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Role of endothelin-1 clearance in the haemodynamic responses to endothelin-1 in the pulmonary and hindquarter vasculature of anaesthetised rats. Eur J Pharmacol 2019; 855:124-136. [DOI: 10.1016/j.ejphar.2019.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 05/03/2019] [Accepted: 05/03/2019] [Indexed: 11/17/2022]
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Angus JA, Hughes RJA, Wright CE. Distortion of K B estimates of endothelin-1 ET A and ET B receptor antagonists in pulmonary arteries: Possible role of an endothelin-1 clearance mechanism. Pharmacol Res Perspect 2018; 5. [PMID: 29226623 PMCID: PMC5723704 DOI: 10.1002/prp2.374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 10/23/2017] [Indexed: 11/08/2022] Open
Abstract
Dual endothelin ETA and ETB receptor antagonists are approved therapy for pulmonary artery hypertension (PAH). We hypothesized that ETB receptor‐mediated clearance of endothelin‐1 at specific vascular sites may compromise this targeted therapy. Concentration‐response curves (CRC) to endothelin‐1 or the ETB agonist sarafotoxin S6c were constructed, with endothelin receptor antagonists, in various rat and mouse isolated arteries using wire myography or in rat isolated trachea. In rat small mesenteric arteries, bosentan displaced endothelin‐1 CRC competitively indicative of ETA receptor antagonism. In rat small pulmonary arteries, bosentan 10 μmol L−1 left‐shifted the endothelin‐1 CRC, demonstrating potentiation consistent with antagonism of an ETB receptor‐mediated endothelin‐1 clearance mechanism. Removal of endothelium or L‐NAME did not alter the EC50 or Emax of endothelin‐1 nor increase the antagonism by BQ788. In the presence of BQ788 and L‐NAME, bosentan displayed ETA receptor antagonism. In rat trachea (ETB), bosentan was a competitive ETB antagonist against endothelin‐1 or sarafotoxin S6c. Modeling showed the importance of dual receptor antagonism where the potency ratio of ETA to ETB antagonism is close to unity. In conclusion, the rat pulmonary artery is an example of a special vascular bed where the resistance to antagonism of endothelin‐1 constriction by ET dual antagonists, such as bosentan or the ETB antagonist BQ788, is possibly due to the competition of potentiation of endothelin‐1 by blockade of ETB‐mediated endothelin‐1 clearance located on smooth muscle and antagonism of ETA‐ and ETB‐mediated contraction. This conclusion may have direct application for the efficacy of endothelin‐1 antagonists for treating PAH.
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Affiliation(s)
- James A Angus
- Cardiovascular Therapeutics Unit, Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Vic., Australia
| | - Richard J A Hughes
- Cardiovascular Therapeutics Unit, Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Vic., Australia
| | - Christine E Wright
- Cardiovascular Therapeutics Unit, Department of Pharmacology and Therapeutics, University of Melbourne, Melbourne, Vic., Australia
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Rapoport RM, Merkus D. Endothelin-1 Regulation of Exercise-Induced Changes in Flow: Dynamic Regulation of Vascular Tone. Front Pharmacol 2017; 8:517. [PMID: 29114220 PMCID: PMC5660699 DOI: 10.3389/fphar.2017.00517] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/24/2017] [Indexed: 12/12/2022] Open
Abstract
Although endothelin (ET)-1 is a highly potent vasoconstrictor with considerable efficacy in numerous vascular beds, the role of endogenous ET-1 in the regulation of vascular tone remains unclear. The perspective that ET-1 plays little role in the on-going regulation of vascular tone at least under physiologic conditions is supported by findings that potential ET-1 constriction is minimized by the release of the vasodilator and ET-1 synthesis inhibitor, nitric oxide (NO). Indeed, ET-1 release and constriction is self-limited by ET-1-induced, endothelial ETB receptor-mediated release of NO. Moreover, even if the balance between ET-1 and NO were reversed as the result of lowered NO activity, as occurs in a number of pathophysiologies associated with endothelial dysfunction, the well-known resistance of ET-1 constriction to reversal (as determined with exogenous ET-1) precludes ET-1 in the dynamic, i.e., moment-to-moment, regulation of vascular tone. On the other hand, and as presently reviewed, findings of ET-1-dependent modulation of organ blood flow with exercise under physiologic conditions demonstrate the dynamic regulation of vascular tone by ET-1. We speculate that this regulation is mediated at least in part through changes in ET-1 synthesis/release caused by pulsatile flow-induced shear stress and NO.
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Affiliation(s)
- Robert M Rapoport
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Thoraxcenter, Cardiovascular Research School COEUR, Erasmus University Medical School Rotterdam, Rotterdam, Netherlands
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Madsen KM, Neerhof MG, Wessale JL, Thaete, LG. Influence of ETB Receptor Antagonism on Pregnancy Outcome in Rats. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/107155760100800409] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
| | | | | | - Larry G. Thaete,
- Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, Northwestern University Medical School, Evanston Northwestern Healthcare, Evanston; Pharmaceutical Discovery, Abbott Laboratories, Abbott Park, Illinois
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Endothelin-1: Biosynthesis, Signaling and Vasoreactivity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 77:143-75. [PMID: 27451097 DOI: 10.1016/bs.apha.2016.05.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Endothelin-1 (ET-1) is an extremely potent vasoconstrictor peptide originally isolated from endothelial cells. Its synthesis, mainly regulated at the gene transcription level, involves processing of a precursor by a furin-type proprotein convertase to an inactive intermediate, big ET-1. The latter peptide can then be cleaved directly by an endothelin-converting enzyme (ECE) into ET-1 or reach the active metabolite through a two-step process involving chymase hydrolyzing big ET-1 to ET-1 (1-31), itself needing conversion to ET-1 by neprilysin (NEP) to exert physiological activity. ET-1 signals through two G protein-coupled receptors, endothelin receptor A (ETA) and endothelin receptor B (ETB). Both receptors induce an increase in intracellular Ca(2+), mainly from the extracellular space through voltage-independent mechanisms, the receptor-operated channels and store-operated channels. ET-1 also induces signaling through epidermal growth factor receptor transactivation, oxidative stress induction, rho-kinase, and the activation (ETA) or inhibition (ETB) of the adenylate cyclase/cyclic adenosine monophosphate pathway. Arterial vasoconstriction is mediated mainly by the ETA receptor. ET-1, via endothelium-located ETB, relaxes arteries or constricts vessels following activation of the same receptor type on the smooth muscle, where it can interact with ETA. In addition, ETB-dependent vasoconstriction seems more prominent in the venous vasculature. A better understanding of how ET-1 is synthesized and how ETA and ETB receptors interact could help design better pharmacological agents in the treatment of cardiovascular diseases where targeting the ET-1 system is indicated.
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Brochu I, Houde M, Desbiens L, Simard E, Gobeil F, Semaan W, Bkaily G, D'Orléans-Juste P. High salt-induced hypertension in B2 knockout mice is corrected by the ETA antagonist, A127722. Br J Pharmacol 2014; 170:266-77. [PMID: 23713522 DOI: 10.1111/bph.12259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 05/12/2013] [Accepted: 05/17/2013] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND PURPOSE The contribution of endothelin-1 (ET-1) in a B2KO mouse model of a high salt-induced arterial hypertension was investigated. EXPERIMENTAL APPROACH Wild-type (WT) or B2KO mice receiving a normal diet (ND) or a high-salt diet (HSD) were monitored by radiotelemetry up to a maximum of 18 weeks. At the 12th week of diet, subgroups under ND or HSD received by gavage the ETA antagonist A127722 during 5 days. In addition, blood samples were collected and, following euthanasia, the lungs, heart and kidneys were extracted, homogenized and assayed for ET-1 by RIA. In a separate series of experiments, the ETA antagonist, BQ123 was tested against the pressor responses to a NOS inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) in anaesthetized WT and B2KO mice. KEY RESULTS In B2KO, but not WT mice, 12 weeks of HSD triggered a maximal increase of the mean arterial pressure (MAP) of 19.1 ± 2.8 mmHg, which was corrected by A127722 to MAP levels found in B2KO mice under ND. Significant increases in immunoreactive ET-1 were detected only in the lungs of B2KO mice under HSD. On the other hand, metabolic studies showed that sodium urinary excretion was markedly reduced in B2KO compared with WT mice under ND. Finally, BQ123 (2 mg·kg(-1)) reduced by 50% the pressor response to L-NAME (2 mg·kg(-1)) in B2KO, but not WT mice under anaesthesia. CONCLUSIONS AND IMPLICATIONS Our results support the concept that functional B2 receptors oppose high salt-induced increments in MAP, which are corrected by an ETA receptor antagonist in this mouse model of experimental hypertension.
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Affiliation(s)
- I Brochu
- Department of Pharmacology, Medical School, Université de Sherbrooke, Sherbrooke, QC, Canada
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De Mey JGR, Vanhoutte PM. End o' the line revisited: moving on from nitric oxide to CGRP. Life Sci 2014; 118:120-8. [PMID: 24747136 DOI: 10.1016/j.lfs.2014.04.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 04/04/2014] [Accepted: 04/05/2014] [Indexed: 12/24/2022]
Abstract
When endothelin-1(ET-1) was discovered it was hailed as the prototypical endothelium-derived contracting factor (EDCF). However, over the years little evidence emerged convincingly demonstrating that the peptide actually contributes to moment-to-moment changes in vascular tone elicited by endothelial cells. This has been attributed to the profound inhibitory effect of nitric oxide (NO) on both the production (by the endothelium) and the action (on vascular smooth muscle) of ET-1. Hence, the peptide is likely to initiate acute changes in vascular diameter only under extreme conditions of endothelial dysfunction when the NO bioavailability is considerably reduced if not absent. The present essay discusses whether or not this concept should be revised, in particular in view of the potent inhibitory effect exerted by calcitonin gene related peptide (CGRP) released from sensorimotor nerves on vasoconstrictor responses to ET-1.
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Affiliation(s)
- Jo G R De Mey
- Institute of Molecular Medicine, University of South Denmark, Odense, Denmark; Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
| | - Paul M Vanhoutte
- Institute of Molecular Medicine, University of South Denmark, Odense, Denmark; Department of Pharmacology and Pharmacy and State Key Laboratory for Pharmaceutical Biotechnology, University of Hong Kong, Hong Kong, China.
