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Sample records for endothelin receptor antagonists

  1. Endothelin receptor antagonists and cardiovascular diseases of aging.

    PubMed

    Love, M P; McMurray, J J

    2001-01-01

    Our understanding of the role of the endothelin system in human cardiovascular physiology and pathophysiology has evolved very rapidly since the initial description of its constituent parts in 1988. Endothelin-1 (ET-1) is the predominant endothelin isoform in the human cardiovascular system and has potent vasoconstrictor, mitogenic and antinatriuretic properties which have implicated it in the pathophysiology of a number of cardiovascular diseases. The effects of ET-1 have been shown to be mediated by 2 principal endothelin receptor subtypes: ET(A) and ET(B). The development of a range of peptidic and nonpeptidic endothelin receptor antagonists represents an exciting breakthrough in human cardiovascular therapeutics. Two main classes of endothelin receptor antagonist have been developed for possible human therapeutic use: ET(A)-selective and nonselective antagonists. Extensive laboratory and clinical research with these agents has highlighted their promise in various cardiovascular diseases. Randomised, placebo-controlled clinical trials have yielded very encouraging results in patients with hypertension and chronic heart failure with more preliminary data suggesting a possible role in the treatment and prevention of atherosclerosis and stroke. Much more research is needed, however, before endothelin receptor antagonists can be considered for clinical use.

  2. Endothelin receptor antagonists for subarachnoid hemorrhage.

    PubMed

    Guo, Jia; Shi, Zhenghong; Yang, Kehu; Tian, Jin Hui; Jiang, Lei

    2012-09-12

    A subarachnoid hemorrhage (SAH) is a serious and potentially life-threatening condition where blood leaks out of blood vessels over the surface of the brain. Delayed ischemic neurological deficit (DIND) and the related feature of vasospasm, where patients experience a delayed deterioration, have long been recognized as the leading potentially treatable cause of death and disability in patients with SAH. Endothelin is a potent, long-lasting endogenous vasoconstrictor that has been implicated in the pathogenesis of DIND. Therefore, endothelin receptor antagonists (ETAs) have emerged as a promising therapeutic option for SAH-induced cerebral vasospasm. To assess the efficacy and tolerability of ETAs for SAH. We searched the Cochrane Stroke Group Trials Register (December 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 11), MEDLINE (1950 to December 2011), EMBASE (1946 to December 2011) and the Chinese Biomedical Database (1978 to December 2011). In an effort to identify further published, unpublished and ongoing trials we searched additional Chinese databases, ongoing trials registers, Google Scholar and Medical Matrix, handsearched journals, scanned reference lists, and contacted researchers and pharmaceutical companies. We only included randomized controlled trials (RCTs) that compared an ETA with placebo for SAH in adult (18 years of age or older) patients who met the diagnostic criteria for SAH based on clinical symptoms, with confirmation on computerized tomography scan results or angiography. Two review authors independently selected RCTs according to the inclusion criteria. We resolved disagreements by discussion with a third review author. Two review authors independently selected relevant articles and assessed their eligibility according to the inclusion and exclusion criteria. We resolved disagreements by discussion with a third review author. We used the random-effects model and expressed the results as

  3. Clinical pharmacokinetics and pharmacodynamics of the endothelin receptor antagonist macitentan.

    PubMed

    Sidharta, P N; Treiber, A; Dingemanse, J

    2015-05-01

    Pulmonary arterial hypertension (PAH) is a progressive disease of the lung vascular system, which leads to right-sided heart failure and ultimately death if untreated. Treatments to regulate the pulmonary vascular pressure target the prostacyclin, nitric oxide, and endothelin (ET) pathways. Macitentan, an oral, once-daily, dual ETA and ETB receptor antagonist with high affinity and sustained receptor binding is the first ET receptor antagonist to show significant reduction of the risk of morbidity and mortality in PAH patients in a large-scale phase III study with a long-term outcome. Here we present a review of the available clinical pharmacokinetic, pharmacodynamic, pharmacokinetic/pharmacodynamic relationship, and drug-drug interaction data of macitentan in healthy subjects, patients with PAH, and in special populations.

  4. Endothelin receptor antagonists influence cardiovascular morphology in uremic rats.

    PubMed

    Nabokov, A V; Amann, K; Wessels, S; Münter, K; Wagner, J; Ritz, E

    1999-02-01

    In is generally held that renal failure results in blood pressure (BP)-independent structural changes of the myocardium and the vasculature. The contribution, if any, of endothelin (ET) to these changes has been unknown. We morphometrically studied random samples of the left ventricle myocardium and small intramyocardial arteries in subtotally (5/6) nephrectomized (SNx) male Sprague-Dawley rats treated with either the selective ETA receptor antagonist BMS182874 (30 mg/kg/day) or the nonselective ETA/ETB receptor antagonist Ro46-2005 (30 mg/kg/day) in comparison with either sham-operated rats, untreated SNx, or SNx rats treated with the angiotensin-converting enzyme inhibitor trandolapril (0.1 mg/kg/day). Eight weeks later, systolic BP was lower in trandolapril-treated SNx compared with untreated SNx animals. No decrease in BP was seen following either ET receptor antagonist at the dose used. A significantly increased volume density of the myocardial interstitium was found in untreated SNx rats as compared with sham-operated controls. Such interstitial expansion was prevented by trandolapril and either ET receptor antagonist. SNx caused a substantial increase in the wall thickness of small intramyocardial arteries. The increase was prevented by trandolapril or BMS182874 treatment. The arteriolar wall:lumen ratio was significantly lower in all treated groups when compared with untreated SNx. In contrast, only trandolapril, but not the ET receptor antagonists, attenuated thickening of the aortic media in SNx animals. The ETA-selective and ETA/ETB-nonselective receptor antagonists appear to prevent development of myocardial fibrosis and structural changes of small intramyocardial arteries in experimental chronic renal failure. This effect is independent of systemic BP.

  5. Small-molecule endothelin receptor antagonists: a review of patenting activity across therapeutic areas.

    PubMed

    Mucke, Hermann A M

    2009-06-01

    In the field of nonpeptide NCEs with endothelin receptor antagonist activity, a burst in corporate IP filings occurred in the 1990s once the human endothelin system had been characterized, but patent activity has declined in the past decade. Universities have not been active in this area of research to a degree that would have led to many patent applications. While three endothelin receptor antagonists (bosentan, sitaxentan and ambrisentan) are already available for the treatment of pulmonary arterial hypertension, the use of such compounds for the larger therapy areas of heart failure, cancer and nephropathy is still being evaluated in late-stage clinical trials. Marketed and advanced-stage endothelin receptor blockers have remarkably little chemical diversity; thus, the substantially larger chemical space defined by patenting remains to be explored.

  6. Endothelin-1 receptor antagonist: effects on endothelin- and cyclosporine-treated mesangial cells.

    PubMed

    Takeda, M; Breyer, M D; Noland, T D; Homma, T; Hoover, R L; Inagami, T; Kon, V

    1992-06-01

    Endothelin-1 (Et) has profound effects on glomerular microcirculation and mesangial cell contraction. A parameter of mesangial cell contraction was examined by measuring myosin light chain phosphorylation (MLCP) in glomerular mesangial cells in the presence and absence of a newly developed endothelin-1 receptor antagonist (EtA). Addition of Et alone (10 nM) caused a marked increase in MLCP, which, on average, rose by 53 +/- 6% above the level in cells exposed to vehicle (P less than 0.0005). This effect was shown to continue for at least one hour; MLCP at 60 minutes was 64 +/- 12% higher than controls, (P less than 0.025), constituting a unique observation of an in vitro parameter which parallels the characteristic in vivo effect of Et. Treatment of cells with EtA virtually abolished this Et-induced increase in MLCP, which rose by only 2 +/- 3% and -1 +/- 4% for doses of EtA of 44 nM and 66 nM, respectively. Examination of the intracellular calcium concentration, [Ca2+]i, revealed that EtA almost completely abolished the transient increase in [Ca2+]i evoked by Et and also suppressed the early portions of the sustained increase in [Ca2+]i. EtA was ineffective in abolishing [Ca2+]i increase in response to arginine vasopressin. Finally, to evaluate EtA's efficacy in a pathophysiologic setting, we also studied mesangial cells exposed to cyclosporine (Cs). Exposure of mesangial cells to Cs (10(-5) M) for 60 minutes caused a significant increase in MLCP, on average, by 38 +/- 6% above control (P less than 0.0005), while cells exposed to Cs in the presence of EtA increased MLCP significantly less, by only 15 +/- 9%. These data provide further evidence for Et's long-lasting cellular actions, and demonstrate inhibitory effects of an Et receptor antagonist after direct cellular exposure to Et and also after Cs exposure, a pathophysiologic setting which likely involves Et.

  7. [Hepatotoxicity in patients treated with endothelin receptor antagonists: systematic review and meta-analysis of randomized clinical trials].

    PubMed

    Macías Saint-Gerons, Diego; de la Fuente Honrubia, César; Montero Corominas, Dolores; Catalá-López, Ferrán

    2014-04-22

    We evaluated the risk of hepatotoxicity associated to endothelin receptor antagonists. Systematic searches in PubMed/MEDLINE, the Cochrane Library as well as regulatory agencies websites were performed. Randomized controlled trials in patients receiving endothelin receptor antagonists (bosentan, sitaxentan or ambrisentan) in at least one treatment group were included. Prior to data extraction, definitions of hepatotoxicity were established. Effect sizes with 95% confidence intervals were calculated using random effects models. Heterogeneity was analysed using Cochran's Q and I(2) tests. Publication bias was assessed using Egger's method and funnel plots were generated. Twenty-one trials met the inclusion criteria (3,644 patients). Bosentan was the evaluated drug in 1,689 (74%) patients who received endothelin receptor antagonists. Compared with controls, relative risk for any hepatic adverse reaction was 2.92 (1.85-4.62; I(2)=30.6%). When hepatotoxicity was defined as elevations of liver alanine or aspartate aminotransferases equal or greater than 3 times the upper limit of normal, relative risk was 2.98 (1.69-5.25; I(2) = 40.9%). No evidence of publication bias was found (Egger's method: p = 0.68). Our results suggest an increased risk of hepatotoxicity in patients receiving endothelin receptor antagonists. Given the limited data available for endothelin receptor antagonists other than bosentan, it is not possible to draw firm conclusions about the individual risk associated for the remaining endothelin receptor antagonists. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  8. Chemical function based pharmacophore generation of endothelin-A selective receptor antagonists.

    PubMed

    Funk, Oliver F; Kettmann, Viktor; Drimal, Jan; Langer, Thierry

    2004-05-20

    Both quantitative and qualitative chemical function based pharmacophore models of endothelin-A (ET(A)) selective receptor antagonists were generated by using the two algorithms HypoGen and HipHop, respectively, which are implemented in the Catalyst molecular modeling software. The input for HypoGen is a training set of 18 ET(A) antagonists exhibiting IC(50) values ranging between 0.19 nM and 67 microM. The best output hypothesis consists of five features: two hydrophobic (HY), one ring aromatic (RA), one hydrogen bond acceptor (HBA), and one negative ionizable (NI) function. The highest scoring Hip Hop model consists of six features: three hydrophobic (HY), one ring aromatic (RA), one hydrogen bond acceptor (HBA), and one negative ionizable (NI). It is the result of an input of three highly active, selective, and structurally diverse ET(A) antagonists. The predictive power of the quantitative model could be approved by using a test set of 30 compounds, whose activity values spread over 6 orders of magnitude. The two pharmacophores were tested according to their ability to extract known endothelin antagonists from the 3D molecular structure database of Derwent's World Drug Index. Thereby the main part of selective ET(A) antagonistic entries was detected by the two hypotheses. Furthermore, the pharmacophores were used to screen the Maybridge database. Six compounds were chosen from the output hit lists for in vitro testing of their ability to displace endothelin-1 from its receptor. Two of these are new potential lead compounds because they are structurally novel and exhibit satisfactory activity in the binding assay.

  9. Bosentan, a mixed endothelin receptor antagonist, induces antidepressant-like activity in mice.

    PubMed

    Pinho-Ribeiro, Felipe A; Borghi, Sergio M; Staurengo-Ferrari, Larissa; Filgueiras, Guilherme B; Estanislau, Célio; Verri, Waldiceu A

    2014-02-07

    Endothelins are peptides described initially as potent vasoactive mediators. Recently, studies reported that endothelins can modulate the production and release of cytokines by immune cells. In turn, cytokines are involved in depression disorders and also in the effectiveness of some antidepressants. Therefore, we investigated the effects of treating mice with bosentan, a mixed endothelin receptor antagonist, in widely used models for assessing antidepressant activity of compounds, the forced swimming (FST) and the tail suspension tests (TST). Moreover, the influence of bosentan treatment on circulating IL-6 levels was also addressed after FST. The results show that bosentan treatment induced a bell shaped dose-dependent antidepressant-like effect with increase in circulating IL-6 levels in animals exposed to FST. Bosentan also presented antidepressant-like effect in TST. Similar results were obtained with nortriptyline treatment in the FST and TST. Possible anxiogenic effect of bosentan was excluded using the elevated plus maze test. Therefore, this is the first study to demonstrate the antidepressant-like activity of bosentan in mice, unveiling a previous unrecognized role of endothelin in depression and its possible relation with increased circulating IL-6 levels.

  10. HJP272, a novel endothelin receptor antagonist, attenuates lipopolysaccharide-induced acute lung injury in hamsters.

    PubMed

    Patel, Shikha; Liu, Xingjian; Liu, Ming; Stephani, Ralph; Patel, Hardik; Cantor, Jerome

    2014-10-01

    Previous studies from this laboratory indicate that endothelin-1 (ET-1), a potent vasoconstrictor, may play an important role in lipopolysaccharide (LPS)-induced release of neutrophils from the pulmonary microvasculature. To further test this concept, Syrian hamsters were treated with a novel endothelin receptor A (ETA) antagonist (HJP272) prior to intratracheal instillation of LPS. The effect of HJP272 on the LPS-induced inflammatory reaction was determined by measuring: (1) lung histopathological changes, (2) total neutrophils in bronchoalveolar lavage fluid (BALF), (3) expression of tumor necrosis factor receptor 1 (TNFR1) by BALF macrophages, and (4) alveolar septal cell apoptosis. Treatment with HJP272 significantly reduced each of these parameters during a 24-hr period following LPS instillation, supporting the concept that limiting the activity of ET-1 may reduce the extent of lung injury. This hypothesis was further tested by giving ET-1 prior to LPS instillation, which resulted in a marked enhancement of LPS-induced lung inflammation, as measured by BALF neutrophils and TNFR1-positive macrophages. Furthermore, the increase in neutrophils resulting from treatment with ET-1 was significantly reduced by HJP272, again demonstrating the ability of ETA receptor antagonists to limit the influx of these cells into the lung. These findings suggest a potential therapeutic role for these agents in diseases where neutrophils are a significant cause of lung injury, such as bronchopneumonia, respiratory distress syndrome, and chronic obstructive pulmonary disease.

  11. Distinct Actions of Endothelin A-Selective Versus Combined Endothelin A/B Receptor Antagonists in Early Diabetic Kidney Disease

    PubMed Central

    Saleh, Mohamed A.; Pollock, Jennifer S.

    2011-01-01

    Selective endothelin A (ETA) and combined ETA and ETB receptor antagonists are being investigated for use in treating diabetic nephropathy. However, the receptor-specific mechanisms responsible for producing the potential benefits have not been discerned. Thus, we determined the actions of ETA and ETB receptors on measures of glomerular function and renal inflammation in the early stages of diabetic renal injury in rats through the use of selective and combined antagonists. Six weeks after streptozotocin (STZ)-induced hyperglycemia, rats were given 2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid (ABT-627) (5 mg/kg/day), a selective ETA antagonist; (2R,3R,4S)-4-(benzo[d][1,3]dioxol-5-yl)-2-(3-fluoro-4-methoxyphenyl)-1-(2-(N-propylpentylsulfonamido)ethyl)pyrrolidine-3-carboxylic acid hydrochloride (A-182086) (10 mg/kg/day), a combined ETA/B antagonist; or vehicle for 1 week. Sham controls received STZ vehicle (saline). Hyperglycemia led to significant proteinuria, increased glomerular permeability to albumin (Palb), nephrinuria, and an increase in total matrix metalloprotease (MMP) and transforming growth factor-β1 (TGF-β1) activities in glomeruli. Plasma and glomerular soluble intercellular adhesion molecule-1 (sICAM-1) and monocyte chemoattractant protein-1 (MCP-1) were elevated after 7 weeks of hyperglycemia. Daily administration of both ABT-627 and A-182086 for 1 week significantly attenuated proteinuria, the increase in Palb, nephrinuria, and total MMP and TGF-β1 activity. However, glomerular sICAM-1 and MCP-1 expression was attenuated with ABT-627, but not A-182086, treatment. In summary, both selective ETA and combined ETA/B antagonists reduced proteinuria and glomerular permeability and restored glomerular filtration barrier component integrity, but only ETA-selective blockade had anti-inflammatory and antifibrotic effects. We conclude that selective ETA antagonists are more likely to be

  12. Slow receptor dissociation kinetics differentiate macitentan from other endothelin receptor antagonists in pulmonary arterial smooth muscle cells.

    PubMed

    Gatfield, John; Mueller Grandjean, Celia; Sasse, Thomas; Clozel, Martine; Nayler, Oliver

    2012-01-01

    Two endothelin receptor antagonists (ERAs), bosentan and ambrisentan, are currently approved for the treatment of pulmonary arterial hypertension (PAH), a devastating disease involving an activated endothelin system and aberrant contraction and proliferation of pulmonary arterial smooth muscle cells (PASMC). The novel ERA macitentan has recently concluded testing in a Phase III morbidity/mortality clinical trial in PAH patients. Since the association and dissociation rates of G protein-coupled receptor antagonists can influence their pharmacological activity in vivo, we used human PASMC to characterize inhibitory potency and receptor inhibition kinetics of macitentan, ambrisentan and bosentan using calcium release and inositol-1-phosphate (IP(1)) assays. In calcium release assays macitentan, ambrisentan and bosentan were highly potent ERAs with K(b) values of 0.14 nM, 0.12 nM and 1.1 nM, respectively. Macitentan, but not ambrisentan and bosentan, displayed slow apparent receptor association kinetics as evidenced by increased antagonistic potency upon prolongation of antagonist pre-incubation times. In compound washout experiments, macitentan displayed a significantly lower receptor dissociation rate and longer receptor occupancy half-life (ROt(1/2)) compared to bosentan and ambrisentan (ROt(1/2):17 minutes versus 70 seconds and 40 seconds, respectively). Because of its lower dissociation rate macitentan behaved as an insurmountable antagonist in calcium release and IP(1) assays, and unlike bosentan and ambrisentan it blocked endothelin receptor activation across a wide range of endothelin-1 (ET-1) concentrations. However, prolongation of the ET-1 stimulation time beyond ROt(1/2) rendered macitentan a surmountable antagonist, revealing its competitive binding mode. Bosentan and ambrisentan behaved as surmountable antagonists irrespective of the assay duration and they lacked inhibitory activity at high ET-1 concentrations. Thus, macitentan is a competitive ERA with

  13. The pathophysiology of endothelin in complications after solid organ transplantation: a potential novel therapeutic role for endothelin receptor antagonists.

    PubMed

    Raina, Amresh; Horn, Edward T; Benza, Raymond L

    2012-11-15

    Although short-term allograft survival after solid organ transplantation has improved during the past two decades, improvement in long-term graft survival has been less pronounced. Common complications after transplantation include chronic allograft rejection, nephrotoxicity from calcineurin inhibitors (CNIs), and systemic hypertension, which all impact posttransplantation morbidity and mortality. Endothelin (ET)-1, a potent endogenous vasoconstrictor, inducer of fibrosis, and vascular smooth muscle cell proliferation, may play a key role in both the development of CNI-induced nephrotoxicity and endothelial vasculopathy in chronic allograft rejection. ET-1 levels increase after isograft implantation, and ET-1 plays a key role in CNI-induced renal vasoconstriction, sodium retention, and hypertension. Preclinical studies have demonstrated that endothelin receptor antagonists (ERAs) can reduce or prevent CNI-induced hypertension after renal transplantation. In addition, ERAs can ameliorate CNI-induced renal vasoconstriction and improve proteinuria and preserve renal function in animal models of renal transplantation. ET-1 may also play a significant role in cardiac allograft vasculopathy, and in animal models, ERAs improve pulmonary function and ischemic-reperfusion injury in lung transplantation and hepatic function and structure in liver transplantation. Emerging pharmacokinetic data suggest that the selective ERA ambrisentan may be used safely in conjunction with the most commonly used immunosuppressive agents tacrolimus and mycophenolate, albeit with appropriate dose adjustment. The weight of available evidence pointing toward a potential beneficial role of ERAs in ameliorating common complications after solid organ transplantation must be balanced with potential toxicities of ERAs but suggests that a randomized clinical trial of ERAs in transplant patients is warranted.

  14. Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice.

    PubMed

    Serafim, Karla G G; Navarro, Suelen A; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Cunha, Thiago M; Alves-Filho, Jose C; Cunha, Fernando Q; Casagrande, Rubia; Verri, Waldiceu A

    2015-11-01

    Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

  15. Endothelin-1 receptor antagonists in fetal development and pulmonary arterial hypertension.

    PubMed

    de Raaf, Michiel Alexander; Beekhuijzen, Manon; Guignabert, Christophe; Vonk Noordegraaf, Anton; Bogaard, Harm Jan

    2015-08-15

    The Pregnancy Prevention Program (PPP) is in place to prevent drug-induced developmental malformations. Remarkably, among the ten PPP-enlisted drugs are three endothelin-1 (ET-1) receptor antagonists (ERA's: ambrisentan, bosentan and macitentan), which are approved for the treatment of Pulmonary Arterial Hypertension (PAH). This review describes the effects of ERA's in PAH pathobiology and cardiopulmonary fetal development. While ERA's hamper pathological remodeling of the pulmonary vasculature and as such exert beneficial effects in PAH, they disturb fetal development of cardiopulmonary tissues. By blocking ET-1-mediated positive inotropic effects and myocardial fetal gene induction, ERA's may affect right ventricular adaptation to the increased pulmonary vascular resistance in both the fetus and the adult PAH patient.

  16. Macitentan: entry-into-humans study with a new endothelin receptor antagonist.

    PubMed

    Sidharta, Patricia N; van Giersbergen, Paul L M; Halabi, Atef; Dingemanse, Jasper

    2011-10-01

    To study the pharmacokinetics, pharmacodynamics, and tolerability of rising single doses of macitentan, an endothelin receptor antagonist, in healthy male subjects. This double-blind, placebo-controlled study was performed in seven groups of eight healthy male subjects. Doses of 0.2, 1, 5, 25, 100, 300 and 600 mg or placebo (two subjects per group) were administered. Plasma macitentan and endothelin-1 and serum total bile salt concentrations were measured and analysed non-compartmentally. Plasma and urine were analysed qualitatively for the presence of metabolites and one of these, ACT-132577, was also measured quantitatively in plasma. Standard tolerability measurements were performed throughout the study. Macitentan was slowly absorbed and, at a dose of 300 mg, the t(1/2) (95% confidence interval, CI) was 17.5 h (14.1, 21.8). The dose-proportionality coefficient β for C(max) (95% CI) was 0.83 (0.79, 0.87) indicating less than dose-proportional pharmacokinetics of macitentan. In plasma, a pharmacologically active oxidative depropyl metabolite, ACT-132577, was found whereas in urine two minor metabolites were detected. The t(1/2) of ACT-132577 (95% CI) was 65.6 h (53.1, 80.9). Macitentan dose-dependently increased endothelin-1 concentrations up to 2.2-fold (95% CI 1.4, 2.4) at a dose of 600 mg, but had no consistent effect on total bile salts. Macitentan was well tolerated up to and including a dose of 300 mg, the maximum tolerated dose. Headache, nausea and vomiting were dose-limiting adverse events. The pharmacokinetic and tolerability profile of macitentan is consistent with a once-a-day dosing regimen and warrants further investigation in clinical studies.

  17. Tezosentan, an endothelin receptor antagonist, limits liver injury in endotoxin challenged cirrhotic rats

    PubMed Central

    Urbanowicz, W; Sogni, P; Moreau, R; Tazi, K A; Barriere, E; Poirel, O; Martin, A; Guimont, M C; Cazals-Hatem, D; Lebrec, D

    2004-01-01

    Background/aims: Lipopolysaccharide (LPS) induces liver injury which is associated with upregulated endothelin (ET)-1 production. The aim of this study was to investigate the effects of tezosentan, a non-selective ETA and ETB receptor antagonist, in LPS challenged rats with cirrhosis. Methods: Rats with cirrhosis received LPS and then tezosentan or placebo one hour later. Four hours after LPS administration, rats were killed to measure serum transaminase activity and plasma tumour necrosis factor α (TNF-α) levels. Hepatic inducible nitric oxide synthase (iNOS), myeloperoxidase (MPO), a marker of neutrophil infiltration, and cyclooxygenase (COX)-2 expression were also measured. Results: LPS administration significantly decreased arterial pressure and significantly increased plasma endothelin levels. Following LPS and tezosentan administration, serum aspartate aminotransferase and alanine aminotransferase activities were similar to those in the control group while they were increased by more than 700% with LPS alone. Plasma TNF-α levels were significantly lower in rats receiving LPS and tezosentan (182 (38) pg/ml) compared with those receiving LPS alone (821 (212) pg/ml). Tezosentan significantly decreased hepatic MPO activity and hepatic neutrophils but had no effect on LPS induced iNOS or COX-2. Survival rate was significantly higher in rats receiving LPS plus tezosentan (80%) than in rats receiving LPS alone (50%). Conclusion: In LPS challenged cirrhotic rats, tezosentan administration prevents LPS induced liver injury by decreasing intrahepatic neutrophil infiltration. In addition, tezosentan increases survival in these rats. PMID:15542526

  18. The Effect of Endothelin Receptor Antagonists in the Endotoxin-Induced Uveitis Rabbit Model.

    PubMed

    Esra Karaca, Emine; Uzun, Feyzahan; Dileköz, Ergin; Öztürk Fincan, Gökçe Sevim; Ercan, Sevim; Kul, Oğuz; Bağrıaçık, Emin Ümit; Or, Meral

    2017-07-14

    To investigate the effect of Bosentan (non-selective endothelin receptor antagonist) and BQ123 (ETA receptor antagonist) on intraocular inflammation in an endotoxin-induced uveitis (EIU) rabbit model METHODS: Uveitis was induced by intravitreal injection of lipopolysaccharide (LPS). The animals were divided into 7 groups and there were 6 rabbits in each group (saline, saline and ethanol, Bosentan, BQ123, Lipopolysaccharide(LPS), Bosentan and LPS, BQ123 and LPS injected groups). Bosentan and BQ123 were applied before LPS injection. Aqueous humor was collected at 24th hour postinjections and enucleation was performed for the evaluation of histopathological changes. BQ123 decreased clinical score, cell counts and protein amount more than Bosentan and it was significant for cell counts (p = 0.018). Bosentan significantly diminished inflammatory reactions more than BQ123 as shown in histopathological specimens (p = 0.002). ETA receptor blockage is effective on uveitis treatment by its protective effect on blood aqueous barrier.

  19. Endothelin antagonists: new bullets against lung injury?

    PubMed

    Leeman, Marc

    2005-06-01

    Acute lung injury is a syndrome of inflammation and of increased permeability of the blood-gas barrier. Endothelins are thought to exert proinflammatory effects. Kuklin and colleagues show that the endothelin receptor antagonist tezosentan reduces pulmonary edema in endotoxemic sheep, in parallel with a prevention of protein kinase C-alpha activation. In turn, the level of some cytokines increased after tezosentan treatment. Whether these contrasting effects of endothelin blockade on inflammatory mechanisms have clinical relevance and whether these agents might benefit patients with acute lung injury is unknown.

  20. Change in pharmacological effect of endothelin receptor antagonists in rats with pulmonary hypertension: Role of ETB-receptor expression levels

    PubMed Central

    Sauvageau, Stéphanie; Thorin, Eric; Villeneuve, Louis; Dupuis, Jocelyn

    2013-01-01

    Background and purpose The endothelin (ET) system is activated in pulmonary arterial hypertension (PAH). The therapeutic value of pharmacological blockade of ET receptors has been demonstrated in various animal models and led to the current approval and continued development of these drugs for the therapy of human PAH. However, we currently incompletely comprehend what local modifications of this system occur as a consequence of PAH, particularly in small resistance arteries, and how this could affect the pharmacological response to ET receptor antagonists with various selectivities for the receptor subtypes. Therefore, the purposes of this study were to evaluate potential modifications of the pharmacology of the ET system in rat pulmonary resistance arteries from monocrotaline (MCT)-induced pulmonary arterial hypertension. Experimental approach ET-1 levels were quantified by ELISA. PreproET-1, ETA and ETB receptor mRNA expressions were quantified in pulmonary resistance arteries using Q-PCR, while protein expression was evaluated by Western blots. Reactivity to ET-1 of isolated pulmonary resistance arteries was measured in the presence of ETA (A-147627), ETB (A-192621) and dual ETA/B (bosentan) receptor antagonists. Key results In rats with PAH, plasma ET-1 increased (p < 0.001) while pulmonary levels were reduced (p < 0.05). In PAH arteries, preproET-1 (p < 0.05) and ETB receptor (p < 0.001) gene expressions were reduced, as were ETB receptor protein levels (p < 0.05). ET-1 induced similar vasoconstrictions in both groups. In arteries from sham animals, neither bosentan nor the ETA or the ETB receptor antagonists modified the response. In arteries from PAH rats, however, bosentan and the ETA receptor antagonist potently reduced the maximal contraction, while bosentan also reduced sensitivity (p < 0.01). Conclusions and implications The effectiveness of both selective ETA and dual ETA/B receptor antagonists is markedly increased in PAH. Down-regulation of

  1. Effects of antagonists for endothelin ET(A) and ET(B) receptors on coronary endothelial and myocardial function after ischemia-reperfusion in anesthetized goats.

