selective alpha(2)-adrenoceptor antagonists showed low pA(2) values (yohimbine, 7.25 and idazoxan, 7.49), suggesting a minor role, if any, for alpha(1D)- and alpha(2)-adrenoceptors. To check the proportionate role of alpha(1A)- and alpha(1B)-adrenoceptors, we blocked alpha(1B)-adrenoceptors with chloroethylclonidine (CEC, 30 microM, 45 min), that reduced the maximal effect of noradrenaline by about 60%. The remnant CEC-insensitive noradrenaline contraction was assumed to be unrelated to alpha(1B)-adrenoceptor, and was inhibited by 5-methyl-urapidil (pA(2)=8.94) and by the Ca(2+) channel blocker nifedipine (3 microM), confirming the involvement of alpha(1A)-adrenoceptors. The presence of mRNA encoding alpha(1A)- and alpha(1B)-adrenoceptor was also shown on RT-PCR assays. Unexpectedly, alpha(1D)-transcripts were also detected in these assays. Taken together, our results show that ATP co-transmission could not be detected, and that neurotransmission involves the interaction of noradrenaline with both alpha(1A)- and alpha(1B)-, but not with alpha(1D)- or alpha(2)-adrenoceptor. The fact that the functional alpha(1D)-adrenoceptor could not be detected in spite of the presence of the corresponding mRNA, remains to be investigated.
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MESH Headings
- Acetyl-CoA C-Acyltransferase/metabolism
- Adenosine Triphosphate/metabolism
- Adrenergic Uptake Inhibitors/pharmacology
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Calcium Channel Blockers/pharmacology
- Clonidine/analogs & derivatives
- Clonidine/pharmacology
- Dioxanes/pharmacology
- Dose-Response Relationship, Drug
- Electric Stimulation
- Male
- Muscle Contraction/drug effects
- Nifedipine/pharmacology
- Norepinephrine/metabolism
- Norepinephrine/pharmacology
- Prazosin/pharmacology
- Purinergic P2 Receptor Antagonists
- RNA, Messenger/analysis
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Purinergic P2/metabolism
- Reserpine/pharmacology
- Reverse Transcriptase Polymerase Chain Reaction
- Spiperone/pharmacology
- Suramin/pharmacology
- Sympathetic Nervous System/drug effects
- Sympathetic Nervous System/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Testis/drug effects
- Testis/innervation
- Testis/metabolism
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Hosoda C, Tanoue A, Shibano M, Tanaka Y, Hiroyama M, Koshimizu TA, Cotecchia S, Kitamura T, Tsujimoto G, Koike K. Correlation between vasoconstrictor roles and mRNA expression of alpha1-adrenoceptor subtypes in blood vessels of genetically engineered mice. Br J Pharmacol 2006; 146:456-66. [PMID: 16113694 PMCID: PMC1576278 DOI: 10.1038/sj.bjp.0706325] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We examined the contribution of each alpha(1)-adrenoceptor (AR) subtype in noradrenaline (NAd)-evoked contraction in the thoracic aortas and mesenteric arteries of mice. Compared with the concentration-response curves (CRCs) for NAd in the thoracic aortas of wild-type (WT) mice, the CRCs of mutant mice showed a significantly lower sensitivity. The pD(2) value in rank order is as follows: WT mice (8.21) > alpha(1B)-adrenoceptor knockout (alpha(1B)-KO) (7.77) > alpha(1D)-AR knockout (alpha(1D)-KO) (6.44) > alpha(1B)- and alpha(1D)-AR double knockout (alpha(1BD)-KO) (5.15). In the mesenteric artery, CRCs for NAd did not differ significantly between either WT (6.52) and alpha(1B)-KO mice (7.12) or alpha(1D)-KO (6.19) and alpha(1BD)-KO (6.29) mice. However, the CRC maximum responses to NAd in alpha(1D)- and alpha(1BD)-KO mice were significantly lower than those in WT and alpha(1B)-KO mice. Except in the thoracic aortas of alpha(1BD)-KO mice, the competitive antagonist prazosin inhibited the contraction response to NAd with high affinity. However, prazosin produced shallow Schild slopes in the vessels of mice lacking the alpha(1D)-AR gene. In the thoracic aorta, pA(2) values in WT mice for KMD-3213 and BMY7378 were 8.25 and 8.46, respectively, and in alpha(1B)-KO mice they were 8.49 and 9.13, respectively. In the mesenteric artery, pA(2) values in WT mice for KMD-3213 and BMY7378 were 8.34 and 7.47, respectively, and in alpha(1B)-KO mice they were 8.11 and 7.82, respectively. These