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Rapoport RM. Acute nitric oxide synthase inhibition and endothelin-1-dependent arterial pressure elevation. Front Pharmacol 2014; 5:57. [PMID: 24744731 PMCID: PMC3978292 DOI: 10.3389/fphar.2014.00057] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/15/2014] [Indexed: 11/13/2022] Open
Abstract
Key evidence that endogenous nitric oxide (NO) inhibits the continuous, endothelin (ET)-1-mediated drive to elevate arterial pressure includes demonstrations that ET-1 mediates a significant component of the pressure elevated by acute exposure to NO synthase (NOS) inhibitors. This review examines the characteristics of this pressure elevation in order to elucidate potential mechanisms associated with the negative regulation of ET-1 by NO and, thereby, provide potential insight into the vascular pathophysiology underlying NO dysregulation. We surmise that the magnitude of the ET-1-dependent component of the NOS inhibitor-elevated pressure is (1) independent of underlying arterial pressure and other pressor pathways activated by the NOS inhibitors and (2) dependent on relatively higher NOS inhibitor dose, release of stored and de novo synthesized ET-1, and ETA receptor-mediated increased vascular resistance. Major implications of these conclusions include: (1) the marked variation of the ET-1-dependent component, i.e., from 0 to 100% of the pressure elevation, reflects the NO-ET-1 regulatory pathway. Thus, NOS inhibitor-mediated, ET-1-dependent pressure elevation in vascular pathophysiologies is an indicator of the level of compromised/enhanced function of this pathway; (2) NO is a more potent inhibitor of ET-1-mediated elevated arterial pressure than other pressor pathways, due in part to inhibition of intravascular pressure-independent release of ET-1. Thus, the ET-1-dependent component of pressure elevation in vascular pathophysiologies associated with NO dysregulation is of greater magnitude at higher levels of compromised NO.
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Affiliation(s)
- Robert M Rapoport
- Research Service, Department of Pharmacology and Cell Biophysics, Veterans Affairs Medical Center, University of Cincinnati College of Medicine Cincinnati, OH, USA
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Silva Marques J, Martins SR, Calisto C, Gonçalves S, Almeida AG, de Sousa JC, Pinto FJ, Diogo AN. An exploratory panel of biomarkers for risk prediction in pulmonary hypertension: emerging role of CT-proET-1. J Heart Lung Transplant 2013; 32:1214-21. [PMID: 23916896 DOI: 10.1016/j.healun.2013.06.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 05/24/2013] [Accepted: 06/20/2013] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Pulmonary arterial hypertension (PAH) is a rare, deadly condition. Although risk stratification is extremely important for assessment of prognosis and to guide therapy, there is lack of evidence concerning the role of novel biomarkers. In a pivotal study, we sought to comparatively investigate the predictive power of several new biomarkers in PAH. METHODS Patients with prevalent PAH were enrolled in the study protocol, which included clinical, functional and echocardiographic assessment. Blood samples were collected at baseline for determination of NT-proBNP, CT-proET-1, MR-proANP, MR-proADM, copeptin and troponin I. Patients were clinically followed-up up to 12 months for first occurrence of hospital admission due to PAH-related clinical worsening, heart/lung transplantation or all-cause mortality. RESULTS Among the 28 included patients the pre-specified end-point occurred in 8 (29% event rate). There were higher baseline levels of CT-proET-1, copeptin, MR-proANP, NT-proBNP and troponin I in patients who reached the composite end-point. They also had larger right atria. In multivariate Cox regression, CT-proET-1 was the only biomarker associated with increased hazard of reaching the primary composite end-point (hazard ratio per tertile increase = 10.1; 95% CI 2.0 to 50.6). CONCLUSIONS CT-proET-1 provided prognostic information independent of other biomarkers. Importantly, we have provided the first evidence that CT-proET-1 may be superior to commonly used biomarkers.
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Affiliation(s)
- João Silva Marques
- Department of Cardiology I, Lisbon Academic Medical Centre, Lisbon, Portugal.
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Bourque SL, Davidge ST, Adams MA. The interaction between endothelin-1 and nitric oxide in the vasculature: new perspectives. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1288-95. [PMID: 21368267 DOI: 10.1152/ajpregu.00397.2010] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) and endothelin-1 (ET-1) are natural counterparts in vascular function, and it is becoming increasingly clear that an imbalance between these two mediators is a characteristic of endothelial dysfunction and is important in the progression of vascular disease. Here, we review classical and more recent data that suggest that ET-1 should be regarded as an essential component of NO signaling. In particular, we review evidence of the role of ET-1 in models of acute and chronic NO synthase blockade. Furthermore, we discuss the possible mechanisms by which NO modulates ET-1 activity. On the basis of these studies, we suggest that NO tonically inhibits ET-1 function, and in conditions of diminished NO bioavailability, the deleterious effects of unmitigated ET-1 actions result in vasoconstriction and eventually lead to vascular remodeling and dysfunction.
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Affiliation(s)
- Stephane L Bourque
- Department of Obstetrics and Gynaecology, University of Alberta, Edmonton, Canada
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Boesen EI, Pollock JS, Pollock DM. Contrasting effects of intervention with ETA and ETB receptor antagonists in hypertension induced by angiotensin II and high-salt diet. Can J Physiol Pharmacol 2011; 88:802-7. [PMID: 20725138 DOI: 10.1139/y10-051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelin (ET) receptor antagonists are antihypertensive and renoprotective in angiotensin II (AngII)-induced hypertension if administered when AngII infusion commences, but their effects on established hypertension are poorly understood. We therefore tested the effects of intervening with an ETA (ABT-627) or ETB (A-192621) receptor antagonist after establishing hypertension with AngII (65 ng/min s.c.) plus 8% NaCl diet (AngII-HS) in rats. Prior to administration of ABT-627, AngII-HS and AngII-HS plus ABT-627 groups displayed robust hypertension (mean arterial pressure (MAP), 170 +/- 5 and 165 +/- 5 mm Hg versus 110 +/- 3 mm Hg in normal salt control rats at day 7, P < 0.05). Administering ABT-627 from day 8 of AngII-HS treatment prevented further rises in MAP (168 +/- 5 and 191 +/- 3 mm Hg at day 13 in AngII-HS plus ABT-627 and AngII-HS, P < 0.001), without blunting the significant increases in urinary protein (19-fold), albumin (25-fold), or MCP-1 excretion (6- to 8-fold) or the reduction in creatinine clearance. Administering A-192621 from day 8 mildly exacerbated AngII-HS induced hypertension (P < 0.05 for AngII-HS versus AngII-HS plus A-192621 on days 11 and 12 only) and reduced plasma nitrite/nitrate concentration (P < 0.05), without affecting proteinuria, albuminuria, or creatinine clearance. These results confirm the importance of ETA receptor signaling in maintaining AngII-HS hypertension and suggest that including ETB receptor blockade in therapeutic approaches to treating hypertension would be ineffective or even counterproductive.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Boulevard, Augusta, GA 30912, USA.
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Goyal SN, Bharti S, Arora S, Golechha M, Arya DS. Endothelin receptor antagonist BQ-123 ameliorates myocardial ischemic-reperfusion injury in rats: a hemodynamic, biochemical, histopathological and electron microscopic evidence. Biomed Pharmacother 2010; 64:639-46. [PMID: 20888175 DOI: 10.1016/j.biopha.2010.06.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 06/16/2010] [Indexed: 10/19/2022] Open
Abstract
We investigated the effect of BQ-123, a selective endothelin-A (ET(A)) receptor antagonist in ischemia-reperfusion (IR) induced myocardial infarction (MI) with and without endothelin-1 (ET-1) challenge. MI was produced in rats by occlusion of left anterior descending coronary artery for 40 min and reperfusion for 120 min. ET-1 was administered immediately prior to coronary occlusion whereas vehicle or BQ-123 was administered 20 min after the occlusion. IR control group exhibited marked hemodynamic changes along with significant impairment of left ventricular functions. In addition, oxidative stress was increased, as evidenced by marked reduction in the activities of antioxidants and cardiac injury markers in myocardium. Furthermore, light microscopic and ultrastructural changes revealed myocardial necrosis, edema and inflammation. Prior administration of ET-1 acts synergistically with IR injury and further aggravates the impairment of ventricular functions, increased percent infarct area and decreased antioxidant levels. However, treatment with BQ-123 (1 mg/kg, IV) with or without ET-1 caused significant improvement in cardiac functions, percent infarct area, decreased malonaldehyde level, restored myocardial enzymes activities and maintained the redox status of the myocardium as compared to IR control group. Further, histopathological and ultrastructural studies reconfirmed the protective action of BQ-123. The results of present study suggest that ET-1 acting via ET(A) receptor may exaggerate myocardial damage produced by IR injury and selective blockade of ET(A) receptor by BQ-123 might offer potential cardioprotective action.
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Affiliation(s)
- S N Goyal
- Cardiovascular Laboratory, Department of Pharmacology, All India Institute of Medical Sciences, New Delhi 110029, India
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D'Amours M, Chbinou N, Beaudoin J, Lebel M, Larivière R. Increased ET-1 and Reduced ETBReceptor Expression in Uremic Hypertensive Rats. Clin Exp Hypertens 2010; 32:61-9. [DOI: 10.3109/10641960902993095] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Vuckovic A, Rondelet B, Brion JP, Naeije R. Expression of vasoactive intestinal peptide and related receptors in overcirculation-induced pulmonary hypertension in piglets. Pediatr Res 2009; 66:395-9. [PMID: 19581838 DOI: 10.1203/pdr.0b013e3181b33804] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The pathobiology of pulmonary arterial hypertension (PAH) is not understood completely. Recent observations in patients with PAH and in knockout models have raised the idea that a defect in vasoactive intestinal peptide (VIP) may be involved in PAH physiopathology. Therefore, we investigated the expressions of VIP, the related pituitary adenylate cyclase-activating polypeptide (PACAP), and their receptors (VPAC1, VPAC2, and PAC1) in piglets with overcirculation-induced pulmonary hypertension as an early-stage PAH model. Seventeen piglets were randomized to an anastomosis between the innominate and the main pulmonary artery, or to a sham operation. After 3 mo, a hemodynamic evaluation was performed and the lung tissue was sampled for biologic and histologic studies. The shunting increased pulmonary vascular resistance (PVR) by 100% and arteriolar medial thickness by 85%. VIP and VPAC1 gene expressions were decreased and increased, respectively. VPAC1 gene expression was positively correlated to PVR. VPAC2 and PAC1 immunoreactivity was seen in pulmonary arterial smooth muscle. VIP and PACAP immunostaining was observed in nerve fibers surrounding the pulmonary arterial smooth muscle. In conclusion, overcirculation-induced pulmonary hypertension is accompanied by a down-regulation of VIP signaling, without change in PACAP expression. These results are consistent with the notion that abnormal VIP signaling takes part in PAH pathogenesis.
