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Kohan DE, Bedard P, Jenkinson C, Hendry B, Komers R. Mechanism of protective actions of sparsentan in the kidney: lessons from studies in models of chronic kidney disease. Clin Sci (Lond) 2024; 138:645-662. [PMID: 38808486 PMCID: PMC11139641 DOI: 10.1042/cs20240249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/30/2024]
Abstract
Simultaneous inhibition of angiotensin II AT1 and endothelin ETA receptors has emerged as a promising approach for treatment of chronic progressive kidney disease. This therapeutic approach has been advanced by the introduction of sparsentan, the first dual AT1 and ETA receptor antagonist. Sparsentan is a single molecule with high affinity for both receptors. It is US Food and Drug Administration approved for immunoglobulin A nephropathy (IgAN) and is currently being developed as a treatment for rare kidney diseases, such as focal segmental glomerulosclerosis. Clinical studies have demonstrated the efficacy and safety of sparsentan in these conditions. In parallel with clinical development, studies have been conducted to elucidate the mechanisms of action of sparsentan and its position in the context of published evidence characterizing the nephroprotective effects of dual ETA and AT1 receptor inhibition. This review summarizes this evidence, documenting beneficial anti-inflammatory, antifibrotic, and hemodynamic actions of sparsentan in the kidney and protective actions in glomerular endothelial cells, mesangial cells, the tubulointerstitium, and podocytes, thus providing the rationale for the use of sparsentan as therapy for focal segmental glomerulosclerosis and IgAN and suggesting potential benefits in other renal diseases, such as Alport syndrome.
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Affiliation(s)
- Donald E. Kohan
- Division of Nephrology, University of Utah Health, Salt Lake City, UT, U.S.A
| | | | | | - Bruce Hendry
- Travere Therapeutics, Inc., San Diego, CA, U.S.A
| | - Radko Komers
- Travere Therapeutics, Inc., San Diego, CA, U.S.A
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2
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Jaimes L, Vinet R, Knox M, Morales B, Benites J, Laurido C, Martínez JL. A Review of the Actions of Endogenous and Exogenous Vasoactive Substances during the Estrous Cycle and Pregnancy in Rats. Animals (Basel) 2019; 9:E288. [PMID: 31146394 PMCID: PMC6617363 DOI: 10.3390/ani9060288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 04/04/2019] [Accepted: 04/22/2019] [Indexed: 12/12/2022] Open
Abstract
Vascular endothelium plays a key role in regulating cardiovascular homeostasis by controlling the vascular tone. Variations in sex hormones during the reproductive cycle of females affect the homeostasis of the cardiovascular system. Also, the evidence shows that estrogens show a cardioprotective effect. On this basis, this study describes some vascular responses induced by vasoactive substances during the estrous cycle in rats. We obtained the information available on this topic from the online databases that included scientific articles published in the Web of Science, PubMed, and Scielo. Many investigations have evaluated the vasoactive response of substances such as acetylcholine and norepinephrine during the estrous cycle. In this review, we specifically described the vascular response to vasoactive substances in rats during the estrous cycle, pregnancy, and in ovariectomized rats. In addition, we discussed the existence of different signaling pathways that modulate vascular function. The knowledge of these effects is relevant for the optimization and development of new treatments for some vascular pathologies.
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Affiliation(s)
- Luisauris Jaimes
- Faculty of Chemistry and Biology, University de Santiago de Chile, Estación Central 9160020, Chile; (L.J.); (B.M.)
| | - Raúl Vinet
- CMBi, Faculty of Pharmacy, Universidad de Valparaíso, Valparaíso 2360102, Chile; (R.V.); (M.K.)
- Regional Centre for Studies in Food and Health (CREAS, Grant R17A10001), Valparaíso 2362696, Chile
| | - Marcela Knox
- CMBi, Faculty of Pharmacy, Universidad de Valparaíso, Valparaíso 2360102, Chile; (R.V.); (M.K.)
| | - Bernardo Morales
- Faculty of Chemistry and Biology, University de Santiago de Chile, Estación Central 9160020, Chile; (L.J.); (B.M.)
| | - Julio Benites
- Faculty of Health Science, Universidad Arturo Prat, Iquique 1100000, Chile;
| | - Claudio Laurido
- Faculty of Chemistry and Biology, University de Santiago de Chile, Estación Central 9160020, Chile; (L.J.); (B.M.)
| | - José L. Martínez
- Vice Chancellor of Investigation, Development and Innovation, Universidad de Santiago de Chile, Estación Central 9160020, Chile
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3
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Komers R, Plotkin H. Dual inhibition of renin-angiotensin-aldosterone system and endothelin-1 in treatment of chronic kidney disease. Am J Physiol Regul Integr Comp Physiol 2016; 310:R877-84. [PMID: 27009050 PMCID: PMC4896079 DOI: 10.1152/ajpregu.00425.2015] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 03/11/2016] [Indexed: 12/19/2022]
Abstract
Inhibition of the renin-angiotensin-aldosterone system (RAAS) plays a pivotal role in treatment of chronic kidney diseases (CKD). However, reversal of the course of CKD or at least long-term stabilization of renal function are often difficult to achieve, and many patients still progress to end-stage renal disease. New treatments are needed to enhance protective actions of RAAS inhibitors (RAASis), such as angiotensin-converting enzyme (ACE) inhibitors (ACEIs) or angiotensin receptor blockers (ARBs), and improve prognosis in CKD patients. Inhibition of endothelin (ET) system in combination with established RAASis may represent such an approach. There are complex interactions between both systems and similarities in their renal physiological and pathophysiological actions that provide theoretical rationale for combined inhibition. This view is supported by some experimental studies in models of both diabetic and nondiabetic CKD showing that a combination of RAASis with ET receptor antagonists (ERAs) ameliorate proteinuria, renal structural changes, and molecular markers of glomerulosclerosis, renal fibrosis, or inflammation more effectively than RAASis or ERAs alone. Practically all clinical studies exploring the effects of RAASis and ERAs combination in nephroprotection have thus far applied add-on designs, in which an ERA is added to baseline treatment with ACEIs or ARBs. These studies, conducted mostly in patients with diabetic nephropathy, have shown that ERAs effectively reduce residual proteinuria in patients with baseline RAASis treatment. Long-term studies are currently being conducted to determine whether promising antiproteinuric effects of the dual blockade will be translated in long-term nephroprotection with acceptable safety profile.
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Intapad S, Ojeda NB, Varney E, Royals TP, Alexander BT. Sex-Specific Effect of Endothelin in the Blood Pressure Response to Acute Angiotensin II in Growth-Restricted Rats. Hypertension 2015; 66:1260-6. [PMID: 26459423 DOI: 10.1161/hypertensionaha.115.06257] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 09/21/2015] [Indexed: 01/18/2023]
Abstract
The renal endothelin system contributes to sex differences in blood pressure with males demonstrating greater endothelin type-A receptor-mediated responses relative to females. Intrauterine growth restriction programs hypertension and enhance renal sensitivity to acute angiotensin II in male growth-restricted rats. Endothelin is reported to work synergistically with angiotensin II. Thus, this study tested the hypothesis that endothelin augments the blood pressure response to acute angiotensin II in male growth-restricted rats. Systemic and renal hemodynamics were determined in response to acute angiotensin II (100 mg/kg per minute for 30 minutes) with and without the endothelin type-A receptor antagonist, Atrasentan (ABT-627; 10 ng/kg per minute for 30 minutes), in rats pretreated with enalapril (250 mg/L for 1 week) to normalize the endogenous renin-angiotensin system. Endothelin type-A receptor blockade reduced angiotensin II-mediated increases in blood pressure in male control and male growth-restricted rats. Endothelin type-A receptor blockade also abolished hyper-responsiveness to acute angiotensin II in male growth-restricted rats. Yet, blood pressure remained significantly elevated above baseline after endothelin type-A receptor blockade, suggesting that factors in addition to endothelin contribute to the basic angiotensin II-induced pressor response in male rats. We also determined sex-specific effects of endothelin on acute angiotensin II-mediated hemodynamic responses. Endothelin type-A receptor blockade did not reduce acute angiotensin II-mediated increases in blood pressure in female control or growth-restricted rats, intact or ovariectomized. Thus, these data suggest that endothelin type-A receptor blockade contributes to hypersensitivity to acute angiotensin II in male growth-restricted rats and further supports the sex-specific effect of endothelin on blood pressure.
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Affiliation(s)
- Suttira Intapad
- Department of Pediatrics (N.B.O.), Department of Physiology and Biophysics (S.I., N.B.O., E.V., T.P.R., B.T.A.), and the Center for Developmental Disorders Research (S.I., N.B.O., B.T.A.), University of Mississippi Medical Center, Jackson
| | - Norma B Ojeda
- Department of Pediatrics (N.B.O.), Department of Physiology and Biophysics (S.I., N.B.O., E.V., T.P.R., B.T.A.), and the Center for Developmental Disorders Research (S.I., N.B.O., B.T.A.), University of Mississippi Medical Center, Jackson
| | - Elliott Varney
- Department of Pediatrics (N.B.O.), Department of Physiology and Biophysics (S.I., N.B.O., E.V., T.P.R., B.T.A.), and the Center for Developmental Disorders Research (S.I., N.B.O., B.T.A.), University of Mississippi Medical Center, Jackson
| | - Thomas P Royals
- Department of Pediatrics (N.B.O.), Department of Physiology and Biophysics (S.I., N.B.O., E.V., T.P.R., B.T.A.), and the Center for Developmental Disorders Research (S.I., N.B.O., B.T.A.), University of Mississippi Medical Center, Jackson
| | - Barbara T Alexander
- Department of Pediatrics (N.B.O.), Department of Physiology and Biophysics (S.I., N.B.O., E.V., T.P.R., B.T.A.), and the Center for Developmental Disorders Research (S.I., N.B.O., B.T.A.), University of Mississippi Medical Center, Jackson.