pharmacological findings were in fairly good agreement with findings from comparison of CRCs, with the exception of the mesenteric arteries of WT and alpha(1B)-KO mice, which showed low affinities to BMY7378. We performed a quantitative analysis of the mRNA expression of each alpha(1)-AR subtype in these vessels in order to examine the correlation between mRNA expression level and the predominance of each alpha(1)-AR subtype in mediating vascular contraction. The rank order of each alpha(1)-AR subtype in terms of its vasoconstrictor role was in fairly good agreement with the level of expression of mRNA of each subtype, that is, alpha(1D)-AR > alpha(1B)-AR > alpha(1A)-AR in the thoracic aorta and alpha(1D)-AR > alpha(1A)-AR > alpha(1B)-AR in the mesenteric artery. No dramatic compensatory change of alpha(1)-AR subtype in mutant mice was observed in pharmacological or quantitative mRNA expression analysis.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiology
- Gene Expression Regulation/drug effects
- In Vitro Techniques
- Indoles/pharmacology
- Male
- Mesenteric Arteries/drug effects
- Mesenteric Arteries/metabolism
- Mesenteric Arteries/physiology
- Mice
- Mice, Knockout
- Norepinephrine/pharmacology
- Piperazines/pharmacology
- Prazosin/pharmacology
- RNA, Messenger/analysis
- RNA, Messenger/metabolism
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-1/physiology
- Vasoconstriction/drug effects
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Affiliation(s)
- Chihiro Hosoda
- Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan
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39
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Affiliation(s)
- H Glossmann
- Institut für Biochemische Pharmakologie der Leopold-Franzens-Universität Innsbruck, Austria
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40
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Exton JH. The roles of calcium and phosphoinositides in the mechanisms of alpha 1-adrenergic and other agonists. Rev Physiol Biochem Pharmacol 2005; 111:117-224. [PMID: 2906170 DOI: 10.1007/bfb0033873] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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41
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Hoque A, Owen JR, Bates JN, Lewis SJ. Effects of Thiol Chelation on α1-Adrenoceptor-Induced Vasoconstriction In Vivo. J Cardiovasc Pharmacol 2005; 46:627-36. [PMID: 16220070 DOI: 10.1097/01.fjc.0000181718.25323.91] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The aims of this study were to determine whether systemic injections of the lipophobic thiol chelator, para-hydroxymercurobenzoic acid (PHMBA) would reduce the vasoconstrictor responses elicited by the alpha1-adrenoceptor agonist, phenylephrine, in urethane-anesthetized rats by chelation of thiol residues in alpha1-adrenoceptors in vascular smooth muscle rather than voltage-sensitive Ca(2+)-channels (Ca(2+)VERSUS-channels). The magnitudes and durations of the vasoconstrictor responses elicited by phenylephrine were markedly reduced after the injections of PHMBA. In contrast, the maximal phenylephrine-induced responses were not affected whereas the durations of these responses were markedly attenuated after injection of the Ca(2+)VERSUS-channel blocker, nifedipine. Nifedipine elicited pronounced and sustained falls in mean arterial blood pressure and vascular resistances in PHMBA-treated rats. Moreover, the vasodilator actions of the nitric oxide-donor, sodium nitroprusside were minimally attenuated by PHMBA whereas they were markedly attenuated by nifedipine. These findings support evidence that the vasoconstrictor responses due to activation of alpha1-adrenoceptors are initiated by mobilization of intracellular pools of Ca(2+) whereas they are sustained by opening of Ca(2+)VERSUS-channels. These findings also suggest that PHMBA diminishes the vasoconstrictor effects of phenylephrine by chelation of thiol residues in alpha1-adrenoceptors rather than by blockade of Ca(2+)VERSUS-channels, and that chelation of these thiol residues prevents agonist occupation and/or activation of these receptors and subsequent mobilization of intracellular pools of Ca(2+).