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Affiliation(s)
- Aline Vuckovic
- Laboratory of Physiology and Physiopathology, Université Libre de Bruxelles, B-1070 Brussels, Belgium.
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Labonté J, Brochu I, Simard E, D'Orléans-Juste P. Distinct modulation of the endothelin-1 pathway in iNOS-/- and eNOS-/- mice. Can J Physiol Pharmacol 2008; 86:516-25. [PMID: 18758499 DOI: 10.1139/y08-042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that constitutive endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) have opposite effects on the regulation of endothelin and its receptors. We therefore sought to determine whether deletions of iNOS or eNOS genes in mice modulate pressor responses to endothelin and the expression of ETA and ETB receptors in a similar fashion. Despite unchanged baseline hemodynamic parameters, anesthetized iNOS-/- mice displayed reduced pressor responses to endothelin-1, but not to that of IRL-1620, a selective ETB agonist. Protein content of cardiac ETA receptors was reduced in iNOS-/- mice compared with wild-type mice, but that of ETB receptors was unchanged. Anesthetized eNOS-/- mice presented a hypertensive state, accompanied by an enhanced pressor response to intravenous endothelin-1, whereas the pressor response to IRL-1620 was reduced. Protein levels were also found to be increased for ETA receptors, but reduced for ETB receptors, in cardiac tissues of eNOS-/- mice. In conscious animals, both strains responded equally to the hypotensive effect of an ETA antagonist, ABT-627, whereas orally administered A-192621, an ETB antagonist, increased MAP to a greater extent in eNOS-/- than in wild-type mice. Furthermore, significant levels of immunoreactive endothelin were found in mesenteric arteries in eNOS-/- but not in iNOS-/- or wild-type congeners. Our study shows that repression of iNOS or eNOS has differential effects on endothelin-1 and its receptors. We have also shown that the heart is the main organ in which iNOS or eNOS repression induces important alterations in protein content of endothelin receptors in adult mice.
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Affiliation(s)
- Julie Labonté
- Department of Pharmacology, Medical School, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada
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Simard E, Jin D, Takai S, Miyazaki M, Brochu I, D'Orléans-Juste P. Chymase-Dependent Conversion of Big Endothelin-1 in the Mouse in Vivo. J Pharmacol Exp Ther 2008; 328:540-8. [DOI: 10.1124/jpet.108.142992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Progestins oppose the effects of estradiol on the endothelin-1 receptor type B in coronary arteries from ovariectomized hyperlipidemic rabbits. Menopause 2008; 15:503-10. [PMID: 18188139 DOI: 10.1097/gme.0b013e318156f803] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Progestins may be associated with the adverse cardiovascular outcomes observed with estrogen plus progestogen therapy, but the mechanism is not resolved. In this study we examined the effect of 17beta-estradiol (E2) alone and in combination with two progestins on the endothelin-1 (ET-1) system in coronary arteries. DESIGN Watanabe heritable hyperlipidemic rabbits were treated orally with either E2 (4 mg/d), medroxyprogesterone acetate (MPA) (10 mg/d), norethisterone acetate (NETA) (2 mg/d), E2 + MPA, E2 + NETA, or placebo for 16 weeks (n=10 in each group). Coronary arteries were used for mRNA and myograph analyses. RESULTS E2 alone but not in combination with MPA or NETA increased ETB mRNA expression in coronary arteries. Accordingly, E2 alone but not in combination with MPA or NETA reduced the maximal contraction to ET-1, and the reduction was sustained after ETA but not after ETB blockade. E2 reduced preproendothelin-1 mRNA expression; however, this effect was not blunted by MPA or NETA. ETA and ET-converting enzyme-1 mRNA expression was unaffected by treatment. CONCLUSIONS The data suggest that long-term E2 treatment selectively attenuates ET-1-induced vasoconstriction, possibly by increasing ETB gene expression in rabbit coronary arteries and that this effect is abolished by the two progestins investigated. This observation may help to explain how progestins oppose the supposed beneficial effects of estrogen on the arterial wall.
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Boesen EI, Sasser JM, Saleh MA, Potter WA, Woods M, Warner TD, Pollock JS, Pollock DM. Interleukin-1beta, but not interleukin-6, enhances renal and systemic endothelin production in vivo. Am J Physiol Renal Physiol 2008; 295:F446-53. [PMID: 18524861 DOI: 10.1152/ajprenal.00095.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The inflammatory cytokines IL-1beta and IL-6 have been shown to stimulate production of endothelin-1 (ET-1) by several cell types in vitro, but their effects on renal ET-1 production in vivo are not known. To test whether IL-1beta and IL-6 stimulate renal ET-1 production and release in vivo, urine was collected from male C57BL/6 mice over 24-h periods at baseline and on days 7 and 14 of a 14-day subcutaneous infusion of IL-1beta (10 ng/h), IL-6 (16 ng/h), or vehicle. By day 14, plasma ET-1 was significantly increased by IL-1beta infusion (1.7 +/- 0.1 vs. 0.8 +/- 0.1 pg/ml for vehicle, P < 0.001). Compared with vehicle infusion, IL-1beta infusion induced significant increases in urinary ET-1 excretion rate and urine flow but did not affect conscious mean arterial pressure (telemetry). IL-1beta infusion significantly increased renal cortical and medullary IL-1beta content (ELISA) and prepro-ET-1 mRNA expression (quantitative real-time PCR). In contrast, 14 days of IL-6 infusion had no significant effect on plasma ET-1 or urinary ET-1 excretion rate. To determine whether IL-1beta stimulates ET-1 release via activation of NF-kappaB, inner medullary collecting duct (IMCD-3) cells were incubated for 24 h with IL-1beta, and ET-1 release and NF-kappaB activation were measured (ELISA). IL-1beta activated NF-kappaB and increased ET-1 release in a concentration-dependent manner. The effect of IL-1beta on ET-1 release could be partially inhibited by pretreatment of IMCD-3 cells with an inhibitor of NF-kappaB activation (BAY 11-7082). These results indicate that IL-1beta stimulates renal and systemic ET-1 production in vivo, providing further evidence that ET-1 participates in inflammatory responses.
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Affiliation(s)
- Erika I Boesen
- Department of Pharmacology and Vascular Biology Center, Medical College of Georgia, Augusta, Georgia, USA
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21
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Rodrigue ME, Brochu I, D' orleans-Juste P, Larivierea R, Lebel M. Effect of erythropoietin on blood pressure and on the vascular endothelial ET-1/ETB receptor system. Am J Hypertens 2008; 21:639-43. [PMID: 18437122 DOI: 10.1038/ajh.2008.37] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Recombinant human erythropoietin (rhEPO) increases blood pressure (BP) and the vascular production of endothelin-1 in renal failure rats. This study was designed to investigate the effect of rhEPO on BP and on the ET-1/ET(B)R system in rats with normal renal function. To further characterize the effect of rhEPO on the ET-1/ET(B)R system, we also studied heterozygous (+/-) ET(B)R knockout (KO) mice. METHODS The animals received either the vehicle or rhEPO (100 U/kg subcutaneously three times per week). ET(B)R(+/-) mice were compared with ET(A)R(+/-) and wild-type (WT) mice. In rats, the ET(B)R mRNA expression was assessed in blood vessels as well as the vascular ET(B)R density using immunohistochemistry. In mice, ET-1 concentration was measured in the thoracic aorta. RESULTS RhEPO administration increased hematocrit levels in all treated animals. This therapy had no effect on BP in normal rats, but it did increase vascular and renal cortex ET(B)R mRNA expression. Immunohistochemistry confirmed that the ET(B)R density was increased in blood vessel endothelium in these normal rats. In contrast, rhEPO increased BP in ET(B)R(+/-) mice and this pressor effect was associated with higher ET-1 concentrations in the thoracic aorta. CONCLUSIONS RhEPO exerts a pleotropic effect on the endothelial ET-1/ET(B)R system. The increase in endothelial ET(B)R expression may contribute to maintaining normal BP during rhEPO administration in normal animals. Conversely, conditions with deficient ET(B)R expression, such as in ET(B)R(+/-) mice, may lead to hypertension while receiving the same therapy.
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Farhat N, Matouk CC, Mamarbachi AM, Marsden PA, Allen BG, Thorin E. Activation of ETB receptors regulates the abundance of ET-1 mRNA in vascular endothelial cells. Br J Pharmacol 2008; 153:1420-31. [PMID: 18278064 DOI: 10.1038/bjp.2008.25] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND AND PURPOSE The factors that influence the cellular levels of endothelin-1 (ET-1) include transcription, mRNA localization, stability and translation, post-translational maturation of preproET-1 and degradation of ET-1. We investigated the regulation of ET-1 mRNA abundance by extracellular ET-1 in porcine aortic endothelial cells (PAECs). EXPERIMENTAL APPROACH Passsage one cultures of PAECs were incubated in starving medium in the presence or absence of ET-1 and antagonists or pharmacological inhibitors. PreproET-1 mRNA, endothelin-1 promoter activity, Erk and p38 MAPK activation were determined. KEY RESULTS Exogenous ET-1 reduced cellular ET-1 mRNA content: a reduction of 10 000-fold was observed after 4 h. ET-1 simultaneously reduced the stability of ET-1 mRNA and increased the loading of RNA Polymerase II at the endothelin-1 promoter. In the absence of exogenous ET-1, the ETB-selective antagonist, BQ788, increased ET-1 mRNA. An ETA-selective antagonist had no effect. ET-1 mRNA returned to control levels within 24 h. Whereas activation of p38 MAPK induced by ET-1 peaked at 30 min and returned to control levels within 90 min, Erk1/2 remained active after 4 h of stimulation. Inhibition of p38 MAPK prevented the ET-1-induced decrease in ET-1 mRNA. In contrast, Erk1/2 inhibition increased ET-1 mRNA. Similarly, inhibition of receptor internalization increased ET-1 mRNA in the presence or absence of exogenous ET-1. CONCLUSIONS AND IMPLICATIONS These results suggest that extracellular ET-1 regulates the abundance of ET-1 mRNA in PAECs, in an ETB receptor-dependent manner, by modulating both mRNA stability and transcription via mechanisms involving receptor endocytosis and both ERK and p38 MAPK pathways.