    PubMed

    Climent, Belén; Fernández, Nuria; García-Villalón, Angel Luis; Monge, Luis; Sánchez, Ana; Diéguez, Godofredo

    2006-05-01

    To compare the effects of antagonists for endothelin ET(A) and ET(B) receptors on the action of ischemia-reperfusion on endothelial and myocardial function, 30 min of partial or total occlusion followed by 60 min of reperfusion of the left circumflex coronary artery was induced in anesthetized goats treated with intracoronary administration of saline (vehicle), BQ-123 (endothelin ET(A) receptors antagonist) or BQ-788 (endothelin ET(B) receptors antagonist). During reperfusion after partial occlusion, coronary vascular conductance and left ventricle dP/dt were decreased after saline or BQ-788, and they normalized after BQ-123. In these three groups of animals, the coronary effects of acetylcholine (3-100 ng) and sodium nitroprusside (1-10 microg) during reperfusion were as under control. During reperfusion after total occlusion, coronary vascular conductance and left ventricle dP/dt were decreased after saline, and they normalized after BQ-123 or BQ-788. In these three groups of animals, the coronary effects of acetylcholine but not those of sodium nitroprusside during reperfusion were decreased after saline, and they reversed after BQ-123 or BQ-788. Therefore, selective antagonists of endothelin ET(B) and ET(A) receptors may produce similar protection of coronary vasculature and myocardium against reperfusion after severe ischemia. Selective antagonists of endothelin ET(B) receptors, contrarily to those of endothelin ET(A) receptors, may be ineffective to protect coronary vasculature and myocardium against reperfusion after mild ischemia.

  2. Absorption, distribution, metabolism, and excretion of macitentan, a dual endothelin receptor antagonist, in humans.

    PubMed

    Bruderer, Shirin; Hopfgartner, Gérard; Seiberling, Michael; Wank, Janine; Sidharta, Patricia N; Treiber, Alexander; Dingemanse, Jasper

    2012-09-01

    Macitentan is a tissue-targeting, dual endothelin receptor antagonist, currently under phase 3 investigation in pulmonary arterial hypertension. In this study the disposition and metabolism of macitentan were investigated following administration of a single oral 10 mg dose of (14)C-macitentan to six healthy male subjects. The total radioactivity in matrices was determined using liquid scintillation counting. The proposed structure of metabolites was based on mass spectrometry characteristics and, when available, confirmed by comparison with reference compounds. Mean (± SD) cumulative recovery of radioactivity from faeces and urine was 73.6% (± 6.2%) of the administered radioactive dose, with 49.7% (± 3.9%) cumulative recovery from urine, and 23.9% (± 4.8%) from faeces. In plasma, in addition to parent macitentan, ACT-132577, a pharmacologically active metabolite elicited by oxidative depropylation and the carboxylic acid metabolite ACT-373898 were identified. In urine, four entities were identified, with the hydrolysis product of ACT-373898 as the most abundant one. In faeces, five entities were identified, with the hydrolysis product of macitentan and ACT-132577 as the most abundant one. Concentrations of total radioactivity in whole blood were lower compared to plasma, which indicates that macitentan and its metabolites poorly bind to or penetrate into erythrocytes.

  3. Macrophage and myofibroblast involvement in ischemic acute renal failure is attenuated by endothelin receptor antagonists.

    PubMed

    Forbes, J M; Leaker, B; Hewitson, T D; Becker, G J; Jones, C L

    1999-01-01

    Endothelin (ET) may be a mediator of injury following ischemia-induced acute renal failure (ARF). ET receptor (ETR) antagonists have been reported to increase survival rates and lower serum creatinines when administered postrenal ischemia-reperfusion injury in the rat. Renal cellular and extracellular matrix responses to this therapy have not been addressed. We investigated the use of ETR antagonists, PD 156707 (ETA) and SB 209670 (ETA and ETB) in the treatment of sublethal postischemic ARF. The right kidney of female Sprague-Dawley rats weighing approximately 200 g was removed. After five days, the left renal pedicle was occluded for 45 minutes. Twenty-four hours after renal ischemia, one of two ETR antagonists, PD 156707 (N = 7) or SB 209670 (N = 8), was administered. Experimental animals were compared with an ischemic group receiving only saline (N = 9). Three nephrectomized groups that did not undergo ischemia but that received infusions of saline (N = 6), PD 156707 (N = 6), and SB 209670 (N = 6), respectively, were also studied. Animals were sacrificed one week postischemia. Quantitation of monocytes and macrophages (Mo/Mphi), alpha-smooth muscle actin-positive myofibroblasts, and collagens type III and IV was performed by immunohistochemical staining. Cell kinetics were examined by staining for apoptosis with terminal deoxyuridine triphosphate (dUTP) nick end labeling and for proliferation with proliferating cell nuclear antigen. All ischemic groups of rats initially developed raised serum creatinine levels; however, no significant difference was observed between the groups (Kruskal-Wallis). Creatinines returned to preischemic values in all groups by the time of sacrifice. No significant difference in kidney weights or body weights was found between groups. Histologically, infiltration of Mo/Mphi was significantly reduced in groups treated with ETR antagonists (P < 0.001). The presence of myofibroblasts was also significantly reduced in the antagonist

  4. Testis dysfunction by isoproterenol is mediated by upregulating endothelin receptor A, leptin and protein kinase Cvarepsilon and is attenuated by an endothelin receptor antagonist CPU0213.

    PubMed

    Cheng, Yu-Si; Dai, De-Zai; Dai, Yin

    2010-07-01

    This study has examined whether upregulation of endothelin receptor A, leptin and phosphorylated protein kinase Cvarepsilon contributes to stress-induced testicular damaged and its possible reversal by endothelial (ET) antagonism. Adult male Sprague-Dawley rats were randomly divided into control and isoproterenol (ISO 1mg/kg, subcutaneous (s.c.), 10 days) groups, and intervened with the ET receptor antagonist CPU0213 (20mg/kg, s.c.), on days 6-10. In ISO group, testicular succinate dehydrogenase, lactate dehydrogenase, acid phosphotase, and gamma-glutamyl transpeptidase, and serum testosterone decreased, whereas FSH increased, relative to control. The seminiferous tubules were damaged in association with testicular upregulation of protein abundance of leptin and pPKCvarepsilon, and mRNA and protein expression of leptin receptor (OBRb) and ET(A). CPU0213 was effective in ameliorating these abnormalities. Over-expression of ET(A) and leptin accounting for the testis dysfunction is likely to be mediated by pPKCvarepsilon in the ISO treated rats. The upregulated ET pathway appears to be critical in pathologies of the testis.

  5. Simultaneous quantification of endothelin receptor antagonists and phosphodiesterase 5 inhibitors currently used in pulmonary arterial hypertension.

    PubMed

    Enderle, Yeliz; Witt, Lukas; Wilkens, Heinrike; Grünig, Ekkehard; Haefeli, Walter E; Burhenne, Jürgen

    2017-09-05

    Combination treatment with endothelin receptor antagonists (ERA) and phosphodiesterase 5 inhibitors (PDE5I) improved efficacy of pulmonary arterial hypertension (PAH) therapy. However, drug-drug interactions, variable exposure, non-adherence can influence plasma levels. For these reasons, drug quantification may be advantageous particularly in patients with poor treatment responses. We developed, validated, and applied an assay for the simultaneous quantification of ambrisentan, bosentan, macitentan, sildenafil, and tadalafil as well as their main (and partly active) metabolites in human plasma. This method is based on LC-MS/MS separation for a rapid and sensitive quantification with stable isotopically labelled analogues as internal standards for each drug and metabolite. Sample preparation was carried out using a solid phase extraction protocol based on Oasis HLB material. The separation was achieved on a Kinetex C18 column and multiple reaction monitoring in negative ionization mode was used for sensitive detection. The calibrations were linear for all analytes with correlation coefficients >0.99 within the concentration range observed under a therapeutic PAH dosing scheme with lower limits of quantification between 0.34ng/mL (OH-ambrisentan) and 10ng/mL (despropyl-macitentan). Intra- and inter-day precision at LLOQ and QC levels ranged between 2.03% and 19.8%, and 0.65% and 14.0%, respectively. The sample turnover time was 12min. The applicability of this versatile LC/MS/MS assay was verified by the successful analysis of clinical routine samples of patients on PAH medication. This new method allows for the first time to assess trough drug and metabolite levels of the currently approved PDE5I and ERAs in PAH patients, thus enabling for measurement of samples in clinical routine. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Endothelin-receptor antagonist can reduce blood pressure in patients with hypertension: a meta-analysis.

    PubMed

    Yuan, Wenming; Cheng, Genyang; Li, Bin; Li, Yansheng; Lu, Shan; Liu, Dong; Xiao, Jing; Zhao, Zhanzheng

    2017-06-01

    The aim of this meta-analysis was to assess the effectiveness and safety of endothelin-receptor antagonist (ERA) in the patients with hypertension. Searches of the PubMed, EMBASE, and CENTRAL databases were conducted to include all the randomized control trials (RCTs). Eighteen trials including 4898 patients were used in the meta-analysis, of which nine were classified as low risk of bias and the other nine as unclear risk of bias. There was no statistically significant difference in all-cause mortality between ERA and placebo groups [6 trials, fixed effects model, RR 1.53 (0.89-2.62); random effects model, RR 1.45 (0.84-2.52)]. ERA significantly reduced 24-h ambulatory blood pressure and sitting blood pressure in patients with hypertension [5 trials, 24-h SBP: WMD -7.65 (-8.95 to -6.36), 24-h DBP: WMD -5.92 (-7.50 to -4.33); 18 trials, SBP: WMD -6.12 (-7.87 to -4.36), DBP: WMD -3.81 (-4.82 to -2.80)]. However, ERA had more adverse events [within 24 h: 3 trials, RR 1.16 (0.82-1.65); after 24 h, 13 trials, RR 1.21 (1.08-1.36)] and severe adverse events than placebo controls [SAE: 9 trials, RR 1.34 (1.13-1.60)]. In addition, there is a potential need for further RCTs that focus on the use of ERA in patients with hypertension.

  7. Selective endothelin a (ETA) receptor antagonist (BQ-123) reduces both myocardial infarct size and oxidant injury.

    PubMed

    Ozdemir, Ramazan; Parlakpinar, Hakan; Polat, Alaadin; Colak, Cemil; Ermis, Necip; Acet, Ahmet

    2006-02-15

    Endothelins (ET) can be considered stress-responsive regulators working in paracrine and autocrine fashion. It has been suggested that elevated levels of ET may be responsible for the low coronary re-flow phenomena. Ischemia-reperfusion (I/R) was shown to stimulate ET release in rat heart; however, the mechanism(s) of this effect has not been clarified. Therefore, this study was focused to investigate the effect of BQ-123, selective ETA receptor antagonist, on three aspects of myocardial ischemia-reperfusion (MI/R) injury: hemodynamic parameters, infarct size and oxidant-antioxidant status in the absence and presence of ET-1 in an vivo rat model. To produce MI/R, a branch of the descending left coronary artery was occluded for 30 min followed by 2h reperfusion. ECG changes, blood pressure (BP), and heart rate (HR) were measured before occlusion and continued both occlusion and reperfusion. Forty rats were randomly assigned to five groups equally: (1) sham-operated rats without coronary ligation, (2) I/R group, (3) I/R+BQ-123-treated group (10 microg/kg/min i.v.), (4) I/R+ET-treated group (25 ng/kg/min i.v.), (5) I/R+ET+BQ-123-treated group. The results are expressed as mean+/-S.E.M. In the ET-1 plus I/R group, the ratio between the infarcted area and area at risk 56+/-1% was significantly higher than I/R group (49+/-1%). In the BQ-123 group with or without exogenous ET-1 treatment in I/R group, this ratio was significantly lower at 40+/-2 and 37+/-1%, respectively. As compared to sham group, I/R increased lipid peroxidation whereas decreased nitric oxide (NO), glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD) contents. This decreased antioxidant enzymatic defense could result in aggravated oxidative damage in I/R group rat hearts. ET-1 administration group showed severe oxidative damage. BQ-123 administrations to I/R group with or without ET-1 caused significantly decrease in lipid peroxidation and increased in SOD, CAT activities and NO generation

  8. Cardioprotective effects of bosentan, a mixed endothelin type A and B receptor antagonist, during myocardial ischaemia and reperfusion in rats.

    PubMed

    Singh, Arya Dharamvir; Amit, Saxena; Kumar, Ojha Shreesh; Rajan, Mittal; Mukesh, Nandave

    2006-06-01

    The present study evaluated the cardioprotective potential of bosentan, a mixed endothelin type A and B receptor antagonist, in the myocardial ischaemia-reperfusion model of myocardial infarction. Adult male wistar rats (175-225 g) were divided into three groups: sham operated, non-myocardial ischaemia-reperfusion (SHAM); saline-treated myocardial ischaemia-reperfusion control (CON); bosentan-treated myocardial ischaemia-reperfusion (BOS). All animals were anaesthetized and subjected to 40 min. occlusion of left anterior descending coronary artery followed by 120 min. of reperfusion. Saline or drug was administered to the CON or BOS group, respectively, 20 min. after the left anterior descending coronary artery occlusion. Haemodynamic parameters viz. systolic arterial pressure, diastolic arterial pressure and heart rate were recorded throughout the experimental period. Hearts were subsequently excised and processed for histopathological and infarct size evaluation and for biochemical estimation of cardiac specific enzyme creatine kinase-MB (CK-MB) and myocardial malondialdehyde, a lipid peroxidation marker. Myocardial ischaemic reperfusion resulted in severe myocardial injury, depression of haemodynamic function, significant increase in malondialdehyde levels and decline in CK-MB isoenzyme activity in the heart tissue. Administration of bosentan (3 mg/kg, intravenously) slightly improved haemodynamic effects, decreased myocardial oxygen consumption, significantly (P<0.01) attenuated the rise in malondialdehyde levels and loss of myocardial CK-MB isoenzyme activity compared to the CON group, whereas bosentan administration significantly reduced the percentage area of fiber loss and infarct area. It is therefore concluded that endothelin-1 may mediate myocardial damage produced by ischaemia and reperfusion and that dual blockade of endothelinA and endothelinB receptors may have potential as a mode of therapy for myocardial infarction.

  9. Early intervention with a potent endothelin-A/endothelin-B receptor antagonist aggravates left ventricular remodeling after myocardial infarction in rats.

    PubMed

    Oie, Erik; Yndestad, Arne; Robins, Simon P; Børnerheim, Reidar; Asberg, Anders; Attramadal, Håvard

    2002-05-01

    Intervention with selective endothelin (ET)A receptor antagonists within 24h after myocardial infarction (MI) in rats has been reported to aggravate left ventricular (LV) remodeling. In contrast, beneficial effects are reported when initiation of treatment is delayed 7 days or more after MI. However, bosentan, a mixed ET(A)/ET(B) receptor antagonist with low affinity for the ET receptors, has been shown to exert beneficial effects independent of the time point of initiation of treatment after MI. The aim of the present study was to investigate to what extent early intervention with a mixed ET(A)/ET(B) receptor antagonist with higher affinity at the ET receptors (SB 209670) would also exert beneficial effects on postinfarction LV remodeling. After ligation of the left coronary artery, rats were randomized to treatment with SB 209670 (6.25 mg x kg(-1) SC b.i.d., n = 10) or vehicle (n = 12) for 26 days, starting 48h after MI. Treatment with SB 209670 adversely affected the postinfarction remodeling process causing further dilatation of the LV (LV end-diastolic diameter: 10.4+/-0.5 vs 9.1+/-0.2 mm; LV end-systolic diameter: 8.5+/-0.4 vs 7.2+/-0.2 mm, P < 0.05). However, SB 209670 did not significantly affect infarct size, compensatory cardiac hypertrophy, nor the myocardial mRNA levels of procollagen type I and III, and prolyl 4-hydroxylase and lysyl oxidase, 2 important enzymes affecting collagen secretion, stability and functionality. In addition, SB 209670 had no significant effects on LV collagen cross-linking or extent of fibrosis. Thus, our data demonstrate that early intervention with a potent, mixed ET(A)/ET(B) receptor antagonist after MI may promote dilatation of the LV without significant alterations of infarct size and extracellular matrix composition. Our data support the notion that the timing of initiation of ET receptor antagonism after MI is critical and that potent ET receptor antagonists may be harmful during the first few days after MI.

  10. Comparison of 2 endothelin-receptor antagonists on in vitro responses of equine palmar digital arterial and venous rings to endothelin-1

    PubMed Central

    Venugopal, Changaram S.; Hosgood, Giselle; Eades, Susan C.; Moore, Rustin M.

    2006-01-01

    Abstract The goals of this study were to determine the concentration–response (C–R) relationship of endothelin-1 (ET-1), compare 2 ET-receptor antagonists and determine the antagonist concentrations that block the vasomotor effects of ET-1, and compare the effectiveness of ET-1 and previously studied vasoconstrictors in equine palmar digital arterial and venous rings in vitro. Vessel rings from 8 nonlaminitic horses were placed in Tyrode’s solution, 1 side fixed to the floor of an organ bath and the other side fixed to a force-displacement transducer. Two separate studies were conducted: (I) incubation with a single ET-receptor antagonist (PD142893 or PD145065 at a concentration of 10−7, 10−6, or 10−5 M), followed by determination of an ET-1 C–R curve (using concentrations of 10−10 to 10−6 M) for medial vessel rings; and (II) comparison of ET-1 with norepinephrine and histamine (10−10 to 10−6 M) and comparison of contractile responses of medial and lateral vessel rings. In study I, ET-1 administration caused pronounced and sustained concentration-dependent contraction of vessel rings; these contractile responses were decreased by 10−5 M PD142893 and were completely blocked by 10−5 M PD145065. Venous rings had greater apparent maximum contraction in response to ET-1 than arterial rings. In study II, the relative sensitivity of norepinephrine was found to be equivalent to that of ET-1, whereas that of histamine was lower. No significant differences were observed between responses of medial versus lateral vessel rings. Thus, ET-1 is a potent vasoconstrictor of equine palmar digital arteries and veins, and the ET-receptor antagonist PD145065 is more effective than PD142893 in inhibiting these contractile effects in vitro. PMID:16850942

  11. Endothelin receptor antagonists for persistent pulmonary hypertension in term and late preterm infants.

    PubMed

    More, Kiran; Athalye-Jape, Gayatri K; Rao, Shripada C; Patole, Sanjay K

    2016-08-18

    Endothelin, a powerful vasoconstrictor, is one of the mediators in the causation of persistent pulmonary hypertension of the newborn (PPHN). Theoretically, endothelin receptor antagonists (ETRA) have the potential to improve the outcomes of infants with PPHN. To assess the efficacy and safety of ETRA in the treatment of PPHN in full-term, post-term and late preterm infants.To assess the efficacy and safety of selective ETRAs (which block only the ETA receptors) and non-selective ETRAs (which block both ETA and ETB receptors) separately. CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and CINAHL databases were searched until December 2015. Randomised, cluster-randomised or quasi-randomised controlled trials were eligible. Two review authors independently searched the literature, selected the studies, assessed the risk of bias and extracted the data. A fixed-effect model was used for meta-analysis. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence. Two randomised controlled trials of ETRA met the inclusion criteria. Both studies utilized oral Bosentan. The first study was done in a setting where inhaled nitric oxide (iNO) therapy was not available. Forty-seven infants (≥ 34 weeks' gestation) were randomised to receive either Bosentan or placebo. The second study was a multicentre study where iNO therapy was the standard of care for PPHN. Twenty-one infants were randomised to receive either 'iNO plus Bosentan' or 'iNO plus placebo'.In the first study, there was no significant difference in the incidence of death before hospital discharge between the Bosentan and placebo groups (1/23 vs 3/14; RR 0.20, 95% CI 0.02 to 1.77; RD -0.17, 95% CI -0.40 to 0.06). A higher proportion of infants in the Bosentan group showed improvement in oxygenation index (OI) at the end of therapy (21/24 vs 3/15; RR 4.38, 95% CI 1.57 to 12.17; RD 0.68, 95% CI 0.43 to 0.92; number needed to

  12. Amelioration of cold injury-induced cortical brain edema formation by selective endothelin ETB receptor antagonists in mice.

    PubMed

    Michinaga, Shotaro; Nagase, Marina; Matsuyama, Emi; Yamanaka, Daisuke; Seno, Naoki; Fuka, Mayu; Yamamoto, Yui; Koyama, Yutaka

    2014-01-01

    Brain edema is a potentially fatal pathological condition that often occurs in stroke and head trauma. Following brain insults, endothelins (ETs) are increased and promote several pathophysiological responses. This study examined the effects of ETB antagonists on brain edema formation and disruption of the blood-brain barrier in a mouse cold injury model (Five- to six-week-old male ddY mice). Cold injury increased the water content of the injured cerebrum, and promoted extravasation of both Evans blue and endogenous albumin. In the injury area, expression of prepro-ET-1 mRNA and ET-1 peptide increased. Intracerebroventricular (ICV) administration of BQ788 (ETB antagonist), IRL-2500 (ETB antagonist), or FR139317 (ETA antagonist) prior to cold injury significantly attenuated the increase in brain water content. Bolus administration of BQ788, IRL-2500, or FR139317 also inhibited the cold injury-induced extravasation of Evans blue and albumin. Repeated administration of BQ788 and IRL-2500 beginning at 24 h after cold injury attenuated both the increase in brain water content and extravasation of markers. In contrast, FR139317 had no effect on edema formation when administrated after cold injury. Cold injury stimulated induction of glial fibrillary acidic protein-positive reactive astrocytes in the injured cerebrum. Induction of reactive astrocytes after cold injury was attenuated by ICV administration of BQ788 or IRL-2500. These results suggest that ETB receptor antagonists may be an effective approach to ameliorate brain edema formation following brain insults.

  13. Amelioration of Cold Injury-Induced Cortical Brain Edema Formation by Selective Endothelin ETB Receptor Antagonists in Mice

    PubMed Central

    Michinaga, Shotaro; Nagase, Marina; Matsuyama, Emi; Yamanaka, Daisuke; Seno, Naoki; Fuka, Mayu; Yamamoto, Yui; Koyama, Yutaka

    2014-01-01

    Brain edema is a potentially fatal pathological condition that often occurs in stroke and head trauma. Following brain insults, endothelins (ETs) are increased and promote several pathophysiological responses. This study examined the effects of ETB antagonists on brain edema formation and disruption of the blood-brain barrier in a mouse cold injury model (Five- to six-week-old male ddY mice). Cold injury increased the water content of the injured cerebrum, and promoted extravasation of both Evans blue and endogenous albumin. In the injury area, expression of prepro-ET-1 mRNA and ET-1 peptide increased. Intracerebroventricular (ICV) administration of BQ788 (ETB antagonist), IRL-2500 (ETB antagonist), or FR139317 (ETA antagonist) prior to cold injury significantly attenuated the increase in brain water content. Bolus administration of BQ788, IRL-2500, or FR139317 also inhibited the cold injury-induced extravasation of Evans blue and albumin. Repeated administration of BQ788 and IRL-2500 beginning at 24 h after cold injury attenuated both the increase in brain water content and extravasation of markers. In contrast, FR139317 had no effect on edema formation when administrated after cold injury. Cold injury stimulated induction of glial fibrillary acidic protein-positive reactive astrocytes in the injured cerebrum. Induction of reactive astrocytes after cold injury was attenuated by ICV administration of BQ788 or IRL-2500. These results suggest that ETB receptor antagonists may be an effective approach to ameliorate brain edema formation following brain insults. PMID:25000290

  14. Influence of specific and non-specific endothelin receptor antagonists on renal morphology in rats with surgical renal ablation.

    PubMed

    Nabokov, A; Amann, K; Wagner, J; Gehlen, F; Münter, K; Ritz, E

    1996-03-01

    Studies in experimental models of chronic renal failure suggest an important role for the endothelin system in the development of renal scarring. Endothelin receptor (ETR) anatagonists interfere with progression, but it has not been resolved (i) whether this is true for all models of renal damage, (ii) to what extent the effect is modulated by systemic blood pressure and (iii) whether the effect is similar for ETAR and ETA/ETBR antagonists. 5/6 subtotal nephrectomy (SNX) by surgical ablation in male Sprague-Dawley rats. Comparison of ACE inhibitor Trandolapril (0.1 mg/kg/day), ETAR antagonist BMS 182874 (30 mg/kg/day) and ETAR/ETBR antagonist Ro 46-2005 (30 mg/kg/day) by gavage. Duration of the experiment eight weeks. Systolic blood pressure by tail plethysmography. Perfusion fixation of kidneys and morphometric analysis ET-1 and ETA/ETBR by quantitative PCR. SNX caused a significant (P < 0.01) increase of systolic blood pressure (170 +/- 8.6 mmHg) compared to sham operated controls (131 +/- 5.3 mmHg). Blood pressure was significantly (P < 0.001) lower with Trandolapril (128 +/- 5.3 mmHg), but not with BMS 182874 (153 +/- 5.9 mmHg) or Ro 46-2005 (167 +/- 7.6 mmHg). Compared to sham operated rats (0.03 +/- 0.01) glomerulosclerosis index (GSI) was significantly (P < 0.01) higher in the untreated SNX group (0.9 +/- 0.15). Significantly lower GSI was found in Trandolapril treated (0.29 +/- 0.04), BMS 182874 treated (0.36 +/- 0.05), and Ro 46-2005 treated animals (0.45 +/- 0.11). The effect of BMS 182874 was accompanied by lower tubulointerstitial damage index. Mean glomerular volume was dramatically increased (P < 0.001) in SNX rats as compared to sham operated animals. This glomerular enlargement was partially prevented by Trandolapril (P < 0.05), but not by either ETR antagonist. ET-1 mRNA tended to be higher in SNX irrespective of treatment, while ETAR and ETBR mRNA were significantly lower. Both specific (ETAR) and non-specific (ETA/ETBR) endothelin antagonists

  15. Antifibrotic effects of ambrisentan, an endothelin-A receptor antagonist, in a non-alcoholic steatohepatitis mouse model

    PubMed Central

    Okamoto, Toshiaki; Koda, Masahiko; Miyoshi, Kennichi; Onoyama, Takumi; Kishina, Manabu; Matono, Tomomitsu; Sugihara, Takaaki; Hosho, Keiko; Okano, Junichi; Isomoto, Hajime; Murawaki, Yoshikazu

    2016-01-01

    AIM To examine the effects of the endothelin type A receptor antagonist ambrisentan on hepatic steatosis and fibrosis in a steatohepatitis mouse model. METHODS Fatty liver shionogi (FLS) FLS-ob/ob mice (male, 12 wk old) received ambrisentan (2.5 mg/kg orally per day; n = 8) or water as a control (n = 5) for 4 wk. Factors were compared between the two groups, including steatosis, fibrosis, inflammation, and endothelin-related gene expression in the liver. RESULTS In the ambrisentan group, hepatic hydroxyproline content was significantly lower than in the control group (18.0 μg/g ± 6.1 μg/g vs 33.9 μg/g ± 13.5 μg/g liver, respectively, P = 0.014). Hepatic fibrosis estimated by Sirius red staining and areas positive for α-smooth muscle actin, indicative of activated hepatic stellate cells, were also significantly lower in the ambrisentan group (0.46% ± 0.18% vs 1.11% ± 0.28%, respectively, P = 0.0003; and 0.12% ± 0.08% vs 0.25% ± 0.11%, respectively, P = 0.047). Moreover, hepatic RNA expression levels of procollagen-1 and tissue inhibitor of metalloproteinase-1 (TIMP-1) were significantly lower by 60% and 45%, respectively, in the ambrisentan group. Inflammation, steatosis, and endothelin-related mRNA expression in the liver were not significantly different between the groups. CONCLUSION Ambrisentan attenuated the progression of hepatic fibrosis by inhibiting hepatic stellate cell activation and reducing procollagen-1 and TIMP-1 gene expression. Ambrisentan did not affect inflammation or steatosis. PMID:27574547

  16. Pharmacokinetics and preliminary safety data of a single oral dose of bosentan, a dual endothelin receptor antagonist, in cats.

    PubMed

    Puza, N; Papich, M G; Reinero, C; Chang, C H; Yu, D-H; Sharp, C; DeClue, A

    2014-04-01

    The objective of this study was to evaluate the pharmacokinetic properties and adverse effect profile of single-dose oral bosentan, a dual endothelin receptor antagonist, in healthy cats. Pharmacokinetic parameters were determined following a single mean ± SD oral dose of 3.2 ± 0.6 mg/kg of bosentan in 6 adult cats. Blood was collected for quantification of bosentan via high-performance liquid chromatography with ultraviolet detection. Blood and urine were evaluated for CBC, plasma biochemical profile, and urinalysis, and repeat physical examinations were performed to evaluate for adverse effects. The mean terminal half-life of bosentan was 20.4 ± 17.2 h. The mean peak plasma concentration was 0.49 ± 0.24 g/mL, and the mean time to maximum plasma concentration was 6.8 ± 8.6 h. The area under the curve was 5.14 ± 3.81 h·μg/mL. Oral bosentan tablets were absorbed in cats, and no clinically important adverse events were noted. Further evaluation of repeat dosing, investigation into the in vivo efficacy of decreasing endothelin-1 concentrations in cats, as well as safety in conjunction with other medications is warranted.

  17. Pharmacokinetic and pharmacodynamic evaluation of macitentan , a novel endothelin receptor antagonist for the treatment of pulmonary arterial hypertension.

    PubMed

    Sidharta, Patricia N; Krähenbühl, Stephan; Dingemanse, Jasper

    2015-03-01

    Pulmonary arterial hypertension (PAH) is a chronic disorder of the pulmonary vasculature characterized by elevated mean pulmonary arterial pressure eventually leading to right-sided heart failure and premature death. Macitentan is an oral, once-daily, dual endothelin (ET)A and ETB receptor antagonist with high affinity and sustained receptor binding that was approved in the USA, Europe, Canada, and Switzerland for the treatment of PAH. This review discusses the pharmacokinetics (PK) and pharmacodynamics (PD) of macitentan and its drug interaction potential based on preclinical and clinical data. Up to date, macitentan is the only registered treatment for PAH that significantly reduced morbidity and mortality as a combined endpoint in a long-term event-driven study. The safety profile of macitentan is favorable with respect to hepatic safety and edema/fluid retention and may be better than that of other ET receptor antagonists such as bosentan and ambrisentan. The PK profile supports a once-a-day dosing regimen. Macitentan has limited interactions with other drugs. Based on these characteristics macitentan is an important new addition to the treatment of PAH.

  18. Effect of clazosentan, a selective endothelin A receptor antagonist, and tezosentan, a dual endothelin A/B antagonist, on pulsatile shear stress induced constriction of the iliac in the anaesthetized pig.