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Affiliation(s)
- Azizul Hoque
- Department of Cardiology, University of Louisville, Louisville, KY, USA
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42
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Lewis SJ, Hoque A, Walton TM, Kooy NW. Potential role of nitration and oxidation reactions in the effects of peroxynitrite on the function of β-adrenoceptor sub-types in the rat. Eur J Pharmacol 2005; 518:187-94. [PMID: 16043170 DOI: 10.1016/j.ejphar.2005.06.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 06/14/2005] [Accepted: 06/20/2005] [Indexed: 11/26/2022]
Abstract
This study examined the hemodynamic responses elicited by the beta-adrenoceptor agonist, isoproterenol (1 and 10 microg/kg, i.v.) before and after administration of (i) peroxynitrite (10 x 10 micromol/kg, i.v.), (ii) the thiol chelator, para-hydroxymercurobenzoic acid (pHMBA, 75 micromol/kg, i.v.), and (iii) the electron acceptor, nitroblue tetrazolium (NBT, 10 micromol/kg, i.v.) in pentobarbital-anesthetized rats. The tachycardia elicited by the lower dose of isoproterenol was diminished whereas the tachycardia elicited by the higher dose was not attenuated after administration of peroxynitrite. The falls in hindquarter and renal vascular resistances elicited by both doses of isoproterenol were substantially diminished whereas the isoproterenol-induced falls in mesenteric vascular resistance were not changed after administration of peroxynitrite. All of the isoproterenol-induced responses were markedly attenuated after administration of pHMBA or NBT. These findings suggest that the oxidation and/or nitration of beta-adrenoceptors impair the ability of isoproterenol to bind to and/or activate these G protein-coupled receptors. beta1-, beta2- and beta3-adrenoceptors contain extracellular cysteine residues susceptible to oxidation (i.e., disulfide-bridge formation) whereas only the beta1- and beta2-adrenoceptors contain extracellular tyrosine residues susceptible to nitration. These findings also suggest that sustained impairment of beta1- and beta2-adrenoceptor function by peroxynitrite is due to nitration of extracellular tyrosine residues in these receptors. By analogy, beta3-adrenoceptors may not be permanently affected by peroxynitrite because these receptors are devoid of extracellular tyrosine residues.
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Affiliation(s)
- Stephen J Lewis
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389, USA.
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43
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Coutinho-Silva R, Knight GE, Burnstock G. Impairment of the splenic immune system in P2X2/P2X3 knockout mice. Immunobiology 2005; 209:661-8. [PMID: 15804044 DOI: 10.1016/j.imbio.2004.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The isolated spleens from male and female mice lacking P2X(2) and P2X(3) receptors (P2X(2)/P2X(3) knockout (KO) mice) and those from wild-type (WT) mice were investigated by flow cytometry, immunohistochemistry and functionally by organ-bath pharmacology. The spleens from the P2X(2)/P2X(3) KO mice weighed significantly more than the corresponding WT mice. Flow cytometry was used to isolate the mononuclear cells, which were then phenotyped. T-lymphocytes, B-lymphocytes and macrophages were identified and counted. It was found that the increase in size of the spleens from the KO animals corresponded to an increase in the numbers of mononuclear cells present and that all three cell types (T-lymphocytes, B-lymphocytes and macrophages) increased in much the same proportion as those from the WT animals. Immunohistochemical localisation of P2Y(1), P2Y(2) and P2X(1) receptors revealed their presence on the spleen capsule and trabeculae. P2X(1) receptors were also present on blood vessels. There was no difference in the expression of these receptors between the WT and P2X(2)/P2X(3) KO spleens. Functional studies revealed the presence of multiple P2 receptors inducing the contraction of the spleen capsule, from both WT and KO mice. There was no difference in the contractions induced by adenosine 5'-triphosphate (ATP), alpha,beta-methylene ATP, 2-methylthio ADP or uridine triphosphate from WT and KO mice. It is concluded that mice lacking both P2X(2) and P2X(3) receptors have enlarged spleens and that this is correlated with an increase in the number of immune cells, perhaps as a consequence of a compromised immune system and chronic infection.