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Miners JS, Palmer JC, Tayler H, Palmer LE, Ashby E, Kehoe PG, Love S. Aβ degradation or cerebral perfusion? Divergent effects of multifunctional enzymes. Front Aging Neurosci 2014; 6:238. [PMID: 25309424 PMCID: PMC4160973 DOI: 10.3389/fnagi.2014.00238] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 08/20/2014] [Indexed: 12/17/2022] Open
Abstract
There is increasing evidence that deficient clearance of β-amyloid (Aβ) contributes to its accumulation in late-onset Alzheimer disease (AD). Several Aβ-degrading enzymes, including neprilysin (NEP), endothelin-converting enzyme (ECE), and angiotensin-converting enzyme (ACE) reduce Aβ levels and protect against cognitive impairment in mouse models of AD. In post-mortem human brain tissue we have found that the activity of these Aβ-degrading enzymes rise with age and increases still further in AD, perhaps as a physiological response that helps to minimize the build-up of Aβ. ECE-1/-2 and ACE are also rate-limiting enzymes in the production of endothelin-1 (ET-1) and angiotensin II (Ang II), two potent vasoconstrictors, increases in the levels of which are likely to contribute to reduced blood flow in AD. This review considers the possible interdependence between Aβ-degrading enzymes, ischemia and Aβ in AD: ischemia has been shown to increase Aβ production both in vitro and in vivo, whereas increased Aβ probably enhances ischemia by vasoconstriction, mediated at least in part by increased ECE and ACE activity. In contrast, NEP activity may help to maintain cerebral perfusion, by reducing the accumulation of Aβ in cerebral blood vessels and lessening its toxicity to vascular smooth muscle cells. In assessing the role of Aβ-degrading proteases in the pathogenesis of AD and, particularly, their potential as therapeutic agents, it is important to bear in mind the multifunctional nature of these enzymes and to consider their effects on other substrates and pathways.
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Affiliation(s)
- J Scott Miners
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Jennifer C Palmer
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Hannah Tayler
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Laura E Palmer
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Emma Ashby
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Patrick G Kehoe
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
| | - Seth Love
- Dementia Research Group, School of Clinical Sciences, Faculty of Medicine and Dentistry, University of Bristol Bristol, UK
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Hammad FT, Wheatley AM, Davis G. Bosentan normalizes the GFR response to renal nerve stimulation following reversible unilateral ureteric obstruction in the rat. Physiol Res 2014; 63:713-22. [PMID: 25157662 DOI: 10.33549/physiolres.932667] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We investigated the renal response to direct renal nerve stimulation, 2 weeks following reversal of 24-h unilateral (left) ureteric obstruction. Renal nerve stimulation caused a 13-15 % fall in renal blood flow, in 4 groups of anesthetized rats following ureteric obstruction (n=9) or a sham operation (n=7) both with (n=9) and without (n=7) treatment with the mixed ET(A/B) receptor antagonist, bosentan. In the sham-operated rats, renal nerve stimulation did not change glomerular filtration rate but reduced urine flow rate (37+/-3 %, P<0.001), and absolute (38+/-4 %, P<0.001) and fractional (35+/-5 %, P<0.01) sodium excretion. Following unilateral ureteric obstruction, renal nerve stimulation increased glomerular filtration rate by 22+/-3 % (P<0.01), but reduced urine flow rate (14+/-2 %, P<0.001) and fractional sodium excretion (23+/-5 %, P<0.01). Bosentan treatment had no effect on baseline or renal responses to renal nerve stimulation in the sham group but normalized the renal response to renal nerve stimulation in the unilateral ureteric obstruction group. We conclude that 14 days after a 24-h period of unilateral ureteric obstruction there is an increase in GFR in response to direct renal nerve stimulation, which is due, in part, to the actions of endothelin at the time of obstruction.
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Affiliation(s)
- F T Hammad
- Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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Lu J, Ling Z, Chen W, Du H, Xu Y, Fan J, Long Y, Chen S, Xiao P, Liu Z, Zrenner B, Yin Y. Effects of renal sympathetic denervation using saline-irrigated radiofrequency ablation catheter on the activity of the renin-angiotensin system and endothelin-1. J Renin Angiotensin Aldosterone Syst 2014; 15:532-9. [PMID: 24496516 DOI: 10.1177/1470320313506480] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Jiayi Lu
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Zhiyu Ling
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Weijie Chen
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Huaan Du
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Yanping Xu
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Jinqi Fan
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Yi Long
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Shaojie Chen
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Peilin Xiao
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | - Zengzhang Liu
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
| | | | - Yuehui Yin
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, China
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Dab H, Hachani R, Dhaouadi N, Sakly M, Hodroj W, Randon J, Bricca G, Kacem K. Regulation of aortic extracellular matrix synthesis via noradrenergic system and angiotensin II in juvenile rats. PHARMACEUTICAL BIOLOGY 2012; 50:1219-1225. [PMID: 22853187 DOI: 10.3109/13880209.2012.664554] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
CONTEXT Extracellular matrix (ECM) synthesis regulation by sympathetic nervous system (SNS) or angiotensin II (ANG II) was widely reported, but interaction between the two systems on ECM synthesis needs further investigation. OBJECTIVE We tested implication of SNS and ANG II on ECM synthesis in juvenile rat aorta. MATERIALS AND METHODS Sympathectomy with guanethidine (50 mg/kg, subcutaneous) and blockade of the ANG II AT1 receptors (AT1R) blocker with losartan (20 mg/kg/day in drinking water) were performed alone or in combination in rats. mRNA and protein synthesis of collagen and elastin were examined by Q-RT-PCR and immunoblotting. RESULTS Collagen type I and III mRNA were increased respectively by 62 and 43% after sympathectomy and decreased respectively by 31 and 60% after AT1R blockade. Combined treatment increased collagen type III by 36% but not collagen type I. The same tendency of collagen expression was observed at mRNA and protein levels after the three treatments. mRNA and protein level of elastin was decreased respectively by 63 and 39% and increased by 158 and 15% after losartan treatment. Combined treatment abrogates changes induced by single treatments. DISCUSSION AND CONCLUSION The two systems act as antagonists on ECM expression in the aorta and combined inhibition of the two systems prevents imbalance of mRNA and protein level of collagen I and elastin induced by single treatment. Combined inhibition of the two systems prevents deposit or excessive reduction of ECM and can more prevent cardiovascular disorders.
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Affiliation(s)
- Houcine Dab
- Unité de Physiologie Intégrée, Laboratoire de Pathologies Vasculaires, Université de Carthage, Faculté des Sciences de Bizerte, Tunisia.
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10
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Endothelium-derived vasoactive agents, AT1 receptors and inflammation. Pharmacol Ther 2011; 131:187-203. [DOI: 10.1016/j.pharmthera.2010.11.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 11/03/2010] [Indexed: 12/25/2022]
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11
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Dab H, Kacem K, Hachani R, Dhaouadi N, Hodroj W, Sakly M, Randon J, Bricca G. Physiological regulation of extracellular matrix collagen and elastin in the arterial wall of rats by noradrenergic tone and angiotensin II. J Renin Angiotensin Aldosterone Syst 2011; 13:19-28. [DOI: 10.1177/1470320311414752] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The interactions between the effects of the sympathetic nervous system (SNS) and angiotensin II (ANG II) on vascular extracellular matrix (ECM) synthesis were determined in rats. The mRNA and protein content of collagen I, collagen III and elastin in the abdominal aorta (AA) and femoral artery (FA) was investigated in Wistar–Kyoto rats treated for 5 weeks with guanethidine, a sympathoplegic, losartan, an ANG II AT1 receptor (AT1R) blocker, or both. The effects of noradrenaline (NE) and ANG II on collagen III and elastin mRNA, and the receptor involved, were tested in cultured vascular smooth muscle cells (VSMCs) in vitro. Guanethidine increased collagen types I and III and decreased elastin, while losartan had an opposite effect, although without effect on collagen III. The combination of treatments abrogated changes induced by simple treatment with collagen I and elastin, but increased collagen III mRNA in AA and not in FA. NE stimulated collagen III mRNA via β receptors and elastin via α1 and α2 receptors. ANG II stimulated collagen III but inhibited elastin mRNA via AT1R. Overall, SNS and ANG II exert opposite and antagonistic effects on major components of ECM in the vascular wall. This may be of relevance for the choice of a therapeutic strategy in vascular diseases.