    PubMed

    Ruane-O'Hora, Therese; Rae, Mark George; Markos, Farouk

    2011-08-01

    1. The effects of changes in mean and pulsatile shear stress on the diameter of the iliac of the anaesthetized pig were investigated in the presence of clazosentan and tezosentan. 2. A total of 17 pigs were used. Mean shear stress was increased by infusing acetylcholine downstream (2-20 μg/min) through the deep femoral artery. Pulsatile shear stress was enhanced first by injecting varying volumes (1-10 mL) of calcium gluconate (stock 10 mg/mL) directly into the left ventricle. Second, by electrical stimulation of the left sympathetic nerves to the heart (1-16 Hz, 4 min duration, supramaximal voltage). 3. An increase in mean shear stress induced a vasodilation that was not altered significantly by the selective endothelin A antagonist clazosentan (10 mg/kg i.v.). Similarly, the vasoconstriction induced by an increase in pulsatile shear stress brought about by either calcium gluconate injections or left sympathetic nerve stimulation was unaffected by clazosentan. However, tezosentan (10 mg/kg i.v.), significantly attenuated the vasoconstriction induced by an increase in pulsatile shear stress. 4. In conclusion, an increase in pulsatile shear stress causes vasoconstriction of the pig iliac artery, which is attenuated by dual endothelin receptor antagonism, but not by specific endothelin A blockade.

  19. Effect of endothelin receptor antagonist bosentan on plasma leptin concentration in acute myocardial infarction in rats.

    PubMed

    Ostrowski, Robert P.; Januszewski, Sławomir; Kowalska, Zdzisława; Kapuściński, Andrzej

    2003-09-01

    The aim of the study was to evaluate the effect of endothelin receptor antagonism on plasma leptin level after myocardial infarction (MI). In Wistar rats under chloral hydrate anesthesia, MI was performed by ligation of the left coronary artery. The animals were divided into the following groups: control-sham (thoracotomy only), and two MI groups with or without bosentan treatment. Bosentan was given daily by gavage at the dose of 100 mg/kg. Treatment of animals started 2 days before MI and continued up to the fifth day. Concentration of leptin was measured by radioimmunoassay by means of 125I labeled antigen in the following time intervals: before MI or sham operation, 4, 24 and 48 h after surgery. Electrocardiogram (ECG), blood pressure, heart rate, arterial pO(2), pCO(2) and pH were periodically monitored. Two days after the MI animals were perfused retrograde into descending aorta with 2% triphenyltetrazolium chloride (TTC) and hearts were fixed by immersion in formalin for microscopic examination. Hearts were sectioned transaxially and size of MI was quantitated with morphometric methods. ECG, TTC staining and microscopic results confirmed development of MI. Morphometric methods did not show significant differences in infarct size between bosentan treated and untreated groups. Concentration of leptin in plasma in untreated group significantly increased already 4 h after MI. In bosentan treated animals this increase appeared only after 24 h. In animals treated with bosentan also a significant diminution of MI mortality was observed. Our results indicate that bosentan has an important effect on leptin concentration in ischemic cardiovascular pathology.

  20. Endothelin and endothelin receptors in the renal and cardiovascular systems.

    PubMed

    Vignon-Zellweger, Nicolas; Heiden, Susi; Miyauchi, Takashi; Emoto, Noriaki

    2012-10-15

    Endothelin-1 (ET-1) is a multifunctional hormone which regulates the physiology of the cardiovascular and renal systems. ET-1 modulates cardiac contractility, systemic and renal vascular resistance, salt and water renal reabsorption, and glomerular function. ET-1 is responsible for a variety of cellular events: contraction, proliferation, apoptosis, etc. These effects take place after the activation of the two endothelin receptors ET(A) and ET(B), which are present - among others - on cardiomyocytes, fibroblasts, smooth muscle and endothelial cells, glomerular and tubular cells of the kidney. The complex and numerous intracellular pathways, which can be contradictory in term of functional response depending on the receptor type, cell type and physiological situation, are described in this review. Many diseases share an enhanced ET-1 expression as part of the pathophysiology. However, the use of endothelin blockers is currently restricted to pulmonary arterial hypertension, and more recently to digital ulcer. The complexity of the endothelin system does not facilitate the translation of the molecular knowledge to clinical applications. Endothelin antagonists can prevent disease development but secondary undesirable effects limit their usage. Nevertheless, the increasing understanding of the effects of ET-1 on the cardiac and renal physiology maintains the endothelin system as a promising therapeutic target.

  1. Sulfenic Acid Modification of Endothelin B Receptor is Responsible for the Benefit of a Nonsteroidal Mineralocorticoid Receptor Antagonist in Renal Ischemia

    PubMed Central

    Barrera-Chimal, Jonatan; Prince, Sonia; Fadel, Fouad; El Moghrabi, Soumaya; Warnock, David G.; Kolkhof, Peter; Jaisser, Frédéric

    2016-01-01

    AKI is associated with high mortality rates and the development of CKD. Ischemia/reperfusion (IR) is an important cause of AKI. Unfortunately, there is no available pharmacologic approach to prevent or limit renal IR injury in common clinical practice. Renal IR is characterized by diminished nitric oxide bioavailability and reduced renal blood flow; however, the mechanisms leading to these alterations are poorly understood. In a rat model of renal IR, we investigated whether the administration of the novel nonsteroidal mineralocorticoid receptor (MR) antagonist BR-4628 can prevent or treat the renal dysfunction and tubular injury induced by IR. Renal injury induced by ischemia was associated with increased oxidant damage, which led to a cysteine sulfenic acid modification in endothelin B receptor and consequently decreased endothelial nitric oxide synthase activation. These modifications were efficiently prevented by nonsteroidal MR antagonism. Furthermore, we demonstrated that the protective effect of BR-4628 against IR was lost when a selective endothelin B receptor antagonist was coadministered. These data describe a new mechanism for reduced endothelial nitric oxide synthase activation during renal IR that can be blocked by MR antagonism with BR-4628. PMID:26361797

  2. Synergistic growth inhibitory effects of the dual endothelin-1 receptor antagonist bosentan on pancreatic stellate and cancer cells.

    PubMed

    Fitzner, Brit; Brock, Peter; Holzhüter, Stephanie-Anna; Nizze, Horst; Sparmann, Gisela; Emmrich, Jörg; Liebe, Stefan; Jaster, Robert

    2009-02-01

    Pancreatic stellate cells (PSC) play a key role in pancreatic fibrosis. Activation of PSC occurs in response to pro-fibrogenic stimuli and is maintained by autocrine loops of mediators, such as endothelin (ET)-1. Here, we have evaluated effects of the dual ET receptor antagonist bosentan in models of pancreatic fibrogenesis and cancer. Cell culture studies revealed that PSC and DSL6A pancreatic cancer cells expressed both ET-1 and ET receptors. Bosentan efficiently inhibited proliferation of both cell types and collagen synthesis in PSC. Expression of the myofibroblastic marker alpha-smooth muscle actin, connective tissue growth factor, and ET-1 itself in PSC was reduced, while expression of matrix metalloproteinase-9 was enhanced. Like PSC, DSL6A cells secrete less ET-1 when cultured with bosentan. In a rat model of pancreatic fibrosis, chronic pancreatitis induced by dibutyltin dichloride, a tendency towards a diminished disease progression was observed in a subgroup of rats with less severe disease. Together, our results indicate that bosentan exerts antifibrotic and antitumor effects in vitro. Its efficiency in vivo warrants further investigation.

  3. Effect of endothelin receptor antagonists on clinically relevant outcomes after experimental subarachnoid hemorrhage: a systematic review and meta-analysis

    PubMed Central

    Laban, Kamil G; Vergouwen, Mervyn DI; Dijkhuizen, Rick M; Sena, Emily S; Macleod, Malcolm R; Rinkel, Gabriel JE; van der Worp, H Bart

    2015-01-01

    In clinical trials, endothelin receptor antagonists (ETRAs) reduced vasospasm but did not improve functional outcome after subarachnoid hemorrhage (SAH). We assessed the effects of treatment with ETRAs on clinically relevant outcomes in animal studies modelling SAH by performing a systematic review of the literature for controlled animal studies of ETRAs for the treatment of SAH. Primary outcomes were neurobehavioral outcomes and case fatality. Secondary outcomes were cerebral vasospasm and cerebral blood flow. Summary estimates were calculated using normalized mean difference random effects meta-analysis. We included 27 studies (55 experiments, 639 animals). Neurobehavioral scores were reported in none of the experiments, and case fatality in 8 (15%). Treatment with ETRAs was associated with a pooled odds ratio for case fatality of 0.61 (95% confidence interval (CI), 0.27 to 1.39); a 54% increase (95% CI, 39 to 69) in cerebral arterial diameter; and a 93% increase (95% CI, 58 to 129) in cerebral blood flow. We conclude that there is no evidence from animal studies that treatment with an ETRA improves clinically relevant outcomes after SAH. The reduction in cerebral vasospasm observed in animal studies is consistent with that observed in clinical trials, an effect that is not associated with better functional outcome in patients. PMID:25944590

  4. Renoprotective effects of a combined endothelin type A/type B receptor antagonist in experimental malignant hypertension.

    PubMed

    Kohno, M; Yokokawa, K; Yasunari, K; Kano, H; Minami, M; Ueda, M; Tatsumi, Y; Yoshikawa, J

    1997-09-01

    We previously showed that plasma endothelin-1 (ET-1) concentration was increased in deoxycorticosterone acetate (DOCA)-salt-induced malignant hypertension in spontaneously hypertensive rats (SHR). In contrast, in normal SHR, this value is similar to that seen in Wistar-Kyoto (WKY) rats. The purpose of this study was to examine the effects of the new combined ET type A/type B (ETA/B) receptor antagonist, TAK-044, on the development of hypertension in this model of malignant hypertension. TAK-044 10 mg/kg, which effectively blocks both ETA and ETB receptors, was administered intraperitoneally once per day for 4 weeks in DOCA-salt SHR, and the effects on ET-1 and other parameters were compared with the same values in untreated WKY rats, untreated DOCA-salt SHR, and hydralazine-treated DOCA-salt SHR. DOCA-salt caused marked increases in blood pressure, blood urea nitrogen (BUN), serum creatinine, and plasma ET-1 concentrations in SHR. Both TAK-044 and hydralazine significantly suppressed the increase in blood pressure in DOCA-salt SHR to the same extent. Both treatments also suppressed the increase in BUN and serum creatinine, but this attenuation was less marked with hydralazine than with TAK-044. Neither TAK-044 nor hydralazine affected plasma ET-1 concentration in this model. TAK-044 significantly reduced kidney weight in DOCA-salt SHR, whereas the decrease seen with hydralazine was less marked. Prevention of DOCA-salt-induced renal structural injury (mesangial hypercellularity, glomerular sclerotic changes, and tubulointerstitial damage) in this model was clearly greater with TAK-044 treatment than with hydralazine treatment. These results suggest that endogenous ET-1 may, at least in part, contribute to renal functional and structural damage in malignant DOCA-salt SHR. Our results raise the possibility of renoprotective effects of ETA/B receptor blockers in certain forms of malignant hypertension.

  5. Endothelin

    PubMed Central

    Hyndman, Kelly A.; Dhaun, Neeraj; Southan, Christopher; Kohan, Donald E.; Pollock, Jennifer S.; Pollock, David M.; Webb, David J.; Maguire, Janet J.

    2016-01-01

    The endothelins comprise three structurally similar 21-amino acid peptides. Endothelin-1 and -2 activate two G-protein coupled receptors, ETA and ETB, with equal affinity, whereas endothelin-3 has a lower affinity for the ETA subtype. Genes encoding the peptides are present only among vertebrates. The ligand-receptor signaling pathway is a vertebrate innovation and may reflect the evolution of endothelin-1 as the most potent vasoconstrictor in the human cardiovascular system with remarkably long lasting action. Highly selective peptide ETA and ETB antagonists and ETB agonists together with radiolabeled analogs have accurately delineated endothelin pharmacology in humans and animal models, although surprisingly no ETA agonist has been discovered. ET antagonists (bosentan, ambrisentan) have revolutionized the treatment of pulmonary arterial hypertension, with the next generation of antagonists exhibiting improved efficacy (macitentan). Clinical trials continue to explore new applications, particularly in renal failure and for reducing proteinuria in diabetic nephropathy. Translational studies suggest a potential benefit of ETB agonists in chemotherapy and neuroprotection. However, demonstrating clinical efficacy of combined inhibitors of the endothelin converting enzyme and neutral endopeptidase has proved elusive. Over 28 genetic modifications have been made to the ET system in mice through global or cell-specific knockouts, knock ins, or alterations in gene expression of endothelin ligands or their target receptors. These studies have identified key roles for the endothelin isoforms and new therapeutic targets in development, fluid-electrolyte homeostasis, and cardiovascular and neuronal function. For the future, novel pharmacological strategies are emerging via small molecule epigenetic modulators, biologicals such as ETB monoclonal antibodies and the potential of signaling pathway biased agonists and antagonists. PMID:26956245

  6. Longterm treatment with endothelin receptor antagonist bosentan and iloprost improves fingertip blood perfusion in systemic sclerosis.

    PubMed

    Cutolo, Maurizio; Ruaro, Barbara; Pizzorni, Carmen; Ravera, Francesca; Smith, Vanessa; Zampogna, Giuseppe; Paolino, Sabrina; Seriolo, Bruno; Cimmino, Marco; Sulli, Alberto

    2014-05-01

    To evaluate the longterm effects of endothelin-1 (ET-1) antagonism on peripheral blood perfusion (PBP) in patients with systemic sclerosis (SSc). Twenty-six patients with SSc already receiving cyclic intravenous iloprost (ILO) for severe Raynaud phenomenon were enrolled. Thirteen patients continued the treatment for a further 3 years (ILO group) and 13 patients, because of the appearance of digital ulcers, received in addition bosentan (BOS; 125 mg twice/day) for 3 years (ILO + BOS group). Both PBP at fingertips and nailfold microangiopathy were evaluated yearly by laser Doppler flowmetry and nailfold videocapillaroscopy, respectively. A progressive significant increase of PBP was observed in the ILO + BOS group during the 3 followup years (p = 0.0007, p = 0.0002, p = 0.01, respectively). In contrast, an insignificant progressive decrease of PBP was observed in the ILO group. Difference of perfusion between the PBP evaluations at basal temperature and at 36 °C (to test capillary dilation capacity), was found progressively decreased during the 3-year followup only in the ILO group (p = 0.05, p = 0.26, p = 0.09, respectively). A progressive increase of nailfold capillary number was observed only in the ILO + BOS group after 2 and 3 years of followup (p = 0.05). Longterm treatment of SSc patients with ET-1 antagonism, in combination with ILO, seems to increase fingertip blood perfusion, as well as both capillary dilation capacity and number.

  7. Effect of cyclosporine and rifampin on the pharmacokinetics of macitentan, a tissue-targeting dual endothelin receptor antagonist.

    PubMed

    Bruderer, Shirin; Aänismaa, Päivi; Homery, Marie-Claude; Häusler, Stephanie; Landskroner, Kyle; Sidharta, Patricia N; Treiber, Alexander; Dingemanse, Jasper

    2012-03-01

    Macitentan is a dual endothelin receptor antagonist under phase 3 investigation in pulmonary arterial hypertension. We investigated the effect of cyclosporine (Cs) and rifampin on the pharmacokinetics of macitentan and its metabolites ACT-132577 and ACT-373898 in healthy male subjects. In addition, in vitro studies were performed to investigate interactions between macitentan and its active metabolite ACT-132577 with human organic anion-transporting polypeptides (OATPs). The clinical study (AC-055-111) was conducted as a two-part, one-sequence, crossover study. Ten subjects in each part received multiple-dose macitentan followed by multiple-dose co-administration of Cs (part A) or rifampin (part B). In the presence of Cs, steady-state area under the plasma concentration-time profiles during a dose interval (AUC(τ)) for macitentan and ACT-373898 increased 10% and 7%, respectively, and decreased 3% for ACT-132577. Steady-state AUC(τ) of macitentan and ACT-373898 in the presence of rifampin decreased 79% and 64%, respectively. For ACT-132577, no relevant difference in AUC(τ) between the two treatments was observed. Macitentan co-administered with Cs or rifampin was well tolerated. The complementary in vitro studies demonstrated no marked differences in uptake rates of macitentan and ACT-132577 between the wild-type and OATP over-expressing cells over the concentration range tested. Concomitant treatment with Cs did not have any clinically relevant effect on the exposure to macitentan or its metabolites, at steady-state. Concomitant treatment with rifampin reduced significantly the exposure to macitentan and its metabolite ACT-373898 at steady-state but did not affect the exposure to the active metabolite ACT-132577 to a clinically relevant extent.

  8. Investigation of mutual pharmacokinetic interactions between macitentan, a novel endothelin receptor antagonist, and sildenafil in healthy subjects.

    PubMed

    Sidharta, Patricia N; van Giersbergen, Paul L M; Wolzt, Michael; Dingemanse, Jasper

    2014-11-01

    To study the mutual pharmacokinetic interactions between macitentan, an endothelin receptor antagonist, and sildenafil in healthy male subjects. In this open-label, randomized, three way crossover study, 12 healthy male subjects received the following oral treatments: A) a loading dose of 30 mg macitentan on day 1 followed by 10 mg once daily for 3 days, B) sildenafil 20 mg three times a day for 3 days and a single 20 mg dose on day 4 and C) both treatments A and B concomitantly. Plasma concentration-time profiles of macitentan and its active metabolite ACT-132577 (treatments A and C) and sildenafil and its N-desmethyl metabolite (treatments B and C) were determined on day 4 and analyzed non-compartmentally. The pharmacokinetics of macitentan were not affected by sildenafil. In the presence of sildenafil Cmax and AUCτ of the metabolite ACT-132577 decreased with geometric mean ratios (90% confidence interval (CI)) of 0.82 (0.76, 0.89) and 0.85 (90% CI 0.80, 0.91), respectively. In the presence of macitentan, plasma concentrations of sildenafil were higher than during treatment with sildenafil alone, resulting in increased Cmax and AUCτ values. The respective geometric mean ratios were 1.26 (90% CI 1.07, 1.48) and 1.15 (90% CI 0.94, 1.41). The pharmacokinetics of N-desmethylsildenafil were not affected by macitentan. All treatments were well tolerated. A minor, not clinically relevant, pharmacokinetic interaction was observed between macitentan and sildenafil. Based on these results, no dose adjustment of either compound appears necessary during concomitant treatment with macitentan and sildenafil. © 2014 The British Pharmacological Society.

  9. Investigation of the effects of ketoconazole on the pharmacokinetics of macitentan, a novel dual endothelin receptor antagonist, in healthy subjects.

    PubMed

    Atsmon, Jacob; Dingemanse, Jasper; Shaikevich, Dimitri; Volokhov, Inna; Sidharta, Patricia N

    2013-08-01

    Macitentan is a potent, orally active, non-peptide antagonist of endothelin receptors with tissue-targeting properties, currently undergoing clinical development for the treatment of pulmonary arterial hypertension. The formation of its active metabolite, ACT-132577, as well as overall elimination of the drug, is catalyzed by the cytochrome P450 (CYP) system, predominantly CYP3A4 and to a lesser extent CYP2C19 isoenzyme. Macitentan is not a substrate of P-glycoprotein. Hepatic uptake is mostly driven by passive diffusion and is not dependent on organic anion-transporting polypeptide transport. This study aimed to investigate the magnitude of a possible effect of a potent CYP3A4 inhibitor, ketoconazole, on the pharmacokinetics of macitentan. In a two-period, randomized, open-label, crossover study, 10 healthy subjects received each of the following treatments: Treatment A in which a single oral dose of 10 mg macitentan was administered on day 1 and Treatment B which consisted of initial daily treatment with ketoconazole 400 mg for 4 days, coadministration of macitentan and ketoconazole on the fifth day and continued administration of ketoconazole for 19 additional days. In the presence of ketoconazole, the exposure to macitentan expressed as area under the plasma concentration-time curve was increased by approximately a factor of 2 and to ACT-132577 was reduced by approximately 26 %. Macitentan was well-tolerated with or without ketoconazole in this study and no relevant differences in safety parameters between the treatments were observed. Although macitentan metabolism is indeed affected by CYP3A4 inhibition, the changes are not considered to be clinically significant and macitentan can be administered concomitantly with CYP3A4 inhibitors without need for dose adjustment.

  10. Investigation of mutual pharmacokinetic interactions between macitentan, a novel endothelin receptor antagonist, and sildenafil in healthy subjects

    PubMed Central

    Sidharta, Patricia N; van Giersbergen, Paul L M; Wolzt, Michael; Dingemanse, Jasper

    2014-01-01

    Aim To study the mutual pharmacokinetic interactions between macitentan, an endothelin receptor antagonist, and sildenafil in healthy male subjects. Methods In this open-label, randomized, three way crossover study, 12 healthy male subjects received the following oral treatments: A) a loading dose of 30 mg macitentan on day 1 followed by 10 mg once daily for 3 days, B) sildenafil 20 mg three times a day for 3 days and a single 20 mg dose on day 4 and C) both treatments A and B concomitantly. Plasma concentration−time profiles of macitentan and its active metabolite ACT-132577 (treatments A and C) and sildenafil and its N-desmethyl metabolite (treatments B and C) were determined on day 4 and analyzed non-compartmentally. Results The pharmacokinetics of macitentan were not affected by sildenafil. In the presence of sildenafil Cmax and AUCτ of the metabolite ACT-132577 decreased with geometric mean ratios (90% confidence interval (CI)) of 0.82 (0.76, 0.89) and 0.85 (90% CI 0.80, 0.91), respectively. In the presence of macitentan, plasma concentrations of sildenafil were higher than during treatment with sildenafil alone, resulting in increased Cmax and AUCτ values. The respective geometric mean ratios were 1.26 (90% CI 1.07, 1.48) and 1.15 (90% CI 0.94, 1.41). The pharmacokinetics of N-desmethylsildenafil were not affected by macitentan. All treatments were well tolerated. Conclusion A minor, not clinically relevant, pharmacokinetic interaction was observed between macitentan and sildenafil. Based on these results, no dose adjustment of either compound appears necessary during concomitant treatment with macitentan and sildenafil. PMID:24962473

  11. Association of oral endothelin receptor antagonists with risks of cardiovascular events and mortality: meta-analysis of randomized controlled trials.

    PubMed

    Pan, Yu; Hu, Chun; Chen, Pei Hua; Gu, Yan Hong; Qiao, Qing Yan; Pan, Li Hua; Zhou, Dong Chi; Gu, Hui Fang; Fu, Shun Kun; Jin, Hui Min

    2017-03-01

    Endothelin receptor antagonists (ERAs) are widely used in a variety of disorders, including pulmonary artery hypertension, systemic sclerosis, diabetic and kidney diseases, and several tumors. However, reported adverse events, especially increased risks of cardiovascular disease (CVD) morbidity and mortality, have cast doubt on their potential clinical application. Therefore, we conducted this meta-analysis to confirm whether ERAs increased CVD risk and mortality. We systematically searched PubMed (1966-2015), EMBASE (1974-2015), ClinicalTrials.gov, and the Cochrane Controlled Clinical Trials Register Database for randomized controlled trials published between Jan 1, 1990 and Mar 18, 2015. Inclusion criteria included a study duration of more than 3 weeks, the use of a randomized control group receiving an oral ERA or placebo, and the availability of outcome data for cardiovascular events and all-cause death. A total of 33 trials met the inclusion criteria. There were 8098 cases in the ERA group and 5074 cases in the placebo group. Compared with the control group, the risk ratio (RR) for all-cause death in the ERA group was 0.983 [95% confidence interval (CI), 0.883 to 1.094, P = 0.754]. The summary RR for cardiovascular events was 1.651 in the ERA group (95% CI, 1.164 to 2.34, P = 0.005). The pooled results showed that ERAs treatment could lead to more edema, anemia, and abnormal transaminase levels. Also, there was an increased proportion of discontinued therapy in the ERA treatment because of side effects (RR = 1.322, 95% CI, 1.036 to 1.686, P = 0.025). There were no significant differences in the experienced episodes of headache and dyspnea between the active therapy and control groups. ERAs therapy is not significantly associated with increased all-cause death, but there are more cardiovascular events and edema or fluid retention, anemia, and liver enzymes disorder. Large clinical randomized controlled studies are needed to further confirm the

  12. Efficacy, safety and clinical pharmacology of macitentan in comparison to other endothelin receptor antagonists in the treatment of pulmonary arterial hypertension.

    PubMed

    Dingemanse, Jasper; Sidharta, Patricia N; Maddrey, Willis C; Rubin, Lewis J; Mickail, Hani

    2014-03-01

    Macitentan is a novel dual endothelin receptor antagonist (ERA) showing sustained receptor occupancy. In vitro and in vivo animal studies have demonstrated its potency in antagonizing endothelin-induced disorders. A large morbidity/mortality study in patients with pulmonary arterial hypertension (PAH) taking macitentan has been completed recently. This drug evaluation reviews the efficacy, safety and clinical pharmacology of macitentan in the treatment of PAH. The large Phase III study (SERAPHIN) tested macitentan in more than 700 PAH patients and has provided unique long-term outcome data for this ERA, not available for other members of this class. The effect on a composite clinically relevant morbidity/mortality end point was highly significant at a 10 mg/day dose. The safety profile of macitentan appears to be superior with respect to hepatic safety and edema/fluid retention than bosentan and ambrisentan, respectively, and is similar when considering decrease in hemoglobin concentration. The drug has a low propensity for drug-drug interactions and has one circulating pharmacologically active metabolite. The pharmacokinetics of macitentan in patients with renal or hepatic impairment does not require dose adjustments. Based on its characteristics, macitentan is an important addition to the therapeutic armamentarium in the long-term treatment of PAH. Its potential use in other disorders is under investigation.

  13. An overview of the preclinical toxicity and potential carcinogenicity of sitaxentan (Thelin®), a potent endothelin receptor antagonist developed for pulmonary arterial hypertension.

    PubMed

    Owen, Keith; Cross, David M; Derzi, Mazin; Horsley, Elizabeth; Stavros, Fiona L

    2012-10-01

    Sitaxentan (Thelin®), an endothelin receptor antagonist with a long duration of action and high specificity for the endothelin receptor A subtype, was used to treat pulmonary arterial hypertension. It was withdrawn from the market due to an idiosyncratic risk of drug-induced liver injury identified from emerging clinical trial data and clinical case reports. The preclinical safety profile of sitaxentan is presented, including single- and repeat-dose toxicity in mice, rats, and dogs and carcinogenicity in mice and rats. Sitaxentan-related adverse effects included coagulopathy in rats and dogs, increased serum alkaline phosphatase activity in mice and dogs, and hepatic hypertrophy in all species. Decreased albumin, erythrocyte count, hemoglobin concentration and hematocrit, and increased coagulation times and liver weight were also noted. These effects generally occurred at systemic exposures (AUC(0-24)) that were substantially greater than those seen in humans. Twice-daily (vs. once daily) dosing resulted in increased toxicity, which correlated with increased trough plasma sitaxentan concentrations. Sitaxentan appeared to have a low potential for testicular and hepatic toxicity and was not carcinogenic. These studies suggested that sitaxentan would have a reasonable margin of safety when used as directed in humans and supported a positive benefit:risk assessment at the time of marketing approval.

  14. Evolution of endothelin receptors in vertebrates.

    PubMed

    Braasch, Ingo; Schartl, Manfred

    2014-12-01

    Endothelin receptors are G protein coupled receptors (GPCRs) of the β-group of rhodopsin receptors that bind to endothelin ligands, which are 21 amino acid long peptides derived from longer prepro-endothelin precursors. The most basal Ednr-like GPCR is found outside vertebrates in the cephalochordate amphioxus, but endothelin ligands are only present among vertebrates, including the lineages of jawless vertebrates (lampreys and hagfishes), cartilaginous vertebrates (sharks, rays, and chimaeras), and bony vertebrates (ray-finned fishes and lobe-finned vertebrates including tetrapods). A bona fide endothelin system is thus a vertebrate-specific innovation with important roles for regulating the cardiovascular system, renal and pulmonary processes, as well as for the development of the vertebrate-specific neural crest cell population and its derivatives. Expectedly, dysregulation of endothelin receptors and the endothelin system leads to a multitude of human diseases. Despite the importance of different types of endothelin receptors for vertebrate development and physiology, current knowledge on endothelin ligand-receptor interactions, on the expression of endothelin receptors and their ligands, and on the functional roles of the endothelin system for embryonic development and in adult vertebrates is very much biased towards amniote vertebrates. Recent analyses from a variety of vertebrate lineages, however, have shown that the endothelin system in lineages such as teleost fish and lampreys is more diverse and is divergent from the mammalian endothelin system. This diversity is mainly based on differential evolution of numerous endothelin system components among vertebrate lineages generated by two rounds of whole genome duplication (three in teleosts) during vertebrate evolution. Here we review current understanding of the evolutionary history of the endothelin receptor family in vertebrates supplemented with surveys on the endothelin receptor gene complement of

  15. Endothelin(A)-endothelin(B) receptor cross talk in endothelin-1-induced contraction of smooth muscle.

    PubMed

    Rapoport, Robert M; Zuccarello, Mario

    2012-11-01

    The efficacy of selective endothelin (ET) receptor antagonists may be limited by a functional interaction between the ET(A) and ET(B) receptors. This interaction, also termed "cross talk", is characterized by the dependency of the inhibition of an ET-1 response due to antagonism of one ET receptor subtype upon concomitant antagonism of the other ET receptor subtype. Although a reduction in ET(A)-ET(B) receptor cross talk would presumably increase the efficacy of selective ET receptor antagonists, an approach that accomplishes this aim is largely absent due to a lack of mechanistic understanding. Toward this goal, we evaluated the characteristics and potential dependencies of cross talk in smooth muscle. Smooth muscle was adopted as an exemplar not only because cross talk is widely reported in this tissue type, thereby allowing numerous comparisons, but also significant controversy surrounds the use of selective versus nonselective ET receptor antagonists in ET-1-related pathophysiologies involving smooth muscle. Based on this evaluation, we suggest that ET(A)-ET(B) receptor cross talk is a dynamic process directed by either or both ET receptor subtypes and expressed to varying magnitudes depending on the ET-1 and selective ET receptor antagonist concentrations, tone due to intraluminal pressure/stretch, agonists acting at receptors other than the ET(A)/ET(B) receptors, and endothelial/epithelial function. It is speculated that ET(A)-ET(B) receptor cross talk occurs through signal transduction pathways along with changes at the receptor level. Pharmacologic intervention of the signaling pathways could increase the therapeutic efficacy of ET receptor antagonists.