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Affiliation(s)
- Robson Coutinho-Silva
- Autonomic Neuroscience Institute, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK
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44
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Hieble JP, Ruffolo RR. Recent advances in the identification of a 1- and a 2-adrenoceptor subtypes: therapeutic implications. Expert Opin Investig Drugs 2005; 6:367-87. [PMID: 15989605 DOI: 10.1517/13543784.6.4.367] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cloning of multiple subtypes of both alpha1- and alpha2-adrenoceptors has renewed interest in the therapeutic application of agents interacting with these receptors. Effort has primarily been directed towards the design of uroselective alpha1-adrenoceptor antagonists for the treatment of benign prostatic hyperplasia (BPH). Evidence is accumulating for the involvement of a novel alpha1-adrenoceptor, designated as alpha1L-adrenoceptor, in alpha1-adrenoceptor-mediated smooth muscle contraction in prostatic and other urogenital tissues. While several antagonists showing a high degree of uroselectivity in animal models have been identified, their clinical superiority over the currently available alpha1-adrenoceptor antagonists has not yet been demonstrated. It is possible that the interaction with alpha1-adrenoceptors, as yet uncharacterised subtypes, at non-prostatic sites contributes to the therapeutic activity of this drug class in BPH. The alpha1-adrenoceptor subtypes involved in the control of vascular tone are currently being evaluated, and the profile of interaction with the various alpha1-adrenoceptor subtypes may play a key role in the efficacy of cardiovascular drugs such as carvedilol. Alpha2-adrenoceptor agonists are now being employed for a variety of therapeutic applications, most involving actions on receptors within the central nervous system (CNS). These agents are useful in the treatment of hypertension, glaucoma, opiate withdrawal and attention deficit hyperactivity disorder (ADHD), and as analgesics and adjuncts to general anaesthesia. While subtype selectivity has not yet been applied to the design of new alpha2-adrenoceptor agonists for these applications, recent gene mutation/knock-out experiments have identified the alpha2-subtypes involved in some of these actions, and optimisation of a therapeutic profile may be possible. Furthermore, the design of agents combining affinities for multiple adrenoceptor subtypes, or the combination of a specific adrenoceptor affinity profile with another pharmacological action, may offer advantages over molecules selective for an individual adrenoceptor subtype.
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Affiliation(s)
- J P Hieble
- Division of Pharmacological Sciences, SmithKline Beecham Pharmaceuticals, 709 Swedeland Road, King of Prussia, PA 19406, USA
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45
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Zhang Y, Yan J, Chen K, Song Y, Lu Z, Chen M, Han C, Zhang Y. Different roles of alpha1-adrenoceptor subtypes in mediating cardiomyocyte protein synthesis in neonatal rats. Clin Exp Pharmacol Physiol 2005; 31:626-33. [PMID: 15479171 DOI: 10.1111/j.1440-1681.2004.04063.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
1. Three different alpha1-adrenoceptor subtypes, designated alpha1A, alpha1B and alpha1D, have been cloned and identified pharmacologically in cardiomyocytes. In vitro studies have suggested that alpha1-adrenoceptors play an important role in facilitating cardiac hypertrophy. However, it remains controversial as to which subtype of alpha1-adrenoceptors is involved in this response. In the present study, we investigated the different role of each alpha1-adrenoceptor subtype in mediating cardiomyocyte protein synthesis, which is a most important characteristic of cardiac hypertrophy in cultured neonatal rat cardiomyocytes. 2. Cardiomyocyte hypertrophy was monitored by the following characteristic phenotypic changes: (i) an increase in protein synthesis; (ii) an increase in total protein content; and (iii) an increase in cardiomyocyte size. 3. The role of each alpha1-adrenoceptor subtype in mediating cardiomyocyte protein synthesis was investigated by the effect of specific alpha1-adrenoceptor subtype-selective antagonists on noradrenaline-induced [3H]-leucine incorporation. In addition, pKB values for alpha1-adrenoceptor subtype-selective antagonists were calculated and compared with the corresponding pKi values to further identify their effects. 4. Activation of alpha1-adrenoceptors by phenylephrine or noradrenaline in the presence of propranolol significantly increased [3H]-leucine incorporation, protein content and cell size. 5. Pre-incubating cardiomyocytes with 5-methyl-urapidil, RS 17053 or WB 4101 significantly inhibited noradrenaline-induced [3H]-leucine incorporation. However, there was no effect when cardiomyocytes were pre-incubated with BMY 7378. The correlation coefficients between pKB values for alpha1-adrenoceptor subtype-selective antagonists and pKi values obtained from cloned alpha1A-, alpha1B- or alpha1D-adrenoceptors were 0.92 (P <0.01), 0.66 (P >0.05) and 0.24 (P >0.05), respectively. 6. Our results suggest that the alpha1-adrenoceptor is dominantly responsible for adrenergic hypertrophy of cultured cardiomyocytes in neonatal rats. The efficiency in mediating cardiomyocyte protein synthesis is alpha1A > alpha1B >> alpha1D.