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Affiliation(s)
- Houcine Dab
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
- Université de Carthage. Unité de Physiologie Intégrée, Laboratoire de Pathologies Vasculaires, Faculté des Sciences de Bizerte, Tunisia
| | - Kamel Kacem
- Université de Carthage. Unité de Physiologie Intégrée, Laboratoire de Pathologies Vasculaires, Faculté des Sciences de Bizerte, Tunisia
| | - Rafik Hachani
- Université de Carthage. Unité de Physiologie Intégrée, Laboratoire de Pathologies Vasculaires, Faculté des Sciences de Bizerte, Tunisia
| | - Nadra Dhaouadi
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
- Université de Carthage. Unité de Physiologie Intégrée, Laboratoire de Pathologies Vasculaires, Faculté des Sciences de Bizerte, Tunisia
| | - Wassim Hodroj
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
| | - Mohsen Sakly
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
| | - Jacques Randon
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
| | - Giampiero Bricca
- INSERM ERI-22, Agressions Vasculaires et Réponses Tissulaires, Université de Claude Bernard, Lyon I, France
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Abstract
Since its discovery in 1988 as an endothelial cell-derived peptide that exerts the most potent vasoconstriction of any known endogenous compound, endothelin (ET) has emerged as an important regulator of renal physiology and pathophysiology. This review focuses on how the ET system impacts renal function in health; it is apparent that ET regulates multiple aspects of kidney function. These include modulation of glomerular filtration rate and renal blood flow, control of renin release, and regulation of transport of sodium, water, protons, and bicarbonate. These effects are exerted through ET interactions with almost every cell type in the kidney, including mesangial cells, podocytes, endothelium, vascular smooth muscle, every section of the nephron, and renal nerves. In addition, while not the subject of the current review, ET can also indirectly affect renal function through modulation of extrarenal systems, including the vasculature, nervous system, adrenal gland, circulating hormones, and the heart. As will become apparent, these pleiotropic effects of ET are of fundamental physiologic importance in the control of renal function in health. In addition, to help put these effects into perspective, we will also discuss, albeit to a relatively limited extent, how alterations in the ET system can contribute to hypertension and kidney disease.
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Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah, USA.
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13
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Kohan DE, Rossi NF, Inscho EW, Pollock DM. Regulation of blood pressure and salt homeostasis by endothelin. Physiol Rev 2011; 91:1-77. [PMID: 21248162 DOI: 10.1152/physrev.00060.2009] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Endothelin (ET) peptides and their receptors are intimately involved in the physiological control of systemic blood pressure and body Na homeostasis, exerting these effects through alterations in a host of circulating and local factors. Hormonal systems affected by ET include natriuretic peptides, aldosterone, catecholamines, and angiotensin. ET also directly regulates cardiac output, central and peripheral nervous system activity, renal Na and water excretion, systemic vascular resistance, and venous capacitance. ET regulation of these systems is often complex, sometimes involving opposing actions depending on which receptor isoform is activated, which cells are affected, and what other prevailing factors exist. A detailed understanding of this system is important; disordered regulation of the ET system is strongly associated with hypertension and dysregulated extracellular fluid volume homeostasis. In addition, ET receptor antagonists are being increasingly used for the treatment of a variety of diseases; while demonstrating benefit, these agents also have adverse effects on fluid retention that may substantially limit their clinical utility. This review provides a detailed analysis of how the ET system is involved in the control of blood pressure and Na homeostasis, focusing primarily on physiological regulation with some discussion of the role of the ET system in hypertension.
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Affiliation(s)
- Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA.
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Gupta R, Mohanan A, Joshi D. Development and Validation of a Rat Model for Examining the AT1 and ETA Receptor-Blocking Activity of Dual AT1 and ETA Receptor Blockers. High Blood Press Cardiovasc Prev 2009. [DOI: 10.2165/00151642-200916020-00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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15
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Banes-Berceli AKL, Ketsawatsomkron P, Ogbi S, Patel B, Pollock DM, Marrero MB. Angiotensin II and endothelin-1 augment the vascular complications of diabetes via JAK2 activation. Am J Physiol Heart Circ Physiol 2007; 293:H1291-9. [PMID: 17526654 DOI: 10.1152/ajpheart.00181.2007] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The JAK/STAT pathway is activated in vitro by angiotensin II (ANG II) and endothelin-1 (ET-1), which are implicated in the development of diabetic complications. We hypothesized that ANG II and ET-1 activate the JAK/STAT pathway in vivo to participate in the development of diabetic vascular complications. Using male Sprague-Dawley rats, we performed a time course study [days 7, 14, and 28 after streptozotocin (STZ) injection] to determine changes in phosphorylation of JAK2, STAT1, and STAT3 in thoracic aorta using standard Western blot techniques. On day 7 there was no change in phosphorylation of JAK2, STAT1, and STAT3. Phosphorylation of JAK2, STAT1, and STAT3 was significantly increased on days 14 and 28 and was inhibited by treatment with candesartan (AT(1) receptor antagonist, 10 mg x kg(-1) x day(-1) orally in drinking water), atrasentan (ET(A) receptor antagonist, 10 mg x kg(-1) x day(-1) orally in drinking water), and AG-490 (JAK2 inhibitor, 5 mg x kg(-1) x day(-1) intraperitoneally). On day 28, treatment with all inhibitors prevented the significant increase in systolic blood pressure (SBP; tail cuff) of STZ-induced diabetic rats (SBP: 157 +/- 9.0, 130 +/- 3.3, 128 +/- 6.8, and 131 +/- 10.4 mmHg in STZ, STZ-candesartan, STZ-atrasentan, and STZ-AG-490 rats, respectively). In isolated tissue bath studies, diabetic rats displayed impaired endothelium-dependent relaxation in aorta (maximal relaxation: 95.3 +/- 3.0, 92.6 +/- 7.4, 76.9 +/- 12.1, and 38.3 +/- 13.1% in sham, sham + AG-490, STZ + AG-490, and STZ rats, respectively). Treatment of rats with AG-490 restored endothelium-dependent relaxation in aorta from diabetic rats at 14 and 28 days of treatment. These results demonstrate that JAK2 activation in vivo participates in the development of vascular complications associated with STZ-induced diabetes.
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MESH Headings
- Angiotensin II/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/enzymology
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiopathology
- Atrasentan
- Benzimidazoles/pharmacology
- Biphenyl Compounds
- Blood Glucose/metabolism
- Blood Pressure
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/enzymology
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetic Angiopathies/enzymology
- Diabetic Angiopathies/etiology
- Diabetic Angiopathies/metabolism
- Diabetic Angiopathies/physiopathology
- Endothelin A Receptor Antagonists
- Endothelin-1/metabolism
- Enzyme Activation
- Intracellular Signaling Peptides and Proteins/metabolism
- Janus Kinase 2/antagonists & inhibitors
- Janus Kinase 2/metabolism
- Male
- Phosphorylation
- Protein Kinase Inhibitors/pharmacology
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/metabolism
- Protein Tyrosine Phosphatases/metabolism
- Pyrrolidines/pharmacology
- Rats
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Endothelin A/metabolism
- STAT1 Transcription Factor/metabolism
- STAT3 Transcription Factor/metabolism
- Signal Transduction
- Tetrazoles/pharmacology
- Time Factors
- Tyrphostins/pharmacology
- Vasodilation
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Affiliation(s)
- Amy K L Banes-Berceli
- Vascular Biology Center, Department of Physiology, Medical College of Georgia, Augusta, GA 30912-3000, USA.
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16
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An SJ, Boyd R, Wang Y, Qiu X, Wang HD. Endothelin-1 expression in vascular adventitial fibroblasts. Am J Physiol Heart Circ Physiol 2006; 290:H700-8. [PMID: 16113066 DOI: 10.1152/ajpheart.00326.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelial cells are a major source of endothelin (ET)-1, but the possibility that vascular adventitial fibroblasts generate ET-1 has not been explored. We hypothesized that aortic adventitial fibroblasts have the ability to produce ET-1, which may contribute to extracellular matrix synthesis. Vascular adventitial fibroblasts were isolated from mouse aorta and incubated with various concentrations of angiotensin II (ANG II). mRNA levels of preproET-1 and type I procollagen were detected with relative RT-PCR. ET-1 levels in culture medium were measured with ELISA. Protein levels of procollagen were detected with Western blotting. ANG II (10 and 100 nM, 1 μM) induced a time- and concentration-dependent increase in preproET-1 mRNA levels ( P < 0.05). Induction of preproET-1 mRNA was accompanied by release of immunoreactive peptide ET-1 ( P < 0.05). ANG II-evoked increases in preproET-1 mRNA expression and ET-1 release were blocked by losartan (100 μM), an AT1 receptor antagonist, but not PD-123319 (100 μM), an AT2 receptor antagonist. To further confirm our findings, we cloned and then sequenced vascular fibroblast preproET-1 bidirectionally with T7 and M13 reverse sequencing primers. Their nucleotide sequences were identical to preproET-1 cDNA from mouse vascular endothelial cells (accession no. AB081657 ). Moreover, ANG II-induced type I procollagen mRNA and protein expression were inhibited by BQ-123 (10 μM), an ETA receptor inhibitor, but not BQ-788 (10 μM), an ETB receptor inhibitor, suggesting a significant role of adventitial ET-1 in regulation of extracellular matrix synthesis. The results demonstrate that vascular adventitial fibroblasts are able to synthesize and release ET-1 in response to ANG II.