  16. Endothelin receptor polymorphisms in the cardiovascular system: potential implications for therapy and screening.

    PubMed

    Holzhauser, Luise; Zolty, Ronald

    2014-11-01

    Since its discovery in 1988, the endothelin system has been employed in multiple physiological and pathological roles. Endothelin-1 (ET-1) is not only a major regulator of vascular tone and cardiac contractility but also exerts mitogenic effects and is involved in inflammatory responses. ET-1 acts via two endothelin receptors located mainly on smooth muscle and endothelial cells through complex intracellular pathways differing between receptors and cell types. Polymorphisms of the endothelin receptor A have been associated not only with the risk in pulmonary arterial hypertension (PAH), systolic heart failure and systemic hypertension but are also of prognostic significance in dilated cardiomyopathy. Polymorphisms of endothelin receptors might lead to altered endothelin signaling and influence the response to endothelin receptor antagonist therapy in PAH in light of pharmacogenetics. This review will summarize the role of ET-1 within major cardiovascular pathologies and discuss endothelin receptor polymorphisms with special emphasis on potential therapeutic and screening implications.

  17. Effects of TAK-044, a nonselective endothelin receptor antagonist, on the spontaneous and indomethacin- or methylene blue-induced constriction of the ductus arteriosus in rats.

    PubMed

    Takizawa, T; Horikoshi, E; Shen, M H; Masaoka, T; Takagi, H; Yamamoto, M; Kasai, K; Arishima, K

    2000-05-01

    We studied the effects of TAK-044, a nonselective endothelin (ET) receptor antagonist, on the indomethacin- or methylene blue-induced constriction of the ductus arteriosus (DA) in rats and compared them with the effects on spontaneous DA constriction. Injection of TAK-044 into 21-day-old fetuses in utero was performed through the uterine wall of laparotomized mother rats under light ether anesthesia. The fetuses were autopsied 3 hr after treatment with TAK-044 (10 mg/kg) in utero and simultaneous administration to the laparotomized mother rats of indomethacin (3 mg/kg, p.o.) or methylene blue (100 mg/kg, i.p.). In the second experiment, pregnant rats were decapitated on day 21 of gestation to obtain newborn rats by cesarean delivery. Newborn rats which were given TAK-044 (2, 10 mg/kg) immediately after or 1 hr before cesarean delivery were autopsied at various times after birth. In both experiments, pups were rapidly frozen in an acetone-dry ice mixture at autopsy to evaluate the DA constriction by the whole-body freezing and shaving method. TAK-044 injection into the fetus 3 hr before autopsy completely inhibited the DA constriction induced by maternal treatment with indomethacin or methylene blue. TAK-044 caused dose-dependent inhibition of the spontaneous closure of the DA after birth. The inhibitory effect was more pronounced in pups which were given TAK-044 in utero 1 hr before birth; however, the inhibitory effect was incomplete in newborn pups. These results, together with the previous finding that BQ-123, an ETA-specific receptor antagonist, inhibits the ductal constriction induced by oxygen in vitro [Coceani et al., 1992], indicate that the ETA receptor plays a significant role in the indomethacin- or methylene blue-induced DA constriction as well as in the spontaneous DA constriction after birth, and also indicate that the inhibition of ETA receptor by TAK-044 was more easily achieved in fetuses than in neonates.

  18. Renal actions of endothelin-1 in newborn piglets: dose-effect relation and the effects of receptor antagonist (BQ-123) and cyclooxygenase inhibitor (indomethacin).

    PubMed

    Bhat, R; John, E; Chari, G; Shankararao, R; Fornell, L; Gulati, A; Vidyasagar, D

    1995-11-01

    Although the effects of endothelin-1 (ET-1) on intact or perfused adult kidney are well understood, its effects in the fetus and the newborn have not been well studied. We examined the effects of infusions of 25, 50, and 100 ng/kg of ET-1 per minute on mean blood pressure (MBP), cardiac index (CI), renal blood flow (RBF), glomerular filtration rate (GFR), and urine volume (UV) in 7- to 10-day-old piglets (n = 24). In addition, the effects of pretreatment with a receptor antagonist (BQ-123) and with a cyclooxygenase inhibitor (indomethacin) were studied in 12 separate piglets. ET-1 produced a dose- and level-dependent decrease in CI (60%), RBF (50% to 75%), GFR (66% to 80%) and MBP 15% to 17%. These changes returned to 75% to 80% of baseline 60 minutes after discontinuation of ET-1. Low-dose infusion (25 ng/kg) did not result in any changes in systemic or renal hemodynamics. Plasma half-life of ET-1 in piglets was 2.1 +/- 0.4 minutes. Pretreatment with the specific ETA receptor antagonist BQ-123 completely blocked the ET-1-induced systemic and renal hemodynamic changes. Indomethacin blocked the ET-1-induced rise in MBP but failed to block any renal changes. In fact, indomethacin accentuated the changes induced by ET-1, especially the changes in RBF, RVR, and GFR. Studies of receptor binding in the renal cortex and medulla showed that, in the cortex, the Ki value for ET-1 was 6.32 +/- 1.57, and for ET-3 it was 20.05 +/- 4.38 (p < 0.05); in the medulla, the Ki values were similar for both ET-1 and ET-3. These results indicate that in piglets the renal vascular bed is highly sensitive to ET-1, and its effects are predominantly mediated through ETA receptors.

  19. Endothelin ETA receptor antagonism in cardiovascular disease.

    PubMed

    Nasser, Suzanne A; El-Mas, Mahmoud M

    2014-08-15

    Since the discovery of the endothelin system in 1988, it has been implicated in numerous physiological and pathological phenomena. In the cardiovascular system, endothelin-1 (ET-1) acts through intracellular pathways of two endothelin receptors (ETA and ETB) located mainly on smooth muscle and endothelial cells to regulate vascular tone and provoke mitogenic and proinflammatory reactions. The endothelin ETA receptor is believed to play a pivotal role in the pathogenesis of several cardiovascular disease including systemic hypertension, pulmonary arterial hypertension (PAH), dilated cardiomyopathy, and diabetic microvascular dysfunction. Growing evidence from recent experimental and clinical studies indicates that the blockade of endothelin receptors, particularly the ETA subtype, grasps promise in the treatment of major cardiovascular pathologies. The simultaneous blockade of endothelin ETB receptors might not be advantageous, leading possibly to vasoconstriction and salt and water retentions. This review summarizes the role of ET-1 in cardiovascular modulation and the therapeutic potential of endothelin receptor antagonism.

  20. Treatment of experimental human breast cancer and lung cancer brain metastases in mice by macitentan, a dual antagonist of endothelin receptors, combined with paclitaxel

    PubMed Central

    Lee, Ho Jeong; Hanibuchi, Masaki; Kim, Sun-Jin; Yu, Hyunkyung; Kim, Mark Seungwook; He, Junqin; Langley, Robert R.; Lehembre, François; Regenass, Urs; Fidler, Isaiah J.

    2016-01-01

    Background We recently demonstrated that brain endothelial cells and astrocytes protect cancer cells from chemotherapy through an endothelin-dependent signaling mechanism. Here, we evaluated the efficacy of macitentan, a dual endothelin receptor (ETAR and ETBR) antagonist, in the treatment of experimental breast and lung cancer brain metastases. Methods The effect of macitentan on astrocyte- and brain endothelial cell-mediated chemoprotective properties was measured in cytotoxic assays. We compared survival of mice bearing established MDA-MB-231 breast cancer or PC-14 non–small cell lung cancer (NSCLC) brain metastases that were treated with vehicle, macitentan, paclitaxel, or macitentan plus paclitaxel. Cell division, apoptosis, tumor vasculature, and expression of survival-related proteins were assessed by immunofluorescent microscopy. Results Cancer cells and tumor-associated endothelial cells expressed activated forms of AKT and MAPK in vehicle- and paclitaxel-treated groups in both metastasis models, but these proteins were downregulated in metastases of mice that received macitentan. The survival-related proteins Bcl2L1, Gsta5, and Twist1 that localized to cancer cells and tumor-associated endothelial cells in vehicle- and paclitaxel-treated tumors were suppressed by macitentan. Macitentan or paclitaxel alone had no effect on survival. However, when macitentan was combined with paclitaxel, we noted a significant reduction in cancer cell division and marked apoptosis of both cancer cells and tumor-associated endothelial cells. Moreover, macitentan plus paclitaxel therapy significantly increased overall survival by producing complete responses in 35 of 35 mice harboring brain metastases. Conclusions Dual antagonism of ETAR and ETBR signaling sensitizes experimental brain metastases to paclitaxel and may represent a new therapeutic option for patients with brain metastases. PMID:26995790

  1. Treatment of experimental human breast cancer and lung cancer brain metastases in mice by macitentan, a dual antagonist of endothelin receptors, combined with paclitaxel.

    PubMed

    Lee, Ho Jeong; Hanibuchi, Masaki; Kim, Sun-Jin; Yu, Hyunkyung; Kim, Mark Seungwook; He, Junqin; Langley, Robert R; Lehembre, François; Regenass, Urs; Fidler, Isaiah J

    2016-04-01

    We recently demonstrated that brain endothelial cells and astrocytes protect cancer cells from chemotherapy through an endothelin-dependent signaling mechanism. Here, we evaluated the efficacy of macitentan, a dual endothelin receptor (ETAR and ETBR) antagonist, in the treatment of experimental breast and lung cancer brain metastases. The effect of macitentan on astrocyte- and brain endothelial cell-mediated chemoprotective properties was measured in cytotoxic assays. We compared survival of mice bearing established MDA-MB-231 breast cancer or PC-14 non-small cell lung cancer (NSCLC) brain metastases that were treated with vehicle, macitentan, paclitaxel, or macitentan plus paclitaxel. Cell division, apoptosis, tumor vasculature, and expression of survival-related proteins were assessed by immunofluorescent microscopy. Cancer cells and tumor-associated endothelial cells expressed activated forms of AKT and MAPK in vehicle- and paclitaxel-treated groups in both metastasis models, but these proteins were downregulated in metastases of mice that received macitentan. The survival-related proteins Bcl2L1, Gsta5, and Twist1 that localized to cancer cells and tumor-associated endothelial cells in vehicle- and paclitaxel-treated tumors were suppressed by macitentan. Macitentan or paclitaxel alone had no effect on survival. However, when macitentan was combined with paclitaxel, we noted a significant reduction in cancer cell division and marked apoptosis of both cancer cells and tumor-associated endothelial cells. Moreover, macitentan plus paclitaxel therapy significantly increased overall survival by producing complete responses in 35 of 35 mice harboring brain metastases. Dual antagonism of ETAR and ETBR signaling sensitizes experimental brain metastases to paclitaxel and may represent a new therapeutic option for patients with brain metastases. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved

  2. The effect of tezosentan, a non-selective endothelin receptor antagonist, on shear stress-induced changes in arterial diameter of the anaesthetized dog

    PubMed Central

    Markos, F; Hennessy, B A; Fitzpatrick, M; O'Sullivan, J; Snow, H M

    2002-01-01

    The effects of changes in the mean (Sm) and pulsatile (Sp) components of arterial wall shear stress on arterial dilatation of the iliac artery of the anaesthetized dog were examined in the absence and presence of the endothelin receptor antagonist tezosentan (10 mg kg−1 I.V.; Ro 61-0612; [5-isopropyl-pyridine-2-sulphonic acid 6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2-(2-1H-tetrazol-5-yl-pyridin-4-yl)-pyrimidin-4-ylamide]). Changes in shear stress were brought about by varying local peripheral resistance and stroke volume using a distal infusion of acetylcholine and stimulation of the left ansa subclavia. An increase in Sm from 1.81 ± 0.3 to 7.29 ± 0.7 N m−2 (means ± S.E.M.) before tezosentan caused an endothelium-dependent arterial dilatation which was unaffected by administration of tezosentan for a similar increase in Sm from 1.34 ± 0.6 to 5.76 ± 1.4 N m−2 (means ± S.E.M.). In contrast, increasing the Sp from 7.1 ± 0.8 to a maximum of 11.5 ± 1.1 N m−2 (means ± S.E.M.) before tezosentan reduced arterial diameter significantly. Importantly, after administration of tezosentan subsequent increases in Sp caused arterial dilatation for the same increase in Sp achieved prior to tezosentan, increasing from a baseline of 4.23 ± 0.4 to a maximum of 9.03 ± 0.9 N m−2 (means ± S.E.M.; P < 0.001). In conclusion, the results of this study provide the first in vivo evidence that pulsatile shear stress is a stimulus for the release of endothelin from the vascular endothelium. PMID:12411533

  3. Endothelin in human brain and pituitary gland: Presence of immunoreactive endothelin, endothelin messenger ribonucleic acid, and endothelin receptors

    SciTech Connect

    Takahashi, K.; Ghatei, M.A.; Jones, P.M.; Murphy, J.K.; Lam, H.C.; O'Halloran, D.J.; Bloom, S.R. )

    1991-03-01

    The presence of immunoreactive (IR) endothelin, endothelin mRNA, and endothelin receptors in human brain and pituitary gland has been studied by RIA, Northern blot hybridization, and receptor assay. IR endothelin was detected in all five brain regions examined (cerebral cortex, cerebellum, brain stem, basal ganglia, and hypothalamus) (6-10 fmol/g wet wt) and spinal cord (22 +/- 6 fmol/g wet wt, n = 7, mean +/- SEM). Higher concentrations of IR endothelin were found in the pituitary gland (147 +/- 30 fmol/g wet wt). Fast protein liquid chromatographic analysis of the IR endothelin in pituitary gland showed a large IR peak in the position of endothelin-3 and a smaller peak in the position of endothelin-1, whereas IR endothelin in the hypothalamus and brain stem was mainly endothelin-1. Endothelin messenger RNA was detected by Northern blot hybridization in the pituitary but not in hypothalamus. The receptor assay showed that 125I-endothelin-1 binding sites were present in large numbers in all five brain regions but were much less abundant in the pituitary gland. Binding capacity and dissociation constant were 5052 +/- 740 fmol/mg protein and 0.045 +/- 0.007 nM in brain stem and 963 +/- 181 fmol/mg protein and 0.034 +/- 0.009 nM in hypothalamus. In the pituitary gland, there were two classes of binding sites for endothelin with dissociation constants of 0.059 +/- 0.002 nM (binding capacity = 418 +/- 63 fmol/mg protein) and 0.652 +/- 0.103 nM (binding capacity = 1717 +/- 200 fmol/mg protein). Endothelin-1, -2 and -3 were almost equipotent in displacing the binding (IC50 approximately 0.04 nM). These findings are in accord with the possibility that endothelin acts as a neurotransmitter, neuromodulator or neurohormone in man.

  4. [The effect of an endothelin receptor antagonist in Eisenmenger syndrome: a single-center experience of 11 patients].

    PubMed

    Poindron, D; Godart, F; Duhamel, A; Richard, A; Francart, C; Brevière, G M; Rey, C

    2006-05-01

    The Eisenmenger syndrome is a complication of congenital heart disease with significant left-to-right shunts, such as large ventricular septal defects, and corresponds to fixed pulmonary hypertension with shunt reversal. Bosentan, an inhibitor of endothelin A and B receptors, is a new molecule previously validated in the treatment of primary pulmonary hypertension. The authors report their monocentric experience of bosentan in 11 consecutive patients with the Eisenmenger syndrome treated for at least one year. This retrospective study comprised 7 females and 4 males with an average age of 34 years (range 17 to 51 years). The underlying lesion was ventricular septal defect (n = 4), atrial septal defect (n = 3), pulmonary atresia with septal defect (n = 4 of which 2 were treated palliatively). Before treatment, the patients were classified according to the NHYA functional class (I, II, IIIa and IIIb, IV or, respectively from 1 to 5) with a distribution in this series between Classes IIIa and IV (average 3.81 +/- 0.75) and from 3 to 10 on Borg's dyspnoea scale (average 6.54 +/- 2.29). The ambient oxygen saturation (SaO2) at rest was, on average 77 +/- 9%, the haemoglobin concentration 16.6 +/- 2.4 g/dl; hepatic transaminase levels were normal. The 6 minute walk test before treatment was 216 +/- 111 m with marked desaturation on exercise (49 +/- 18%). With Bosentan, patients were globally much better clinically with a decrease in dyspnoea, improvement in NHYA class and increased 6 minute walking perimeter. Improvement in NYHA class was observed from 3 months' treatment (3.0 +/- 0.8, p = 0.0002) and was sustained to one year (2.54 +/- 0.7, p< 0.001). An improvement of dyspnoea on Borg's scale was observed from the second month's treatment (5.56 +/- 1.65, p = 0.0201) and persisted throughout follow up to one year (3.81 +/- 1.32, p < 0.0001). Similarly, the 6 minute walking perimeter increased from the first control at 6 months (323 +/- 82 m, p < 0.0001) and at one year

  5. Protection from renal ischemia reperfusion injury by an endothelin-A receptor antagonist BQ-123 in relation to nitric oxide production.

    PubMed

    Erdogan, Hasan; Fadillioglu, Ersin; Emre, Memet Hanifi

    2006-12-07

    The aim of this study was to investigate whether the protective effect of endothelin-A (ET(A)) receptor antagonist BQ-123 against renal ischemia reperfusion (I/R) injury is related to nitric oxide (NO) production. Sprague-Dawley rats were divided into six groups: control, I/R, N sup omega nitro-L-arginine methyl ester (L-NAME), BQ, BQ+L-NAME, BQ+L-NAME+L-Arg groups. After urethane anesthesia, 30min renal ischemia and 2h reperfusion were performed in all groups except control group. Mean arterial pressures (MAP) during reperfusion in all L-NAME-treated groups were higher than during pre-ischemia and ischemia, however, MAP at 60th and 120th minute of reperfusion in control and BQ groups were lower than during ischemia. MAP of L-NAME-treated groups were significantly higher than the other groups during reperfusion period. The I/R caused lipid peroxidation and protein oxidation, however, BQ-123 treatment prevented oxidant injury. The inhibition of NO production prevented effect of BQ-123 treatment. Also, BQ-123 treatment caused an increase in superoxide dismutase and catalase activities. Both BQ-123 and L-NAME treatments prevented high xanthine oxidase activity. BQ-123 prevented risen myeloperoxidase activity and L-NAME reversed this effect of BQ-123 just like the addition of L-arginine to the treatment altered the effect of L-NAME. The plasma BUN was affected as increasing manner from L-NAME treatments; on the other hand, plasma Cr and Na concentrations were affected as decreasing manner from BQ-123 treatments. ET(A) receptor antagonist BQ-123 may be revealed a protective agent against renal I/R injury with a possible secondary pathway via its antioxidant effects. We suggest that BQ-123 may mediate the protective effect via a NO-dependent mechanism.

  6. Safety, tolerability, pharmacokinetics, and pharmacodynamics of macitentan, an endothelin receptor antagonist, in an ascending multiple-dose study in healthy subjects.

    PubMed

    Sidharta, Patricia N; van Giersbergen, Paul L M; Dingemanse, Jasper

    2013-11-01

    This multiple-ascending-dose study investigated safety, tolerability, pharmacokinetics, and pharmacodynamics, of macitentan, a new endothelin receptor antagonist (ERA) with sustained receptor binding and enhanced tissue penetration properties compared to other ERAs. Healthy male subjects (n = 32) received once daily oral doses of macitentan (1 - 30 mg) or placebo for 10 days. Administration of macitentan was safe and well tolerated. Macitentan had no effect on bile salts, suggesting an improved liver safety profile. The multiple-dose pharmacokinetics of macitentan were dose-proportional and were characterized by a median tmax and apparent elimination half-life varying from 6.0 to 8.5 and 14.3 to 18.5 hours, respectively, for the different doses and minimal accumulation. ACT-132577, a metabolite with lower potency than macitentan, had a half-life of about 48 hours and accumulated approximately 8.5-fold. Compared to placebo, administration of macitentan caused a dose-dependent increase in plasma ET-1 with maximum effects attained at 10 mg. A small dose-dependent increase in the 6β-hydroxycortisol/cortisol urinary excretion ratio was observed, although there were no statistically significant differences between treatments including placebo. Effects of macitentan on cytochrome P450 enzyme 3A4 should be further evaluated in dedicated studies. The present results support investigation of macitentan in the management of pulmonary arterial hypertension and ET-1-dependent pathologies. © 2013, The American College of Clinical Pharmacology.

  7. Macitentan, a dual endothelin receptor antagonist for the treatment of pulmonary arterial hypertension, does not affect cardiac repolarization in healthy subjects.

    PubMed

    Lindegger, Nicolas; Sidharta, Patricia N; Reseski, Kathrin; Dingemanse, Jasper

    2014-10-01

    Macitentan is an orally active dual endothelin receptor antagonist, which demonstrated a reduction of the risk of morbidity/mortality events in pulmonary arterial hypertension patients. This double-blind, randomized, placebo- and positive-controlled, four-way crossover thorough QTc study was designed to investigate the effects of therapeutic and supratherapeutic doses of macitentan on cardiac repolarization in healthy male and female subjects. Each subject received the following treatments: moxifloxacin 400 mg, macitentan 10 mg, macitentan 30 mg, and placebo. Each treatment period lasted 9 days and was followed by at least 10 days of washout. The primary endpoint of this study was the baseline-adjusted, placebo-corrected QT interval corrected using the Fridericia method (ΔΔQTcF). Pharmacokinetic (PK), safety, and tolerability assessments were performed during each treatment. A total of 64 subjects were randomized. The upper bound of the 2-sided 90% confidence interval for ΔΔQTcF following macitentan was <10 ms at all time points and no correlation was observed between ΔΔQTcF and PK parameters. Findings in the analysis of the morphological patterns of the ECGs were randomly distributed across all treatments and did not indicate an association with macitentan. Macitentan was well tolerated in this study. Headache and nasopharyngitis were the most frequently reported adverse events. No effects on clinical laboratory and vital signs parameters were observed. In summary, repeated doses of macitentan 10 mg and 30 mg did not indicate any pro-arrhythmic potential. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Evaluation of the endothelin receptor antagonists ambrisentan, darusentan, bosentan, and sitaxsentan as substrates and inhibitors of hepatobiliary transporters in sandwich-cultured human hepatocytes.

    PubMed

    Hartman, J Craig; Brouwer, Kenneth; Mandagere, Arun; Melvin, Lawrence; Gorczynski, Richard

    2010-06-01

    To evaluate potential mechanisms of clinical hepatotoxicity, 4 endothelin receptor antagonists (ERAs) were examined for substrate activity and inhibition of hepatic uptake and efflux transporters in sandwich-cultured human hepatocytes. The 4 transporters studied were sodium-dependent taurocholate cotransporter (NTCP), organic anion transporter (OATP), bile salt export pump (BSEP), and multidrug resistance-associated protein 2 (MRP2). ERA transporter inhibition was examined using the substrates taurocholate (for NTCP and BSEP), [(3)H]estradiol-17beta-D-glucuronide (for OATP), and [2-D-penicillamine, 5-D-penicillamine]enkephalin (for MRP2). ERA substrate activity was evaluated using probe inhibitors ritonavir (OATP and BSEP), bromosulfalein (OATP), erythromycin (P-glycoprotein), probenecid (MRP2 and OATP), and cyclosporin (NTCP). ERAs were tested at 2, 20, and 100 micromol*L-1 for inhibition and at 2 micromol*L-1 as substrates. OATP, NTCP, or BSEP transport activity was not reduced by ambrisentan or darusentan. Bosentan and sitaxsentan attenuated NTCP transport at higher concentrations. Only sitaxsentan decreased OATP transport (52%), and only bosentan reduced BSEP transport (78%). MRP2 transport activity was unaltered. OATP inhibitors decreased influx of all ERAs. Darusentan influx was least affected (84%-100% of control), whereas bosentan was most affected (32%-58% of control). NTCP did not contribute to influx of ERAs. Only bosentan and darusentan were shown as substrates for both BSEP and P-glycoprotein efflux. All ERAs tested were substrates for at least one hepatic transporter. Bosentan and sitaxsentan, but not ambrisentan and darusentan, inhibited human hepatic transporters, which provides a potential mechanism for the increased hepatotoxicity observed for these agents in the clinical setting.

  9. Preliminary study of the specific endothelin a receptor antagonist zibotentan in combination with docetaxel in patients with metastatic castration-resistant prostate cancer.

    PubMed

    Trump, Donald L; Payne, Heather; Miller, Kurt; de Bono, Johann S; Stephenson, Joe; Burris, Howard A; Nathan, Faith; Taboada, Maria; Morris, Thomas; Hubner, Andreas

    2011-09-01

    This two-part study assessed the safety and tolerability of combined treatment with zibotentan (ZD4054), a specific endothelin A receptor antagonist, plus docetaxel in patients with metastatic castration-resistant prostate cancer. Part A was an open-label, dose-finding phase to determine the safety and toxicity profile of zibotentan in combination with docetaxel. Patients received once-daily oral zibotentan 10 mg (initial cohort) or 15 mg in combination with docetaxel 75 mg/m(2) (administered on day 1 of each 21-day cycle) for up to 10 cycles. Part B was a double-blind phase which evaluated the safety and preliminary activity of zibotentan plus docetaxel. Patients were randomized 2:1 to receive zibotentan (at the highest tolerated dose identified in part A) plus docetaxel or placebo plus docetaxel. Six patients were enrolled in part A (n  = 3, zibotentan 10 mg; n = 3, zibotentan 15 mg). No dose-limiting toxicity was observed, thus zibotentan 15 mg in combination with docetaxel was evaluated in part B (n = 20, zibotentan plus docetaxel; n = 11, placebo plus docetaxel). CTCAE grade ≥3, most commonly neutropenia or leucopenia, were reported in 10 (50%) and nine (82%) patients in the zibotentan and placebo groups, respectively. One (17%) patient receiving placebo achieved complete response, two (22%) patients receiving zibotentan achieved partial response and stable disease occurred in six (67%) and three (50%) patients receiving zibotentan and placebo, respectively. The tolerability of zibotentan plus docetaxel was consistent with the known profiles of each drug. Sufficient preliminary activity was seen with this combination to merit continued development. Copyright © 2011 Wiley-Liss, Inc.

  10. Endothelial nitric oxide synthase-enhancing G-protein coupled receptor antagonist inhibits pulmonary artery hypertension by endothelin-1-dependent and endothelin-1-independent pathways in a monocrotaline model.

    PubMed

    Liu, Chung-Pin; Dai, Zen-Kong; Huang, Chein-Heng; Yeh, Jwu-Lai; Wu, Bin-Nan; Wu, Jiunn-Ren; Chen, Ing-Jun

    2014-06-01

    This study investigates whether endothelin-1 (ET-1) mediates monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) and right ventricular hypertrophy (RVH), and if so, whether the G-protein coupled receptor antagonist KMUP-1 (7-{2-[4-(2-chlorobenzene)piperazinyl]ethyl}-1,3-dimethylxanthine) inhibits ET-1-mediated PA constriction and the aforementioned pathological changes. In a chronic rat model, intraperitoneal MCT (60 mg/kg) induced PAH and increased PA medial wall thickening and RV/left ventricle + septum weight ratio on Day 21 after MCT injection. Treatment with sublingual KMUP-1 (2.5 mg/kg/day) for 21 days prevented these changes and restored vascular endothelial nitric oxide synthase (eNOS) immunohistochemical staining of lung tissues. Western blotting analysis demonstrated that KMUP-1 enhanced eNOS, soluble guanylate cyclase, and protein kinase G levels, and reduced ET-1 expression and inactivated Rho kinase II (ROCKII) in MCT-treated lung tissue over long-term administration. In MCT-treated rats, KMUP-1 decreased plasma ET-1 on Day 21. KMUP-1 (3.6 mg/kg) maximally appeared at 0.25 hours in the plasma and declined to basal levels within 24 hours after sublingual administration. In isolated PA of MCT-treated rats, compared with control and pretreatment with l-NG-nitroarginine methyl ester (100 μM), KMUP-1 (0.1-100 μM) inhibited ET-1 (0.01 μM)-induced vasoconstriction. Endothelium-denuded PA sustained higher contractility in the presence of KMUP-1. In a 24-hour culture of smooth muscle cells (i.e., PA smooth muscle cells or PASMCs), KMUP-1 (0.1-10 μM) inhibited RhoA- and ET-1-induced RhoA activation. KMUP-1 prevented MCT-induced PAH, PA wall thickening, and RVH by enhancing eNOS and suppressing ET-1/ROCKII expression. In vitro, KMUP-1 inhibited ET-1-induced PA constriction and ET-1-dependent/independent RhoA activation of PASMCs. In summary, KMUP-1 attenuates ET-1-induced/ET-1-mediated PA constriction, and could thus aid in the treatment of PAH

  11. Effect of endothelin-1 and endothelin receptor blockade on the release of microparticles.

    PubMed

    Jung, Christian; Lichtenauer, Michael; Wernly, Bernhard; Franz, Marcus; Goebel, Bjoern; Rafnsson, Arnar; Figulla, Hans-Reiner; Pernow, John

    2016-08-01

    Increased levels of endothelial cell microparticles (EMP) are known to reflect endothelial dysfunction (ED). In diabetes mellitus type 2 (T2DM), the expression of endothelin (ET)-1 is increased. As treatment with an ET-1 antagonist significantly inhibited atherosclerosis in animal models, we sought to investigate whether treatment with ET-1 antagonists affects EMP levels in vitro and in vivo in patients with T2DM. In vitro study: Human umbilical vein endothelial cells (HUVEC) were stimulated with ET-1 alone and ET-1 in combination with a dual ET-A and ET-B endothelin receptor blocker. In vivo study: Patients with T2DM were randomized to treatment with the ET receptor antagonist bosentan or placebo. After 4 weeks, the patients were re-examined and blood samples were obtained. EMP counts in supernatants and plasma samples were determined using flow cytometry. In vitro study: In supernatants of ET-1-stimulated HUVECs, the increased release of EMP was reduced significantly by co-incubation with an ET-1 receptor antagonist (e.g. CD31+/CD42b-EMP decreased from 37·1% ± 2·8 to 31·5% ± 2·8 SEM, P = 0·0078). In vivo study: No changes in EMP levels in blood samples of patients with T2DM were found after 4 weeks of bosentan treatment (n = 36, P = ns). Our in vitro results suggest that ET-1 stimulates the release of EMP from HUVECs via a receptor-dependent mechanism. Co-incubation with an endothelin receptor blocker abolished ET-1-dependent EMP release. However, treatment with bosentan for 4 weeks failed to alter EMP levels in patients with T2DM. Other factors seem to have influenced EMP release in patients with T2DM independent of ET-1 receptor-mediated mechanisms. © 2016 Stichting European Society for Clinical Investigation Journal Foundation.