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Affiliation(s)
- N Farhat
- Department of Biochemistry, University of Montreal, Montreal, Quebec, Canada
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Carrier E, Brochu I, de Brum-Fernandes AJ, D'Orléans-Juste P. The inducible nitric-oxide synthase modulates endothelin-1-dependent release of prostacyclin and inhibition of platelet aggregation ex vivo in the mouse. J Pharmacol Exp Ther 2007; 323:972-8. [PMID: 17885093 DOI: 10.1124/jpet.107.125690] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nitric oxide and other reactive oxygen species generated by nitric-oxide synthases (NOS) modulate, among several other cellular responses, the production of eicosanoids and platelet aggregation. The roles of specific NOS in these two phenomena remain to be determined. Thus, the present study assessed whether inducible NOS (iNOS) and endothelial NOS (eNOS) modulate in a similar manner the production of eicosanoids and platelet aggregation. Mice knocked out for eNOS (eNOS-/-) or iNOS (iNOS-/-) and their wild-type (WT) congeners were used to analyze agonist-induced increases in plasma levels of eicosanoids as well as inhibition of platelet aggregation ex vivo. Systemically administered endothelin-1 (ET-1) triggered an increase in plasma levels of 6-keto prostaglandin F(1alpha) (6-keto PGF(1alpha)) in WT and eNOS-/- but not in iNOS-/- mice. ET-1 (0.01-1 nmol/kg) also induced a dose-dependent inhibition of platelet aggregation in WT and eNOS-/- but not in iNOS-/- mice. Another agonist, bradykinin (10 nmol/kg), triggered the release of 6-keto PGF(1alpha) and inhibited platelet aggregation in all strains of mice studied. In addition, ADP-induced platelet aggregation in vitro was similarly reduced by iloprost (100 nM) in iNOS-/- mice and WT congeners. In another series of experiments, ET-1 (0.1 nmol/kg) significantly increased 8-isoprostane plasma levels in WT but not in iNOS-/- mice. Finally, a 3-week treatment with anti-oxidants inhibited the capacity of ET-1 to significantly increase plasma 6-keto PGF(1alpha) in WT mice. We show for the first time that iNOS is involved in the control of ET-1-induced prostacyclin release and related inhibition of platelet aggregation in the murine model.
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Affiliation(s)
- Emilie Carrier
- Department of Pharmacology, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Rondelet B, Kerbaul F, Vivian GF, Hubloue I, Huez S, Fesler P, Remmelink M, Brimiouille S, Salmon I, Naeije R. Sitaxsentan for the prevention of experimental shunt-induced pulmonary hypertension. Pediatr Res 2007; 61:284-8. [PMID: 17314684 DOI: 10.1203/pdr.0b013e318030d169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We previously reported on the partial prevention of experimental shunt-induced pulmonary arterial hypertension (PAH) by the nonselective endothelin (ET) ET-A/ET-B receptor antagonist bosentan. As the respective roles of the ET-A and ET-B receptor signaling in the pathobiology of the disease remain undefined, we investigated the effects of selective ET-A receptor blockade by sitaxsentan in the same early stage PAH model. Twenty-one 3-wk-old piglets were randomized to placebo or sitaxsentan therapy (1.5 mg/kg/d), after anastomosis of the left subclavian artery to the pulmonary arterial trunk or after a sham operation. Three months later, the animals underwent a hemodynamic evaluation, followed by pulmonary tissue sampling for morphometry and real-time-quantitative-PCR for ET-1, angiopoietin-1, and bone morphogenetic receptor (BMPR) signaling molecules. Three months of left to right shunting induced an increase in pulmonary vascular resistance (PVR) and medial thickness, an overexpression of ET-1, ET-B receptor, and angiopoietin-1, and a decreased expression of BMPR-2 and BMPR-1A. Pretreatment with sitaxsentan prevented shunt-induced increase in PVR and decreased medial thickness by 64%. Sitaxsentan therapy completely prevented the decreased expression of BMPR-2 and limited the overexpression of ET-1, ET-B and angiopoietin-1, and the decreased expression of BMPR-1A. In conclusion, selective ET-A receptor blockade partially prevents shunt-induced PAH.
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Affiliation(s)
- Benoit Rondelet
- Laboratory of Physiology, Department of Cardiac Surgery, Hôpital Erasme, Université Libre de B-1070 Bruxelles, Belgium.
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Boesen EI, Anderson WP, Evans RG, Kett MM. Endogenous endothelins and the response to electrical renal nerve stimulation in anaesthetized rabbits. Auton Neurosci 2007; 132:8-15. [PMID: 16978927 DOI: 10.1016/j.autneu.2006.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 07/25/2006] [Accepted: 08/07/2006] [Indexed: 11/29/2022]
Abstract
The influence of endogenous endothelins on the neural control of renal function is poorly understood. We therefore studied the effects of endothelin blockade (combined ET(A) and ET(B) receptor antagonism using TAK-044) on the acute and prolonged effects of renal nerve stimulation in rabbits, measuring renal blood flow, glomerular filtration rate (GFR), urine flow and sodium excretion. Brief (3 min) stimulation over 0.5-8 Hz produced frequency-dependent reductions in total renal blood flow, cortical blood flow and, less markedly, medullary blood flow. TAK-044 did not significantly alter basal total renal blood flow or cortical blood flow, or their responses to nerve stimulation, but significantly increased basal medullary blood flow (P<0.01) and increased the slope of the stimulation frequency-medullary blood flow relationship (P<0.05). Prolonged (20 min) stimulation at 0, 0.5 and 2 Hz produced frequency-dependent reductions in total renal blood flow, GFR, urine flow and sodium excretion, but not medullary blood flow. Pretreatment with TAK-044 did not significantly alter these responses. Thus, endogenous endothelins do not appear to either augment or lessen the effects of renal nerve activation on total renal blood flow, cortical blood flow, GFR or sodium excretion. The apparent ability of TAK-044 to enhance medullary blood flow responses to renal nerve stimulation may reflect an action of endogenous endothelins to blunt neurally mediated vasoconstriction in the medullary circulation. Alternatively, it may simply be secondary to the effects of endogenous endothelins on basal medullary blood flow.
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Affiliation(s)
- Erika I Boesen
- Department of Physiology, Monash University, Melbourne, Victoria 3800, Australia.
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Dhaun N, Strachan FE, Newby DE, Johnston NR, Ford NF, Hammett JL, Palmisano M, Webb DJ. Vasodilator effects of the endothelin ET receptor selective antagonist BMS-193884 in healthy men. Br J Clin Pharmacol 2006; 60:611-22. [PMID: 16305585 PMCID: PMC1884878 DOI: 10.1111/j.1365-2125.2005.02503.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
AIMS A number of endothelin receptor antagonists (ERAs) are currently in clinical development as potential therapies in states characterized by vasoconstriction, such as systemic hypertension. We investigated the haemodynamic effects of locally and systemically active doses of BMS-193884, an endothelin A (ET(A)) receptor selective ERA, and its influence on vasoconstriction to endothelin-1 (ET-1) in healthy men. METHODS In three separate randomized, placebo-controlled studies, the forearm blood flow (FBF) response to intra-arterial (i.a.) infusion of ET-1 (5 pmol min(-1)) was assessed during i.a. co-infusion of BMS-193884 (5 and 50 nmol min(-1)), and at 12 and at 24 h after oral administration of BMS-193884 (50, 100 and 200 mg at 12 h; and 200 mg at 24 h). Data were examined by repeated-measures analysis of variance (anova) with treatment and subject as factors. RESULTS ET-1 caused significant forearm vasoconstriction, attenuated after oral dosing with BMS-193884 (200 mg) at 12 (P < 0.01) and 24 h (P < 0.0001). BMS-193884 (50 nmol min(-1), i.a.) caused local vasodilatation (25 +/- 11%) when infused alone (P = 0.02) and abolished forearm vasoconstriction to ET-1 (P < 0.0001 vs. ET-1 alone). Orally, BMS-193884 (200 mg) caused a reduction in total systemic vascular resistance at 12 (-14 +/- 9%, P = 0.03) and 24 h (-12 +/- 7%, P < 0.0001). There was no rise in plasma ET-1 levels. CONCLUSION BMS-193884 causes local and systemic vasodilatation and attenuation of local vasoconstriction to ET-1. The absence of a rise in plasma endothelin levels suggests BMS-193884 is selective for the ET(A) receptor. This form of pharmacodynamic modelling may be useful in the development of ERAs in cardiovascular disease.
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Affiliation(s)
- Neeraj Dhaun
- Clinical Pharmacology Unit & Research Centre, University of Edinburgh, Edinburgh, UK.