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Affiliation(s)
- Sheng Jun An
- Dept. of Community Health Sciences, Faculty of Applied Health Sciences, Brock Univ., St. Catharines, ON, Canada L2S 3Y6
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17
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Laplante MA, de Champlain J. The interrelation of the angiotensin and endothelin systems on the modulation of NAD(P)H oxidaseThis paper is one of a selection of papers published in this Special issue, entitled Young Investigator's Forum. Can J Physiol Pharmacol 2006; 84:21-8. [PMID: 16845887 DOI: 10.1139/y05-146] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The NAD(P)H oxidase is an enzyme assembled at the cellular membrane able to produce superoxide anion from NADH or NAD(P)H (nicotinamide adenine dinucleotide phosphate). It is one of the main sources of superoxide anion in cardiovascular tissues and its role in a variety of cardiovascular disorders such as atherosclerosis, cardiac hypertrophy, and endothelial dysfunction was recently proposed. Although, many factors and receptors were shown to lead to the activation of the enzyme, particulary the type 1 angiotensin receptor, the pathways involved are still widely unknown. Despite the identification of factors such as c-Src and protein kinase C implicated in the acute activation of NAD(P)H oxidase, the signalling involved in the sustained activation of the enzyme is probably far more complex than was previously envisioned. In this review, we describe the role of endothelin-1 in NAD(P)H oxidase signalling after a sustained stimulation by angiotensin II. Since most pathologies caused by an NAD(P)H oxidase overactivation develop over a relatively long period of time, it is necessary to better understand the long-term signalling of the enzyme for the development or use of more specific therapeutic tools.
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Affiliation(s)
- Marc-André Laplante
- Research Group on Autonomic Nervous System, Department of Physiology, Faculty of Medicine, Université de Montréal, Succursale Centre-ville, Canada
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18
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Laplante MA, Wu R, Moreau P, de Champlain J. Endothelin mediates superoxide production in angiotensin II-induced hypertension in rats. Free Radic Biol Med 2005; 38:589-96. [PMID: 15683715 DOI: 10.1016/j.freeradbiomed.2004.11.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Revised: 11/18/2004] [Accepted: 11/18/2004] [Indexed: 02/07/2023]
Abstract
Angiotensin II and endothelin-1 (ET) are two hormones involved in cardiovascular diseases and well known for their capacity to induce free radical generation in vascular and cardiac tissues. In addition to its prooxidative effect, angiotensin II can increase the synthesis of ET-1 in vascular smooth muscle cells (VSMC). Our objective was to determine whether the ET-1 synthesis in VSMC is involved in angiotensin II-induced superoxide anion production in rats. Our results show that treatments of isolated VSMC with angiotensin II and ET increased superoxide. However, this increase occurred in a bimodal fashion for angiotensin II with a fast transient production (10 min) and a late sustained production (6 h), while ET-1 induced superoxide formation after a delay of 6 h. LU302872 and BQ-123, a nonselective and a selective ETA receptor antagonists, respectively, prevented angiotensin II-induced superoxide anion production only during the late phase. In contrast, BQ-3020, a selective ETB receptor antagonist, had no effect. In vivo, LU302872 reduced the aortic superoxide production induced by angiotensin II administered for 12 days. In conclusion, our results suggest that the superoxide generation induced by chronic angiotensin II infusion may be mediated by ET-1 acting on ETA receptors in VSMC in vitro. Furthermore, this effect appears to contribute to the excess superoxide production during the chronic activation of the renin-angiotensin system in vivo.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Antihypertensive Agents/pharmacology
- Cells, Cultured
- Endothelin Receptor Antagonists
- Endothelin-1/physiology
- Hypertension/chemically induced
- Hypertension/physiopathology
- In Vitro Techniques
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- NADH, NADPH Oxidoreductases/biosynthesis
- NADPH Oxidase 1
- NADPH Oxidase 4
- NADPH Oxidases/biosynthesis
- Peptides, Cyclic/pharmacology
- Propionates/pharmacology
- Pyrimidines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Superoxides/metabolism
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Affiliation(s)
- Marc-André Laplante
- Research Group on Autonomic Nervous System, Department of Physiology, Université de Montréal, Montréal, Québec, Canada
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19
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Yuyama H, Sonoda R, Shibasaki K, Fujimori A, Sudoh K, Sasamata M, Miyata K. Effect of single oral administration of YM598, a novel selective endothelin ETA receptor antagonist, on blood pressure in normotensive and hypertensive rats. Vascul Pharmacol 2004; 41:27-34. [PMID: 15135329 DOI: 10.1016/j.vph.2004.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2003] [Accepted: 03/29/2004] [Indexed: 11/19/2022]
Abstract
We investigated the effect of YM598, a selective endothelin ETA receptor antagonist, on blood pressure (BP) in normotensive rats (NTR), spontaneously hypertensive rats (SHR) and Dahl salt-sensitive hypertensive rats (Dahl-SS). We also examined the concomitant effect of YM598 with the L-type Ca2+ channel antagonist nifedipine on BP. Single oral administration of YM598 did not affect BP in NTR and SHR. In Dahl-SS, in contrast, YM598 slightly, but not significantly, reduced BP. Concomitant administration of YM598 with nifedipine at doses inducing slight hypotension on respective single administrations resulted in a stronger hypotensive effect than single administration of either compound alone. However, the magnitude of the concomitant hypotensive effect demonstrated only a simple additive effect of the two compounds. These results indicate that YM598 did cause slight hypotensive effects in some types of hypertension. These results also indicate the possibility of additive, but not synergic, hypotensive effects on concomitant administration of ET receptor antagonist and an L-type Ca2+ channel antagonist.
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Affiliation(s)
- Hironori Yuyama
- Institute for Drug Discovery Research, Applied Pharmacology Research, Pharmacology Laboratories, Yamanouchi Pharmaceutical Co., Ltd., 21, Miyukigaoka, Tsukuba, Ibaraki 305-8585, Japan.
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20
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Francis RCE, Höhne C, Kaczmarczyk G, Boemke W. Effect of angiotensin II and endothelin-1 receptor blockade on the haemodynamic and hormonal changes after acute blood loss and after retransfusion in conscious dogs. ACTA ACUST UNITED AC 2004; 180:319-28. [PMID: 15030373 DOI: 10.1111/j.1365-201x.2004.01265.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM This study investigates angiotensin II and endothelin-1 mediated mechanisms involved in the haemodynamic, hormonal, and renal response towards acute hypotensive haemorrhage. METHODS Conscious dogs were pre-treated with angiotensin II type 1 (AT1) and/or endothelin-A (ETA) receptor blockers or not. Protocol 1: After a 60-min baseline period, 25% of the dog's blood was rapidly withdrawn. The blood was retransfused 60 min later and data recorded for another hour. Protocol 2: Likewise, but preceded by AT1 blockade with i.v. Losartan. Protocol 3: Likewise, but preceded by ETA blockade with i.v. ABT-627. Protocol 4: Likewise, but with combined AT1 plus ETA blockade. RESULTS In controls, haemorrhage decreased mean arterial pressure (MAP) by approximately 25%, cardiac output by approximately 40%, and urine volume by approximately 60%, increased angiotensin II (3.1-fold), endothelin-1 (1.13-fold), vasopressin (116-fold), and adrenaline concentrations (3.2-fold). Glomerular filtration rate and noradrenaline concentrations remained unchanged. During AT1 blockade, the MAP decrease was exaggerated (-40%) and glomerular filtration rate fell. During ETA blockade, noradrenaline increased after haemorrhage instead of adrenaline, and the MAP recovery after retransfusion was blunted. The decrease in cardiac output was similar in all protocols. CONCLUSIONS Angiotensin II is more important than endothelin-1 for the short-term regulation of MAP and glomerular filtration rate after haemorrhage, whereas endothelin-1 seems necessary for complete MAP recovery after retransfusion. After haemorrhage, endothelin-1 seems to facilitate adrenaline release and to blunt noradrenaline release. Haemorrhage-induced compensatory mechanisms maintain blood flow more effectively than blood pressure, as the decrease in cardiac output--but not MAP--was similar in all protocols.