  12. Endothelin antagonists for diabetic and non-diabetic chronic kidney disease

    PubMed Central

    Kohan, Donald E; Pollock, David M

    2013-01-01

    Numerous pre-clinical studies have implicated endothelin-1 in the pathogenesis of diabetic and non-diabetic chronic kidney disease (CKD). Renal endothelin-1 production is almost universally increased in kidney disease. The pathologic effects of endothelin-1, including vasoconstriction, proteinuria, inflammation, cellular injury and fibrosis, are likely mediated by the endothelin A (ETA) receptor. ETA antagonism alone, and/or combined ETA/B blockade, reduces CKD progression. Based on the strong pre-clinical data, several clinical trials using ETA antagonists were conducted. Small trials involving acute intravenous endothelin receptor blockade suggest that ETA, but not ETB, blockade exerts protective renal and vascular effects in CKD patients. A large phase 3 trial (ASCEND) examined the effects of avosentan, an endothelin receptor antagonist, on renal disease progression in diabetic nephropathy. Proteinuria was reduced after 3–6 months of treatment. However the study was terminated due to increased morbidity and mortality associated with avosentan-induced fluid retention. Several phase 2 trials using avosentan at lower doses than in ASCEND, atrasentan or sitaxsentan (the latter two being highly ETA-selective) showed reductions in proteinuria on top of renin-angiotensin system blockade. Infrequent and clinically insignificant fluid retention was observed at the most effective doses. Additional trials using ETA blockers are ongoing or being planned in patients with diabetic nephropathy or focal segmental glomerulosclerosis. Moving forward, such studies must be conducted with careful patient selection and attention to dosing in order to minimize adverse side effects. Nonetheless, there is cause for optimism that this class of agents will ultimately prove to be effective for the treatment of CKD. PMID:23228194

  13. Histamine H1 and endothelin ETB receptors mediate phospholipase D stimulation in rat brain hippocampal slices.

    PubMed

    Sarri, E; Picatoste, F; Claro, E

    1995-08-01

    Different neurotransmitter receptor agonists [carbachol, serotonin, noradrenaline, histamine, endothelin-1, and trans-(1S,3R)-aminocyclopentyl-1,3-dicarboxylic acid (trans-ACPD)], known as stimuli of phospholipase C in brain tissue, were tested for phospholipase D stimulation in [32P]Pi-prelabeled rat brain cortical and hippocampal slices. The accumulation of [32P]phosphatidylethanol was measured as an index of phospholipase D-catalyzed transphosphatidylation in the presence of ethanol. Among the six neurotransmitter receptor agonists tested, only noradrenaline, histamine, endothelin-1, and trans-ACPD stimulated phospholipase D in hippocampus and cortex, an effect that was strictly dependent of the presence of millimolar extracellular calcium concentrations. The effect of histamine (EC50 18 microM) was inhibited by the H1 receptor antagonist mepyramine with a Ki constant of 0.7 nM and was resistant to H2 and H3 receptor antagonists (ranitidine and tioperamide, respectively). Endothelin-1-stimulated phospholipase D (EC50 44 nM) was not blocked by BQ-123, a specific antagonist of the ETA receptor. Endothelin-3 and the specific ETB receptor agonist safarotoxin 6c were also able to stimulate phospholipase D with efficacies similar to that of endothelin-1, and EC50 values of 16 and 3 nM, respectively. These results show that histamine and endothelin-1 stimulate phospholipase D in rat brain through H1 and ETB receptors, respectively.

  14. Chemical Synthesis of Tetracyclic Terpenes and Evaluation of Antagonistic Activity on Endothelin-A Receptors and Voltage-gated Calcium Channels

    PubMed Central

    Lu, Jianyu; Aguilar, Angelo; Zou, Bende; Bao, Weier; Koldas, Serkan; Aibin, Shi; Desper, John; Wangemann, Philine; Xie, Xinmin Simon; Hua, Duy H.

    2015-01-01

    A class of tetracyclic terpenes was synthesized and evaluated for antagonistic activity of endothelin-1 (ET-1) induced vasoconstriction and inhibitory activity of voltage-activated Ca2+ channels. Three repeated Robinson annulation reactions were utilized to construct the tetracyclic molecules. A stereoselective reductive Robinson annulation was discovered for the formation of optically pure tricyclic terpenes. Stereoselective addition of cyanide to the hindered α-face of tetracyclic enone (-)-18 was found and subsequent transformation into the aldehyde function was affected by the formation of bicyclic hemiiminal (-)-4. Six selected synthetic tetracyclic terpenes show inhibitory activities in ET-1 induced vasoconstriction in the gerbil spiral modiolar artery with putative affinity constants ranging between 93 and 319 nM. Moreover, one compound, (-)-3, was evaluated further and found to inhibit voltage-activated Ca2+ currents but not to affect Na+ or K+ currents in dorsal root ganglion cells under similar concentrations. These observations imply a dual mechanism of action. In conclusion, tetracyclic terpenes represent a new class of hit molecules for the discovery of new drugs for the treatment of pulmonary hypertension and vascular related diseases. PMID:26190460

  15. Chemical synthesis of tetracyclic terpenes and evaluation of antagonistic activity on endothelin-A receptors and voltage-gated calcium channels.

    PubMed

    Lu, Jianyu; Aguilar, Angelo; Zou, Bende; Bao, Weier; Koldas, Serkan; Shi, Aibin; Desper, John; Wangemann, Philine; Xie, Xinmin Simon; Hua, Duy H

    2015-09-01

    A class of tetracyclic terpenes was synthesized and evaluated for antagonistic activity of endothelin-1 (ET-1) induced vasoconstriction and inhibitory activity of voltage-activated Ca(2+) channels. Three repeated Robinson annulation reactions were utilized to construct the tetracyclic molecules. A stereoselective reductive Robinson annulation was discovered for the formation of optically pure tricyclic terpenes. Stereoselective addition of cyanide to the hindered α-face of tetracyclic enone (-)-18 was found and subsequent transformation into the aldehyde function was affected by the formation of bicyclic hemiiminal (-)-4. Six selected synthetic tetracyclic terpenes show inhibitory activities in ET-1 induced vasoconstriction in the gerbil spiral modiolar artery with putative affinity constants ranging between 93 and 319 nM. Moreover, one compound, (-)-3, was evaluated further and found to inhibit voltage-activated Ca(2+) currents but not to affect Na(+) or K(+) currents in dorsal root ganglion cells under similar concentrations. These observations imply a dual mechanism of action. In conclusion, tetracyclic terpenes represent a new class of hit molecules for the discovery of new drugs for the treatment of pulmonary hypertension and vascular related diseases.

  16. A novel antihypertension agent, sargachromenol D from marine brown algae, Sargassum siliquastrum, exerts dual action as an L-type Ca(2+) channel blocker and endothelin A/B2 receptor antagonist.

    PubMed

    Park, Byong-Gon; Shin, Woon-Seob; Oh, Sangtae; Park, Gab-Man; Kim, Nam Ik; Lee, Seokjoon

    2017-09-01

    We isolated the novel vasoactive marine natural products, (5E,10E)-14-hydroxy-2,6,10-trimethylpentadeca-5,10-dien-4-one (4) and sargachromenol D (5), from Sargassum siliquastrum collected from the coast of the East Sea in South Korea by using activity-guided HPLC purification. The compounds effectively dilated depolarization (50mMK(+))-induced basilar artery contraction with EC50 values of 3.52±0.42 and 1.62±0.63μM, respectively, but only sargachromenol D (5) showed a vasodilatory effect on endothelin-1 (ET-1)-induced basilar artery contraction (EC50=9.8±0.6μM). These results indicated that sargachromenol D (5) could act as a dual antagonist of l-type Ca(2+) channel and endothelin A/B2 receptors. Moreover, sargachromenol D (5) lowered blood pressure in spontaneous hypertensive rats (SHRs) 2h after oral treatment at a dose of 80mg/kg dose and the effect was maintained for 24h. Based on our ex vivo and in vivo experiments, we propose that sargachromenol D (5) is a strong candidate for the treatment of hypertension that is not controlled by conventional drugs, in particular, severe-, type II diabetes-, salt-sensitive, and metabolic disease-induced hypertension. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Chronic administration of an endothelin-A receptor antagonist improves exercise capacity in rats with myocardial infarction-induced congestive heart failure.

    PubMed

    Miyauchi, Takashi; Fujimori, Akira; Maeda, Seiji; Iemitsu, Motoyuki; Sakai, Satoshi; Shikama, Hisataka; Tanabe, Takumi; Matsuda, Mitsuo; Goto, Katsutoshi; Yamaguchi, Iwao

    2004-11-01

    The effects of long-term administration of YM598, a selective endothelin-A antagonist, on improving the exercise tolerance of chronic heart failure model rats were examined using a treadmill exercise loading test. Rats were acclimatized to the treadmill apparatus and the coronary artery was ligated to prepare a myocardial infarction-induced congestive heart failure (CHF) model. Starting 10 days postoperatively, when the acute phase of infarction was over, YM598 was administered orally once daily for approximately 25 weeks at a dose of 1 mg/kg. At weeks 20 and 24 the treadmill test was performed. YM598 prolonged running time, which had been shortened as a result of heart failure. The weights, relative to the body weight, of the left and right ventricles and lungs of surviving rats with CHF were significantly greater than those of sham-operated rats, suggesting hypertrophy of the ventricles and congestion of the lungs. Administration of YM598 markedly reduced ventricular hypertrophy and pulmonary congestion. Examination of cardiac function revealed that, in surviving CHF rats, the peak positive first derivative of left ventricular pressure was significantly lower, and left ventricular end-diastolic pressure, right ventricular systolic pressure and central venous pressure were significantly higher in comparison to sham-operated rats. These data demonstrate that, in rats with CHF, the contractile and diastolic capacity of the left ventricle decreased and pulmonary hypertension and systemic congestion occurred. Long-term administration of YM598 improved left ventricular function of CHF rats to the level of sham-operated rats, and reduced the workload placed on the right side of the heart. Histological examination revealed that long-term treatment with YM598 prevented fibrosis of the surviving left ventricular myocardium. In conclusion, long-term administration of YM598 to rats with CHF improved exercise tolerance and inhibited remodeling of cardiac muscles, leading to

  18. Therapeutic potential of endothelin receptor antagonism in kidney disease.

    PubMed

    Czopek, Alicja; Moorhouse, Rebecca; Webb, David J; Dhaun, Neeraj

    2016-03-01

    Our growing understanding of the role of the endothelin (ET) system in renal physiology and pathophysiology is from emerging studies of renal disease in animal models and humans. ET receptor antagonists reduce blood pressure and proteinuria in chronic kidney disease and cause regression of renal injury in animals. However, the therapeutic potential of ET receptor antagonism has not been fully explored and clinical studies have been largely limited to patients with diabetic nephropathy. There remains a need for more work in nondiabetic chronic kidney disease, end-stage renal disease (patients requiring maintenance dialysis and those with a functioning kidney transplant), ischemia reperfusion injury, and sickle cell disease. The current review summarizes the most recent advances in both preclinical and clinical studies of ET receptor antagonists in the field of kidney disease. Copyright © 2016 the American Physiological Society.

  19. EndothelinA-endothelinB receptor cross-talk in rat basilar artery in situ.

    PubMed

    Yoon, SeongHun; Zuccarello, Mario; Rapoport, Robert M

    2012-04-01

    The rationale for the therapeutic use of dual as opposed to selective endothelin (ET) receptor antagonists stems in part from cross-talk between the ET(A) and ET(B) receptors. However, whether ET(A)-ET(B) receptor cross-talk is present in the cerebral vasculature is difficult to discern since findings of cross-talk contrast even among the few reports available. Thus, this study tested whether ET(A)-ET(B) receptor cross-talk is present in the rat basilar artery. In an in situ cranial window, 0.1 μM sarafotoxin S6c, an ET(B) receptor agonist, relaxed basilar artery basal tone by 54%. ET-1 (3 nM) in the absence and presence of 10 μM BQ123, an ET(A) receptor agonist, induced 13% contraction and 15% relaxation, respectively. In contrast, the 3-nM ET-1 plateau contraction was relaxed by only ∼50% by 3-10 μM BQ123 and 10 μM BQ610, ET(A) receptor antagonists. N(ω)-nitro-L: -arginine, an NO synthase inhibitor, did not enhance contraction to 3 nM ET-1, suggesting that the partial relaxation of the ET-1 plateau contraction did not involve unmasked endothelial ET(B) receptor-mediated relaxation. The ∼50% ET-1 contraction that remained following ET(A) receptor antagonist was relaxed by 3-10 μM BQ788, consistent with an ET(B) receptor-mediated component of contraction. However, 10 μM BQ788 in the absence of prior ET(A) receptor antagonist did not cause relaxation. Subsequent BQ123 addition in the presence of BQ788 completely relaxed the ET-1 contraction. PD145065 (1 μM), an ET(A/B) receptor antagonist, completely relaxed 3-nM ET-1 contracted vessels in both the absence and presence of BQ123. These findings suggest that the inability of ET(A) receptor antagonist to completely relax the ET-1 plateau contraction in rat basilar artery is due to ET(A)-ET(B) receptor cross-talk.

  20. Essential role for endothelin ETB receptors in fever induced by LPS (E. coli) in rats

    PubMed Central

    Fabricio, Aline S C; Silva, Carlos A A; Rae, Giles A; D'Orléans-Juste, Pedro; Souza, Glória E P

    1998-01-01

    The influence of endothelin receptor antagonists on febrile responses to E. coli lipopolysaccharide (LPS), interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and endothelin-1 (ET-1) was assessed in conscious rats.Intravenous (i.v.) LPS (5.0 μg kg−1) markedly increased rectal temperature to a peak of 1.30°C over baseline at 2.5 h. Pretreatment with the mixed endothelin ETA/ETB receptor antagonist bosentan (10 mg kg−1, i.v.) or the selective endothelin ETB receptor antagonist BQ-788 (N-cis-2,6-dimethyl-piperidinocarbonyl-L-γ-methylleucyl-D-1-methoxycarboyl-D-norleucine; 3 pmol, into a lateral cerebral ventricle–i.c.v.) reduced the peak response to LPS to 0.90 and 0.75°C, respectively. The selective endothelin ETA receptor antagonist BQ-123 (cyclo[D-Trp-D-Asp-Pro-D-Val-Leu]; 3 pmol, i.c.v.) was ineffective.Increases in temperature caused by IL-1β (180 fmol, i.c.v.), TNF-α (14.4 pmol, i.c.v.) or IL-1β (150 pmol kg−1, i.v.) were unaffected by BQ-788 (3 pmol, i.c.v.).Central injection of endothelin-1 (0.1 to 3 fmol, i.c.v.) caused slowly-developing and long-lasting increases in rectal temperature (starting 2 h after administration and peaking at 4–6 h between 0.90 and 1.15°C) which were not clearly dose-dependent. The response to endothelin-1 (1 fmol, i.c.v.) was prevented by BQ-788, but not by BQ-123 (each at 3 pmol, i.c.v.). Intraperitoneal pretreatment with the cyclo-oxygenase inhibitor indomethacin (2 mg kg−1), which partially reduced LPS-induced fever, did not modify the hyperthermic response to endothelin-1 (3 fmol, i.c.v.).Therefore, central endothelin(s) participates importantly in the development of LPS-induced fever, via activation of a prostanoid-independent endothelin ETB receptor-mediated mechanism possibly not situated downstream from IL-1β or TNF-α in the fever cascade. PMID:9806338

  1. Endothelin receptors mediating functional responses in human small arteries and veins.

    PubMed Central

    Riezebos, J.; Watts, I. S.; Vallance, P. J.

    1994-01-01

    1. In the present study, responses of human omental small arteries and veins to endothelin-1 and endothelin-3 were characterized by use of the ETB receptor selective agonist, sarafotoxin S6c, the ETA receptor antagonist, BQ123, the ETB receptor antagonist, IRL1038, the NO-synthase inhibitor NG-monomethyl-L-arginine (L-NMMA, 300 microM) and indomethacin (10 microM). 2. Small arteries (internal diameter 413 +/- 22 microns) and parallel running veins (646 +/- 35 microns) were mounted in a myograph under a normalized tension equivalent to 90% of a transmural pressure of 100 mmHg and 19 mmHg in vivo, respectively. 3. In small arteries and veins, endothelin-1 caused a concentration-dependent increase in wall tension (Emax = 3.90 +/- 0.56 mN mm-1 and 1.90 m +/- 0.32 mN mm-1 respectively, P < 0.05) and was equipotent (arteries: pD2 = 8.91 +/- 0.11; veins: pD2 = 8.63 +/- 0.08, NS). In endothelium intact arteries, L-NMMA significantly enhanced the sensitivity to endothelin-1 (pD2 control: 8.92 +/- 0.16; pD2 L-NMMA: 9.37 +/- 0.11; P < 0.05). L-NMMA did not affect the sensitivity of veins to endothelin-1. Indomethacin was without effect in arteries and veins. In veins, endothelin-3 was about a hundred times less potent than endothelin-1 and showed a biphasic response curve. Small arteries did not contract to endothelin-3. Neither small arteries nor veins contracted to sarafotoxin S6c. Furthermore, no relaxation to endothelin-1 or sarafotoxin S6c was seen in any precontracted vessels.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8004404

  2. Muscarinic Receptor Antagonists.

    PubMed

    Matera, Maria Gabriella; Cazzola, Mario

    2017-01-01

    Parasympathetic activity is increased in patients with chronic obstructive pulmonary disease (COPD) and asthma and appears to be the major reversible component of airway obstruction. Therefore, treatment with muscarinic receptor antagonists is an effective bronchodilator therapy in COPD and also in asthmatic patients. In recent years, the accumulating evidence that the cholinergic system controls not only contraction by airway smooth muscle but also the functions of inflammatory cells and airway epithelial cells has suggested that muscarinic receptor antagonists could exert other effects that may be of clinical relevance when we must treat a patient suffering from COPD or asthma. There are currently six muscarinic receptor antagonists licenced for use in the treatment of COPD, the short-acting muscarinic receptor antagonists (SAMAs) ipratropium bromide and oxitropium bromide and the long-acting muscarinic receptor antagonists (LAMAs) aclidinium bromide, tiotropium bromide, glycopyrronium bromide and umeclidinium bromide. Concerns have been raised about possible associations of muscarinic receptor antagonists with cardiovascular safety, but the most advanced compounds seem to have an improved safety profile. Further beneficial effects of SAMAs and LAMAs are seen when added to existing treatments, including LABAs, inhaled corticosteroids and phosphodiesterase 4 inhibitors. The importance of tiotropium bromide in the maintenance treatment of COPD, and likely in asthma, has spurred further research to identify new LAMAs. There are a number of molecules that are being identified, but only few have reached the clinical development.

  3. Involvement of central endothelin receptors in neonatal morphine withdrawal.

    PubMed

    Puppala, Bhagya L; Bhalla, Shaifali; Matwyshyn, George; Gulati, Anil

    2006-06-01

    The involvement of central endothelin (ET) receptors in neonatal morphine tolerance has been demonstrated. The present study investigates the role of central ET receptors in morphine withdrawal in neonatal rats. The aim was to determine whether activation of G-proteins coupled to opioid and ET receptors by morphine and various ET receptor modulators is affected during morphine withdrawal in neonatal rats. Pregnant female rats were rendered tolerant to morphine by chronic exposure to morphine pellets during 7 days. On Day 8, pellets were removed and rats were allowed to undergo withdrawal for 24 hrs. Rat pups were delivered by cesarean section. G-protein stimulation induced by morphine; ET-1; the ET(A) receptor antagonist, BMS182874; and the ET(B) receptor agonist, IRL1620, were determined in the brain of neonatal rats undergoing morphine withdrawal by [35S]GTPgammaS binding assay. Morphine produced higher (P < 0.05) maximal stimulation of G-protein in the morphine-withdrawal group (83.60%) compared with the placebo group (66.81%). ET-1-induced G-protein stimulation was also altered, and the median effective concentration (EC50) during morphine withdrawal (170.60 nM) was significantly higher than placebo (62.5 nM; P< 0.05). The maximal stimulation induced by the ET(A) receptor antagonist, BMS182874, in the morphine-withdrawal group (86.07%; EC50 = 31.25 nM) was significantly higher than in the placebo group (EC50 > 1000 nM). The ET(B) agonist, IRL1620, induced G-protein stimulation was similar in placebo (73.43%, EC50 = 13.26 nM) and morphine-withdrawal groups (75.08%, EC(50) = 11.70 nM), respectively. To our knowledge, this is the first report indicating involvement of central ET(A) receptors in neonatal morphine withdrawal.

  4. Identification of the endothelin-1 receptor in the chick heart

    SciTech Connect

    Miyazaki, H.; Kondoh, M.; Watanabe, H.; Hayashi, T.; Murakami, K.; Takahashi, M.; Yanagisawa, M.; Kimura, S.; Goto, K.; Masaki, T.

    1989-01-01

    This study suggests that binding sites for endothelin-1 (ET-1) are distinct from those for dihydropyridine (DHP)-sensitive, voltage-dependent Ca2+ channels and that ET-1 has its own specific receptors in chick cardiac membranes.

  5. Endothelin A receptor activation on mesangial cells initiates Alport glomerular disease.

    PubMed

    Dufek, Brianna; Meehan, Daniel T; Delimont, Duane; Cheung, Linda; Gratton, Michael Anne; Phillips, Grady; Song, Wenping; Liu, Shiguang; Cosgrove, Dominic

    2016-08-01

    Recent work demonstrates that Alport glomerular disease is mediated through a biomechanical strain-sensitive activation of mesangial actin dynamics. This occurs through a Rac1/CDC42 cross-talk mechanism that results in the invasion of the subcapillary spaces by mesangial filopodia. The filopodia deposit mesangial matrix proteins in the glomerular basement membrane, including laminin 211, which activates focal adhesion kinase in podocytes culminating in the up-regulation of proinflammatory cytokines and metalloproteinases. These events drive the progression of glomerulonephritis. Here we test whether endothelial cell-derived endothelin-1 is up-regulated in Alport glomeruli and further elevated by hypertension. Treatment of cultured mesangial cells with endothelin-1 activates the formation of drebrin-positive actin microspikes. These microspikes do not form when cells are treated with the endothelin A receptor antagonist sitaxentan or under conditions of small, interfering RNA knockdown of endothelin A receptor mRNA. Treatment of Alport mice with sitaxentan results in delayed onset of proteinuria, normalized glomerular basement membrane morphology, inhibition of mesangial filopodial invasion of the glomerular capillaries, normalization of glomerular expression of metalloproteinases and proinflammatory cytokines, increased life span, and prevention of glomerulosclerosis and interstitial fibrosis. Thus endothelin A receptor activation on mesangial cells is a key event in initiation of Alport glomerular disease in this model.

  6. Endothelin Receptors, Mitochondria and Neurogenesis in Cerebral Ischemia

    PubMed Central

    Gulati, Anil

    2016-01-01

    Background: Neurogenesis is most active during pre-natal development, however, it persists throughout the human lifespan. The putative role of mitochondria in neurogenesis and angiogenesis is gaining importance. Since, ETB receptor mediated neurogenesis and angiogenesis has been identified, the role of these receptors with relevance to mitochondrial functions is of interest. Methods: In addition to work from our laboratory, we undertook an extensive search of bibliographic databases for peer-reviewed research literature. Specific technical terms such as endothelin, mitochondria and neurogenesis were used to seek out and critically evaluate literature that was relevant. Results: The ET family consists of three isopeptides (ET-1, ET-2 and ET-3) that produce biological actions by acting on two types of receptors (ETA and ETB). In the central nervous system (CNS) ETA receptors are potent constrictors of the cerebral vasculature and appear to contribute in the causation of cerebral ischemia. ETA receptor antagonists have been found to be effective in animal model of cerebral ischemia; however, clinical studies have shown no efficacy. Mitochondrial functions are critically important for several neural development processes such as neurogenesis, axonal and dendritic growth, and synaptic formation. ET appears to impair mitochondrial functions through activation of ETA receptors. On the other hand, blocking ETB receptors has been shown to trigger apoptotic processes by activating intrinsic mitochondrial pathway. Mitochondria are important for their role in molecular regulation of neurogenesis and angiogenesis. Stimulation of ETB receptors in the adult ischemic brain has been found to promote angiogenesis and neurogenesis mediated through vascular endothelial growth factor and nerve growth factor. It will be interesting to investigate the effect of ETB receptor stimulation on mitochondrial functions in the CNS following cerebral ischemia. Conclusion: The findings of this

  7. Selective blockade of the endothelin subtype A receptor decreases early atherosclerosis in hamsters fed cholesterol.

    PubMed Central

    Kowala, M. C.; Rose, P. M.; Stein, P. D.; Goller, N.; Recce, R.; Beyer, S.; Valentine, M.; Barton, D.; Durham, S. K.

    1995-01-01

    Recent studies suggest that endothelin and its receptors may be involved in atherogenesis. To test this hypothesis, cholesterol-fed hamsters were treated with a selective endothelin subtype A (ETA) receptor antagonist BMS-182874. Characterization of hamster atherosclerotic plaques indicated that they contained a fibrous cap of smooth muscle cells, large macrophage-foam cells, and epitopes of oxidized low density lipoprotein. Messenger RNA for both ETA and ETB receptors was detected in aortic endothelial cells, in medial smooth muscle cells, and in macrophage-foam cells and smooth muscle cells of the fibro-fatty plaques. BMS-182874 inhibited the endothelin-1-induced pressor response whereas the depressor effect was unaltered, suggesting that vascular ETA receptors were selectively blocked in vivo. In hyperlipidemic hamsters, BMS-182874 decreased the area of the fatty streak by reducing the number and size of macrophage-foam cells. The results indicated that ETA receptors and thus endothelin promoted the early inflammatory phase of atherosclerosis. Images Figure 1 Figure 2 Figure 3 Figure 5 PMID:7717449

  8. Autocrine endothelin-3/endothelin receptor B signaling maintains cellular and molecular properties of glioblastoma stem cells.

    PubMed

    Liu, Yue; Ye, Fei; Yamada, Kazunari; Tso, Jonathan L; Zhang, Yibei; Nguyen, David H; Dong, Qinghua; Soto, Horacio; Choe, Jinny; Dembo, Anna; Wheeler, Hayley; Eskin, Ascia; Schmid, Ingrid; Yong, William H; Mischel, Paul S; Cloughesy, Timothy F; Kornblum, Harley I; Nelson, Stanley F; Liau, Linda M; Tso, Cho-Lea

    2011-12-01

    Glioblastoma stem cells (GSC) express both radial glial cell and neural crest cell (NCC)-associated genes. We report that endothelin 3 (EDN3), an essential mitogen for NCC development and migration, is highly produced by GSCs. Serum-induced proliferative differentiation rapidly decreased EDN3 production and downregulated the expression of stemness-associated genes, and reciprocally, two glioblastoma markers, EDN1 and YKL-40 transcripts, were induced. Correspondingly, patient glioblastoma tissues express low levels of EDN3 mRNA and high levels of EDN1 and YKL-40 mRNA. Blocking EDN3/EDN receptor B (EDNRB) signaling by an EDNRB antagonist (BQ788), or EDN3 RNA interference (siRNA), leads to cell apoptosis and functional impairment of tumor sphere formation and cell spreading/migration in culture and loss of tumorigenic capacity in animals. Using exogenous EDN3 as the sole mitogen in culture does not support GSC propagation, but it can rescue GSCs from undergoing cell apoptosis. Molecular analysis by gene expression profiling revealed that most genes downregulated by EDN3/EDNRB blockade were those involved in cytoskeleton organization, pause of growth and differentiation, and DNA damage response, implicating the involvement of EDN3/EDNRB signaling in maintaining GSC migration, undifferentiation, and survival. These data suggest that autocrine EDN3/EDNRB signaling is essential for maintaining GSCs. Incorporating END3/EDNRB-targeted therapies into conventional cancer treatments may have clinical implication for the prevention of tumor recurrence.

  9. Angiotensin II enhances endothelin-1-induced vasoconstriction through upregulating endothelin type A receptor.

    PubMed

    Lin, Yan-Jie; Kwok, Ching-Fai; Juan, Chi-Chang; Hsu, Yung-Pei; Shih, Kuang-Chung; Chen, Chin-Chang; Ho, Low-Tone

    2014-08-22

    Endothelin-1 (ET-1) is the most potent vasoconstrictor by binding to endothelin receptors (ETAR) in vascular smooth muscle cells (VSMCs). The complex of angiotensin II (Ang II) and Ang II type one receptor (AT1R) acts as a transient constrictor of VSMCs. The synergistic effect of ET-1 and Ang II on blood pressure has been observed in rats; however, the underlying mechanism remains unclear. We hypothesize that Ang II leads to enhancing ET-1-mediated vasoconstriction through the activation of endothelin receptor in VSMCs. The ET-1-induced vasoconstriction, ET-1 binding, and endothelin receptor expression were explored in the isolated endothelium-denuded aortae and A-10 VSMCs. Ang II pretreatment enhanced ET-1-induced vasoconstriction and ET-1 binding to the aorta. Ang II enhanced ETAR expression, but not ETBR, in aorta and increased ET-1 binding, mainly to ETAR in A-10 VSMCs. Moreover, Ang II-enhanced ETAR expression was blunted and ET-1 binding was reduced by AT1R antagonism or by inhibitors of PKC or ERK individually. In conclusion, Ang II enhances ET-1-induced vasoconstriction by upregulating ETAR expression and ET-1/ETAR binding, which may be because of the AngII/Ang II receptor pathways and the activation of PKC or ERK. These findings suggest the synergistic effect of Ang II and ET-1 on the pathogenic development of hypertension. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Impaired endothelin calcium signaling coupled to endothelin type B receptors in penile arteries from insulin-resistant obese Zucker rats.