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Quaschning T, Rebhan B, Wunderlich C, Wanner C, Richter CM, Pfab T, Bauer C, Kraemer-Guth A, Galle J, Yanagisawa M, Hocher B. Endothelin B receptor-deficient mice develop endothelial dysfunction independently of salt loading. J Hypertens 2005; 23:979-85. [PMID: 15834283 DOI: 10.1097/01.hjh.0000166838.55688.7e] [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] [Indexed: 11/25/2022]
Abstract
BACKGROUND Rodents without a functional endothelin B (ETB) receptor develop salt-sensitive hypertension. The underlying mechanisms, however, are so far unknown. The ETB receptor is involved in endothelial function by modulating the activity of the endothelial nitric oxide synthesis as well as contributing to the control of endothelial prostacyclin synthesis. In the present study, we analysed whether salt alters endothelial function in rescued ETB receptor-deficient mice. We used mice with a rescue of the lethal phenotype of an ETB knockout. These mice were generated by crossbreeding ETB mice with dopamine-hydroxylase ETB transgenic mice. METHODS Adult rescued ETB-deficient mice were kept in parallel with wild-type control animals for 15 days on standard (0.2% NaCl) or salt-enriched (4% NaCl) chow, respectively. Systolic blood pressure was measured by the tail cuff method and endothelium-dependent and endothelium-independent vascular function was assessed in isolated aortic rings under isometric conditions. RESULTS Systolic blood pressure increased on salt-enriched chow in ETB receptor-deficient mice (166 +/- 12 mmHg), but neither in wild-type mice on high-salt diet (128 +/- 11 mmHg; P < 0.05) nor in ETB receptor-deficient mice on standard chow. The heart rate was similar in all groups at any point of time. Endothelium-dependent relaxation was impaired in ETB receptor-deficient mice (74 +/- 3 versus 96 +/- 5% of preconstriction for wild-type mice; P < 0.05) and was not significantly affected by a salt-enriched diet. Endothelium-independent relaxation was similar among all groups. Contractions to endothelin-1 were not significantly influenced by preincubation with the ETB receptor antagonist BQ-788, but were completely blunted by preincubation with the ETA receptor antagonist BQ-123 in all animals. CONCLUSION Rescued ETB receptor-deficient mice develop salt-sensitive hypertension. Nevertheless, in this animal model of ETB receptor deficiency, endothelial function is impaired independent of salt-enriched diet or hypertension. This indicates that, in this model, salt-induced hypertension is not mediated by endothelial dysfunction.
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Abstract
OBJECTIVE To investigate the role of endothelin in noradrenaline-induced hypertension in rats. DESIGN The dose-response relationship of chronic noradrenaline infusion on arterial pressure was characterized to identify a dose that would produce sustained hypertension, and the effect of combined endothelin ETA and ETB receptor blockade (TAK-044) on the response to this dose was then examined. METHODS AND RESULTS Noradrenaline (or vehicle) was infused intravenously at 1 (subpressor acutely), 24 or 48 microg/kg per h (acute pressor response of 9 +/- 1 and 11 +/- 1 mmHg, respectively) for a 14-day infusion, and blood pressure was measured by radiotelemetry. Noradrenaline infusion at 1 microg/kg per h did not produce a 'slow pressor' rise in blood pressure. During noradrenaline infusions at 24 and 48 microg/kg per h, mean arterial pressure peaked initially on days 2-3 (+10 +/- 1 and 14 +/- 2 mmHg, respectively; P < 0.01), fell towards basal levels after day 3, and then began to rise again at days 5-6 only with 48 microg/kg per h, being 10 +/- 1 mmHg above control levels at days 13-14 (P < 0.05). TAK-044 treatment did not alter the magnitude of the initial (13 +/- 1 mmHg) or eventual (12 +/- 2 mmHg) rise in blood pressure achieved in response to 14 days' infusion of noradrenaline at 48 microg/kg per h, but abolished the transient fall. CONCLUSION Chronic noradrenaline infusion at acutely pressor doses leads either to a transient blood pressure elevation at a moderate dose, or to a triphasic but sustained hypertension at a higher dose, with a temporary escape from the hypertension apparently mediated by endothelin.
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Affiliation(s)
- Erika I Boesen
- Department of Physiology, Monash University, Victoria 3800, Australia
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29
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Staniloae C, Dupuis J, White M, Gosselin G, Dyrda I, Bois M, Crépeau J, Bonan R, Caron A, Lavoie J. Reduced pulmonary clearance of endothelin in congestive heart failure: a marker of secondary pulmonary hypertension. J Card Fail 2004; 10:427-32. [PMID: 15470654 DOI: 10.1016/j.cardfail.2004.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Endothelin-1 (ET-1) levels are elevated in congestive heart failure (CHF) in relation with the severity of pulmonary hypertension. We evaluated whether a reduced pulmonary ET-1 clearance could contribute to this elevation. METHODS AND RESULTS We determined pulmonary ET-1 clearance in 24 patients with CHF in relation with hemodynamics, plasma ET-1, and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. Pulmonary ET-1 extraction, measured by the single bolus indicator-dilution technique, was reduced to 32 +/- 14% in comparison to historic controls (47 +/- 7%). Plasma ET-1 clearance by the lungs (924 +/- 588 mL/min) was also much lower than in controls (1424 +/- 79 mL/min). Clearance correlated inversely with mean pulmonary artery pressure (PAP, r = -.47, P = .017) and pulmonary capillary wedge pressure (r = -.47, P = .017) and positively with the rate of left ventricular (LV) relaxation LV -dP/dt (r = .593, P = .004). After multivariate analysis, only mean PAP and LV -dP/dt were independently correlated with ET-1 clearance (r = -.40, P = .03, and r = .55, P = .005, respectively). Plasma ET-1 levels did not correlate with clearance (r = .038, P = .86), and there was no significant arteriovenous ET-1 gradient. There was a mild nonsignificant correlation between plasma ET-1 and pulmonary artery systolic pressure (r = .38, P = .06), but a strong correlation with right atrial pressure (r = .696, P < .0001) and NT-proBNP levels (r = .51, P = .001), which were maintained after multivariate linear regression (r = .60, P = .001, and r = .32, P = .04, respectively). CONCLUSION Pulmonary ET-1 clearance is reduced in CHF in relation with the severity of pulmonary hypertension. This reduced clearance does not significantly modulate plasma ET-1 levels. Whether this is only a marker of secondary pulmonary hypertension or could modulate pulmonary vascular tone will require further studies.
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Affiliation(s)
- Cezar Staniloae
- Department of Medicine, Montreal Heart Institute, Quebec, Canada
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Gaertner R, Lepailleur-Enouf D, Gonzalez W, Nicoletti A, Mandet C, Philippe M, Mercadier JJ, Michel JB. Pulmonary endothelium as a site of synthesis and storage of interleukin-6 in experimental congestive heart failure. Eur J Heart Fail 2003; 5:435-42. [PMID: 12921804 DOI: 10.1016/s1388-9842(03)00002-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Pulmonary endothelium is an early upstream hemodynamic target of left ventricular dysfunction. Interleukin 6 (IL-6) is a pro-inflammatory cytokine reported to increase in congestive heart failure (CHF) patients. AIMS We sought to determine the origin of IL-6, IL-6 receptor (IL-6R) and gp130 in experimental CHF. METHODS We used rats with coronary artery ligation as an experimental model of either compensated or decompensated heart failure. Lung and aorta samples were analysed by RT-PCR, ELISA and immunohistochemistry for IL-6 and its receptors. RESULTS IL-6 mRNA expression increased in the lung of rats with decompensated heart failure and was positively correlated with infarct severity whereas IL-6R mRNA decreased in the lung of myocardial infarction rats and gp130 mRNA remained unchanged. In contrast, there were no changes in IL-6 mRNA expression in the aorta and left ventricular myocardium. IL-6 peptide content as determined by ELISA and Western Blot in lung tissue was 2-fold higher in decompensated heart failure as compared to control rats. These data were confirmed by immunohistochemistry showing a preferential endothelial localization of IL-6 in the CHF lung. IL-6 peptide was also present in the pleural effusion of decompensated heart failure and was positively correlated with IL-6 mRNA expression in the lungs of decompensated HF rats. Pulmonary IL-6 overexpression was associated with nuclear translocation of NF-kappaB and cytosolic degradation of IkappaB. CONCLUSION Dysfunctional pulmonary endothelium is a source of synthesis and storage of IL-6 in an experimental model of CHF.
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Affiliation(s)
- Roger Gaertner
- INSERM U460, Cardiovascular Remodelling, CHU Xavier-Bichat, 16 rue Henri Huchard, 75018, Paris, France
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Michel RP, Langleben D, Dupuis J. The endothelin system in pulmonary hypertension. Can J Physiol Pharmacol 2003; 81:542-54. [PMID: 12839266 DOI: 10.1139/y03-008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pulmonary hypertension (PH) may result from numerous clinical entities affecting the pulmonary circulation primarily or secondarily. It is recognized that vascular endothelial dysfunction contributes to the development and perpetuation of PH by creating an imbalance between vasodilating and antiproliferative forces and between vasoconstrictive and proliferative forces. In that context, endothelin-1 (ET-1) overproduction was rapidly targeted as a plausible contributor to the pathogenesis of PH. The lung is recognized as the major site for ET production and clearance. In all animal models of PH studied, circulating plasma ET-1 levels are elevated, accompanied by an increase in lung tissue expression of the peptide. The use of selective ETA and dual ETA-ETB receptor antagonists in these models both in prevention and in therapeutic studies have confirmed the contribution of ET-1 to the rise in pulmonary vascular tone, pulmonary medial hypertrophy, and right ventricular hypertrophy. This is found consistently in models affecting the pulmonary circulation primarily or producing PH secondarily. Recent clinical trials in patients with pulmonary arterial hypertension have confirmed the therapeutic effectiveness of ET-receptor antagonists in humans. We offer a systematic review of the pathogenic role of the ET system in the development of PH as well as the rationale behind the preclinical and ongoing clinical trials with this new class of agents.
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Affiliation(s)
- René P Michel
- Department of Pathology, McGill University Health Center, Montreal, QC, Canada
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Larivière R, Lebel M. Endothelin-1 in chronic renal failure and hypertension. Can J Physiol Pharmacol 2003; 81:607-21. [PMID: 12839272 DOI: 10.1139/y03-012] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Investigation into the role of endothelin-1 (ET-1) in renal function has revealed two major direct actions leading to the control of extracellular volume and blood pressure. These are the regulation of renal hemodynamics and glomerular filtration rate and the modulation of sodium and water excretion. In the rat remnant kidney model of chronic renal failure, ET-1 production is increased in blood vessels and renal tissues. These changes are related to an increase in preproET-1 expression and correlate with the rise in blood pressure, the development of cardiovascular hypertrophy, and the degree of renal insufficiency and injury. Selective ETA receptor blockade prevents the progression of hypertension and the vascular and renal damage, supporting a role for ET-1 in chronic renal failure progression. The increase in ET-1 production can be associated with other local mediators, including angiotensin II, transforming growth factor-beta1 and nitric oxide, the local production of which is also altered in chronic renal failure. In human patients with essential hypertension, atherosclerosis, and nephrosclerosis, plasma ET-1 levels are increased compared with patients with uncomplicated essential hypertension. Similarly, plasma ET-1 concentrations are markedly increased in patients with end-stage renal disease undergoing dialysis, and this correlates with blood pressure, suggesting that ET-1 may contribute to hypertension in these patients. The treatment of anemia in patients with renal failure with human recombinant erythropoietin increases blood pressure by accentuating the underlying endothelial dysfunction and the elevated vascular ET-1 production. Overall, these results support a role for ET-1 in hypertension and the end-organ damage associated with chronic renal failure. ETA receptor blockade may then represent a potential target for the management of hypertension and cardiovascular and renal protection.