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Affiliation(s)
- R C E Francis
- Experimental Anaesthesia, Department of Anaesthesiology and Intensive Care Medicine, Charitè, Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany
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21
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Yao L, Kobori H, Rahman M, Seth DM, Shokoji T, Fan Y, Zhang GX, Kimura S, Abe Y, Nishiyama A. Olmesartan Improves Endothelin-Induced Hypertension and Oxidative Stress in Rats. Hypertens Res 2004; 27:493-500. [PMID: 15302986 PMCID: PMC2574494 DOI: 10.1291/hypres.27.493] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recent studies have indicated that both endothelin (ET) and angiotensin (Ang) II stimulate oxidative stress, which contributes to the development of hypertension. Here, we examined the effects of Ang II type 1 (AT1) receptor blockade on reactive oxygen species (ROS) formation in ET-dependent hypertension. Chronic ET-1 infusion (2.5 pmol/kg/min, i.v., n=7) into rats for 14 days increased systolic blood pressure from 113+/-1 to 141+/-2 mmHg. ET-1-infused rats showed greater plasma renin activity (8.1+/-0.8 Ang I/ml/h), and greater Ang I (122+/-28 fmol/ml) and Ang II levels (94+/-13 fmol/ml) than vehicle (0.9% NaCl)-infused rats (3.1+/-0.6 Ang I/ml/h, 45+/-8 and 47+/-7 fmol/ml, respectively, n=6). Angiotensin converting enzyme and AT1 receptor expression in aortic tissues were similar between the vehicle- and ET-1-infused rats. Vascular superoxide anion (O2-) production and plasma thiobarbituric acid-reactive substance (TBARS) levels were greater in ET-1-infused rats (27+/-1 counts per minutes [CPM]/mg dry tissue weight and 8.9+/-0.8 micromol/l, respectively) than vehicle-infused rats (16+/-1 CPM/mg and 5.1+/-0.1 micromol/l, respectively). The ET-1-induced hypertension was prevented by simultaneous treatment with a new AT1 receptor antagonist, olmesartan (0.01% in chow, 117+/-5 mmHg, n =7), or hydralazine (15 mg/kg/day in drinking water, 118+/-4 mmHg, n=6). Olmesartan prevented ET-1-induced increases in vascular O2- production (15+/-1 CPM/mg) and plasma TBARS (5.0+/-0.1 micromol/l). Vascular O2- production and plasma TBARS were also decreased by hydralazine (21+/-1 CPM/mg and 7.0+/-0.3 micromol/l, respectively), but these levels were significantly higher than in vehicle-infused rats. These data suggest that ET-dependent hypertension is associated with augmentation of Ang II levels and ROS formation. The combined effects of the elevations in circulating ET-1 and Ang II, as well as the associated ROS production, may contribute to the development of hypertension induced by chronic ET-1 infusion.
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Affiliation(s)
- Li Yao
- Department of Pharmacology, Kagawa Medical University, Japan
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22
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McNeill JR. Role of endothelin in regulation of resistance, fluid-exchange, and capacitance functions of the systemic circulation. Can J Physiol Pharmacol 2003; 81:522-32. [PMID: 12839264 DOI: 10.1139/y03-016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This article reviews data at the in vivo whole animal and human level. The importance of both flow and pressure recordings and of the methods used to record these variables is emphasized. Exogenous administration of endothelin-1 evokes a transient depressor response mediated by endothelial endothelinB receptors, but the predominate effect of endothelin-1 is a sustained increase in blood pressure resulting from increases in total peripheral resistance. Resistance in the superior mesenteric, renal, and hindquarter vascular beds of animals and forearm resistance in humans is increased. Both endothelinA and, to a lesser extent, endothelinB receptors on vascular smooth muscle mediate the increases in resistance. Endothelin-1 evokes decreases in the precapillary/postcapillary resistance ratio, resulting in increased capillary pressure and net transcapillary filtration. Endothelin-1 evokes increases in mean circulatory filling pressure in animals and in constriction of the human dorsal hand vein. This venoconstrictor activity is mediated primarily through endothelinA and to a lesser extent endothelinB receptors. Endogenously generated endothelin contributes to the hemodynamic effects of angiotensin and vasopressin in certain animal models of hypertension. Antagonists of endothelin evoke modest hemodynamic changes in healthy humans and in some healthy animals, and they decrease vascular resistance dramatically in several salt-sensitive rat models of hypertension and also in some hypertensive human subjects. Thus, endogenously generated ET appears to play a modest role in the healthy organism, but it likely plays a major role in many pathophysiological states as described in companion articles in this issue.
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Affiliation(s)
- J Robert McNeill
- Cardiovascular Risk Factor Reduction Unit and Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada.
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23
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Ono K, Matsumori A. Endothelin antagonism with bosentan: current status and future perspectives. CARDIOVASCULAR DRUG REVIEWS 2002; 20:1-18. [PMID: 12070530 DOI: 10.1111/j.1527-3466.2002.tb00078.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Endothelin receptor antagonists have been proposed for the treatment of a variety of disorders in which the endothelins may act as pathogenic mediators, such as hypertension, congestive heart failure, and cerebral vasospasm. Bosentan is a nonpeptide competitive antagonist, which can be a good tool for studying the endothelin system. It is specific for the endothelin system and blocks the actions of endothelin at both mammalian receptors (A and B). Bosentan has recently moved into Phase III clinical trial. This review will attempt to overview the experimental and clinical effects of bosentan.
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Affiliation(s)
- Koh Ono
- Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine, Kyoto Japan 606-8297
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24
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Bayerle-Eder M, Langenberger H, Pleiner J, Polska E, Mensik C, Eichler HG, Wolzt M, Schmetterer L. Endothelin ETA receptor-subtype specific antagonism does not mitigate the acute systemic or renal effects of exogenous angiotensin II in humans. Eur J Clin Invest 2002; 32:230-5. [PMID: 11952807 DOI: 10.1046/j.1365-2362.2002.00974.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Angiotensin II (Ang II) is assumed to play a pathophysiological role in a variety of vascular diseases. Animal studies indicate that these effects are partly attributed to stimulation of endothelin-1 (ET-1) release. The aim of the present study was to investigate whether the acute effects of Ang II on systemic and renal haemodynamics in healthy subjects can be influenced by endothelin ET(A)-receptor blockade. DESIGN The study design was balanced, randomized, placebo-controlled, double blind, two-way cross-over, in 10 healthy male subjects. METHODS Subjects received stepwise increasing intravenous doses of Ang II (0.65, 1.25, 2.5, 5 ng kg(-1) min(-1) for 15 min per dose level) in the presence or absence of BQ-123 (60 microg min(-1)), a specific ETA-receptor antagonist. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were assessed by the para-aminohippurate and inulin plasma clearance method, respectively. Renal vascular resistance (RVR) was calculated from mean arterial pressure (MAP) and renal plasma flow. RESULTS Ang II decreased RPF by 34% and GFR by 9% and increased RVR by 94% and MAP by 27% (ANOVA, P < 0.001 vs. baseline, for all parameters). BQ-123 did not alter these renal and systemic haemodynamic responses to a significant degree. In addition, BQ-123 had no significant haemodynamic effect under baseline conditions. CONCLUSIONS Short-term increase of circulating Ang II levels causes systemic and renal pressor effects, which are not mitigated by endothelin ETA-receptor blockade. This suggests that the pressor response to Ang II cannot be accounted for by the acute release of vasoactive ET-1.
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Affiliation(s)
- M Bayerle-Eder
- Department of Clinical Pharmacology, Vienna University, Vienna, Austria
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25
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Yu M, Gopalakrishnan V, Wilson TW, McNeill JR. Endothelin antagonist reduces hemodynamic responses to vasopressin in DOCA-salt hypertension. Am J Physiol Heart Circ Physiol 2001; 281:H2511-7. [PMID: 11709418 DOI: 10.1152/ajpheart.2001.281.6.h2511] [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: 01/01/2023]
Abstract
The contribution of endothelin to the changes in blood pressure, cardiac output, and total peripheral resistance evoked by arginine vasopressin and angiotensin II was investigated in deoxycorticosterone acetate (DOCA)-salt hypertensive rats by infusing the peptides intravenously before and after pretreatment with the endothelin receptor antagonist bosentan. Blood pressure was recorded with radiotelemetry devices and cardiac output was recorded with ultrasonic transit time flow probes in conscious unrestrained animals. The dose-related decreases in cardiac output induced by vasopressin and angiotensin II were unaffected by bosentan. In contrast, the dose-related increases in total peripheral resistance evoked by vasopressin were blunted in both DOCA-salt hypertensive and sham normotensive rats, but this effect of bosentan was greater in the DOCA-salt hypertensive group. In contrast with vasopressin, bosentan failed to change hemodynamic responses to angiotensin II. The exaggerated vascular responsiveness (total peripheral resistance) of the DOCA-salt hypertensive group to vasopressin was largely abolished by bosentan. These results suggest that endothelin contributes to the hemodynamic effects of vasopressin but not angiotensin II in the DOCA-salt model of hypertension.
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Affiliation(s)
- M Yu
- Cardiovascular Risk Factor Reduction Unit and Department of Pharmacology, College of Medicine, Univesity of Saskatchewan, Saskatoon, Canada
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26
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Ficai S, Herizi A, Mimran A, Jover B. Endothelin blockade in angiotensin II hypertension: prevention and treatment studies in the rat. Clin Exp Pharmacol Physiol 2001; 28:1100-3. [PMID: 11903325 DOI: 10.1046/j.1440-1681.2001.03568.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The participation of endothelin (ET) in the development and maintenance of hypertension induced by angiotensin (Ang) II was assessed using the non-specific ET receptor antagonist bosentan (30 mg/kg per day). 2. In the prevention study, bosentan was given 24 h prior to and during the 17 day period of AngII infusion (200 ng/kg per min, s.c., osmotic pump), whereas in the treatment study, bosentan was administered from day 10 to day 17. Tail-cuff pressure (TCP) was measured before and on days 10 and 17 of AngII infusion. At the end of studies, heart weight index was calculated as the ratio of heart to bodyweight (HWI) and the wall thickness of the carotid artery (perfusion/fixation at 120 mmHg) was measured. Tail-cuff pressure increased from 129 +/- 3 to 179 +/- 7 and 189 +/- 9 mmHg on days 10 and 17 of AngII infusion, respectively. 3. Final TCP was markedly lowered in rats pretreated with bosentan, whereas TCP remained comparable with untreated hypertensive rats when bosentan was given from day 10 of AngII infusion (177 +/- 9 mmHg). 4. The increase in cardiac mass associated with AngII hypertension was similarly attenuated in the two groups receiving bosentan. 5. The HWI was 3.49 +/- 0.12 mg/g in untreated hypertensive rats and 3.18 +/- 0.08 and 3.11 +/- 0.09 mg/g in rats pretreated with bosentan and those receiving the antagonist from day 10. 6. The increase in carotid wall thickness induced by AngII was prevented, but not reversed, by bosentan. 7. These results support the hypothesis that endogenous ET participates only in the initial phase of AngII hypertension. In addition, the beneficial effect of bosentan of cardiac mass but not on arterial wall thickness is in favour of a role of ET as a local mediator of the cardiac hypertrophic effect of AngII, independently of the level of blood pressure and duration of hypertension.
