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The Adenosinergic System as a Therapeutic Target in the Vasculature: New Ligands and Challenges. Molecules 2017; 22:molecules22050752. [PMID: 28481238 PMCID: PMC6154114 DOI: 10.3390/molecules22050752] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/24/2017] [Accepted: 05/02/2017] [Indexed: 12/20/2022] Open
Abstract
Adenosine is an adenine base purine with actions as a modulator of neurotransmission, smooth muscle contraction, and immune response in several systems of the human body, including the cardiovascular system. In the vasculature, four P1-receptors or adenosine receptors—A1, A2A, A2B and A3—have been identified. Adenosine receptors are membrane G-protein receptors that trigger their actions through several signaling pathways and present differential affinity requirements. Adenosine is an endogenous ligand whose extracellular levels can reach concentrations high enough to activate the adenosine receptors. This nucleoside is a product of enzymatic breakdown of extra and intracellular adenine nucleotides and also of S-adenosylhomocysteine. Adenosine availability is also dependent on the activity of nucleoside transporters (NTs). The interplay between NTs and adenosine receptors’ activities are debated and a particular attention is given to the paramount importance of the disruption of this interplay in vascular pathophysiology, namely in hypertension., The integration of important functional aspects of individual adenosine receptor pharmacology (such as in vasoconstriction/vasodilation) and morphological features (within the three vascular layers) in vessels will be discussed, hopefully clarifying the importance of adenosine receptors/NTs for modulating peripheral mesenteric vascular resistance. In recent years, an increase interest in purine physiology/pharmacology has led to the development of new ligands for adenosine receptors. Some of them have been patented as having promising therapeutic activities and some have been chosen to undergo on clinical trials. Increased levels of endogenous adenosine near a specific subtype can lead to its activation, constituting an indirect receptor targeting approach either by inhibition of NT or, alternatively, by increasing the activity of enzymes responsible for ATP breakdown. These findings highlight the putative role of adenosinergic players as attractive therapeutic targets for cardiovascular pathologies, namely hypertension, heart failure or stroke. Nevertheless, several aspects are still to be explored, creating new challenges to be addressed in future studies, particularly the development of strategies able to circumvent the predicted side effects of these therapies.
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Sousa JB, Vieira-Rocha MS, Arribas SM, González MC, Fresco P, Diniz C. Endothelial and Neuronal Nitric Oxide Activate Distinct Pathways on Sympathetic Neurotransmission in Rat Tail and Mesenteric Arteries. PLoS One 2015; 10:e0129224. [PMID: 26075386 PMCID: PMC4468141 DOI: 10.1371/journal.pone.0129224] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/06/2015] [Indexed: 02/07/2023] Open
Abstract
Nitric oxide (NO) seems to contribute to vascular homeostasis regulating neurotransmission. This work aimed at assessing the influence of NO from different sources and respective intracellular pathways on sympathetic neurotransmission, in two vascular beds. Electrically-evoked [3H]-noradrenaline release was assessed in rat mesenteric and tail arteries in the presence of NO donors or endothelial/neuronal nitric oxide synthase (NOS) inhibitors. The influence of NO on adenosine-mediated effects was also studied using selective antagonists for adenosine receptors subtypes. Location of neuronal NOS (nNOS) was investigated by immunohistochemistry (with specific antibodies for nNOS and for Schwann cells) and Confocal Microscopy. Results indicated that: 1) in mesenteric arteries, noradrenaline release was reduced by NO donors and it was increased by nNOS inhibitors; the effect of NO donors was only abolished by the adenosine A1 receptors antagonist; 2) in tail arteries, noradrenaline release was increased by NO donors and it was reduced by eNOS inhibitors; adenosine receptors antagonists were devoid of effect; 3) confocal microscopy showed nNOS staining in adventitial cells, some co-localized with Schwann cells. nNOS staining and its co-localization with Schwann cells were significantly lower in tail compared to mesenteric arteries. In conclusion, in mesenteric arteries, nNOS, mainly located in Schwann cells, seems to be the main source of NO influencing perivascular sympathetic neurotransmission with an inhibitory effect, mediated by adenosine A1 receptors activation. Instead, in tail arteries endothelial NO seems to play a more relevant role and has a facilitatory effect, independent of adenosine receptors activation.