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Affiliation(s)
- Yongzhen Zhang
- Institute of Vascular Medicine, Peking University Third Hospital and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, PR China.
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46
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Tambaro S, Ruiu S, Dessi C, Mongeau R, Marchese G, Pani L. Evaluation of tamsulosin and alfuzosin activity in the rat vas deferens: relevance to ejaculation delays. J Pharmacol Exp Ther 2004; 312:710-7. [PMID: 15470085 DOI: 10.1124/jpet.104.074740] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of two alpha-adrenergic receptor antagonists widely employed in the therapy of benign prostatic hyperplasia, tamsulosin [(-)-(R)-5-[2-[[2-(0-ethoxyphenoxy) ethyl]amino]propyl]-2-methoxybenzenesulfonamide] and alfuzosin [(+/-)-N-[3-[(4-amino-6,7-dimethoxy-2-quinazolinyl) methylamino]propyl] tetrahydro-2-furancarboxamide], was investigated in the rat vas deferens. Because several clinical studies have shown that tamsulosin causes ejaculatory disorders, this study also evaluated the possible mechanisms implicated in these disorders by comparing the effect of tamsulosin with that of alfuzosin. Tamsulosin competitively antagonized the contractions induced by noradrenaline in vitro in the epididymal portion of the vas deferens with a potency pA(2) value of 9.2 +/- 0.8. In the prostatic portion, tamsulosin increased the amplitude of intermittent spikes induced by exogenous noradrenaline (100-1000 microM). In both portions of the vas deferens, alfuzosin behaved as an alpha-adrenergic antagonist blocking the contractions induced by exogenous noradrenaline without altering spikes. The administration of tamsulosin (3 microg/kg i.v.) significantly reduced the contractions evoked by electrical pulses in the epididymal portion, whereas it increased those produced in the prostatic portion. Intravenous tamsulosin antagonized the contraction produced by exogenous noradrenaline, whereas alfuzosin administration (10 microg/kg i.v.) did not change the electrically induced contractions in both portions of the rat vas deferens and did not antagonize the contractions produced by exogenous noradrenaline. The fact that tamsulosin unusually enhances noradrenaline-induced intermittent spike contractions and nerve stimulation-induced twitches in the prostatic portions might be linked to its greater propensity to cause sexual dysfunctions.
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Affiliation(s)
- Simone Tambaro
- Neuroscienze PharmaNess Scarl, Via Palabanda 9, 09124 Calgliari, Italy
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47
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Zacharia J, Hillier C, Macdonald A. Pharmacological characterization of α1-adrenoceptors in mouse isolated femoral small arteries. Eur J Pharmacol 2004; 503:155-63. [PMID: 15496310 DOI: 10.1016/j.ejphar.2004.09.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 09/06/2004] [Accepted: 09/10/2004] [Indexed: 11/19/2022]
Abstract
Arteries were isolated from male DBA/2 mice and mounted on a small vessel wire myograph for isometric recording. Responses to exogenous noradrenaline were inhibited with high affinity by prazosin (pKB, 9.3) and 5-methyl-urapidil (pKB, 9.2) and with low affinity by 8-[2-[4-(2-methoxyphenyl)-1 piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione (BMY 7378) (pA(2), 6.7). Chloroethylclonidine (10 microM) produced only a small reduction in the maximum response to noradrenaline. Responses to electrical field stimulation were also inhibited with high affinity by prazosin (pIC50, 9.3-9.5) and 5-methyl-urapidil (pIC50, 8.0-8.3). Responses were sensitive to BMY 7378 at low frequencies of stimulation (pIC50 at 2 Hz, 8.2) but not at high frequencies (pIC50 at 20 Hz, 6.5). In conclusion, contractions to exogenous and endogenous noradrenaline in mouse femoral small arteries are mediated mainly by alpha1A-adrenoceptors. alpha1D-adrenoceptors are not involved in responses to exogenous noradrenaline but appear to be activated by neurally released noradrenaline at a low frequency of stimulation.