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Affiliation(s)
- S Ficai
- Groupe Rein et Hypertension, Faculté de Médecine, University Montpellier I, Montpellier, France
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27
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Shastri S, McNeill JR, Wilson TW, Poduri R, Kaul C, Gopalakrishnan V. Cysteinyl leukotrienes mediate enhanced vasoconstriction to angiotensin II but not endothelin-1 in SHR. Am J Physiol Heart Circ Physiol 2001; 281:H342-9. [PMID: 11406502 DOI: 10.1152/ajpheart.2001.281.1.h342] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We assessed whether cysteinyl leukotrienes mediate the vasoconstrictor responses to angiotensin II and endothelin-1 in the mesenteric vascular bed of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) perfused ex vivo at a constant flow rate of 5 ml/min with Krebs buffer. Maximal perfusion pressure response (E(max)) but not EC(50) values to angiotensin II (P < 0.001) and endothelin-1 (P < 0.01) were significantly higher in the SHR, whereas the responses to potassium chloride remained unchanged. Inclusion of the selective 5-lipoxygenase inhibitor AA-861 or the cysteinyl leukotriene receptor antagonist MK-571 significantly reduced the vasoconstrictor responses to angiotensin II but not to endothelin-1 and potassium chloride. The reduction in E(max) to angiotensin II was more pronounced in SHR (P < 0.001) than in WKY (P < 0.05) rats. Cysteinyl leukotrienes LTC(4)-, LTD(4)-, and LTE(4) (1 microM)-evoked vasoconstrictor responses were significantly higher in SHR (P < 0.05), whereas LTB(4) failed to evoke any response in either strain. These data suggest that 5-lipoxygenase metabolites, particularly cysteinyl leukotrienes, contribute to the exaggerated vasoconstrictor responses to angiotensin II but not to endothelin-1.
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Affiliation(s)
- S Shastri
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education & Research, SAS Nagar, 160 062, India
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28
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Boemke W, Hocher B, Schleyer N, Krebs MO, Kaczmarczyk G. Hemodynamic, renal, and endocrine responses to acute ET(A) blockade at different ANG II plasma levels. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1322-31. [PMID: 11294750 DOI: 10.1152/ajpregu.2001.280.5.r1322] [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: 11/22/2022]
Abstract
Angiotensin (ANG) II effects may be partly mediated by endothelin (ET)-1. This study analyses the hemodynamic, renal, and hormonal responses of acute ET(A) receptor antagonism (LU-135252) at two ANG II plasma levels in eight conscious dogs. Protocol 1 involved a 60-min baseline, followed by two doses of ANG II for 60 min each (4 and 20 ng. kg(-1). min(-1)), termed ANG II 4 (slightly increased) and ANG II 20 (pathophysiologically increased ANG II plasma concentration). Protocol 2 was the same as protocol 1 but included 15 mg/kg iv LU-135252 after the baseline period. Protocol 3 was a 3-h time control. ANG II without LU-135252 did not increase plasma big ET-1 and ET-1, whereas LU-135252 increased ET-1 transiently after injection. This transient ET-1 increase was not reflected in urinary ET-1 excretion. The ANG II induced decreases in sodium, water, and potassium excretion, glomerular filtration rate, and fractional sodium excretion were not different with and without LU-135252. Mean arterial pressure increased during ANG II and was not lower with LU-135252 (-6 mmHg, not significant). Most importantly, during ANG II 20 LU-135252 prevented the decrease in cardiac output. Simultaneously, systemic vascular resistance increased 40% less, pulmonary vascular resistance was maintained at baseline levels, and central venous and wedge pressure were lower. Because ANG II stimulated endothelin de novo synthesis should just have started after 2 h of ANG II infusion, there must be mechanisms other than blocking the coupling of de novo synthesized endothelins to the ET(A) receptors to explain the effects of acute ET(A) receptor inhibition in our setting.
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Affiliation(s)
- W Boemke
- Experimental Anesthesia, Campus Virchow-Klinikum, Medical Faculty of Charité, 13353 Berlin, Germany.
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Bergström G, Nyström HC, Jia J, Evans RG. Effects of the ET(A)/ET(B) antagonist, TAK-044, on blood pressure and renal excretory function after unclipping of conscious one-kidney-one-clip hypertensive rats. J Hypertens 2001; 19:659-65. [PMID: 11327643 DOI: 10.1097/00004872-200103001-00020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Restoring renal perfusion pressure (unclipping) of one-kidney-one-clip renal hypertensive (1 K1C) rats normalizes mean arterial pressure (MAP) rapidly. This has been attributed to salt/volume losses or release of the putative renal medullary depressor hormone (RMDH). OBJECTIVE To investigate the effects of endothelin receptor A and B (ET(A)/ET(B)) antagonism on unclipping. DESIGN AND METHODS Telemetric devices were implanted in male Wistar 1K1C rats for measurement of conscious MAP. Hypertension was reversed by unclipping with the animal under brief anaesthesia. Seven rats were treated with the ET(A)/ET(B) antagonist, TAK-044 (two doses of 10 mg/kg intraperitoneally in 24 h), and eight rats received its vehicle. In order to investigate whether endothelin receptor antagonism could release RMDH under resting conditions, TAK-044 was administered to telemetered non-clipped intact and chemically renal medullectomized rats (BEA treatment). RESULTS TAK-044 did not affect resting MAP, urine flow or sodium excretion in 1K1C rats. However, after unclipping, the TAK-044-treated group showed a more marked reduction in MAP during the first 24 h after unclipping (P< 0.01). TAK-044 also reduced urine flow and sodium excretion during the first 8 h after unclipping (P< 0.05). TAK-044 reduced resting MAP (P< 0.05) to a similar extent in intact and BEA rats. CONCLUSIONS TAK-044 potentiated the reduction in MAP after unclipping, independently of changes in urine flow and sodium excretion. It also reduced MAP in normotensive rats--an effect that was not dependent on an intact renal medulla. Potentiation of the depressor response to unclipping by TAK-044 could be the result of an interaction of endogenous endothelin receptors with renal depressor mechanisms--possibly, the release, actions, or both, of the putative RMDH.
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Affiliation(s)
- G Bergström
- Department of Physiology, University of Göteborg, Sweden.
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Quest DW, Gopalakrishnan V, McNeill JR, Wilson TW. Effect of losartan on angiotensin II-mediated endothelin and prostanoid excretion in humans. Am J Hypertens 2000; 13:1288-94. [PMID: 11130773 DOI: 10.1016/s0895-7061(00)01210-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Angiotensin II (Ang II) stimulates renal prostanoid and vascular endothelin-1 (ET-1) release. Most known Ang II effects are mediated by AT1 receptors. Our aim was to determine whether AT1 receptor activation mediates Ang II-evoked renal prostanoid and ET-1 release. Eleven healthy men were randomized in a crossover, double-blind fashion to receive 100 mg/day of losartan or matching placebo, for 8 days. Blood and urine were sampled before and after a 2-h infusion of Ang II at a rate previously determined to increase mean arterial pressure (MAP) by 25 to 30 mm Hg in each subject. After a 14-day washout, subjects received the alternate treatment. Pretreatment with losartan had little effect on baseline MAP, but increased plasma renin activity, and virtually eliminated the pressor response to Ang II infusion. Angiotensin II significantly increased prostanoid excretion after placebo; the prostanoid response to Ang II was even greater after losartan. Plasma ET-1 was not altered by Ang II infusion, with or without losartan. In contrast, urine ET-1 excretion rate decreased to 40% of baseline after Ang II but not after losartan pretreatment; losartan alone had no effect. We conclude that Ang II decreases renal ET-1 synthesis and release through the AT1 receptor. In contrast, Angiotensin II-mediated renal prostanoid synthesis does not require activation of AT1 receptors. These findings indicate that AT1 receptor antagonists could provide renal protection through indirect mechanisms.
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Affiliation(s)
- D W Quest
- Department of Pharmacology, University of Saskatchewan, Saskatoon, SK, Canada.