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Affiliation(s)
- Richard Larivière
- Research Center and Division of Nephrology, CHUQ, L'Hôtel-Dieu de Québec Hospital, 9 rue McMahon, Québec, QC G1R 2J6, Canada.
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D'Orléans-Juste P, Labonté J, Bkaily G, Choufani S, Plante M, Honoré JC. Function of the endothelinB receptor in cardiovascular physiology and pathophysiology. Pharmacol Ther 2002; 95:221-38. [PMID: 12243796 DOI: 10.1016/s0163-7258(02)00235-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
One of the two receptors by which the potent vasoactive effects of endothelin (ET)-1 are mediated is the ET(B) receptor (ET(BR)), which is found in several tissues, but, more importantly from a cardiovascular point of view, on the endothelial cell. The endothelial cell also has the unique capability of releasing ET-1, as well as other factors, such as the endothelial-derived relaxing factors and prostacyclin, which counteract the myotropic effects of the peptide. The secretory and contractile responses to ET-1 rely on G-protein-coupled ET(BR)s, as well as ET(A)-G-protein-coupled receptor-like proteins. The mitogenic properties of ET-1 via ET(A) receptors (ET(AR)s) coupled to mitogen-activated protein kinases and tyrosine kinases on the vascular smooth muscle may occur in conjunction with the anti-apoptotic characteristics of the endothelial ET(BR)s. Interestingly, most of the relevant antagonists and agonists for both ET(AR)s and ET(BR)s have been developed by the pharmaceutical industry. This highlights the therapeutical potential of compounds that act on ET receptors. In normal as well as in physiopathological conditions, the ET(BR) plays an important role in the control of vascular tone, and must be taken into account when using ET receptor antagonists for the treatment of cardiovascular diseases. For the management of congestive heart failure, renal failure and primary pulmonary hypertension, the most recent literature supports the use of selective ET(AR) antagonists rather than mixed antagonists of ET(AR)s and ET(BR)s. Nonetheless, validation of this view will have to await the first clinical trials comparing the actions of ET(A) to mixed ET(A)/ET(B) receptor antagonists.
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Affiliation(s)
- P D'Orléans-Juste
- Department of Pharmacology, Institut de Pharmacologie de Sherbrooke, Medical School, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, J1H 5N4, Québec, Canada.
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Abstract
Endothelins are a family of peptides, which comprises endothelin-1 (ET-1), endothelin-2 (ET-2) and endothelin-3 (ET-3), each containing 21 amino-acids. ET-1 is a peptide secreted mostly by vascular endothelial cells, the predominant isoform expressed in vasculature and the most potent vasoconstrictor currently known. ET-1 also has inotropic, chemotactic and mitogenic properties. In addition, it influences salt and water homeostasis through its effects on the renin-angiotensin-aldosterone system (RAAS), vasopressin and atrial natriuretic peptide and stimulates the sympathetic nervous system. The overall action of endothelin is to increase blood pressure and vascular tone. Therefore, endothelin antagonists may play an important role in the treatment of cardiac, vascular and renal diseases associated with regional or systemic vasoconstriction and cell proliferation, such as essential hypertension, pulmonary hypertension, chronic heart failure and chronic renal failure. Long-term anti-endothelin therapy may improve symptoms and favourably alter the progression of heart failure. Endothelin appears to participate in induction and progression of sclerotic renal changes, leading to progression to end-stage renal disease. Anti-endothelin therapy might offer additional benefits in the prevention of progression of chronic renal failure in addition to the known benefits of RAAS inhibition. Clinical trials have demonstrated potentially important benefits of endothelin antagonists for patients with essential hypertension, pulmonary hypertension and heart failure. Further studies are necessary to determine the role of anti-endothelin therapy in the treatment of cardiovascular diseases and determine the different roles of selective receptor antagonism vs. mixed ET(A/B)-receptor antagonism in human diseases.
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Affiliation(s)
- Alexei V Agapitov
- Department of Internal Medicine, University of Iowa, Iowa City, 52242, USA
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Palacios B, Lim SL, Pang CCY. Role of endothelin ET(A)- and ET(B)-receptors in haemodynamic compensation following haemorrhage in anaesthetized rats. Br J Pharmacol 2002; 135:876-82. [PMID: 11861314 PMCID: PMC1573196 DOI: 10.1038/sj.bjp.0704530] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. This study examined the role of endothelin ET(A) and ET(B) receptors on haemodynamic compensation following haemorrhage (-17.5 ml kg(-1)) in thiobutabarbitone-anaesthetized rats. Rats were divided into four groups (n=6 each): time-control, haemorrhage-control, haemorrhage after treatment with FR 139317 (ET(A)-receptor antagonist), and haemorrhage after treatment with BQ-788 (ET(B)-receptor antagonist). 2. In the time-control rats, there were no significant changes in any haemodynamics for the duration of the experiments. Relative to the time-control rats, rats given haemorrhage had reduced mean arterial pressure (MAP), cardiac output (CO) and mean circulatory filling pressure (MCFP), but increased systemic vascular resistance (R(SV)). Venous resistance (R(V)) was slightly (but insignificantly) reduced by haemorrhage. MAP, however, gradually returned towards baseline (-17+/-4 and -3+/-2 mmHg at 10 and 60 min after haemorrhage, respectively) as a result of a further increase in R(SV). 3. Pre-treatment with FR 139317 (i.v. 1 mg kg(-1), followed by 1 mg kg(-1) h(-1)) accentuated haemorrhage-induced hypotension through abolition of the increase in R(SV). FR 139317 did not modify haemorrhage-induced changes in CO, MCFP and R(V). 4. Pre-treatment of BQ-788 (3 mg kg(-1)) did not affect MAP or MCFP following haemorrhage; however, CO was lower, and R(SV) as well as R(V) were higher relative to the readings in the haemorrhaged-control rats. 5. These results show that following compensated haemorrhage, ET maintains arterial resistance and blood pressure via the activation of ET(A) but not ET(B) receptors.
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Affiliation(s)
- Beatriz Palacios
- Department of Pharmacology & Therapeutics, Faculty of Medicine, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, B.C., Canada, V6T 1Z3
| | - Su Lin Lim
- Department of Pharmacology & Therapeutics, Faculty of Medicine, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, B.C., Canada, V6T 1Z3
| | - Catherine C Y Pang
- Department of Pharmacology & Therapeutics, Faculty of Medicine, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, B.C., Canada, V6T 1Z3
- Author for correspondence:
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Lavallée M, Takamura M, Parent R, Thorin E. Crosstalk between endothelin and nitric oxide in the control of vascular tone. Heart Fail Rev 2001; 6:265-76. [PMID: 11447301 DOI: 10.1023/a:1011448007222] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Several lines of evidence indicate that nitric oxide (NO) impairs endothelin (ET) production/action in vitro. Acute pressor responses caused by the blockade of NO formation with arginine analogues in vivo are blunted by selective ET(A) or dual ET(A)/ET(B) receptor blockade whereas blockade of NO formation magnifies ET-induced constriction of various vascular territories. Given that ET receptor blockade has normally limited effects on mean arterial pressure, the reversal of pressor responses caused by the blockade of NO formation with ET receptor blockade most likely reflects a significant crosstalk between NO and ET. Suppression of NO formation also leads to significant increases in ET production caused by agents targeting the endothelium, such as acetylcholine and thrombin. In addition, the inhibitory effect of shear stress on endothelial cells ET production also involves NO as an intermediate.Paradoxically, chronic exposure to organic nitrates which causes nitrate tolerance leads to an augmented vascular ET content. An increased angiotensin II (AII) production is apparently pivotal in this process. This article reviews observations pointing to the importance of NO/ET interactions as a fundamental and common regulatory mechanism shared across species. As a consequence of this crosstalk between NO and ET, experimental strategies designed to assess endothelial NO-dependent activity by the blockade of NO formation may be mitigated by magnified ET-dependent influences.
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Affiliation(s)
- M Lavallée
- Department of Physiology, Faculty of Medicine, Université de Montréal, and Institut de Cardiologie de Montréal, Montréal, Québec, Canada.
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Affiliation(s)
- J Dupuis
- Montreal Heart Institute and University of Montreal, Montreal, H1T 1C8, Quebec, Canada.
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Evans RG, Madden AC, Oliver JJ, Lewis TV. Effects of ET(A) - and ET(B)-receptor antagonists on regional kidney blood flow, and responses to intravenous endothelin-1, in anaesthetized rabbits. J Hypertens 2001; 19:1789-99. [PMID: 11593099 DOI: 10.1097/00004872-200110000-00013] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine the roles of endothelin (ET)-receptor subtypes in the effects of exogenous and endogenous ETs on regional kidney blood flow in anaesthetized rabbits. DESIGN AND METHODS The effects on regional kidney blood flow of the ET(A) antagonist BQ610, and the ET(B) antagonist BQ788, were tested. We also examined the effects of intravenous and renal arterial bolus doses of ET-1, and how these responses are modified by pretreatment with BQ610 and BQ788. RESULTS BQ610 reduced mean arterial pressure (MAP, 3%), and increased total renal blood flow (RBF, 10%), cortical perfusion (CBF, 11%) and medullary perfusion (MBF, 16%). BQ788 increased MAP (6%) and reduced RBF (16%) and CBF (13%) but not MBF. The effects of BQ788 were abolished by pretreatment with BQ610. Intravenous ET-1 (300 ng/kg) reduced RBF and CBF, but increased MBF. BQ788 potentiated ET-1 mediated reductions in CBF, and abolished increases in MBF. BQ610 blunted reductions in RBF and CBF produced by ET-1, but did not significantly affect MBF responses. The renal vascular effects of intravenous ET-1 were mimicked by lower doses (1-30 ng/kg) administered into the renal artery. CONCLUSIONS Endogenous ETs act at ET(A)-receptors to reduce MBF and CBF, but ET(B)-receptors have little direct role in physiological control of renal haemodynamics. Bolus doses of ET-1 act at ET(B)-receptors in the kidney to increase MBF. The effects of bolus ET-1 on the cortical vasculature appear to result from the competing influences of ET(A)-mediated vasoconstriction and ET(B)-mediated vasodilatation.