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Affiliation(s)
- Joana Beatriz Sousa
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- LAQV/REQUIMTE, University of Porto, Porto, Portugal
- * E-mail:
| | - Maria Sofia Vieira-Rocha
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- LAQV/REQUIMTE, University of Porto, Porto, Portugal
| | - Silvia M. Arribas
- Department of Physiology, Faculty of Medicine, Universidad Autónoma de Madrid, Madrid, Spain
| | - Maria Carmen González
- Department of Physiology, Faculty of Medicine, Universidad Autónoma de Madrid, Madrid, Spain
| | - Paula Fresco
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Carmen Diniz
- Laboratory of Pharmacology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal
- LAQV/REQUIMTE, University of Porto, Porto, Portugal
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Sousa JB, Fresco P, Diniz C. Endothelial dysfunction impairs vascular neurotransmission in tail arteries. Neurochem Int 2014; 80:7-13. [PMID: 25447765 DOI: 10.1016/j.neuint.2014.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 10/28/2014] [Accepted: 11/03/2014] [Indexed: 12/11/2022]
Abstract
The present study intends to clarify if endothelium dysfunction impairs vascular sympathetic neurotransmission. Electrically-evoked tritium overflow (100 pulses/5 Hz) was evaluated in arteries (intact and denuded) or exhibiting some degree of endothelium dysfunction (spontaneously hypertensive arteries), pre-incubated with [(3)H]-noradrenaline in the presence of enzymes (nitric oxide synthase (NOS); nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; xanthine oxidase; cyclooxygenase; adenosine kinase) inhibitors and a nucleoside transporter inhibitor. Inhibition of endothelial nitric oxide synthase with L-NIO dihydrochloride reduced tritium overflow in intact arteries whereas inhibition of neuronal nitric oxide synthase with Nω-Propyl-L-arginine hydrochloride was devoid of effect showing that only endothelial nitric oxide synthase is involved in vascular sympathetic neuromodulation. Inhibition of enzymes involved in reactive oxygen species or prostaglandins production with apocynin and allopurinol or indomethacin, respectively, failed to alter tritium overflow. A facilitation or reduction of tritium overflow was observed in the presence of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or of 5-iodotubericidin, respectively, but only in intact arteries. These effects can be ascribed to a tonic inhibitory effect mediated by A1 receptors. In denuded and hypertensive arteries, 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c] pyrimidine (SCH 58261) reduced tritium overflow, suggesting the occurrence of a tonic activation of A2A receptors. When endogenous adenosine bioavailability was increased by the nucleoside transporter inhibitor, S-(4-Nitrobenzyl)-6-thioinosine, tritium overflow increased in intact, denuded and hypertensive arteries. Among the endothelium-derived substances studied that could alter vascular sympathetic transmission only adenosine/adenosine receptor mediated mechanisms were clearly impaired by endothelium injury/dysfunction.
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Affiliation(s)
- Joana B Sousa
- REQUIMTE/FARMA, Laboratório de Farmacologia, Departamento de Ciências do Medicamento, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal; MedinUP- Centro de Investigação Farmacológica e Inovação Medicamentosa, Portugal
| | - Paula Fresco
- REQUIMTE/FARMA, Laboratório de Farmacologia, Departamento de Ciências do Medicamento, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal; MedinUP- Centro de Investigação Farmacológica e Inovação Medicamentosa, Portugal
| | - Carmen Diniz
- REQUIMTE/FARMA, Laboratório de Farmacologia, Departamento de Ciências do Medicamento, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal; MedinUP- Centro de Investigação Farmacológica e Inovação Medicamentosa, Portugal.
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Leal S, Sá C, Gonçalves J, Fresco P, Diniz C. Immunohistochemical characterization of adenosine receptors in rat aorta and tail arteries. Microsc Res Tech 2008; 71:703-9. [PMID: 18570336 DOI: 10.1002/jemt.20609] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Adenosine plays an important role in the cardiovascular system, activating adenosine A(1), A(2A), A(2B), and A(3) receptors, and regulating blood flow either by acting directly on vascular cells or indirectly because of its effects on the central or peripheral nervous systems. The aim of the present study was to investigate whether the pattern of distribution of adenosine receptor subtypes is different on elastic and muscular, using abdominal aorta and tail arteries as models. Immunohistochemistry using anti-A(1), anti-A(2A), anti-A(2B), and anti-A(3) receptor antibodies was performed on perfused-fixed/paraffin-embedded arteries from Wistar rats. 3,3'-Diaminobenzidine tetrahydrochloride (DAB; activated by hydrogen peroxide) staining revealed significant differences in the abundance of A(1), A(2A), and A(3) receptors between abdominal aorta and tail artery and allowed the identification of distinct distribution patterns for A(1), A(2A), A(2B), and A(3) receptors in the tunica adventitia, media, and intima of muscular and elastic arteries. Data are compatible with several previous functional reports supporting that different adenosine receptor subtype expression and/or their distribution in the vessel wall may influence their respective contribution to the control of blood flow.