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Kelly DJ, Skinner SL, Gilbert RE, Cox AJ, Cooper ME, Wilkinson-Berka JL. Effects of endothelin or angiotensin II receptor blockade on diabetes in the transgenic (mRen-2)27 rat. Kidney Int 2000; 57:1882-94. [PMID: 10792607 DOI: 10.1046/j.1523-1755.2000.00038.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Endothelin (ET) and angiotensin II (Ang II) are vasoactive/trophic peptides that may contribute to the progression of diabetic nephropathy. The transgenic (mRen-2)27 rat exhibits overexpression of Ang II at sites of normal physiological expression. Unlike other rat strains, the streptozotocin-induced diabetic Ren-2 rat develops progressive renal pathology associated with a declining glomerular filtration rate (GFR) and provides a convenient model to evaluate the role of these vasoactive peptides in the nephropathic process. METHODS AND RESULTS Oral administration of either the endothelin A (ETA) and ETB receptor antagonist bosentan or the angiotensin type 1 (AT1) receptor antagonist valsartan for 12 weeks reduced systolic blood pressure (SBP) of nondiabetic and diabetic Ren-2 rats to normotensive levels. Diabetic renal pathology was associated with intense renin mRNA and protein in the proximal tubules and juxtaglomerular cells along with overexpression of transforming growth factor-beta1 (TGF-beta1) and collagen IV mRNA in glomeruli and tubules. With valsartan but not bosentan, renin mRNA and protein in the proximal tubules were not detected. Valsartan but not bosentan reduced TGF-beta1 and collagen IV mRNA and the severity of diabetic renal pathology. A declining GFR with diabetes was attenuated by both treatments. Albuminuria in diabetic rats rose further with bosentan but was reduced with valsartan. CONCLUSIONS Despite producing normotension, severe diabetic renal pathology was not prevented by bosentan, suggesting dissociation of ET, albuminuria, and hypertension from the structural injury in this diabetic model. The beneficial effects afforded by valsartan therapy strengthen the importance of the local renin-angiotensin system in mediating progressive diabetic renal injury.
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Affiliation(s)
- D J Kelly
- Department of Medicine, Austin and Repatriation Medical Center, Heidelberg West, and Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
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Gardiner SM, March JE, Kemp PA, Bennett T. Cardiovascular responses to angiotensins I and II in normotensive and hypertensive rats; effects of NO synthase inhibition or ET receptor antagonism. Br J Pharmacol 1999; 128:1795-803. [PMID: 10588936 PMCID: PMC1571813 DOI: 10.1038/sj.bjp.0702978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We compared the cardiovascular responses to angiotensins (I and II), and any possible modulatory influences thereupon of nitric oxide (NO) or endothelin (ET) in conscious male, normotensive, Hannover Sprague-Dawley (SD) rats, and hypertensive, heterozygous ((mRen-2)27), transgenic (TG) rats. 2. The pressor effects of angiotensin I or of angiotensin II were not consistently different in SD and TG rats. The accompanying absolute reductions in renal and mesenteric vascular conductances were smaller in TG rats, but probably due to the baseline vasoconstriction in those animals. 3. Inhibition of NO synthase with L-NAME had no significant effects on the pressor responses to angiotensin I or angiotensin II in either SD or TG rats. L-NAME reduced the absolute, but not percentage, reductions in renal and mesenteric vascular conductances in response to angiotensin I and angiotensin II. L-NAME abolished the hindquarters vasodilator effects of angiotensin I and angiotensin II in both strains of rat. 4. ET receptor antagonism (with SB209670) had no significant influence on the pressor or renal or mesenteric vasoconstrictor effects of angiotensin II in SD rats. In TG rats, the pressor responses to angiotensin II were unaffected by SB209670; the accompanying falls in renal and mesenteric vascular conductances were enhanced in absolute, but not in percentage terms. 5. These results provide no evidence for a buffering action of NO, or a modulatory influence of ET, on the pressor or vasoconstrictor effects of angiotensin I and/or angiotensin II in SD rats. Furthermore, there is no evidence for an altered sensitivity to angiotensin I or angiotensin II, and no evidence for a differential modulatory influence of either NO or ET in TG, compared to SD, rats.
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Affiliation(s)
- S M Gardiner
- School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK
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D'Amico M, Di Filippo C, Filippelli A, Rossi F. Endothelin receptor antagonists reduce the pressor effects of angiotensin II into the periaqueductal gray area of rats. Life Sci 1999; 65:PL95-9. [PMID: 10465357 DOI: 10.1016/s0024-3205(99)00327-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Injection of ANGII (0.01, 0.1 and 1 nmol/rat) into the periaqueductal gray (PAG) area significantly (P<0.01) increased, in a dose-dependent manner, the mean arterial blood pressure (MAP). The increases in blood pressure induced by ANGII (1 nmol; 37 +/- 4 mmHg, n=5) were greatly reduced (>85%) by pre-administration of the ET(A) receptor antagonist FR139317 (5 nmol/rat) to the PAG area, but were unaffected by the ET(B) receptor antagonist BQ-788 (5 nmol/rat). SB209670, non-selective ET(A)/ET(B) receptor antagonist, also reduced the effect induced by ANGII. These results suggest that endogenous endothelin-1, via an action on ET(A) receptors, may contribute to the pressor effects of ANGII within the PAG area of rats.
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Affiliation(s)
- M D'Amico
- Institute of Pharmacology and Toxicology, Faculty of Medicine and Surgery, 2nd University of Naples, Italy
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Fraser TB, Mangos GJ, Turner SW, Whitworth JA. Adrenocorticotrophic hormone-induced hypertension in the rat: effects of the endothelin antagonist bosentan. Clin Exp Pharmacol Physiol 1999; 26:628-33. [PMID: 10474778 DOI: 10.1046/j.1440-1681.1999.03101.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The effects of the endothelin antagonist bosentan on adrenocorticotrophic hormone (ACTH)-induced hypertension were examined in the conscious male Sprague-Dawley rat. 2. In order to confirm endothelin antagonism, 18 rats were randomly divided into two groups: receiving either (i) endothelin-1 (0.125, 0.25, 0.5 and 1 nmol/kg, i.v.); or (ii) endothelin-1 at these doses following bosentan (100 mg/kg gavage) and mean arterial pressure recorded (study A). Subsequently, 40 male rats (320 +/- 5 g) were randomly divided into four groups (n = 10): (i) Sham (0.9% saline, s.c.) + 5% acacia gum gavage; (ii) ACTH (500 micrograms/kg per day, s.c.) + 5% acacia gum gavage; (iii) Sham injection + bosentan (100 mg/kg per day) gavage; or (iv) ACTH + bosentan. Six control days (C1-C6) were followed by 11 treatment days (T0-T10). Systolic blood pressure, water intake, urine volume, food intake and bodyweight were measured every second day (study B). 3. Bosentan significantly attenuated the endothelin-1-induced blood pressure rise at 0.125 nmol/kg (P < 0.05), but not at higher doses. 4. Bosentan at a dose which attenuated endothelin-1-induced blood pressure increase had no effect on either blood pressure or metabolic parameters in ACTH-treated rats. 5. These results suggest that endothelin does not play a major role in ACTH-induced hypertension.
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Affiliation(s)
- T B Fraser
- Department of Medicine, St George Hospital, University of New South Wales, Sydney, Australia
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Aneman A, Bengtsson J, Snygg J, Holm M, Pettersson A, Fändriks L. Differentiation of the peptidergic vasoregulatory response to standardized splanchnic hypoperfusion by acute hypovolaemia or sepsis in anaesthetized pigs. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 166:293-300. [PMID: 10468666 DOI: 10.1046/j.1365-201x.1999.00574.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study was performed to integratively investigate the vasoregulatory response during standardized splanchnic hypoperfusion in pigs. Splanchnic perfusion was reduced to 50% of baseline by: haemorrhage by 20 and 40% of the estimated total blood volume; femoral venous infusion of live E. coli to establish sepsis of systemic origin; portal venous infusion of live E. coli to establish sepsis of splanchnic origin. Invasive haemodynamic monitoring and radioimmunoassay analyses of arterial plasma concentrations of angiotensin II, endothelin-1 and atrial natriuretic peptide were carried out. Acute hypovolaemia reduced systemic and splanchnic vascular resistances following transient increases and increased angiotensin II levels (+587%), whereas endothelin-1 and atrial natriuretic peptide levels did not change significantly. Systemic sepsis following femoral venous infusion of E. coli resulted in increased splanchnic vascular resistance and increased levels of angiotensin II (+274%), endothelin-1 (+134%) and atrial natriuretic peptide (+185%). Infusion of E. coli via the portal venous route induced an increase in splanchnic vascular resistance associated with particularly elevated levels of angiotensin II (+1770%) as well as increased endothelin-1 (+201%) and atrial natriuretic peptide (+229%) concentrations. Hypovolaemia and sepsis, although standardized with a predefined level of splanchnic hypoperfusion, elicited differentiated cardiovascular and vasopeptidergic responses. Sepsis, particularly of portal origin, notably increased splanchnic vascular resistance related to increased production of the vasoconstrictors angiotensin II and endothelin-1. The role of atrial natriuretic peptide as a vasodilator seems to be of subordinate importance in hypovolaemia and sepsis.