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Affiliation(s)
- R G Evans
- Department of Physiology, Monash University, Victoria, Australia.
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Thorin E. Influence of nitric oxide synthase inhibition and endothelin-1 receptor blockade on acetylcholine-induced coronary artery contraction in vitro in dilated and ischemic cardiomyopathies. J Cardiovasc Pharmacol 2001; 38:90-8. [PMID: 11444506 DOI: 10.1097/00005344-200107000-00010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The normal dilatory response to acetylcholine (ACH) is reduced in coronary vessels from patients with dilated cardiomyopathy (DCM) and reversed to a contraction in patients with coronary artery disease (CAD) and ischemic cardiomyopathy (ICM). This study investigated the influence of nitric oxide synthase inhibition and endothelin (ET)-1 receptor blockade on the reactivity to ACH of coronary arteries isolated from patients with end-stage congestive heart failure (CHF) associated or not with CAD. Small (approximately 400 microm) epicardial right coronary arteries were isolated from explanted hearts of patients undergoing transplantation for DCM or ICM. Segments were mounted on a wire myograph to record changes in isometric tension. ACH (1 microM) dilated pre-contracted vessels from DCM hearts but contracted pre-contracted vessels from ICM hearts. In the absence of pre-contraction, ACH (10(-9)-3 x 10(-5) M) induced a small contraction of rings from DCM hearts and a larger contraction (p < 0.05) of rings from ICM hearts. N(omega)-nitro-L-arginine (L-NNA, 100 microM), a NO synthase inhibitor, increased (p < 0.05) sensitivity and maximal response to ACH of vessels from DCM hearts only. In the presence of L-NNA, blockade of ET(A) with BQ123 (1 microM) prevented the effects of L-NNA in DCM, whereas blockade of ET(A/B) receptors with bosentan (10 microM) only reduced vascular sensitivity to ACH without significantly reducing the maximal contraction to ACH in DCM. The antagonists had no effects in vessels from ICM hearts. ACH, however, induced similar contractions of vessels without endothelium in DCM and ICM. These results suggest that ACH induces a contraction by stimulating smooth muscle muscarinic receptors. In coronary arteries isolated from DCM hearts, the contraction is regulated by NO and ET-1, whereas these factors seem to have little influence in ICM. This suggests that endothelial muscarinic receptors are either not expressed or uncoupled in ICM hearts.
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Affiliation(s)
- E Thorin
- Department of Surgery, University of Montreal, and the Montreal Heart Institute, Quebec, Canada.
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Takamura M, Parent R, Cernacek P, Lavallée M. Influence of dual ET(A)/ET(B)-receptor blockade on coronary responses to treadmill exercise in dogs. J Appl Physiol (1985) 2000; 89:2041-8. [PMID: 11053360 DOI: 10.1152/jappl.2000.89.5.2041] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that endothelin (ET) release during exercise may be triggered by alpha-adrenergic-receptor activation and thereby influence coronary hemodynamics and O(2) metabolism in dogs. Exercise resulted in coronary blood flow increases (to 1.88+/-0.26 from 1.10+/- 0.12 ml x min(-1) x g(-1)) and in a fall (P<0.01) in coronary sinus O(2) saturation (17.4+/-1.5 to 9.6+/-0.7 vol%), whereas myocardial O(2) consumption (MVO(2)) increased (109+/-13% from 145+/-16 microl O(2) min(-1) x g(-1)). Tezosentan, a dual ET(A)/ET(B)-receptor blocker, slightly reduced mean arterial pressure (MAP) and increased heart rate throughout exercise. The relationship between coronary sinus O(2) saturation and MVO(2) was shifted upward (P<0.05) after tezosentan administration; i.e., as MVO(2) increased during exercise, coronary sinus O(2) saturation was disproportionately higher after ET-receptor blockade. After propranolol, tezosentan resulted in significant decreases (P<0.05) in left ventricular pressure, the first derivative of left ventricular pressure over time, and MAP during exercise. As MVO(2) increased during exercise, coronary sinus O(2) saturation levels after tezosentan became superimposable over those observed before ET-receptor blockade. Thus dual blockade of ET(A)/ET(B) receptors alters coronary hemodynamics and O(2) metabolism during exercise, but ET activity failed to increase beyond baseline levels.
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Affiliation(s)
- M Takamura
- Department of Medicine, Institut de Cardiologie de Montréal, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H1T 1C8
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Abstract
The endothelial cells release both relaxing [nitric oxide (NO), endothelium-derived hyperpolarizing factor (EDHF), prostacyclin] and contracting factors [endoperoxides, thromboxane A(2), superoxide anions, endothelin-1 (ET)]. The production of ET is inhibited by NO. The latter also strongly opposes the direct effects of the former on vascular smooth muscle. With aging and vascular disease, the production of enothelial NO declines, and thus ET can be released, act and contribute to the symptoms.
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Affiliation(s)
- P M Vanhoutte
- Institut de Recherches Internationales Servier, 6, Place des Pléïades, 92415 cedex, Courbevoie, France
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Strachan FE, Crockett TR, Mills NL, Gray GA, Webb DJ. Constriction to ETB receptor agonists, BQ-3020 and sarafotoxin s6c, in human resistance and capacitance vessels in vivo. Br J Clin Pharmacol 2000; 50:27-30. [PMID: 10886114 PMCID: PMC2014967 DOI: 10.1046/j.1365-2125.2000.00213.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS The aim of the study was to examine the effects of the ETB receptor selective agonists sarafotoxin S6c (SFTX6c) and BQ-3020 on the forearm resistance and capacitance vessels in healthy subjects in vivo. METHODS The local response to intra-arterial or intravenous infusion of SFTX6c (5 pmol min-1) or BQ-3020 (50 pmol min-1) was assessed, on separate occasions, in eight healthy men (aged 20-28 years). Data (mean +/- s.e.mean) were examined by ANOVA. Results are expressed as percentage change from baseline at 90 min. RESULTS SFTX6c and BQ-3020 reduced forearm blood flow, following local intra-arterial infusion (-25 +/- 7% and -27 +/- 7%, respectively; P < 0.001) and reduced hand vein diameter, following local intravenous infusion (-30 +/- 8% and -16 +/- 7%, respectively; P < 0.001). CONCLUSIONS We have shown that locally active infusions of the selective ETB receptor agonists SFTX6c and BQ-3020 cause arterial constriction and venoconstriction in healthy human blood vessels in vivo. These results indicate that ETB receptor stimulation may mediate vasoconstriction in humans.
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Affiliation(s)
- F E Strachan
- Clinical Pharmacology Unit & Research Centre, Department of Medical Sciences, University of Edinburgh, Western General Hospital,
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Tanus-Santos JE, Sampaio RC, Hyslop S, Franchini KG, Moreno H. Endothelin ET(A) receptor antagonism attenuates the pressor effects of nicotine in rats. Eur J Pharmacol 2000; 396:33-7. [PMID: 10822051 DOI: 10.1016/s0014-2999(00)00194-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The increased endothelin-1 levels observed after smoking may result from nicotine-stimulated endothelin-1 production by endothelial cells. In this study, we investigated the effects of selective endothelin ET(A) receptors antagonist Cycle D-a-aspartyl-L-prolyl-D-isoleucyl-D-tryptophyl (JKC 301) and of endothelin ET(B) receptors antagonist N-cis-2, 6-dimethylpiperidino-carbonyl-L-gamma-methyl-leucyl-D-L-m ethoxycarbonyl-tryptophanyl-norleucine (BQ 788) on the changes in mean arterial pressure, heart rate, and plasma thromboxane B(2) (the stable product of thromboxane A(2)) levels caused by increasing doses of nicotine (0.6, 2, 6, and 20 micromol/kg) in anesthetised rats. Nicotine (0.6, 2, and 6 micromol/kg) significantly increased the mean arterial pressure in control and BQ 788-pretreated rats, while only a nicotine dose of 2 micromol/kg) increased the mean arterial pressure in JKC 301-pretreated animals. There were no differences in the nicotine-induced changes in heart rate or in the increases in thromboxane B(2) levels among the groups treated with saline, JKC 301 and BQ 788. These results demonstrate that whereas the antagonism of endothelin ET(A) receptors attenuated the increase in blood pressure after nicotine injections, endothelin ET(B) receptor antagonism had no such effect. In addition, the antagonism of endothelin ET(A) or ET(B) receptors did not affect thromboxane A(2) production after nicotine administration. These findings suggest that endothelin-1 may have a role in the acute effects of nicotine.
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Affiliation(s)
- J E Tanus-Santos
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), P.O. Box 6111, 13081-970, SP, Campinas, Brazil
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Evans RG, Madden AC, Cotterill E. ET-receptor subtypes: roles in regional renal vascular actions of exogenous and endogenous endothelins in anesthetized rabbits. J Cardiovasc Pharmacol 2000; 35:677-85. [PMID: 10813367 DOI: 10.1097/00005344-200005000-00001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The roles of endothelin (ET)-receptor subtypes, in the regional renal vascular effects of exogenous and endogenous ETs, were examined in pentobarbitone-anesthetized rabbits. The effects of renal arterial infusion of ET-1 (0.05-12.8 ng/kg/min) and the ET(B)-agonist [Ala1,3,11,15]-ET-1 (12.5-800 ng/kg/min) were compared. We then tested the effects of the ET(A)-antagonist BQ610 and the ET(B)-antagonist BQ788 (both 200 microg/kg plus 100 microg/kg/h, i.v.) on basal hemodynamics and on responses to renal arterial ET-1. Both ET-1 and [Ala1,3,11,15]-ET-1 dose-dependently reduced total renal blood flow (RBF) and cortical blood flow (CBF), but not medullary blood flow (MBF). ET-1 was 34-fold more potent than [Ala1,3,11,15-ET-1. BQ610 reduced mean arterial pressure (MAP; 14%), and increased RBF (21%) and CBF (12%), but not MBF. BQ788 increased MAP (13%), and reduced RBF (29%) and CBF (15%) but not MBF. Coadministration of both agents increased RBF (18%) and CBF (9%), without significantly affecting MAP. Neither antagonist (alone or combined) significantly affected responses to renal arterial ET-1. We conclude that the predominant renal vascular effects of exogenous and endogenous ETs are cortical vasoconstriction, but not at vascular sites controlling MBF. ET(A)-receptors contribute to the renal vasoconstrictor effects of endogenous ETs. ET(B2)-like receptors appear to contribute to the vasoconstrictor effects of [Ala1,3,11,15]-ET-1.