    PubMed

    Contreras, Cristina; Sánchez, Ana; Martínez, Pilar; Climent, Belén; Benedito, Sara; García-Sacristán, Albino; Hernández, Medardo; Prieto, Dolores

    2013-09-01

    Erectile dysfunction is considered as an early sign of subclinical vascular disease and endothelial dysfunction and a highly prevalent condition in diabetic patients. The current study assessed whether impaired vascular effects of endothelin (ET)-1 may contribute to the vascular dysfunction of penile arteries from a rat model of insulin resistance. The effect of ETA and ETB receptor antagonists was assessed on the intracellular Ca(2+) [Ca(2+) ]i and contractile responses to ET-1 in penile arteries from obese Zucker rats (OZR) and lean Zucker rats (LZR), and ET receptor expression in the arterial wall was assessed by immunohistochemistry. Changes in ET-1 [Ca(2+) ]i and vasoconstriction and ET receptor expression were evaluated in penile arteries from insulin-resistant rats. ET-1-induced vasoconstriction was associated with a higher increase in smooth muscle [Ca(2+) ]i in penile arteries from OZR compared with LZR. Removal of the endothelium inhibited and enhanced contractions to the lowest and highest doses of ET-1, respectively, mainly in OZR. The selective ETA receptor antagonist BQ-123 inhibited ET-1 vasoconstriction and [Ca(2+) ]i response in both LZR and OZR. The ETB receptor antagonist BQ-788 had little effect in healthy arteries but markedly inhibited ET-1-induced increases in [Ca(2+) ]i and vasoconstriction in arteries from OZR. ETA receptors were located on the smooth muscle and endothelium of penile arteries, whereas ETB receptors were found on the arterial endothelium in LZR and OZR, and also on the smooth muscle in OZR, immunostaining for both receptors being higher in OZR. Penile arteries from OZR exhibit an impaired ET-1 Ca(2+) signaling along with changes in the ET receptor profile. Thus, whereas ET-1 contraction and the associated [Ca(2+) ]i increase are mediated by smooth muscle ETA receptors in healthy arteries, ETB receptors contribute to contraction and are coupled to the augmented ET-1 [Ca(2+) ]i response under conditions of insulin resistance

  11. Endothelin@25 – new agonists, antagonists, inhibitors and emerging research frontiers: IUPHAR Review 12

    PubMed Central

    Maguire, J J; Davenport, A P

    2014-01-01

    Since the discovery of endothelin (ET)-1 in 1988, the main components of the signalling pathway have become established, comprising three structurally similar endogenous 21-amino acid peptides, ET-1, ET-2 and ET-3, that activate two GPCRs, ETA and ETB. Our aim in this review is to highlight the recent progress in ET research. The ET-like domain peptide, corresponding to prepro-ET-193–166, has been proposed to be co-synthesized and released with ET-1, to modulate the actions of the peptide. ET-1 remains the most potent vasoconstrictor in the human cardiovascular system with a particularly long-lasting action. To date, the major therapeutic strategy to block the unwanted actions of ET in disease, principally in pulmonary arterial hypertension, has been to use antagonists that are selective for the ETA receptor (ambrisentan) or that block both receptor subtypes (bosentan). Macitentan represents the next generation of antagonists, being more potent than bosentan, with longer receptor occupancy and it is converted to an active metabolite; properties contributing to greater pharmacodynamic and pharmacokinetic efficacy. A second strategy is now being more widely tested in clinical trials and uses combined inhibitors of ET-converting enzyme and neutral endopeptidase such as SLV306 (daglutril). A third strategy based on activating the ETB receptor, has led to the renaissance of the modified peptide agonist IRL1620 as a clinical candidate in delivering anti-tumour drugs and as a pharmacological tool to investigate experimental pathophysiological conditions. Finally, we discuss biased signalling, epigenetic regulation and targeting with monoclonal antibodies as prospective new areas for ET research. PMID:25131455

  12. Endothelin@25 - new agonists, antagonists, inhibitors and emerging research frontiers: IUPHAR Review 12.

    PubMed

    Maguire, J J; Davenport, A P

    2014-12-01

    Since the discovery of endothelin (ET)-1 in 1988, the main components of the signalling pathway have become established, comprising three structurally similar endogenous 21-amino acid peptides, ET-1, ET-2 and ET-3, that activate two GPCRs, ETA and ETB . Our aim in this review is to highlight the recent progress in ET research. The ET-like domain peptide, corresponding to prepro-ET-193-166 , has been proposed to be co-synthesized and released with ET-1, to modulate the actions of the peptide. ET-1 remains the most potent vasoconstrictor in the human cardiovascular system with a particularly long-lasting action. To date, the major therapeutic strategy to block the unwanted actions of ET in disease, principally in pulmonary arterial hypertension, has been to use antagonists that are selective for the ETA receptor (ambrisentan) or that block both receptor subtypes (bosentan). Macitentan represents the next generation of antagonists, being more potent than bosentan, with longer receptor occupancy and it is converted to an active metabolite; properties contributing to greater pharmacodynamic and pharmacokinetic efficacy. A second strategy is now being more widely tested in clinical trials and uses combined inhibitors of ET-converting enzyme and neutral endopeptidase such as SLV306 (daglutril). A third strategy based on activating the ETB receptor, has led to the renaissance of the modified peptide agonist IRL1620 as a clinical candidate in delivering anti-tumour drugs and as a pharmacological tool to investigate experimental pathophysiological conditions. Finally, we discuss biased signalling, epigenetic regulation and targeting with monoclonal antibodies as prospective new areas for ET research.

  13. Endothelin-1 and endothelin receptor mRNA expression in normal and atherosclerotic human arteries.

    PubMed

    Winkles, J A; Alberts, G F; Brogi, E; Libby, P

    1993-03-31

    Endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in a number of human diseases including atherosclerosis. ET-1 binds to two distinct G protein-coupled receptors, known as the ETA and ETB receptor subtypes. In this study, we have examined ET-1, ETA and ETB mRNA expression levels in human vascular cells cultured in vitro and in normal and atherosclerotic human arteries. The results indicate that (a) ET-1 mRNA is constitutively expressed by endothelial cells but not by smooth muscle cells, (b) endothelial cells express only ETB mRNA but smooth muscle cells co-express ETA and ETB mRNA, and (c) in comparison to normal aorta, ET-1 mRNA expression is elevated and endothelin receptor mRNA expression is repressed in atherosclerotic lesions.

  14. Endothelin A-receptor blockade worsens endotoxin-induced hepatic microcirculatory changes and necrosis.

    PubMed

    Nishida, T; Huang, T P; Seiyama, A; Hamada, E; Kamiike, W; Ueshima, S; Kazuo, H; Matsuda, H

    1998-08-01

    Endothelin 1 is considered to be an important regulator of sinusoidal blood flow and increases during endotoxemia. The purpose of this study was to investigate the role of endothelin 1 in hepatic microcirculation, oxygen transport, and liver injury during endotoxemia. Male Sprague-Dawley rats were continuously infused with 2.5 mL/h of saline, 0.8 mg . kg-1 . h-1 of lipopolysaccharide (LPS), 3 mg . kg-1 . h-1 of BQ-485, an endothelin A-receptor antagonist, or LPS plus BQ-485 for 7 hours. BQ-485 infusion had no significant effect on hepatic microcirculation and liver injury. LPS increased the plasma levels of aspartate aminotransferase (AST) and total bilirubin and decreased the hepatic adenosine triphosphate (ATP) level and bile flow rate. LPS + BQ-485 infusion further increased the plasma levels of AST and total bilirubin and decreased the bile flow rate and the hepatic ATP level. Dual-spot microspectroscopy revealed mild decreases in sinusoidal erythrocyte velocity and oxygen transport in the LPS group and profound decreases in these parameters in the LPS + BQ-485 group. Histological examinations revealed massive necrotic changes in the pericentral regions of the LPS + BQ-485 group. These results suggest that blockade of endothelin A receptors disturbs hepatic microcirculation and oxygen transport and aggravates the necrotic injury induced by endotoxin.

  15. Practical synthesis of potential endothelin receptor antagonists of 1,4-benzodiazepine-2,5-dione derivatives bearing substituents at the C3-, N1- and N4-positions.

    PubMed

    Cheng, Ming-Fu; Yu, Hui-Ming; Ko, Bor-Wen; Chang, Yu; Chen, Ming-Yi; Ho, Tong-Ing; Tsai, Yeun-Min; Fang, Jim-Min

    2006-02-07

    The expedient synthesis of various 1,4-benzodiazepine-2,5-dione compounds, particularly those having substituents at the C3-, N1- and N4-positions is achieved. The important features in these synthetic strategies include: (i) using the coupling reaction of isatoic anhydride with alpha-amino ester for direct construction of the core structure of 1,4-benzodiazepine-2,5-dione; (ii) using potassium carbonate as the base of choice for selective alkylation at the N1-site, while using lithiated 2-ethylacetanilide as the required base to furnish the N4-alkylation; and (iii) using 2-nitrobenzoyl chloride as a synthetic equivalent of anthranilic acid to facilitate the polyethylene resin-bound liquid-phase combinatorial synthesis. The prepared 1,4-benzodiazepine-2,5-dione compounds are evaluated for endothelin receptor antagonism by a functional assay that measures the inhibitory activity against the change of intramolecular calcium ion concentration induced by endothelin-1. The preliminary results indicate that 1,4-benzodiazepine-2,5-diones bearing two flanked aryl substituents at the N1- and N4-sites show better inhibitory activity than the corresponding unalkylated and N-monoalkylated compounds. A promising candidate, 1-benzyl-7-chloro-3-isopropyl-4-(3-methoxybenzyl)-1,4-benzodiazepine-2,5-dione (17b), exhibits an IC50 value in low nM range.

  16. Tramadol antinociception is potentiated by clonidine through α₂-adrenergic and I₂-imidazoline but not by endothelin ET(A) receptors in mice.

    PubMed

    Andurkar, Shridhar V; Gendler, Liya; Gulati, Anil

    2012-05-15

    Tramadol is a centrally acting analgesic that acts via μ-opioid agonism and by blocking the neuronal uptake of norepinephrine and serotonin. Clonidine potentiates the antinociceptive effects of tramadol; however the receptors involved in this potentiation have not been studied. Endothelin ET(A) receptor antagonists potentiate antinociceptive effects of morphine and oxycodone; however the effects of endothelin ET(A) receptor antagonists on tramadol antinociception have not been evaluated. This study was conducted to determine the effect of clonidine on tramadol antinociception; the role of opioid, α₂-adrenergic and I₂-imidazoline receptors in clonidine potentiation of tramadol antinociception; and the effect of endothelin ET(A) receptor antagonists in modulating tramadol antinociception. Antinociceptive (tail-flick and hot-plate) latencies were measured in male Swiss Webster mice treated with tramadol; clonidine plus tramadol; or antagonists plus tramadol. Mice were pretreated with naloxone (opioid antagonist), yohimbine (α₂-adrenoceptor antagonist), idazoxan (α₂-adrenoceptor/I₂-imidazoline antagonist), BMS182874 or BQ123 (endothelin ET(A) receptor antagonists) to study the involvement of these receptors. Tramadol produced a dose dependent increase in antinociceptive latencies. Tramadol antinociception was partially blocked by naloxone but not by yohimbine or idazoxan. Clonidine potentiated tramadol antinociception; potentiation was blocked by naloxone, yohimbine and idazoxan. Idazoxan produced a more pronounced blockade of potentiation than yohimbine. BMS182874 or BQ123 had no effect on tramadol antinociception, indicating that endothelin ET(A) receptors are not involved in tramadol antinociception in mice. Results demonstrate the involvement of opioid but not α₂-adrenergic/I₂-imidazoline receptors in tramadol antinociception and that opioid, α₂-adrenergic and I₂-imidazoline receptors are involved in clonidine potentiation of tramadol

  17. Endothelin-1 decreases [Ca2+]i via Na+/Ca2+ exchanger in CHO cells stably expressing endothelin ETA receptor.

    PubMed

    Horinouchi, Takahiro; Nishimoto, Arata; Nishiya, Tadashi; Lu, Lingyun; Kajita, Emi; Miwa, Soichi

    2007-07-02

    Endothelin ET(A) receptor couples to Gq/11 protein that transduces a variety of receptor signals to modulate diverse cellular responses including Ca2+ mobilization. Stimulation of endothelin ETA receptor with endothelin-1 is generally believed to induce an increase in intracellular Ca2+ concentration ([Ca2+]i) via Gq/11 protein. Here we provide the first convincing evidence that endothelin-1 elicited Gq/11 protein-dependent and -independent 'decrease' in [Ca2+]i via Na+/Ca2+ exchanger (NCX) in Chinese hamster ovary (CHO) cells stably expressing human endothelin ETA receptor. In the cells treated with 1 microM thapsigargin, an inhibitor of endoplasmic Ca2+ pump, that induces an increase in [Ca2+]i via capacitative Ca2+ entry, endothelin-1 induced a decrease in [Ca2+]i which was partially inhibited by YM-254890, a specific inhibitor of Gq/11, indicating that Gq/11-dependent and independent pathways are involved in the decrease. The endothelin-1-induced decrease in [Ca2+]i was markedly suppressed by 3',4'-dichlorobenzamil hydrochloride, a potent NCX inhibitor, and also by a replacement of extracellular Na+ with Li+, which was not transported by NCX, indicating a major role of NCX operating in the forward mode in the endothelin-1-induced decrease in [Ca2+]i. Molecular approach with RT-PCR demonstrated the expression of mRNA for NCX1, NCX2 and NCX3. These results suggest that stimulation of endothelin ETA receptor with endothelin-1 activates the forward mode NCX through Gq/11-dependent and -independent mechanisms: the NCX exports Ca2+ out of the cell depending on Na+ gradient across the cell membrane, resulting in the decrease in [Ca2+]i.

  18. Endothelin-1 and endothelin receptors in the basilar artery of the capybara.

    PubMed

    Loesch, Andrzej; Gajkowska, Barbara; Dashwood, Michael R; Fioretto, Emerson T; Gagliardo, Karina M; Lima, Ana R De; Ribeiro, Antonio A C M

    2005-02-01

    Little is known about cerebral vasculature of capybara, which seems may serve as a natural model of studying changes in cerebral circulation due to internal carotid artery atrophy at animal sexual maturation. This is the first study of the light- and electron-immunocytochemical localisation of endothelin-1 (ET-1) and ETA and ETB endothelin receptors in the basilar artery of capybaras (6 to 12-month-old females and males) using an ExtrAvidin detection method. All animals examined showed similar patterns of immunoreactivity. Immunoreactivity for ET-1 was detected in the endothelium and adventitial fibroblasts, whilst immunoreactivity for ETA and ETB receptors was present in the endothelium, vascular smooth muscle, perivascular nerves and fibroblasts. In endothelial cells immunoreactivity to ET-1 was pronounced in the cytoplasm or on the granular endoplasmic reticulum. Similar patterns of immunolabelling were observed for ETA and ETB receptors, though cytoplasmic location of clusters of immunoprecipitate seems dominant. These results suggest that the endothelin system is present throughout the wall of the basilar artery of capybara.

  19. Endothelin B Receptor, a New Target in Cancer Immune Therapy

    PubMed Central

    Kandalaft, Lana E.; Facciabene, Andrea; Buckanovich, Ron J.; Coukos, George

    2010-01-01

    The endothelins and their G protein-coupled receptors A and B have been implicated innumerous diseases and have recently emerged as pivotal players in a variety of malignancies. Tumors over-express the endothelin 1 (ET-1) ligand and the endothelin-A-receptor (ETAR). Their interaction induces tumor growth and metastasis by promoting tumor cell survival and proliferation, angiogenesis, and tissue remodeling. On the basis of results from xenograft models, drug development efforts have focused on antagonizing the autocrine-paracrine effects mediated by ET-1/ETAR. In this review, we discuss a novel role of the endothelin-B-receptor (ETBR) in tumorigenesis and the effect of its blockade during cancer immune therapy. We highlight key characteristics of the B receptor such as its specific overexpression in the tumor compartment; and specifically, in the tumor endothelium, where its activation by ET-1 suppresses T-cell adhesion and homing to tumors. We also review our recent findings on the effects of ETBR-specific blockade in increasing T-cell homing to tumors and enhancing the efficacy of otherwise ineffective immunotherapy. PMID:19567593

  20. Dual Endothelin-A/Endothelin-B Receptor Blockade and Cardiac Remodeling in Heart Failure With Preserved Ejection Fraction.

    PubMed

    Valero-Munoz, Maria; Li, Shanpeng; Wilson, Richard M; Boldbaatar, Batbold; Iglarz, Marc; Sam, Flora

    2016-11-01

    Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension. In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF. These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF. © 2016 American Heart Association, Inc.

  1. Dual Endothelin-A/Endothelin-B Receptor Blockade and Cardiac Remodeling in Heart Failure With Preserved Ejection Fraction

    PubMed Central

    Valero-Munoz, Maria; Li, Shanpeng; Wilson, Richard M.; Boldbaatar, Batbold; Iglarz, Marc; Sam, Flora

    2017-01-01

    Background Despite the increasing prevalence of heart failure with preserved ejection fraction (HFpEF) in humans, there remains no evidence-based therapies for HFpEF. Endothelin-1 (ET-1) antagonists are a possibility because elevated ET-1 levels are associated with adverse cardiovascular effects, such as arterial and pulmonary vasoconstriction, impaired left ventricular (LV) relaxation, and stimulation of LV hypertrophy. LV hypertrophy is a common phenotype in HFpEF, particularly when associated with hypertension. Methods and Results In the present study, we found that ET-1 levels were significantly elevated in patients with chronic stable HFpEF. We then sought to investigate the effects of chronic macitentan, a dual ET-A/ET-B receptor antagonist, on cardiac structure and function in a murine model of HFpEF induced by chronic aldosterone infusion. Macitentan caused LV hypertrophy regression independent of blood pressure changes in HFpEF. Although macitentan did not modulate diastolic dysfunction in HFpEF, it significantly reduced wall thickness and relative wall thickness after 2 weeks of therapy. In vitro studies showed that macitentan decreased the aldosterone-induced cardiomyocyte hypertrophy. These changes were mediated by a reduction in the expression of cardiac myocyte enhancer factor 2a. Moreover, macitentan improved adverse cardiac remodeling, by reducing the stiffer cardiac collagen I and titin n2b expression in the left ventricle of mice with HFpEF. Conclusions These findings indicate that dual ET-A/ET-B receptor inhibition improves HFpEF by abrogating adverse cardiac remodeling via antihypertrophic mechanisms and by reducing stiffness. Additional studies are needed to explore the role of dual ET-1 receptor antagonists in patients with HFpEF. PMID:27810862

  2. A nonsteroidal glucocorticoid receptor antagonist.

    PubMed

    Miner, Jeffrey N; Tyree, Curtis; Hu, Junlian; Berger, Elaine; Marschke, Keith; Nakane, Masaki; Coghlan, Michael J; Clemm, Dave; Lane, Ben; Rosen, Jon

    2003-01-01

    Selective intracellular receptor antagonists are used clinically to ameliorate hormone-dependent disease states. Patients with Cushing's syndrome have high levels of the glucocorticoid, cortisol, and suffer significant consequences from this overexposure. High levels of this hormone are also implicated in exacerbating diabetes and the stress response. Selectively inhibiting this hormone may have clinical benefit in these disease states. To this end, we have identified the first selective, nonsteroidal glucocorticoid receptor (GR) antagonist. This compound is characterized by a tri-aryl methane core chemical structure. This GR-specific antagonist binds with nanomolar affinity to the GR and has no detectable binding affinity for the highly related receptors for mineralocorticoids, androgens, estrogens, and progestins. We demonstrate that this antagonist inhibits glucocorticoid-mediated transcriptional regulation. This compound binds competitively with steroids, likely occupying a similar site within the ligand-binding domain. Once bound, however, the compound fails to induce critical conformational changes in the receptor necessary for agonist activity.

  3. Increased cerebrovascular sensitivity to endothelin-1 in a rat model of obstructive sleep apnea: a role for endothelin receptor B

    PubMed Central

    Durgan, David J; Crossland, Randy F; Lloyd, Eric E; Phillips, Sharon C; Bryan, Robert M

    2015-01-01

    Obstructive sleep apnea (OSA) is associated with cerebrovascular diseases. However, little is known regarding the effects of OSA on the cerebrovascular wall. We tested the hypothesis that OSA augments endothelin-1 (ET-1) constrictions of cerebral arteries. Repeated apneas (30 or 60 per hour) were produced in rats during the sleep cycle (8 hours) by remotely inflating a balloon implanted in the trachea. Four weeks of apneas produced a 23-fold increase in ET-1 sensitivity in isolated and pressurized posterior cerebral arteries (PCAs) compared with PCAs from sham-operated rats (EC50=10−9.2 mol/L versus 10−10.6 mol/L; P<0.001). This increased sensitivity was abolished by the ET-B receptor antagonist, BQ-788. Constrictions to the ET-B receptor agonist, IRL-1620, were greater in PCAs from rats after 2 or 4 weeks of apneas compared with that from sham-operated rats (P=0.013). Increased IRL-1620 constrictions in PCAs from OSA rats were normalized with the transient receptor potential channel (TRPC) blocker, SKF96365, or the Rho kinase (ROCK) inhibitor, Y27632. These data show that OSA increases the sensitivity of PCAs to ET-1 through enhanced ET-B activity, and enhanced activity of TRPCs and ROCK. We conclude that enhanced ET-1 signaling is part of a pathologic mechanism associated with adverse cerebrovascular outcomes of OSA. PMID:25425077

  4. Role of endothelin-1 antagonist; bosentan, against cisplatin-induced nephrotoxicity in male and female rats

    PubMed Central

    Jokar, Zahra; Nematbakhsh, Mehdi; Moeini, Maryam; Talebi, Ardeshir

    2015-01-01

    Background: Cisplatin (CP) is a chemotherapy drug, with the major side effect of nephrotoxicity. The level of endothelin-1 (ET-1) increases during nephrotoxicity, which is accompanied with vasoconstrictive properties. Bosentan (BOS) is a nonselective ET-1 receptor antagonist, having vasodilatory and anti-hypertension effects. The purpose of this study was to investigate the renoprotective effect of BOS against CP-induced nephrotoxicity in male and female rats. Materials and Methods: Male and female rats were divided into six groups; groups 1–3 and 4–6 were male and female rats, respectively. Animals in groups 1 and 4 were considered as negative control and groups 2 and 5 considered as positive control groups received BOS (30 mg/kg/day) alone and CP (2.5 mg/kg/day) alone, respectively, for 1-week. The animals in groups 3 and 6 were treated with both CP and BOS. Finally, serum parameters were measured, and the kidney tissue was subjected to staining to evaluate tissue damage. Results: The serum levels of blood urea nitrogen and creatinine, kidney tissue damage score and kidney weight elevated, and body weight significantly decreased in both CP alone and in CP plus BOS-treated groups when compared with the control groups (P < 0.05), while BOS did not ameliorate these parameters neither in males nor in females. No significant differences were observed in serum levels of nitrite and malondialdehyde between the groups, but kidney tissue level of nitrite decreased significantly in CP alone and CP plus BOS-treated groups (P < 0.05). Conclusion: Renoprotective effect of BOS, as ET-1 blocker, was not observed against CP-induced nephrotoxicity neither in male nor in female rats. This is while BOS promoted the severity of injuries in females. PMID:26015909

  5. Endothelin receptors in rat liver: lipocytes as a contractile target for endothelin 1.

    PubMed Central

    Housset, C; Rockey, D C; Bissell, D M

    1993-01-01

    The endothelins (ETs) form a group of three vasoactive peptides (ET-1, ET-2, and ET-3) for which two types of cellular receptors have been identified, types A and B ET receptors (ETA and ETB receptors, respectively). To address possible targets for ETs within the liver, we isolated the four principal liver cell populations and placed them in short-term primary culture. By ligand-binding assay and mRNA levels, expression of ET receptors was greatest on hepatic lipocytes (Ito cells or fat-storing cells), which are perisinusoidal cells exhibiting features of smooth muscle cells. Moreover, lipocytes expressed both ETA and ETB receptors. The mRNA for ETB receptor, but not for ETA receptor, was detectable in sinusoidal endothelial cells and Kupffer cells; neither mRNA was detectable in hepatocytes. Both ET-1 and ET-3 elicited contraction of activated lipocytes cultured on collagen lattices; the EC50 value for ET-1 was 3 +/- 1 nM and for ET-3 was 17 +/- 12 nM. In cell isolates from injured liver (after administration of carbon tetrachloride), expression of ET receptors was unchanged. However, mRNA for ET-1 was significantly increased in activated lipocytes, suggesting an autocrine loop for the initiation of lipocyte contraction. The findings imply that ET-1 may play a role in regulating sinusoidal perfusion through its effect on lipocytes, particularly in injury states. Images Fig. 3 Fig. 4 PMID:8415690

  6. Growth inhibitory properties of endothelin-1 in human hepatic myofibroblastic Ito cells. An endothelin B receptor-mediated pathway.

    PubMed Central

    Mallat, A; Fouassier, L; Préaux, A M; Gal, C S; Raufaste, D; Rosenbaum, J; Dhumeaux, D; Jouneaux, C; Mavier, P; Lotersztajn, S

    1995-01-01

    Ito cells play a pivotal role in the development of liver fibrosis associated with chronic liver diseases. During this process, Ito cells acquire myofibroblastic features, proliferate, and synthesize fibrosis components. Considering the reported mitogenic properties of endothelin-1 (ET-1), we investigated its effects on the proliferation of human Ito cells in their myofibroblastic phenotype. Both ET receptor A (ETA: 20%) and ET receptor B (ETB: 80%) binding sites were identified, using a selective ETA antagonist, BQ 123, and a selective ETB agonist, sarafotoxin S6C (SRTX-C). ET-1 did not stimulate proliferation of myofibroblastic Ito cells. In contrast, ET-1 inhibited by 60% DNA synthesis and proliferation of cells stimulated with either human serum or platelet-derived growth factor -BB (PDGF-BB). PD 142893, a nonselective ETA/ETB antagonist totally blunted this effect. SRTX-C was as potent as ET-1, while BQ 123 did not affect ET-1-induced growth inhibition. Analysis of the intermediate steps leading to growth-inhibition by ET-1 revealed that activation of mitogen-activated protein kinase by serum or PDGF-BB was decreased by 50% in the presence of SRTX-C. In serum-stimulated cells, SRTX-C reduced c-jun mRNA expression by 50% whereas c-fos or krox 24 mRNA expression were not affected. We conclude that ET-1 binding to ETB receptors causes a potent growth inhibition of human myofibroblastic Ito cells, which suggests that this peptide could play a key role in the negative control of liver fibrogenesis. Our results also point out that, in addition to its well known promitogenic effects, ET-1 may also exert negative control of growth on specific cells. Images PMID:7615814

  7. Embryonic expression of endothelins and their receptors in lamprey and frog reveals stem vertebrate origins of complex Endothelin signaling

    PubMed Central

    Square, Tyler; Jandzik, David; Cattell, Maria; Hansen, Andrew; Medeiros, Daniel Meulemans

    2016-01-01

    Neural crest cells (NCCs) are highly patterned embryonic cells that migrate along stereotyped routes to give rise to a diverse array of adult tissues and cell types. Modern NCCs are thought to have evolved from migratory neural precursors with limited developmental potential and patterning. How this occurred is poorly understood. Endothelin signaling regulates several aspects of NCC development, including their migration, differentiation, and patterning. In jawed vertebrates, Endothelin signaling involves multiple functionally distinct ligands (Edns) and receptors (Ednrs) expressed in various NCC subpopulations. To test the potential role of endothelin signaling diversification in the evolution of modern, highly patterned NCC, we analyzed the expression of the complete set of endothelin ligands and receptors in the jawless vertebrate, the sea lamprey (Petromyzon marinus). To better understand ancestral features of gnathostome edn and ednr expression, we also analyzed all known Endothelin signaling components in the African clawed frog (Xenopus laevis). We found that the sea lamprey has a gnathsotome-like complement of edn and ednr duplicates, and these genes are expressed in patterns highly reminiscent of their gnathostome counterparts. Our results suggest that the duplication and specialization of vertebrate Endothelin signaling coincided with the appearance of highly patterned and multipotent NCCs in stem vertebrates. PMID:27677704

  8. Neuropathic pain induced by spinal cord injury: Role of endothelin ETA and ETB receptors.

    PubMed

    Forner, S; Martini, A C; de Andrade, E L; Rae, G A

    2016-03-23

    Spinal cord injury (SCI) is a devastating neurologic disorder that often inflicts neuropathic pain, which further impacts negatively on the patient's quality of life. Endothelin peptides, which exert their effects via endothelin A (ETAR) and endothelin B (ETBR) receptors, can contribute to sensory changes associated with inflammatory and neuropathic pain, but their role in nociception following SCI is unknown. At different time points after subjecting male Wistar rats to surgery for compression-induced T10 level SCI, the spinal cord levels of ETAR and ETBR were assessed by Western blot and immunohistochemistry, and the corresponding mRNAs by real-time PCR, alongside recordings of behavioural responses to mechanical stimulation of the hind paws with von Frey hairs. SCI was associated with development of hind paw mechanical allodynia from day 14 onwards, and up-regulation of ETAR and ETBR mRNA in the spinal cord and dorsal root ganglia, and of ETAR protein in the spinal cord. SCI increased ETAR protein expression in spinal grey matter. Treatment on day 21 after surgery with the ETAR selective antagonist BQ-123 (40 and 90 pmol, intrathecally) or the dual ETAR/ETBR antagonist bosentan (30 and 100mg/kg, orally) transiently reduced SCI-induced mechanical allodynia, but the ETBR antagonist BQ-788 was ineffective. Altogether, these data show that SCI upregulates ETAR expression in the spinal cord, which appears to contribute to the hind paw mechanical allodynia associated with this condition. Therapies directed towards blockade of spinal ETAR may hold potential to limit SCI-induced neuropathic pain. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Cigarette Smoke Upregulates Rat Coronary Artery Endothelin Receptors In Vivo

    PubMed Central

    Cao, Lei; Zhang, Yaping; Cao, Yong-Xiao; Edvinsson, Lars; Xu, Cang-Bao

    2012-01-01

    Background Cigarette smoking is a strong cardiovascular risk factor and endothelin (ET) receptors are related to coronary artery diseases. The present study established an in vivo secondhand smoke (SHS) exposure model and investigated the hypothesis that cigarette smoke induces ET receptor upregulation in rat coronary arteries and its possible underlying mechanisms. Methodology/Principal Findings Rats were exposed to SHS for 200 min daily for 8 weeks. The coronary arteries were isolated and examined. The vasoconstriction was studied by a sensitive myograph. The expression of mRNA and protein for receptors was examined by real-time PCR, Western blot and immunofluorescence. Compared to fresh air exposure, SHS increased contractile responses mediated by endothelin type A (ETA) and type B (ETB) receptors in coronary arteries. In parallel, the expression of mRNA and protein for ETA and ETB receptors of smoke exposed rats were higher than that of animals exposed to fresh air, suggesting that SHS upregulates ETA and ETB receptors in coronary arteries in vivo. Immunofluorescence staining showed that the enhanced receptor expression was localized to the smooth muscle cells of coronary arteries. The protein levels of phosphorylated (p)-Raf-1 and p-ERK1/2 in smoke exposed rats were significantly higher than in control rats, demonstrating that SHS induces the activation of the Raf/ERK/MAPK pathway. Treatment with Raf-1 inhibitor GW5074 suppressed SHS-induced enhanced contraction mediated by ETA receptors, and inhibited the elevated mRNA and protein levels of ETA and ETB receptors caused by SHS. The results of correlation and regression analysis showed that phosphorylation of Raf and ERK1/2 were independent determinants to affect protein expression of ETB and ETA receptors. Conclusions/Significance Cigarette smoke upregulates ETB and ETA receptors in rat coronary artery, which is associated with the activation of the Raf/ERK/MAPK pathway. PMID:22412974

  10. Plasma endothelin-1 and single nucleotide polymorphisms of endothelin-1 and endothelin type A receptor genes as risk factors for normal tension glaucoma

    PubMed Central

    Kosior-Jarecka, Ewa; Łukasik, Urszula; Aung, Tin; Khor, Chiea Chuen; Kocki, Janusz; Żarnowski, Tomasz

    2016-01-01

    Purpose The purpose of this study was to determine whether four single nucleotide polymorphisms (SNPs) of endothelin and endothelin receptor type A genes can constitute a risk factor for normal tension glaucoma (NTG) and high tension glaucoma (HTG). Methods The study included 160 patients with NTG, 124 patients with HTG, and 165 healthy controls. To analyze the frequency of polymorphic variants of the endothelin EDN gene (K198N) and the endothelin receptor type A gene EDN RA (C1222T, C70G, G231A), DNA was isolated from peripheral blood, and SNP genotyping was performed using the real-time PCR (RT–PCR) method. Plasma endothelin (ET) concentrations were detected using an enzyme immunoassay. Endothelin levels were compared with genotype and allele distributions, patients’ clinical status, and various risk factors for NTG. Results There was a significant difference between the patients with NTG and HTG and the controls (p = 0.035, p = 0.008) regarding the genotype of the C1222T and C70G polymorphism. Plasma concentrations of ET did not differ between the NTG and HTG groups, and no significant correlation with intraocular pressure (IOP), best-corrected visual acuity (BCVA), and the cup to disc ratio (c/d ratio) was seen in patients with NTG. Plasma endothelin levels showed a noticeably positive correlation with age in the NTG group (R = 0.249, p = 0.042). Higher endothelin levels corresponded to more advanced visual field damage. No statistical difference was observed between variant genotypes of K198N and the ET-1 plasma concentration in patients with NTG, whereas a slightly higher ET level was observed in the patients with HTG with the GT genotype in comparison to those with the GG genotype (p = 0.001). The C1222T polymorphism significantly affected the plasma ET level in patients with NTG. The TT genotype carriers had the highest ET level, and the CC genotype carriers the lowest (p = 0.034). The AA variant genotype of the G231A polymorphism exhibited the highest

  11. The Endothelin Type A Receptor as a Potential Therapeutic Target in Preeclampsia

    PubMed Central

    Bakrania, Bhavisha; Duncan, Jeremy; Warrington, Junie P.; Granger, Joey P.