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Affiliation(s)
- A Aneman
- Department of Anaesthesiology and Intensive Care, Sahlgrens University Hospital, Göteborg, Sweden
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Talom RT, Judd SA, McIntosh DD, McNeill JR. High flaxseed (linseed) diet restores endothelial function in the mesenteric arterial bed of spontaneously hypertensive rats. Life Sci 1999; 64:1415-25. [PMID: 10321721 DOI: 10.1016/s0024-3205(99)00075-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effect of high flaxseed diet (HFD) on blood pressure (BP) and mesenteric arterial bed (MAB) reactivity was studied in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. HFD did not affect BP in either SHR (control, 157 +/- 3; HFD, 153 +/- 3 mmHg) or WKY (control, 114 +/- 2; HFD, 117 +/- 2 mmHg) rats. Increases in perfusion pressure of the endothelium-intact MAB to phenylephrine and norepinephrine were higher (p < 0.05) in SHR than in WKY rats and the HFD failed to alter these responses. Vasorelaxant responses to acetylcholine (ACh) and bradykinin (BK) were greater (p < 0.05) in SHR maintained on HFD compared to SHR on control diet. While HFD also enhanced ACh responses in WKY, the effect was less than in SHR. Responses to sodium nitroprusside (SNP), were similar in all groups. Since ACh and BK-induced responses of the MAB were augmented in SHR on HFD, with no changes in BP, it is suggested that HFD improves endothelial vasorelaxant function through a pressure-independent mechanism.
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Affiliation(s)
- R T Talom
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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Münter K, Ehmke H, Kirchengast M. Maintenance of blood pressure in normotensive dogs by endothelin. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H1022-7. [PMID: 10070087 DOI: 10.1152/ajpheart.1999.276.3.h1022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of endothelin (ET)-1 in blood pressure homeostasis and the interaction with the renin-angiotensin system (RAS) was investigated in normotensive conscious dogs. ETA receptors were blocked by LU-135252 (1-30 mg/kg); trandolapril (2 mg/kg) or losartan (10 mg/kg) was used to inhibit the RAS. LU-135252 in oral doses of 3-30 mg/kg significantly reduced mean arterial pressure (MAP) by approximately 10 mmHg maximally, whereas trandolapril or losartan were without any effect. MAP reduction was more pronounced when LU-135252 was combined with either losartan (-15.5 +/- 3.2 mmHg; 2 h postadministration; P < 0.05) or trandolapril (-30.9 +/- 3.6 mmHg; P < 0.05). When endogenous nitric oxide (NO) generation was blocked but NO concomitantly infused, this synergistic effect on MAP was prevented. The data show that ET-1 contributes to the maintenance of blood pressure via ETA receptors. Furthermore, ET-1 and ANG II play a prominent role in the control of blood pressure by opposing the effects of NO. The pronounced blood pressure fall after combined blockade of ETA receptors and the RAS may be mediated by an enhanced release of NO.
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Affiliation(s)
- K Münter
- Preclinical Cardiology, Knoll, 67008 Ludwigshafen, Germany
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Pinto-Sietsma SJ, Paul M. A role for endothelin in the pathogenesis of hypertension: fact or fiction? KIDNEY INTERNATIONAL. SUPPLEMENT 1998; 67:S115-21. [PMID: 9736265 DOI: 10.1046/j.1523-1755.1998.06722.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelin-1 (ET-1) was discovered 10 years ago. Because it is one of the most potent vasoconstrictors in vivo, a pathophysiological role for the peptide as a mediator of hypertension has been postulated. Several clinical studies, however, have been unable to identify elevated ET levels in the plasma of hypertensive patients, suggesting that it does not play a prominent role in this disease. More recently, evidence has been presented that ETs act predominantly at the autocrine/paracrine level and that measurements of plasma levels can give only an indirect view of the activity of the system. In addition, transgenic technology has uncovered new actions of the peptide systems in recent years, which point to a key function of the system in prenatal development. Moreover, investigation of conditions associated with hypertensive end-organ damage, such as chronic renal failure, has led to a re-evaluation of the role of the ET system in hypertension. This article discusses this recent evidence and defines the exact role of the ET system in hypertension and hypertensive end-organ damage.
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Affiliation(s)
- S J Pinto-Sietsma
- Department of Clinical Pharmacology and Toxicology, Free University Berlin, Germany
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Champion HC, Estrada LS, Estrada LN, Filep JG, Kadowitz PJ. Analysis of effects of bosentan (Ro 47-0203), a nonpeptide endothelin ETA/ETB receptor antagonist, in the hind-limb vascular bed of the cat. Can J Physiol Pharmacol 1998. [DOI: 10.1139/y98-001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The effects of bosentan (Ro 47-0203), an endothelin A and B receptor antagonist, on responses to endothelin-1, sarafotoxin 6c, angiotensin II, and arginine vasopressin were investigated in the hind-limb vascular bed of the cat. Under constant-flow conditions, intraarterial injections of endothelin-1 and sarafotoxin 6c induced biphasic changes in hind-limb perfusion pressure characterized by an initial decrease followed by a secondary increase in perfusion pressure. The vasodilator and vasoconstrictor components of the biphasic responses to endothelin-1 and sarafotoxin 6c were reduced by bosentan, and the endothelin receptor antagonist reduced baseline systemic arterial and hind-limb perfusion pressures. Bosentan decreased vasoconstrictor responses to lower doses of angiotensin II, whereas responses to higher doses of angiotensin II and responses to vasopressin, U46619, BAY K8644, norepinephrine, acetylcholine, bradykinin, levcromakalim, PGE1, adrenomedullin, and calcitonin gene-related peptide were not altered. Vasoconstrictor responses to ET-1 were not altered by the angiotensin AT1 receptor antagonist DuP 532 or the AT2 receptor antagonist PD123,319. The results of the present study show that bosentan attenuates vasodilator and vasoconstrictor responses to endothelin-1 and sarafotoxin 6c and vasoconstrictor responses to lower doses of angiotensin II in the hind-limb vascular bed of the cat. These results suggest that endothelin may be involved in mediating responses to lower doses of angiotensin II and in the maintenance of baseline tone in the systemic vascular bed of the cat.Key words: angiotensin II, bosentan (Ro 47-0203), endothelin, regional vascular bed, endothelial-derived peptide.
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Heinemann A, Wachter CH, Peskar BA, Holzer P. Dilatation by angiotensin II of the rat femoral arterial bed in vivo via pressure/flow-induced release of nitric oxide and prostaglandins. Br J Pharmacol 1997; 122:975-84. [PMID: 9401758 PMCID: PMC1565027 DOI: 10.1038/sj.bjp.0701460] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. The haemodynamic effects of angiotensin II (AII) and, for comparison, arginine vasopressin (AVP) in the femoral and superior mesenteric artery of urethane-anaesthetized rats were analysed with the ultrasonic transit time shift technique. 2. I.v. bolus injection of AII (0.1-3 nmol kg-1) and AVP (0.03-1 nmol kg-1) increased blood pressure which was accompanied by a decrease in blood flow through the superior mesenteric artery and an increase in femoral blood flow. The femoral hyperaemia was in part due to vasodilatation as indicated by a rise of femoral vascular conductance up to 200% relative to baseline. The femoral vasodilatation caused by AVP, but not AII, was followed by vasoconstriction. 3. Blockade of angiotensin AT1 receptors by telmisartan (0.2-20 mumol kg-1) prevented all haemodynamic responses to AII. 4. The femoral dilator responses to AII and AVP depended on the increase in vascular perfusion pressure since vasodilatation was reversed to vasoconstriction when blood pressure was maintained constant by means of a gravity reservoir. However, the AII-evoked femoral vasodilatation was not due to an autonomic or neuroendocrine reflex because it was not depressed by hexamethonium (75 mumol kg-1), prazosin (0.25 mumol kg-1) or propranolol (3 mumol kg-1). 5. The AII-induced femoral vasodilatation was suppressed by blockade of nitric oxide (NO) synthesis with NG-nitro-L-arginine methyl ester (L-NAME, 40 mumol kg-1) and reversed to vasoconstriction when L-NAME was combined with indomethacin (30 mumol kg-1), but was left unaltered by antagonism of endothelin ETA/B receptors with bosentan (37 mumol kg-1). 6. These results demonstrate that the effect of AII to increase systemic blood pressure and the resulting rise of perfusion pressure in the femoral artery stimulates the formation of NO and prostaglandins and thereby dilates the femoral arterial bed. This local vasodilator mechanism is sufficient to mask the direct vasoconstrictor response to AII.
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Affiliation(s)
- A Heinemann
- Department of Experimental and Clinical Pharmacology, University of Graz, Austria
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41
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Balakrishnan SM, Gopalakrishnan V, McNeill JR. Endothelin contributes to the hemodynamic effects of vasopressin in spontaneous hypertension. Eur J Pharmacol 1997; 334:55-60. [PMID: 9346328 DOI: 10.1016/s0014-2999(97)01131-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Changes in blood pressure, cardiac output, and total peripheral conductance evoked by intravenous infusions of [Arg8]-vasopressin (vasopressin) were recorded before and after pretreatment with bosentan, a non-selective endothelin antagonist, in conscious unrestrained spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). The presser effects of vasopressin were exaggerated in SHR compared to WKY. Pretreatment with bosentan failed to change hemodynamic responses of WKY to vasopressin, but it blunted the increases in blood pressure and the decreases in conductance evoked by vasopressin in SHR. In contrast, bosentan failed to change cardiac output responses of SHR to vasopressin. Except at the highest dose of vasopressin, bosentan abolished the exaggerated pressor responsiveness of the SHR to vasopressin. The results suggest that endothelin contributes to the exaggerated pressor responsiveness of SHR to vasopressin, and that this effect is exerted at the level of the resistance vessels and not on factors that regulate cardiac output.
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Affiliation(s)
- S M Balakrishnan
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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