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Affiliation(s)
- Joseph Zacharia
- Department of Biological and Biomedical Sciences, School of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland, UK
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Cleary L, Slattery J, Bexis S, Docherty JR. Sympathectomy reveals alpha 1A- and alpha 1D-adrenoceptor components to contractions to noradrenaline in rat vas deferens. Br J Pharmacol 2004; 143:745-52. [PMID: 15451776 PMCID: PMC1575931 DOI: 10.1038/sj.bjp.0705987] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We have previously demonstrated that contractions of rat vas deferens to exogenous noradrenaline involve predominantly alpha(1A)-adrenoceptors, but that contractions to endogenous noradrenaline involve predominantly alpha(1D)-adrenoceptors. In this study, we have examined the effects of sympathectomy on the subtypes of alpha(1)-adrenoceptor in rat vas deferens in radioligand binding and functional studies. In vehicle-treated tissues, antagonist displacement of [(3)H]prazosin binding to alpha(1)-adrenoceptors was consistent with a single population of alpha(1)-adrenoceptors. Binding affinities for a range of alpha(1)-adrenoceptor antagonists were expressed as pK(i) values and correlated with known affinities for alpha(1)-adrenoceptor subtypes. The correlation was significant only with alpha(1A)-adrenoceptors. In tissues from rats sympathectomised with 6-hydroxy-dopamine (2 x 100 mg kg(-1) i.p.), binding affinity for the alpha(1D)-adrenoceptor antagonist BMY 7378 fitted best with a two-site model. In functional studies, the potency of noradrenaline at producing total (phasic plus tonic) but not tonic contractions was increased in tissues from sympathectomised rats. Results obtained from sympathectomised rats suggest that phasic contractions are mainly alpha(1D)-adrenoceptor mediated, whereas tonic contractions are mainly alpha(1A)-adrenoceptor mediated, based on the effects of BMY 7378 and the alpha(1A)-adrenoceptor antagonist RS 100329. It is concluded that the predominant alpha(1)-adrenoceptor in vehicle-treated rat vas deferens is the alpha(1A)-adrenoceptor, both in terms of ligand binding and contractions to exogenous agonists. The alpha(1D)-adrenoceptor is only detectable by ligand binding following chemical sympathectomy, but is involved in noradrenaline-evoked contractions, particularly phasic contractions, of rat vas deferens.
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Affiliation(s)
- Linda Cleary
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
| | - James Slattery
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
| | - Sotiria Bexis
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
| | - James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin 2, Ireland
- Author for correspondence:
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Armenia A, Munavvar AS, Abdullah NA, Helmi A, Johns EJ. The contribution of adrenoceptor subtype(s) in the renal vasculature of diabetic spontaneously hypertensive rats. Br J Pharmacol 2004; 142:719-26. [PMID: 15172958 PMCID: PMC1575052 DOI: 10.1038/sj.bjp.0705842] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Diabetes and hypertension are both associated with an increased risk of renal disease and are associated with neuropathies, which can cause defective autonomic control of major organs including the kidney. This study aimed to examine the alpha(1)-adrenoceptor subtype(s) involved in mediating adrenergically induced renal vasoconstriction in a rat model of diabetes and hypertension. 2. Male spontaneously hypertensive rats (SHR), 220-280 g, were anaesthetized with sodium pentobarbitone 7-day poststreptozotocin (55 mg x kg(-1) i.p.) treatment. The reductions in renal blood flow (RBF) induced by increasing frequencies of electrical renal nerve stimulation (RNS), close intrarenal bolus doses of noradrenaline (NA), phenylephrine (PE) or methoxamine were determined before and after administration of nitrendipine (Nit), 5-methylurapidil (5-MeU), chloroethylclonidine (CEC) and BMY 7378. 3. In the nondiabetic SHR group, mean arterial pressure (MAP) was 146+/-6 mmHg, RBF was 28.0+/-1.4 ml x min(-1) x kg(-1) and blood glucose was 112.3+/-4.7 mg x dl(-1), and in the diabetic SHR Group, MAP was 144+/-3 mmHg, RBF 26.9+/-1.3 ml(-1) min x kg(-1) and blood glucose 316.2+/-10.5 mg x dl(-1). Nit, 5-MeU and BMY 7378 blunted all the adrenergically induced renal vasoconstrictor responses in SHR and diabetic SHR by 25-35% (all P<0.05), but in diabetic rats the responses induced by RNS and NA treated with 5-MeU were not changed. By contrast, during the administration of CEC, vasoconstrictor responses to all agonists were enhanced by 20-25% (all P<0.05) in both the SHR and diabetic SHR. 4. These findings suggest that alpha(1A) and alpha(1D)-adrenoceptor subtypes contribute in mediating the adrenergically induced constriction of the renal vasculature in both the SHR and diabetic SHR. There was also an indication of a greater contribution of presynaptic adrenoceptors, that is, alpha(1B)-, and/or alpha(2)-subtypes.