    2017-01-01

    Preeclampsia (PE) is a disorder of pregnancy typically characterized by new onset hypertension after gestational week 20 and proteinuria. Although PE is one of the leading causes of maternal and perinatal morbidity and death worldwide, the mechanisms of the pathogenesis of the disease remain unclear and treatment options are limited. However, there is increasing evidence to suggest that endothelin-1 (ET-1) plays a critical role in the pathophysiology of PE. Multiple studies report that ET-1 is increased in PE and some studies report a positive correlation between ET-1 and the severity of symptoms. A number of experimental models of PE are also associated with elevated tissue levels of prepro ET-1 mRNA. Moreover, experimental models of PE (placental ischemia, sFlt-1 infusion, Tumor necrosis factor (TNF) -α infusion, and Angiotensin II type 1 receptor autoantibody (AT1-AA) infusion) have proven to be susceptible to Endothelin Type A (ETA) receptor antagonism. While the results are promising, further work is needed to determine whether ET antagonists could provide an effective therapy for the management of preeclampsia. PMID:28264495

  12. Endothelin receptor blockade ameliorates renal injury by inhibition of RhoA/Rho-kinase signalling in deoxycorticosterone acetate-salt hypertensive rats.

    PubMed

    Lee, Tsung-Ming; Chung, Tun-Hui; Lin, Shinn-Zong; Chang, Nen-Chung

    2014-04-01

    Excessive production of fibrosis is a feature of hypertension-induced renal injury. Activation of RhoA/Rho-kinase (ROCK) axis has been shown in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We assessed whether selective endothelin receptor blockers can attenuate renal fibrosis by inhibiting RhoA/ROCK axis in DOCA-salt rats. At 4 weeks after the start of DOCA-salt treatment and uninephrectomization, male Wistar rats were randomized into three groups for 4 weeks: vehicle, ABT-627 (endothelin-A receptor inhibitor) and A192621 (endothelin-B receptor inhibitor). DOCA-salt was characterized by increased blood pressure, decreased renal function, increased proteinuria, increased glomerulosclerosis and tubulointerstitial fibrosis with myofibroblast accumulation, increased renal endothelin-1 levels and RhoA activity along with increased expression of connective tissue growth factor at both mRNA and protein levels as compared with uninephrectomized control male Wistar rats. Treatment with a selective mineralocorticoid receptor antagonist, eplerenone, ameliorated proteinuria. Impaired renal function and histological changes were overcome by treatment with ABT-627, but not with A192621. The beneficial effects of bosentan, a nonspecific endothelin receptor blocker, on proteinuria, RhoA activity, and connective tissue growth factor levels were similar to ABT-627. Furthermore, in an isolated perfuse kidney, a RhoA inhibitor, C3 exoenzyme, and two ROCK inhibitors, fasudil and Y-27632, significantly attenuated connective tissue growth factor levels. These results indicate that DOCA-salt elevates renal endothelin-1 levels and RhoA activity via activation of mineralocorticoid receptor, resulting in renal fibrosis and proteinuria. Endothelin-A receptor blockade can attenuate DOCA-salt-induced renal fibrosis probably through the inhibition of RhoA/ROCK activity and connective tissue growth factor expression.

  13. Endothelin receptor B protects granulocyte macrophage colony-stimulating factor mRNA from degradation.

    PubMed

    Jungck, David; Knobloch, Jürgen; Körber, Sandra; Lin, Yingfeng; Konradi, Jürgen; Yanik, Sarah; Stoelben, Erich; Koch, Andrea

    2015-06-01

    Evidence is lacking on the differential effects of the two therapeutic concepts of endothelin receptor antagonists (ERAs): the blockade of only the endothelin receptor A (ETAR; selective antagonism) versus both ETAR and endothelin receptor B (ETBR; dual blockade). Ambrisentan, a selective ERA, and bosentan, a dual blocker, are both available for therapy. We hypothesized that there are differences in the potential of ERAs to ameliorate inflammatory processes in human airway smooth muscle cells (HASMCs) and aimed to unravel underlying mechanisms. We used HASMC culture, enzyme-linked immunosorbent assay, and quantitative reverse-transcription polymerase chain reaction. Tumor necrosis factor α (TNFα) induced transcription and expression of chemokine (C-X-C motif) ligand 2 (CXCL2), chemokine (C-X-C motif) ligand 3 (CXCL3), granulocyte macrophage colony-stimulating factor (GM-CSF), and matrix metalloproteinase 12 (MMP12) in HASMCs. In concentration-response experiments, bosentan led to a significantly greater reduction of GM-CSF and MMP12 protein release than ambrisentan, whereas there was no significant difference in their effect on GM-CSF and MMP12 mRNA. Both ERAs reduced CXCL3 protein and mRNA equally but had no effect on CXCL2. Blocking mitogen-activated protein kinases revealed that both ETAR and ETBR signal through p38 mitogen-activated protein kinase, but ETBR also signals through extracellular signal-regulated kinase (ERK) 1/2 to induce GM-CSF expression. In the presence of the transcription inhibitor actinomycin D, bosentan, but not ambrisentan, reduced GM-CSF but not MMP12 or CXCL3 mRNA. In conclusion, blockade of each endothelin receptor subtype reduces GM-CSF transcription, but blocking ETBR additionally protects GM-CSF mRNA from degradation via ERK-1/2. Accordingly, blocking both ETAR and ETBR leads to a stronger reduction of TNFα-induced GM-CSF protein expression. This mechanism might be specific to GM-CSF. Our data stress the anti-inflammatory potential

  14. Endothelin-1 downregulates Mas receptor expression in human cardiomyocytes.

    PubMed

    Chen, Zhiheng; Tang, Yamei; Yang, Zuocheng; Liu, Shaojun; Liu, Yong; Li, Yan; He, Wei

    2013-09-01

    Endothelin-1 (ET-1) and the renin-angiotensin system (RAS) are involved in the pathogenesis of cardiac dysfunction. The Mas receptor is a functional binding site for angiotensin (Ang)‑(1-7), which is now considered a critical component of the RAS and exerts cardioprotective effects. To the best of our knowledge, the present study aimed to examine, for the first time, the effects of ET-1 on Mas expression in cultured human cardiomyocytes. Human cardiomyocytes were treated with ET-1 at different concentrations (1, 5, 10, 20 and 30 nM) for varied time periods (0.5, 1.5, 3, 4.5 or 6 h) with or without the transcription inhibitor actinomycin D, endothelin A (ETA) receptor blocker BQ123 and ETB receptor blocker BQ788, or different kinase inhibitors. ET-1 decreased the Mas mRNA level in a statistically significant dose- and time-dependent manner within 4.5 h, which was reflected in the dose-dependent downregulation of Mas promoter activity, Mas protein levels and Ang-(1-7) binding on the cell membrane. Actinomycin D (1 mg/ml), BQ123 (1 µM), p38 mitogen-activated protein kinase (MAPK) siRNA and inhibitor PD169316 (25 µM), completely eliminated the inhibitory effects of ET-1 on Mas expression in human cardiomyocytes. In conclusion, the present study demonstrated that ET-1 downregulates Mas expression at the transcription level in human cardiomyocytes via the ETA receptor by a p38 MAPK‑dependent mechanism. This study provides novel insights into the function of ET-1 and the Ang‑(1-7)/Mas axis in cardiac pathophysiology.

  15. Endothelin-1 receptors in rat tissues: characterization by bosentan, ambrisentan and CI-1020.

    PubMed

    Yokoyama, Yoshinari; Osano, Ayaka; Hayashi, Hideki; Itoh, Kunihiko; Okura, Takashi; Deguchi, Yoshiharu; Ito, Yoshihiko; Yamada, Shizuo

    2014-01-01

    The present study aimed to characterize comparatively endothelin-1 (ET-1) receptors in rat tissues by radioligand binding assay using [(125)I]ET-1 and to examine receptor binding after oral administration of bosentan. Significant amount of specific [(125)I]ET-1 binding was detected in the lung, heart, kidney, bladder and cerebral cortex of rats. ET-1, bosentan, ambrisentan, and CI-1020 inhibited specific [(125)I]ET-1 binding in these tissues in a concentration-dependent manner. The Hill coefficients of each agent in the rat lung and cerebral cortex and those of bosentan and ET-1 in the heart, kidney and bladder were close to unity, while the Hill coefficients of ambrisentan and CI-1020 in the heart, kidney and bladder were less than one. The nonlinear least squares regression analysis revealed the presence of high- and low-affinity ET-1 receptor sites in these tissues for ambrisentan and CI-1020. Oral administration of bosentan caused a dose-dependent decrease in specific [(125)I]ET-1 binding in the rat lung, kidney and bladder, suggesting significant binding of the tissue ET-1 receptors in vivo. In conclusion, it has been shown that a significant amount of pharmacologically relevant ET-1 receptors may exist in rat tissues and that ET-1 receptor antagonists such as bosentan at pharmacological doses may exert some pharmacological effects by binding these ET-1 receptors.

  16. Association between endothelin receptor B nonsynonymous variants and melanoma risk.

    PubMed

    Soufir, Nadem; Meziani, Roubila; Lacapère, Jean-Jacques; Bertrand, Guylene; Fumeron, Frederic; Bourillon, Agnes; Gérard, Bénédicte; Descamps, Vincent; Crickx, Béatrice; Ollivaud, Laurence; Archimbaud, Alain; Lebbe, Céleste; Basset-Seguin, Nicole; Saiag, Philippe; Grandchamp, Bernard

    2005-09-07

    The endothelin signaling pathway plays a crucial role in melanocyte differentiation and migration. In this study, we investigated whether germline mutations of endothelin receptor B (EDNRB), a gene involved in Hirschsprung disease (HSCR), could also predispose for malignant melanoma (MM). The coding region of EDNRB was sequenced in 137 MM patients and in 130 ethnically matched Caucasian control subjects. Six nonsynonymous EDNRB variants were found in 15 patients (11%), but only two were found in four control subjects (3%, odds ratio [OR] = 3.87, 95% confidence interval [CI] = 1.25 to 12; P = .012). Overall, 14 out of 15 MM patients carried EDNRB mutations reported in HSCR, some of which had previously been shown to lead to loss of function. In multivariable logistic regression analysis including skin type, eye and hair color, number of nevi, and dorsal lentigines (freckles), the association between EDNRB mutations and MM risk remained statistically significant (OR = 19.9, 95% CI = 1.34 to 296.2; P = .03). Our data strongly suggest that EDNRB is involved in predisposition for two different multigenic disorders, HSCR and melanoma.

  17. Endothelin-converting enzyme 2 differentially regulates opioid receptor activity

    PubMed Central

    Gupta, A; Fujita, W; Gomes, I; Bobeck, E; Devi, L A

    2015-01-01

    BACKGROUND AND PURPOSE Opioid receptor function is modulated by post-activation events such as receptor endocytosis, recycling and/or degradation. While it is generally understood that the peptide ligand gets co-endocytosed with the receptor, relatively few studies have investigated the role of the endocytosed peptide and peptide processing enzymes in regulating receptor function. In this study, we focused on endothelin-converting enzyme 2 (ECE2), a member of the neprilysin family of metallopeptidases that exhibits an acidic pH optimum, localizes to an intracellular compartment and selectively processes neuropeptides including opioid peptides in vitro, and examined its role in modulating μ receptor recycling and resensitization. EXPERIMENTAL APPROACH The effect of ECE2 inhibition on hydrolysis of the endocytosed peptide was examined using thin-layer chromatography and on μ opioid receptor trafficking using either elisa or microscopy. The effect of ECE2 inhibition on receptor signalling was measured using a cAMP assay and, in vivo, on antinociception induced by intrathecally administered opioids by the tail-flick assay. KEY RESULTS The highly selective ECE2 inhibitor, S136492, significantly impaired μ receptor recycling and signalling by only those ligands that are ECE2 substrates and this was seen both in heterologous cells and in cells endogenously co-expressing μ receptors with ECE2. We also found that ECE2 inhibition attenuated antinociception mediated only by opioid peptides that are ECE2 substrates. CONCLUSIONS AND IMPLICATIONS These results suggest that ECE2, by selectively processing endogenous opioid peptides in the endocytic compartment, plays a role in modulating opioid receptor activity. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24990314

  18. Disruption of the endothelin A receptor in the nephron causes mild fluid volume expansion.

    PubMed

    Stuart, Deborah; Rees, Sara; Woodward, Stephanie K; Koesters, Robert; Strait, Kevin A; Kohan, Donald E

    2012-12-05

    Endothelin, via endothelin A receptors (ETA), exerts multiple pathologic effects that contribute to disease pathogenesis throughout the body. ETA antagonists ameliorate many experimental diseases and have been extensively utilized in clinical trials. The utility of ETA blockers has been greatly limited, however, by fluid retention, sometimes leading to heart failure or death. To begin to examine this issue, the effect of genetic disruption of ETA in the nephron on blood pressure and salt handling was determined. Mice were generated with doxycycline-inducible nephron-specific ETA deletion using Pax8-rtTA and LC-1 transgenes on the background of homozygous loxP-flanked ETA alleles. Arterial pressure, Na metabolism and measures of body fluid volume status (hematocrit and impedance plethysmography) were assessed. Absence of nephron ETA did not alter arterial pressure whether mice were ingesting a normal or high Na diet. Nephron ETA disruption did not detectably affect 24 hr Na excretion or urine volume regardless of Na intake. However, mice with nephron ETA knockout that were fed a high Na diet had mild fluid retention as evidenced by an increase in body weight and a fall in hematocrit. Genetic deletion of nephron ETA causes very modest fluid retention that does not alter arterial pressure. Nephron ETA, under normal conditions, likely do not play a major role in regulation of Na excretion or systemic hemodynamics.

  19. Different contributions of endothelin-A and endothelin-B receptors in the pathogenesis of deoxycorticosterone acetate-salt-induced hypertension in rats.

    PubMed

    Matsumura, Y; Hashimoto, N; Taira, S; Kuro, T; Kitano, R; Ohkita, M; Opgenorth, T J; Takaoka, M

    1999-02-01

    We investigated the involvement of actions mediated by endothelin-A (ETA) and endothelin-B (ETB) receptors in the pathogenesis of deoxycorticosterone acetate (DOCA)-salt-induced hypertension in rats. Two weeks after the start of DOCA-salt treatment, rats were given ABT-627 (10 [mg/kg]/d), a selective ETA receptor antagonist; A-192621 (30 [mg/kg]/d), a selective ETB receptor antagonist; or their vehicle for 2 weeks. Uninephrectomized rats without DOCA-salt treatment served as controls. Treatment with DOCA and salt for 2 weeks led to a mild but significant hypertension; in vehicle-treated DOCA-salt rats, systolic blood pressure increased markedly after 3 to 4 weeks. Daily administration of ABT-627 for 2 weeks almost abolished any further increases in blood pressure, whereas A-192621 did not affect the development of DOCA-salt-induced hypertension. When the degree of vascular hypertrophy of the aorta was histochemically evaluated at 4 weeks, there were significant increases in wall thickness, wall area, and wall-to-lumen ratio in vehicle-treated DOCA-salt rats compared with uninephrectomized control rats. The development of vascular hypertrophy was markedly suppressed by ABT-627. In contrast, treatment with A-192621 significantly exaggerated these vascular changes. In vehicle-treated DOCA-salt rats, renal blood flow and creatinine clearance decreased, and urinary excretion of protein, blood urea nitrogen, fractional excretion of sodium, and urinary N-acetyl-beta-glucosaminidase activity increased. Such damage was overcome by treatment with ABT-627 but not with A-192621; indeed, the latter agent led to worsening of the renal dysfunction. Histopathologic examination of the kidney in vehicle-treated DOCA-salt rats revealed tubular dilatation and atrophy as well as thickening of small arteries. Such damage was reduced in animals given ABT-627, whereas more severe histopathologic changes were observed in A-192621-treated animals. These results strongly support the view

  20. Role of endothelin-1/endothelin receptor signaling in fibrosis and calcification in nephrogenic systemic fibrosis.

    PubMed

    Motegi, Sei-Ichiro; Okada, Etsuko; Uchiyama, Akihiko; Yamada, Kazuya; Ogino, Sachiko; Yokoyama, Yoko; Takeuchi, Yuko; Monma, Fumiko; Suzuki, Tamio; Ishikawa, Osamu

    2014-09-01

    Nephrogenic systemic fibrosis (NSF) is characterized by systemic fibrosis and abnormal calcification in patients with severe renal dysfunction. It is considered that gadolinium (Gd)-containing contrast agents used for magnetic resonance imaging trigger the development of NSF. However, the causative role of Gd and the mechanism of Gd-induced fibrosis and calcification in NSF are unknown. Recently, it has been known that endothelin-1 (ET-1)/ET receptor (ETR) signalling regulates fibrosis and calcification. The objective was to elucidate the role of ET-1/ETR signalling in Gd-induced fibrosis and calcification in NSF. First, we demonstrated that Gd enhanced proliferation and calcification of human adipose tissue-derived mesenchymal stem cells (hMSC) in vitro. Next, we examined the expression of ET-1 and ETR-A in hMSC using proliferation or calcification assay. ET-1 and ETR-A expression in hMSC treated with Gd were elevated. ET-1/ETR signalling inhibitor, bosentan, inhibited Gd-induced proliferation and calcification of hMSC. In addition, bosentan inhibited Gd-induced phosphorylation of ERK and Akt in hMSC. Plasma ET-1 levels of the patients were significantly higher than these of normal individuals and systemic sclerosis patients. In immunofluorescence staining, the expression of ETR-A in fibroblasts in dermal fibrosis lesion of NSF was increased. We conclude that Gd induces proliferation and calcification of hMSC via enhancement of ET-1/ETR signalling. Our results contribute to understand the pathogenesis of NSF. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Role of endothelin receptors in the control of central nervous system parasitism in Trypanosoma cruzi infection in rats.

    PubMed

    Rachid, Milene A; Teixeira, Antônio L; Barcelos, Lucíola S; Machado, Conceição R S; Chiari, Egler; Tanowitz, Herbert B; Camargos, Elizabeth R S; Teixeira, Mauro M

    2010-03-30

    Endothelin has been implicated in the pathogenesis of experimental and human Chagas disease. In the present study, we investigated whether the treatment with bosentan, an antagonist of both ET(A)/ET(B) endothelin receptors, modified parasite load and inflammation in the central nervous system (CNS) of Trypanosomacruzi-infected rats. The cerebellum was the most affected region in the CNS with marked parasitism and inflammation. Treatment with bosentan enhanced parasitemia and CNS parasitism, but control of infection was eventually attained. There was also an increase in the levels of the cytokines TNF-alpha, IL-10, IFN-gamma, CCL2/MCP-1, CCL3/MIP-1alpha and CCL5/RANTES in the brain of infected animals at days 9, 13 and 18 after infection. Overall, bosentan has some effects on the expression of certain cytokines and this may be related to the initial enhanced parasite load. Altogether, our data suggest that endothelin action via ET(A) and ET(B) receptors may play a role in the initial resistance of the CNS to T. cruzi infection in rats. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Role of Endothelin-1/Endothelin-A receptor-mediated signaling pathway in the aortic arch patterning in mice.

    PubMed Central

    Yanagisawa, H.; Hammer, R. E.; Richardson, J. A.; Williams, S. C.; Clouthier, D. E.; Yanagisawa, M.

    1998-01-01

    The intercellular signaling mediated by endothelins and their G protein-coupled receptors has recently been shown to be essential for the normal embryonic development of subsets of neural crest cell derivatives. Endothelin-1 (ET-1) is proteolytically generated from its inactive precursor by endothelin-converting enzyme-1 (ECE-1) and acts on the endothelin-A (ETA) receptor. Genetic disruption of this ET-1/ECE-1/ETA pathway results in defects in branchial arch- derived craniofacial tissues, as well as defects in cardiac outflow and great vessel structures, which are derived from cephalic (cardiac) neural crest. In this study, in situ hybridization of ETA-/- and ECE-1(-)/- embryos with a cardiac neural crest marker, cellular retinoic acid-binding protein-1, shows that the migration of neural crest cells from the neural tube to cardiac outflow tract is not affected in these embryos. Immunostaining of an endothelial marker, platelet endothelial cell adhesion molecule CD-31, shows that the initial formation of the branchial arch arteries is not disturbed in ETA-/- or ECE-1(-)/- embryos. To visualize the subsequent patterning of arch vessels in detail, we generated ETA-/- or ECE-1(-)/- embryos that expressed an SM22alpha-lacZ marker transgene in arterial smooth muscle cells. Wholemount X-gal staining of these mutant embryos reveals that the abnormal regression and persistence of specific arch arteries results in disturbance of asymmetrical remodeling of the arch arteries. These defects include abnormal regression of arch arteries 4 and 6, enlargement of arch artery 3, and abnormal persistence of the bilateral ductus caroticus and right dorsal aorta. These abnormalities eventually lead to various types of great vessel malformations highly similar to those seen in neural crest-ablated chick embryos and human congenital cardiac defects. This study demonstrates that ET-1/ETA-mediated signaling plays an essential role in a complex process of aortic arch patterning by affecting

  3. Brain microvessel endothelin type A receptors are coupled to ceramide production.

    PubMed

    Collado, M Pilar; Latorre, Eduardo; Fernández, Inmaculada; Aragonés, M Dolores; Catalán, R Edgardo

    2003-06-20

    Treatment of brain microvessels with endothelin-1 evoked an early decrease in the sphingomyelin levels concomitantly with an increase in those of ceramides. These responses were time- and concentration-dependent. Evidence also shows that endothelin type A receptors are involved. This is the first report on the involvement of an agonist in the regulation of the ceramide signal transduction system on blood-brain barrier and shows a new pathway likely involved in the regulation of the cerebral microvascular functioning.

  4. Arsenic Activates Endothelin-1 Gi Protein–Coupled Receptor Signaling to Inhibit Stem Cell Differentiation in Adipogenesis

    PubMed Central

    Barchowsky, Aaron

    2013-01-01

    Dysfunctional lipid and glucose metabolism contribute to metabolic syndrome—a major public health concern that enhances cardiovascular disease risk. Arsenic (As(III)) exposure may increase metabolic syndrome and cardiovascular disease risk by impairing adipose tissue differentiation, function, and insulin sensitivity through pathogenic mechanisms that remain unclear. We hypothesized that As(III) signals through the Pertussis toxin (Ptx) sensitive, Gi protein–coupled receptor (GPCR) to impair adipogenesis, as previously demonstrated for its stimulation of vascular oxidant generation, angiogenesis, and remodeling. Because both As(III) and GPCR ligands inhibit progenitor cell differentiation into adipocytes, we investigated the hypothesis in a model of low-passage human mesenchymal stem cells (hMSC). As(III) (0.1–1.0µM) suppressed dexamethasone/insulin-induced hMSC adipogenesis, as indicated by decreased transcriptional promoters of differentiation, decreased fat droplet formation, and decreased expression of differentiated adipocyte markers, such as adiponectin and perilipin. Preincubating hMSC with Ptx prevented 90% of the suppressive effect of As(III). Selective competitive antagonists of Gi-coupled endothelin-1 type A and B receptors were ~60% effective in blocking As(III) inhibition and combination of antagonists to both receptors were 85% effective. In contrast, antagonists to the sphingosine-1-phosphate type 1 receptor (previously shown to mediate As(III) vascular effects) or the angiotensin II type 1 receptor were ineffective in blocking As(III) effects. These studies suggest a majority of arsenic-inhibited adipocyte differentiation, and metabolism requires endothelin-1 GPCRs and that As(III) effects on GPCR signaling are tissue and context specific. This may represent a significant mechanism for the contribution of arsenic exposure to increased metabolic and cardiovascular diseases. PMID:23152186

  5. Endothelin A-receptor blockade in experimental diabetes improves glucose balance and gastrointestinal function.

    PubMed

    Balsiger, Bruno; Rickenbacher, Andreas; Boden, Penelope Jane; Biecker, Erwin; Tsui, Janice; Dashwood, Michael; Reichen, Jürg; Shaw, Sidney George

    2002-08-01

    Secondary complications of diabetes mellitus often involve gastrointestinal dysfunction. In the experimental Goto Kakizaki rat, a model of Type II diabetes, hyperglycaemia and reduced glucose clearance is associated with elevated plasma endothelin (ET)-1 levels and selective decreases in nitric oxide synthase in circular muscle, longitudinal muscle and neuronal elements of the gastrointestinal tract. Functionally, this is accompanied by decreased nitrergic relaxatory responses of jejunal longitudinal muscle to tetrodotoxin-sensitive electrical field stimulation. Long-term treatment with a selective ET A-type receptor antagonist, markedly reduced hyperglycaemia and restored plasma glucose clearance rates towards normal. This was associated with a restoration of N(G)-nitro-L-arginine methyl ester-sensitive relaxatory responses of jejunal longitudinal muscle to electrical field stimulation. The results indicate that beneficial effects of ETA receptor blockade on gastrointestinal function may result from an improvement in insulin sensitivity with concomitant reduction of the severity of hyperglycaemia. ETA receptor blockade may represent a new therapeutic principle for improving glucose tolerance in Type II diabetes and could be beneficial in alleviating or preventing hyperglycaemia-related secondary complications in this condition.

  6. Immunoreactive endothelin-1 and endothelin a receptor in basilar artery perivascular nerves of young and adult capybaras.

    PubMed

    Loesch, Andrzej; Dashwood, Michael R; Coppi, Antonio A

    2013-01-01

    The purpose of this qualitative morphological study was the immunocytochemical and ultrastructural comparison of perivascular nerves of the basilar artery (BA) of young (6-month-old) and adult (12-month-old) capybaras - adult capybaras showed regression of the internal carotid artery (ICA). The study focused on immunolabeling for the vasoactive peptide endothelin-1 (ET-1) and endothelin A receptor (ETA) as well as for the synapse marker synaptophysin (SYP). In the BA of young capybaras, immunoreactivity for ET-1, ETA receptor and SYP was detected in perivascular nerve varicosities and/or intervaricosities. Immunoreactivity for ET-1 and ETA receptor was also displayed by some Schwann cells, which accompanied perivascular nerves. In addition to the presence of the above-described perivascular nerve characteristics, the BA of adult animals also revealed structurally altered perivascular nerves, where axon profiles were irregular in shape with dense axoplasm, while the cytoplasm of Schwann cells was vacuolated and contained myelin-like figures. These structurally altered perivascular nerves displayed immunoreactivity for ET-1, ETA receptor and SYP. These results show that the ET-1 system is present in some of the BA perivascular nerves and it is likely that this system is affected during animal maturation when ICA regression takes place. The role of ET-1 in cerebrovascular nerves is still unclear but its involvement in neural (sensory) control of cerebral blood flow and nerve function is possible. Copyright © 2013 S. Karger AG, Basel.