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Affiliation(s)
- Sandra Leal
- Serviço de Farmacologia, REQUIMTE/FARMA, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, 164, P 4050-047 Porto, Portugal
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Diniz C, Fresco P, Leal S, Gonçalves J. Adenosine receptors involved in modulation of noradrenaline release in isolated rat tail artery. Eur J Pharmacol 2004; 504:17-25. [PMID: 15507216 DOI: 10.1016/j.ejphar.2004.09.048] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Revised: 05/16/2004] [Accepted: 09/21/2004] [Indexed: 11/24/2022]
Abstract
Adenosine receptors involved in the modulation of noradrenaline release from postganglionic sympathetic nerves in rat tail artery were characterized by studying the effects of adenosine-receptor agonists and antagonists on electrically evoked tritium overflow (100 pulses, 5 Hz) and by immunohistochemistry. The adenosine A1 receptor-selective agonist N6-cyclopentyladenosine (CPA; 1-100 nM) and the non-selective adenosine receptor agonist N-ethylcarboxamidoadenosine (NECA; 1-10 microM) decreased tritium overflow. These effects were blocked by the adenosine A1 receptor-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 30 nM). The adenosine A(2A) receptor-selective agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido adenosine (CGS 21680; 1-100 nM) enhanced tritium overflow, an effect blocked by the adenosine A(2A) receptor-selective antagonist 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH 58261; 20 nM) but not changed by the adenosine A(2B) receptor-selective antagonist N-(4-acetylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl) phenoxy]acetamide (MRS 1706; 20 nM). In the presence of DPCPX (30 nM), NECA enhanced tritium overflow, an effect abolished by MRS 1706 but not influenced by SCH 58261. Immunohistochemistry revealed immunoreactivity for all adenosine-receptor subtypes. Areas of co-localization were found for neurofilament with adenosine A1, A(2A) and A(2B) but not A3 receptors. In conclusion, the present study provides functional and morphological evidence for the occurrence of multiple adenosine receptor-mediated modulation of noradrenaline release in the rat tail: inhibition mediated by adenosine A1 receptors and facilitation mediated by both adenosine A(2A) and A(2B) receptors.
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Affiliation(s)
- Carmen Diniz
- Serviço de Farmacologia, CEQOFFUP, Faculdade de Farmácia, Universidade do Porto, Rua Anibal Cunha, 164, P 4050-047 Porto, Portugal
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Moura D, Pinheiro H, Paiva MQ, Guimarães S. Prejunctional effects of angiotensin II and bradykinin in the heart and blood vessels. JOURNAL OF AUTONOMIC PHARMACOLOGY 1999; 19:321-5. [PMID: 10961737 DOI: 10.1111/j.1365-2680.1999.tb00004.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. Angiotensin and bradykinin facilitate the release of noradrenaline from sympathetic nerve terminals and cause positive inotropy in rat isolated atria and ventricles. The effect of bradykinin was enhanced by the ACE inhibitor, ramiprilat. 2. The facilitated release of noradrenaline in rat ventricle by bradykinin was blocked by the beta2-receptor antagonist HOE-140. This response is also reduced by removing the endocardium, suggesting the release of a mediator from the endocardium. 3. The facilitated noradrenaline release by angiotensin II and bradykinin was blocked by the angiotensin receptor antagonist saralasin to the same extent. In contrast, losartan caused only minor blockade in a range of vascular and cardiac tissues. This suggests that angiotensin and bradykinin exert these responses by interacting with a prejunctional receptor different from the established AT1 subtype. 4. These results suggest that bradykinin mediates facilitation of noradrenaline release via the local release of angiotensin onto an atypical AT1 receptor.
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Affiliation(s)
- D Moura
- Institute of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal
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Vaz-da-Silva M, Magina S, Domingues-Costa A, Moura D. The role of the endocardium in the facilitatory effect of bradykinin on electrically-induced release of noradrenaline in rat cardiac ventricle. Br J Pharmacol 1996; 118:364-8. [PMID: 8735639 PMCID: PMC1909634 DOI: 10.1111/j.1476-5381.1996.tb15411.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. The present investigation was undertaken to study the role of bradykinin in noradrenaline release from the ventricle of the rat induced by electrical stimulation. Slices of the left ventricle of adult Wistar rats with or without endocardium were previously loaded with 0.2 microM [3H]-noradrenaline and washed out before electrical stimulation was applied. 2. Bradykinin (0.1-100 nM) concentration-dependently increased tritium release evoked by electrical stimulation (EC50 = 3.5 (1.2-10.2) nM; n = 12). The angiotensin converting enzyme inhibitor, captopril (1 microM), which per se had no effect on tritium release, caused a marked enhancement of the bradykinin facilitatory effect, shifting the concentration-response curve of bradykinin to the left by about one log unit. The compound Hoe 140, a selective inhibitor of B2-bradykinin receptors, competitively antagonized the effect of bradykinin, indicating the involvement of these receptors in the action of bradykinin. 3. In endocardium-free ventricle, bradykinin had no effect either in the absence or in the presence of captopril. 4. These results show that: (1) bradykinin is able to facilitate noradrenaline release evoked by electrical stimulation of the rat ventricle through activation of B2-bradykinin receptors located on endocardial cells; (2) this action of bradykinin which is markedly potentiated by the inhibition of the angiotensin-converting enzyme seems to be exerted through the release of some factor which is formed in the endocardium and diffuses into the myocardium where it acts.
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Affiliation(s)
- M Vaz-da-Silva
- Institute of Pharmacology and Therapeutics, Faculty of Medicine, Portugal
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