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Affiliation(s)
- R G Evans
- Department of Physiology, Monash University, Clayton, Victoria, Australia.
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Thorin E, Parent R, Ming Z, Lavallée M. Contribution of endogenous endothelin to large epicardial coronary artery tone in dogs and humans. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:H524-32. [PMID: 10444477 DOI: 10.1152/ajpheart.1999.277.2.h524] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) may normally impair endothelin (ET) activity in epicardial coronary arteries. Lifting this inhibitory feedback could reveal ET-dependent effects involving ET(A)- and/or ET(B)-receptor activation. In conscious dogs, the blockade of ET(A) receptors (intracoronary Ro-61-1790) increased external circumflex coronary artery diameter (CD) (sonomicrometry) by 0.10 +/- 0.01 from 3.04 +/- 0.12 mm (P < 0.01) without altering coronary blood flow (Doppler). Similarly, CD increased (0.09 +/- 0.01 from 2.91 +/- 0.14 mm; P < 0. 01) when Ro-61-1790 was given after blockade of NO formation with intracoronary N(omega)-nitro-L-arginine methyl ester (L-NAME). In contrast, ET(B)-receptor blockade (intracoronary Ro-46-8443) did not influence baseline CD with and without L-NAME. In vitro, increases in tension caused by N(omega)-nitro-L-arginine (L-NNA) or PGF(2alpha) in arterial rings were reduced by ET(A)- but not ET(B)-receptor blockade. ET(A)-receptor blockade also reduced the increase in tension caused by L-NNA in human coronary arterial rings. Thus ET(A) receptors, but not ET(B) receptors, account for ET-dependent constriction in canine epicardial coronary arteries in vivo. ET-dependent effects were independent of the level of NO formation in vitro and in vivo. In human epicardial coronary arterial rings, ET(A)-receptor blockade also caused significant relaxation.
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Affiliation(s)
- E Thorin
- Department of Surgery, Faculty of Medicine, Université de Montréal, Montréal H3C 3J7, Montréal, Québec, Canada H1T 1C8
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Baylis C. Acute interactions between endothelin and nitric oxide in the control of renal haemodynamics. Clin Exp Pharmacol Physiol 1999; 26:253-7. [PMID: 10081623 DOI: 10.1046/j.1440-1681.1999.03026.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Endogenous endothelin (ET) does contribute to control of renal vascular tone via nitric oxide (NO)-dependent vasodilation in the rat. 2. Endothelin mediates some of the renal vascular responses to acute nitric oxide synthase (NOS) inhibition, being particularly important when a rise in renal perfusion pressure occurs. 3. Tonically produced NO blunts the renal vasoconstrictor responses to acutely administered ET. 4. The similarity between the renal vascular responses to ET administration and NOS inhibition is not fortuitous but, in part, reflects important interactions between these vasoactive agents.
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Affiliation(s)
- C Baylis
- Department of Physiology, West Virginia University, Morgantown 26506-0229, USA.
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Dupuis J, Prié S. The ET(A)-Receptor Antagonist LU 135252 Prevents the Progression of Established Pulmonary Hypertension Induced by Monocrotaline in Rats. J Cardiovasc Pharmacol Ther 1999; 4:33-39. [PMID: 10684522 DOI: 10.1177/107424849900400106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND: An imbalance between the nitric oxide (NO) and endothelin systems may contribute to the development of pulmonary hypertension (PH). We evaluated the effect of the specific ET(A)-receptor antagonist LU 135252 (LU) in rats with established monocrotaline (MCT)-induced PH and the involvement of NO in the control of pulmonary vascular tone. METHODS AND RESULTS: Two weeks after MCT, rats developed PH with a right ventricular pressure (RVP) of 42.3 +/- 8.5 vs 28.2 +/- 4.1 mmHg for controls (mean +/- SD, P <.05). Daily oral therapy with LU (50 mg/kg) or saline was started 2 weeks post-MCT injection for 20 days. LU increased the survival rate nonsignificantly from 41.7% to 66.7%. The surviving MCT + saline rats showed severe PH (RVP of 82.5 +/- 8.9 mmHg) and RV hypertrophy with a right-to-left ventricle + septum weight ratio of 69.6% +/- 10.2%, which were improved by LU to 53.5 +/- 11.1 mmHg and 53.7% +/- 9.9%, respectively (P <.01). In isolated lungs, pulmonary vascular compliance was reduced by PH and unaffected by LU therapy. After the NO synthase inhibitor N(omega)-nitro-L-arginine (10(-4) mol/L), compliance was further reduced, although much less so, in the LU-treated group (P <.01). CONCLUSIONS: In this model, ET(A) antagonist therapy has a favorable effect on survival and pulmonary hemodynamics and reduces the dependency on NO for the attenuation of reduced vascular compliance.
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Affiliation(s)
- J Dupuis
- Department of Medicine, Institut de Cardiologie de Montréal, Montreal, Quebec, Canada
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Hashimoto N, Kuro T, Taira S, Matsumura Y. Different contributions of the endothelin ET(A) receptor to hypertension induced by acute or chronic inhibition of nitric oxide synthesis. J Pharm Pharmacol 1998; 50:1051-8. [PMID: 9811167 DOI: 10.1111/j.2042-7158.1998.tb06921.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of FR139317((R)2-[(R)-2-[(S)-2-[[1-(hexahydro-1H-azepinyl)]carb onyl] amino-4-methyl-pentanoyl] amino-3-[3-(1-methyl-1H-indoyl)]propionyl]-amino-3-(2-pyridyl)prop ionic acid), an endothelin ET(A) receptor antagonist, on systemic and renal haemodynamic responses and excretory responses to chronic or acute nitric oxide (NO) synthase inhibition with NG-nitro-L-arginine (NOARG) have been examined. An intravenous bolus injection of FR139317 (10 mg kg(-1)) to chronic NO-deficient hypertensive rats (2.74 mM NOARG in drinking water for 4 weeks) elicited only a slight decrease in mean arterial pressure (MAP), to the same extent as seen in normotensive control rats. Injection of this drug induced no alteration of the renal haemodynamics of this chronic hypertensive model. Urine formation in control rats was significantly reduced by administration of FR139317. No significant decrease in urine formation was observed in the chronic NO-deficient rats. Acute intravenous injection of NOARG (5 mg kg(-1)) induced a gradual and significant increase in MAP, with a significant decrease in renal blood flow. A slight but insignificant diuretic effect was observed. In animals pretreated with FR139317 (10 mg kg(-1) i.v.) NOARG induced a significantly less potent increase in MAP, whereas similar renal haemodynamic responses to NOARG were observed. In contrast to the FR139317-untreated group, urine formation tended to decrease after administration of NOARG. These results suggest that endothelin, via the ET(A) receptor, contributes to the systemic pressor response to acute NO synthase inhibition, although renal vasoconstriction and functional changes induced by acute NO synthase inhibition are independent of ET(A) receptor-related effects. These results imply that action of endothelin via the ET(A) receptor is not involved in the maintenance of sustained hypertension induced by chronic NO synthase inhibition.
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Affiliation(s)
- N Hashimoto
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, Japan
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Abstract
The endothelins are a family of endothelium-derived peptides that possess characteristically sustained vasoconstrictor properties. Endothelin-1 appears to be the predominant member of the family generated by vascular endothelial cells. In addition to its direct vascular effects, endothelin-1 has inotropic and mitogenic properties, influences homeostasis of salt and water, alters central and peripheral sympathetic activity and stimulates the renin-angiotensin-aldosterone system. Studies with endothelin receptor antagonists have indicated that endothelin-1 probably has complex opposing vascular effects mediated through vascular smooth muscle and endothelial ET(A) and ET(B)receptors. Endogenous generation of endothelin-1 appears to contribute to maintenance of basal vascular tone and blood pressure through activation of vascular smooth muscle ET(A)receptors. At the same time, endogenous endothelin-1 acts through endothelial ET(B) receptors to stimulate formation of nitric oxide tonically and to oppose vasoconstriction. In view of the multiple cardiovascular actions of endothelin-1, there has been much interest in its contribution to the pathophysiology of hypertension. Results of most studies suggest that generation of, or sensitivity to, endothelin-1 is no greater in hypertensive than it is in normotensive subjects. Nonetheless, the deleterious vascular effects of endogenous endothelin-1 may be accentuated by reduced generation of nitric oxide caused by hypertensive endothelial dysfunction. It also appears likely that endothelin participates in the adverse cardiac and vascular remodelling of hypertension, as well as in hypertensive renal damage. Irrespective of whether vascular endothelin activity is increased in hypertension, anti-endothelin agents do produce vasodilatation and lower blood pressure in hypertensive humans. There is more persuasive evidence for increased endothelin-1 activity in secondary forms of hypertension, including pre-eclampsia and renal hypertension. Endothelin-1 also appears to play an important role in pulmonary hypertension, both primary and secondary to diseases such as chronic heart failure. The hypotensive effects of endothelin converting enzyme inhibitors and endothelin receptor antagonists should be useful in the treatment of hypertension and related diseases. Development of such agents will increase knowledge of the physiological and pathological roles of the endothelins, and should generate drugs with novel benefits.
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Affiliation(s)
- W G Haynes
- Department of Internal Medicine, University of Iowa, Iowa City, USA
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