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MESH Headings
- Animals
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Clonidine/administration & dosage
- Clonidine/analogs & derivatives
- Clonidine/pharmacokinetics
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/physiopathology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Electric Stimulation/methods
- Infusions, Intravenous
- Injections, Intraperitoneal
- Injections, Intravenous
- Kidney/blood supply
- Kidney/innervation
- Kidney/physiopathology
- Kidney Cortex/blood supply
- Kidney Cortex/drug effects
- Malaysia
- Male
- Methoxamine/administration & dosage
- Methoxamine/antagonists & inhibitors
- Methoxamine/pharmacokinetics
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiopathology
- Nitrendipine/administration & dosage
- Nitrendipine/pharmacokinetics
- Norepinephrine/administration & dosage
- Norepinephrine/pharmacokinetics
- Phenylephrine/administration & dosage
- Phenylephrine/antagonists & inhibitors
- Phenylephrine/pharmacokinetics
- Piperazines/administration & dosage
- Piperazines/pharmacokinetics
- Rats
- Rats, Inbred SHR
- Receptors, Adrenergic, alpha-1/classification
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
- Streptozocin/administration & dosage
- Streptozocin/adverse effects
- Time Factors
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
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Affiliation(s)
- A Armenia
- School of Pharmaceutical Sciences, University of Science Malaysia, 11800 Penang, Malaysia
| | - A S Munavvar
- School of Pharmaceutical Sciences, University of Science Malaysia, 11800 Penang, Malaysia
| | - N A Abdullah
- Department of Pharmacology, Medical Faculty, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - A Helmi
- School of Pharmaceutical Sciences, University of Science Malaysia, 11800 Penang, Malaysia
| | - E J Johns
- Department of Physiology, University College Cork, Sir Bertram Windle Building, Cork, Ireland
- Author for correspondence:
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Oriowo MA, Chandrasekhar B, Kadavil EA. α1-adrenoceptor subtypes mediating noradrenaline-induced contraction of pulmonary artery from pulmonary hypertensive rats. Eur J Pharmacol 2003; 482:255-63. [PMID: 14660030 DOI: 10.1016/j.ejphar.2003.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of monocrotaline-induced pulmonary hypertension on alpha(1)-adrenoceptor-mediated contractions of pulmonary artery segments was studied. In control and monocrotaline-treated rats, noradrenaline evoked concentration-dependent contractions of the pulmonary artery. There was no change in the potency and affinity of noradrenaline but the maximum response and receptor reserve were significantly reduced. Noradrenaline-induced contractions were competitively antagonized by prazosin, 2-(2-6dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride (WB 4101) and 8-[2-[4-(2methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9 dione dihydrochloride (BMY 7378) with pA(2) values of 9.64+/-0.16, 9.45+/-0.10 and 8.30+/-0.14, respectively. These antagonists also competitively antagonized noradrenaline-induced contractions of pulmonary artery segments isolated from rats with monocrotaline-induced pulmonary hypertension. The pA(2) values were 9.66+/-0.11 (prazosin), 9.62+/-0.09 (WB 4101) and 8.47+/-0.15 (BMY 7378). Chloroethylclonidine (CEC) shifted noradrenaline concentration-response curve to the right and depressed the maximum response. There was no difference between the effects of CEC in both groups. It was therefore concluded that pulmonary hypertension significantly reduced noradrenaline-induced contractions of the rat pulmonary artery without affecting the sensitivity. Studies with receptor-selective antagonists confirmed that alpha(1)D-adrenoceptor subtype is the predominant receptor subtype in the pulmonary artery and this was maintained in this disease state.
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Affiliation(s)
- Mabayoje A Oriowo
- Department of Pharmacology and Toxicology, Faculty of Medicine, Kuwait University, P.O. Box 24923, 13110 Safat, Kuwait.
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