  7. Influence of Mechanical Circulatory Support on Endothelin Receptor Expression in Human Left Ventricular Myocardium from Patients with Dilated Cardiomyopathy (DCM)

    PubMed Central

    Gärtner, Florian; Abraham, Getu; Kassner, Astrid; Baurichter, Daniela; Milting, Hendrik

    2017-01-01

    Background In terminal failing hearts ventricular assist devices (VAD) are implanted as a bridge to transplantation. Endothelin receptor (ETR) antagonists are used for treatment of secondary pulmonary hypertension in VAD patients. However, the cardiac ETR regulation in human heart failure and during VAD support is incompletely understood. Methods In paired left ventricular samples of 12 dilated cardiomyopathy patients we investigated the density of endothelin A (ETA) and B (ETB) receptors before VAD implantation and after device removal. Left ventricular samples of 12 non-failing donor hearts served as control. Receptor quantification was performed by binding of [125I]-ET-1 in the presence of nonselective and ETA selective ETR ligands as competitors. Additionally, the ETR mRNA expression was analyzed using quantitative real-time-PCR. Results The mRNA of ETA but not ETB receptors was significantly elevated in heart failure, whereas total ETR density analyzed by radioligand binding was significantly reduced due to ETB receptor down regulation. ETA and ETB receptor density showed poor correlation to mRNA data (spearman correlation factor: 0.43 and 0.31, respectively). VAD support had no significant impact on the density of both receptors and on mRNA expression of ETA whereas ETB mRNA increased during VAD. A meta-analysis reveals that the ETA receptor regulation in human heart failure appears to depend on non-failing hearts. Conclusions In deteriorating hearts of patients suffering from dilated cardiomyopathy the ETA receptor density is not changed whereas the ETB receptor is down regulated. The mRNA and the proteins of ETA and ETB show a weak correlation. Non-failing hearts might influence the interpretation of ETA receptor regulation. Mechanical unloading of the failing hearts has no impact on the myocardial ETR density. PMID:28095452

  8. Influence of Mechanical Circulatory Support on Endothelin Receptor Expression in Human Left Ventricular Myocardium from Patients with Dilated Cardiomyopathy (DCM).

    PubMed

    Gärtner, Florian; Abraham, Getu; Kassner, Astrid; Baurichter, Daniela; Milting, Hendrik

    2017-01-01

    In terminal failing hearts ventricular assist devices (VAD) are implanted as a bridge to transplantation. Endothelin receptor (ETR) antagonists are used for treatment of secondary pulmonary hypertension in VAD patients. However, the cardiac ETR regulation in human heart failure and during VAD support is incompletely understood. In paired left ventricular samples of 12 dilated cardiomyopathy patients we investigated the density of endothelin A (ETA) and B (ETB) receptors before VAD implantation and after device removal. Left ventricular samples of 12 non-failing donor hearts served as control. Receptor quantification was performed by binding of [125I]-ET-1 in the presence of nonselective and ETA selective ETR ligands as competitors. Additionally, the ETR mRNA expression was analyzed using quantitative real-time-PCR. The mRNA of ETA but not ETB receptors was significantly elevated in heart failure, whereas total ETR density analyzed by radioligand binding was significantly reduced due to ETB receptor down regulation. ETA and ETB receptor density showed poor correlation to mRNA data (spearman correlation factor: 0.43 and 0.31, respectively). VAD support had no significant impact on the density of both receptors and on mRNA expression of ETA whereas ETB mRNA increased during VAD. A meta-analysis reveals that the ETA receptor regulation in human heart failure appears to depend on non-failing hearts. In deteriorating hearts of patients suffering from dilated cardiomyopathy the ETA receptor density is not changed whereas the ETB receptor is down regulated. The mRNA and the proteins of ETA and ETB show a weak correlation. Non-failing hearts might influence the interpretation of ETA receptor regulation. Mechanical unloading of the failing hearts has no impact on the myocardial ETR density.

  9. Role of endothelin-A receptors in optic nerve head red cell flux regulation during isometric exercise in healthy humans.

    PubMed

    Boltz, Agnes; Schmidl, Doreen; Werkmeister, René M; Lasta, Michael; Kaya, Semira; Palkovits, Stefan; Told, Reinhard; Frantal, Sophie; Garhöfer, Gerhard; Schmetterer, Leopold

    2013-01-01

    Endothelin-1 (ET-1) is an important regulator of vascular tone in the eye. It appears to play a role in ocular disease because of its strong vasoconstrictor action, its role in intraocular pressure homeostasis, and its neurotoxic potential. We have previously shown that ET-1 is involved in choroidal red cell flux (RCF) regulation during isometric exercise in healthy humans. In the present study we hypothesized that ET-1 also plays a role in optic nerve head (ONH) RCF regulation during isometric exercise. To test this hypothesis, we performed a randomized, double-masked, placebo-controlled, two-way crossover study in 15 healthy volunteers. Subjects were randomized to receive intravenous infusions of the specific endothelin type A receptor antagonist BQ-123 and placebo on two different study days. During these infusion periods, subjects performed squatting for 6 min to increase ocular perfusion pressure (OPP). ONH RCF was assessed with laser-Doppler flowmetry, and OPP was calculated from mean arterial pressure and intraocular pressure. BQ-123 did not change OPP or ONH RCF at baseline. The relative increase in OPP during isometric exercise was comparable between both groups (between 84 and 88%, P = 0.76 between groups; P < 0.001 vs. baseline). Isometric exercise increased ONH RCF during placebo and BQ-123, but the increase was more pronounced when the endothelin type-A receptor antagonist was administered (placebo, 27.3 ± 5.4%; and BQ-123, 39.2 ± 4.4%; P = 0.007 between groups). The present data indicate that ET-1 regulates red cell flux in the ONH beyond the autoregulatory range.

  10. Improvement of cold injury-induced mouse brain edema by endothelin ETB antagonists is accompanied by decreases in matrixmetalloproteinase 9 and vascular endothelial growth factor-A.

    PubMed

    Michinaga, Shotaro; Seno, Naoki; Fuka, Mayu; Yamamoto, Yui; Minami, Shizuho; Kimura, Akimasa; Hatanaka, Shunichi; Nagase, Marina; Matsuyama, Emi; Yamanaka, Daisuke; Koyama, Yutaka

    2015-09-01

    Brain edema is a potentially fatal pathological state that often occurs after brain injuries such as ischemia and trauma. However, therapeutic agents that fundamentally treat brain edema have not yet been established. We previously found that endothelin ETB receptor antagonists attenuate the formation and maintenance of vasogenic brain edema after cold injury in mice. In this study, the effects of ETB antagonists on matrixmetalloproteinase (MMP)9 and vascular endothelial growth factor (VEGF)-A expression were examined in the cold injury model. Cold injury was performed in the left brain of male ddY mice (5-6 weeks old) for the induction of vasogenic edema. Expression of MMP9 and VEGF-A mRNA in the mouse cerebrum was increased by cold injury. Immunohistochemical observations showed that the MMP9 and VEGF-A were mainly produced in reactive astrocytes in the damaged cerebrum. Intracerebroventricular administration of BQ788 (10 μg) or IRL-2500 (10 μg) (selective ETB antagonists) attenuated brain edema and disruption of the blood-brain barrier after cold injury. BQ788 and IRL-2500 reversed the cold injury-induced increases in MMP9 and VEGF-A expression. The induction of reactive astrocytes producing MMP9 and VEGF-A in the damaged cerebrum was attenuated by BQ788 and IRL-2500. These results suggest that attenuations of astrocytic MMP9 and VEGF-A expression by ETB antagonists may be involved in the amelioration of vasogenic brain edema.

  11. Different endothelin receptors involved in endothelin-1- and sarafotoxin S6B-induced contractions of the human isolated coronary artery.

    PubMed Central

    Bax, W A; Aghai, Z; van Tricht, C L; Wassenaar, C; Saxena, P R

    1994-01-01

    1. Endothelin receptors, that mediate contraction of the human isolated coronary artery, were characterized by use of a number of agonists and antagonists. Contraction induced by the non-selective agonists, endothelin (ET)-1 and sarafotoxin S6b, was compared in endothelium-intact and endothelium-denuded ring segments. The effects of ET-1 and BQ-123 (an ETA receptor antagonist) were investigated both in ring segments and in spirally cut strips. Lastly, the effect of phosphoramidon was studied on contraction induced by big-ET-1. 2. The order of agonist potency (pD2) in endothelium-intact coronary artery ring segments was: ET-1 (8.27) approximately sarafotoxin S6b (8.16) > big-ET-1 (< 7.1) approximately ET-3 (< 6.9). [Ala1,3,11,15]ET-1 (ETB receptor agonist) caused significant contraction only at 1 microM, whereas 0.3 microM big-ET-3 had no effect. Removal of the endothelium in ring segments did not affect the contractile response to ET-1 or to sarafotoxin S6b. 3. After a full concentration-response curve had been obtained to ET-1 or sarafotoxin S6b, further contractions of the endothelium-intact coronary artery segments could only be achieved by applying ET-1 in segments exposed to sarafotoxin S6b, and not the reverse. 4. BQ-123 (0.1 microM) antagonized contractions of endothelium-intact ring segments induced by sarafotoxin S6b (pKB 7.86). Only 10 microM BQ-123 antagonized contractions induced by ET-1 (pKB 5.75). FR139317 was also more potent against sarafotoxin S6b (pKB 8.24-8.47) than against ET-1 (pKB 6.11). [Ala1,3,11,15]ET-1 (1 microM) had no effect on the contractile response to ET-1 or to sarafotoxin S6b.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7889304

  12. Selective endothelin B receptor blockade does not influence BNP-induced natriuresis in man.

    PubMed

    van der Zander, K; Houben, A J H M; Webb, D J; Udo, E; Kietselaer, B; Hofstra, L; De Mey, J G R; de Leeuw, P W

    2006-03-01

    Brain natriuretic peptide (BNP) and endothelin-1 (ET-1) both exhibit natriuretic activity within the human kidney. Furthermore, they both act partly through activation of the endothelial nitric oxide pathway. Since ET-1 may cause vasodilation and natriuresis via stimulation of the ET-B receptor, the aim of the present study was to investigate whether renal ET-B receptors participate in the renal actions of BNP. In this placebo-controlled, crossover study, we infused BNP (4 pmol/kg/min) or placebo (i.v.) for 1 h, with or without co-infusion of the ET-B receptor antagonist BQ-788 (50 nmol/min) for 15 min on 4 separate days, in 10 healthy subjects (mean age 54+/-6 years.). During infusion, we measured effective renal plasma flow (ERPF), and glomerular filtration rate (GFR) using PAH/inulin clearance. Cardiac output was measured before and after infusion, using echocardiography. Blood pressure and heart rate (HR) were monitored as well. Urine and plasma samples were taken every hour to measure diuresis, natriuresis, cyclic 3',5' guanosine monophosphate, and ET-1 levels. BNP with or without ET-B receptor blockade increased natriuresis and diuresis. In addition, BNP alone increased GFR and filtered load, without changing ERPF. BQ-788 infusion did not affect renal hemodynamics or natriuresis. Neither BNP nor BQ-788 altered cardiac output, blood pressure, and heart rate. In conclusion, the present study shows that selective ET-B receptor blockade has no effect on the BNP-induced natriuresis and glomerular filtration rate.

  13. Peripheral endothelin B receptor agonist-induced antinociception involves endogenous opioids in mice

    PubMed Central

    Quang, Phuong N.; Schmidt, Brian L.

    2010-01-01

    Endothelin-1 (ET-1) produced by various cancers is known to be responsible for inducing pain. While ET-1 binding to ETAR on peripheral nerves clearly mediates nociception, effects from binding to ETBR are less clear. The present study assessed the effects of ETBR activation and the role of endogenous opioid analgesia in carcinoma pain using an orthotopic cancer pain mouse model. mRNA expression analysis showed that ET-1 was nearly doubled while ETBR was significantly down-regulated in a human oral SCC cell line compared to normal oral keratinocytes (NOK). Squamous cell carcinoma (SCC) cell culture treated with an ETBR agonist (10−4M, 10−5 M, and 10−6 M BQ-3020) significantly increased production of β-endorphin without any effects on leu-enkephalin or dynorphin. Cancer inoculated in the hind paw of athymic mice with SCC induced significant pain, as indicated by reduction of paw withdrawal thresholds in response to mechanical stimulation, compared to sham-injected and NOK-injected groups. Intratumor administration of 3 mg/kg BQ-3020 attenuated cancer pain by approximately 50% up to 3 hours post-injection compared to PBS-vehicle and contralateral injection, while intratumor ETBR antagonist BQ-788 treatment (100 and 300 μg/kg and 3 mg/kg) had no effects. Local naloxone methiodide (500 μg/kg) or selective μ-opioid receptor antagonist (CTOP, 500 μg/kg) injection reversed ETBR agonist-induced antinociception in cancer animals. We propose that these results demonstrate that peripheral ETBR agonism attenuates carcinoma pain by modulating β-endorphins released from the SCC to act on peripheral opioid receptors found in the cancer microenvironment. PMID:20206445

  14. Effects of dual endothelin receptor blockade on sympathetic activation and arrhythmogenesis during acute myocardial infarction in rats.

    PubMed

    Kolettis, Theofilos M; Baltogiannis, Giannis G; Tsalikakis, Dimitrios G; Tzallas, Alexandros T; Agelaki, Maria G; Fotopoulos, Andreas; Fotiadis, Dimitrios I; Kyriakides, Zenon S

    2008-02-02

    The effects of dual (ETA and ETB) endothelin receptor blockade on ventricular arrhythmogenesis during acute myocardial infarction are not well defined. We randomly allocated Wistar rats to bosentan (100 mg/kg daily, n=24), a dual endothelin receptor antagonist, or vehicle (n=23). After 7 days of treatment, myocardial infarction was induced by permanent coronary ligation. Ventricular tachyarrhythmias were evaluated for 24 h following ligation, using a miniature telemetry electrocardiogram recorder. Action potential duration was measured from monophasic epicardial recordings and sympathetic activation was assessed by heart rate variability and catecholamine serum level measurements. Compared to controls (1012+/-185 s), bosentan (59+/-24 s) markedly decreased (P<0.00001) the total duration of ventricular tachyarrhythmias during the delayed (1-24 h) phase post-ligation, with a modest effect during the early (0-1 h) phase (132+/-38 s, versus 43+/-18 s, respectively, P=0.053). Treatment did not affect infarct size or total mortality. Action potential duration at 90% repolarization prolonged in controls (from 93.1+/-4.7 ms to 117.6+/-6.9 ms), displaying increased temporal dispersion (from 4.14+/-0.45 ms to 10.42+/-2.51 ms, both P<0.001), but was preserved in treated animals. Bosentan decreased norepinephrine, but increased epinephrine levels 24 h post-ligation. Low frequency spectra of heart rate variability, an index of net sympathetic tone, were lower in bosentan-treated rats. Dual endothelin-1 receptor blockade decreases ventricular tachyarrhythmias during myocardial infarction without reperfusion, by preventing repolarization inhomogeneity. Diverse treatment effects on sympathetic activation may ameliorate the antiarrhythmic action.

  15. Salvianolic Acid A, as a Novel ETA Receptor Antagonist, Shows Inhibitory Effects on Tumor in Vitro.

    PubMed

    Zhang, Qiao; Wang, Shifeng; Yu, Yangyang; Sun, Shengnan; Zhang, Yuxin; Zhang, Yanling; Yang, Wei; Li, Shiyou; Qiao, Yanjiang

    2016-08-02

    Endothelin-1 (ET-1) autocrine and paracrine signaling modulate cell proliferation of tumor cells by activating its receptors, endothelin A receptor (ETAR) and endothelin B receptor (ETBR). Dysregulation of ETAR activation promotes tumor development and progression. The potential of ETAR antagonists and the dual-ETAR and ETBR antagonists as therapeutic approaches are under preclinical and clinical studies. Salvianolic acid A (Sal A) is a hydrophilic polyphenolic derivative isolated from Salvia miltiorrhiza Bunge (Danshen), which has been reported as an anti-cancer and cardio-protective herbal medicine. In this study, we demonstrate that Sal A inhibits ETAR activation induced by ET-1 in both recombinant and endogenous ETAR expression cell lines. The IC50 values were determined as 5.7 µM in the HEK293/ETAR cell line and 3.14 µM in HeLa cells, respectively. Furthermore, our results showed that Sal A suppressed cell proliferation and extended the doubling times of multiple cancer cells, including HeLa, DU145, H1975, and A549 cell lines. In addition, Sal A inhibited proliferation of DU145 cell lines stimulated by exogenous ET-1 treatment. Moreover, the cytotoxicity and cardio-toxicity of Sal A were assessed in human umbilical vein endothelial cells (HUVEC) and Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), which proved that Sal A demonstrates no cytotoxicity or cardiotoxicity. Collectively, our findings indicate that Sal A is a novel anti-cancer candidate through targeting ETAR.

  16. [Endothelin-1 in pathogenesis of Raynaud's syndrome].

    PubMed

    Knapik-Kordecka, M; Adamiec, R; Ciosek, W

    2001-06-01

    Endothelin is an endogenous vasoconstrictor and plays an important role in pathogenesis of Raynaud's phenomenon. Plasma endothelin-1 (ET-1) and von Willebrand factor (vWF) concentrations following cold exposure in 52 patients with Raynaud's phenomenon were measured. Statistically significant increase of ET-1 and vWF was found in the study group in compare to healthy volunteers. There was positive correlation between ET-1 and vWF in those cases. The dates suggest that ET-changes indicates a vasospastic effect on vascular injury. Treatment with endothelin-receptor antagonist may prevent structural changes in vessel well.

  17. California dreamin' 'bout endothelin: emerging new therapeutics.

    PubMed

    Warner, T D; Elliott, J D; Ohlstein, E H

    1996-05-01

    Progress in our understanding of endothelins has been extremely rapid since their discovery in 1988. A number of pharmaceutical companies have developed potent, orally active, nonpeptide endothelin receptor antagonists with efficacies in a wide variety of animal disease models and potential for treating human disease. However, only time will tell whether or not these compounds are developed into drugs that are perceived as worthy of a place in the therapeutic marketplace. If this is the case, endothelin will have been promoted from the status of striking scientific discovery to therapeutic target in a remarkably short period.

  18. Endothelin Receptors Expressed by Immune Cells Are Involved in Modulation of Inflammation and in Fibrosis: Relevance to the Pathogenesis of Systemic Sclerosis

    PubMed Central

    Elisa, Tinazzi; Antonio, Puccetti; Giuseppe, Patuzzo; Alessandro, Barbieri; Giuseppe, Argentino; Federico, Confente; Marzia, Dolcino; Ruggero, Beri; Giacomo, Marchi; Andrea, Ottria; Daniela, Righetti; Mariaelisa, Rampudda

    2015-01-01

    Endothelin-1 (ET-1) plays a pivotal role in vasoconstriction, fibrosis, and inflammation, the key features of systemic sclerosis (SSc). ET-1 receptors (ETA and ETB) are expressed on endothelial cells, smooth muscle cells, and fibroblasts, but their presence on immune cells has not been deeply investigated so far. Endothelin receptors antagonists such as bosentan have beneficial effects on vasoconstriction and fibrosis, but less is known about their potential anti-inflammatory effects. We studied the expression of ET-1 receptors on immune cells (T and B lymphocytes, monocytes, and neutrophils) and the link between ET-1 and inflammation in patients with SSc. We show here that ET-1 exerts a proinflammatory effect in CD4+ T cells, since it induces an increased IFN-γ production; preincubation with antagonists of both receptors reduces IFN-γ production. Moreover, following ET-1 stimulation, neutrophils produce proinflammatory mediators, thus amplifying the effects of activated CD4+ T cells. Our data indicate that ET-1 system is involved in the pathogenesis of inflammation and fibrosis typical of SSc, through the activation of T lymphocytes and neutrophils and the consequent release of proinflammatory and profibrotic cytokines. These findings suggest that dual ET-1 receptors antagonist therapy, besides its effect on vasculopathy, has a profound impact on the immune system favouring antiinflammatory and antifibrogenic effects. PMID:26090478

  19. Endothelin receptor subtypes and their functional relevance in human small coronary arteries

    PubMed Central

    Pierre, Lisa N; Davenport, Anthony P

    1998-01-01

    The potent constrictor peptide endothelin (ET) has been implicated in various cardiovascular disorders including myocardial infarction and atherosclerosis. We have investigated the nature of ET receptor subtypes present on human small coronary arteries.Small coronary arteries were mounted in a wire-myograph for in vitro pharmacology. To investigate the ET receptor subtypes present in different segments of the coronary vascular tree, arteries were grouped according to internal diameter. Responses in arteries with small internal diameters (mean 316.7±7.9 μm; Group B) were compared to those in larger arteries (mean 586.2±23.1 μm; Group A).ET-1 consistently and potently contracted arteries from Group A and B, with EC50 values of 1.7 (0.9–3.2) nM (n=15) and 2.3 (1.4–4.2) nM (n=14), respectively. No correlation was observed between ET-1 potency and internal diameter. The response to ET-1 was potently antagonized by the selective ETA receptor antagonist PD156707 in both Group A and Group B, yielding pA2 values of 8.60±0.12 (n=4–6) and 8.38±0.17 (n=4–6), respectively. Slopes from Schild regression were not significantly different from unity.In contrast to ET-1, individual responses to ET-3 were variable. While all arteries from Group A responded to ET-3 (EC50∼69 (23–210) nM) (n=12), no response was obtained in 5 of the 14 tested in Group B. Of those responding, many failed to reach a maximum at concentrations up to 1 μM. ET-1 was more potent than ET-3 in all arteries tested. A biphasic ET-3 response was observed in 8 arteries suggesting that a small ETB population was also present in some patients. The selective ETB receptor agonist sarafotoxin S6c had little or no effect up to 10 nM (n=4–6).Responses to ET-1 and ET-3 were unaffected by removal of the endothelium in arteries from both groups suggesting a lack of functional, relaxant ETB receptors on endothelial cells (n=5).Using autoradiography, specific high density binding of the non

  20. Collecting duct-specific endothelin B receptor knockout increases ENaC activity

    PubMed Central

    Bugaj, Vladislav; Mironova, Elena; Kohan, Donald E.

    2012-01-01

    Collecting duct (CD)-derived endothelin-1 (ET-1) acting via endothelin B (ETB) receptors promotes Na+ excretion. Compromise of ET-1 signaling or ETB receptors in the CD cause sodium retention and increase blood pressure. Activity of the epithelial Na+ channel (ENaC) is limiting for Na+ reabsorption in the CD. To test for ETB receptor regulation of ENaC, we combined patch-clamp electrophysiology with CD-specific knockout (KO) of endothelin receptors. We also tested how ET-1 signaling via specific endothelin receptors influences ENaC activity under differing dietary Na+ regimens. ET-1 significantly decreased ENaC open probability in CD isolated from wild-type (WT) and CD ETA KO mice but not CD ETB KO and CD ETA/B KO mice. ENaC activity in WT and CD ETA but not CD ETB and CD ETA/B KO mice was inversely related to dietary Na+ intake. ENaC activity in CD ETB and CD ETA/B KO mice tended to be elevated under all dietary Na+ regimens compared with WT and CD ETA KO mice, reaching significance with high (2%) Na+ feeding. These results show that the bulk of ET-1 inhibition of ENaC activity is mediated by the ETB receptor. In addition, they could explain the Na+ retention and elevated blood pressure observed in CD ET-1 KO, CD ETB KO, and CD ETA/B KO mice consistent with ENaC regulation by ET-1 via ETB receptors contributing to the antihypertensive and natriuretic effects of the local endothelin system in the mammalian CD. PMID:21918182

  1. ENDOTHELIN-A RECEPTOR ANTAGONISM IN EMBRYO CULTURE: WINDOW OF SENSITIVITY AND TIMING OF DEFECT

    EPA Science Inventory

    BRANNEN, K.C., J.M. ROGERS, and E.S. HUNTER, Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina, and Reproductive Toxicology Division, NHEERL, U.S. EPA, Research Triangle Park, North Carolina. Endothelin-A receptor antagonism in embryo culture: w...

  2. ENDOTHELIN-A RECEPTOR ANTAGONISM IN EMBRYO CULTURE: WINDOW OF SENSITIVITY AND TIMING OF DEFECT

    EPA Science Inventory

    BRANNEN, K.C., J.M. ROGERS, and E.S. HUNTER, Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina, and Reproductive Toxicology Division, NHEERL, U.S. EPA, Research Triangle Park, North Carolina. Endothelin-A receptor antagonism in embryo culture: w...

  3. Functional study of endothelin B receptors in satellite glial cells in trigeminal ganglia.

    PubMed

    Feldman-Goriachnik, Rachel; Hanani, Menachem

    2011-07-13

    There is immunohistochemical evidence for endothelin (ET) receptors in satellite glial cells in sensory ganglia, but there is no information on the function of these receptors. We used calcium imaging to study this question in isolated mouse trigeminal ganglia and found that satellite glial cells are highly sensitive to ET-1, with threshold at 0.05 nM. Responses displayed strong desensitization at ET-1 concentrations of more than 1 nM. A large component of the response persisted when Ca was deleted from the external medium, consistent with Ca release from internal stores. The use of receptor selective agents showed that the responses were mediated by ETB receptors. We conclude that satellite glial cells display endothelin receptors, which may participate in neuron-glia communications in the trigeminal ganglia.

  4. Protective effects of endothelin-1 on acute pancreatitis in rats.

    PubMed

    Kogire, M; Inoue, K; Higashide, S; Takaori, K; Echigo, Y; Gu, Y J; Sumi, S; Uchida, K; Imamura, M

    1995-06-01

    Endothelin-1, a 21-residue peptide isolated from vascular endothelial cells, has a broad spectrum of actions. To clarify the involvement of endothelin-1 in acute pancreatitis, we examined the effects of endothelin-1 and its receptor antagonist BQ-123 on cerulein-induced pancreatitis in rats. Rats were infused intravenously with heparin-saline (control), endothelin-1 (100 pmol/kg/hr), cerulein (5 micrograms/kg/hr), or cerulein plus endothelin-1 for 3.5 hr. In another experiment, cerulein or cerulein plus BQ-123 (3 mg/kg/hr) was infused. Infusion of cerulein caused hyperamylasemia and pancreatic edema. Endothelin-1, when infused with cerulein, decreased the extent of pancreatic edema with a significant increase in the pancreatic dry- to wet-weight ratio. Histological changes induced by cerulein were markedly attenuated when endothelin-1 was given with cerulein. In contrast, endothelin-receptor blockade with BQ-123 further augmented pancreatic edema caused by cerulein. The extent of inflammatory cell infiltration was greater than BQ-123 was given with cerulein. Endothelin-1 or BQ-123 had no influence on hyperamylasemia. This study suggests that endothelin-1 has protective effects on experimental acute pancreatitis.

  5. Cigarette smoke exposure up-regulates endothelin receptor B in human pulmonary artery endothelial cells: molecular and functional consequences

    PubMed Central

    Milara, J; Ortiz, JL; Juan, G; Guijarro, R; Almudever, P; Martorell, M; Morcillo, EJ; Cortijo, J

    2010-01-01

    BACKGROUND AND PURPOSE Pulmonary arteries from smokers and chronic obstructive pulmonary disease patients show abnormal endothelium-dependent vascular reactivity. We studied the effect of cigarette smoke extract (CSE) on endothelin receptor B (ETB) expression in human pulmonary artery endothelial cells (HPAECs) and its role in endothelial dysfunction. EXPERIMENTAL APPROACH ETB receptor expression was measured by real time RT-PCR, Western blot and immunofluorescence. Cell contraction, intracellular Ca2+, F/G-actin, RhoA activity, myosin light chain phosphorylation, ET, NO, thromboxane (Tx)A2 and reactive oxygen species (ROS) were measured by traction microscopy, fluorescence microscopy, phalloidin fluorescence, colorimetric assay, Western blot, elisa and DCFDA fluorescence respectively. KEY RESULTS Cigarette smoke extract dose-dependently increased ETB receptor expression in HPAECs after 24 h incubation. CSE-induced ETB expression was attenuated by bosentan, the ETB receptor antagonist BQ788, the Rho kinase antagonist Y27632 and the antioxidant N-acetylcysteine. A monoclonal antibody to ET-1 prevented CSE-induced ETB receptor overexpression. Twenty-four hour exposure to ET-1 dose-dependently increased ETB receptor expression, mimicking the effect of CSE. CSE-induced ETB receptor overexpression caused greater cell contraction; increased intracellular Ca2+; increased F/G-actin and RhoA activity; increased myosin light chain phosphorylation; augmented TxA2 and ROS production; and decreased NO after acute ET-1 (10 nM). These effects were attenuated by bosentan, BQ788, Y27632 and N-acetylcysteine. CONCLUSIONS AND IMPLICATION Cigarette smoke extract induced ETB receptor overexpression by a feed forward mechanism mediated partly by ET release, promoting HPAEC dysfunction and attenuated by ETB receptor blockade, Rho kinase and ROS inhibition. These results provide support for the use of bosentan in CS-related endothelial dysfunction. PMID:20698855

  6. High-affinity neuropeptide Y receptor antagonists.

    PubMed Central

    Daniels, A J; Matthews, J E; Slepetis, R J; Jansen, M; Viveros, O H; Tadepalli, A; Harrington, W; Heyer, D; Landavazo, A; Leban, J J

    1995-01-01

    Neuropeptide Y (NPY) is one of the most abundant peptide transmitters in the mammalian brain. In the periphery it is costored and coreleased with norepinephrine from sympathetic nerve terminals. However, the physiological functions of this peptide remain unclear because of the absence of specific high-affinity receptor antagonists. Three potent NPY receptor antagonists were synthesized and tested for their biological activity in in vitro, ex vivo, and in vivo functional assays. We describe here the effects of these antagonists inhibiting specific radiolabeled NPY binding at Y1 and Y2 receptors and antagonizing the effects of NPY in human erythroleukemia cell intracellular calcium mobilization perfusion pressure in the isolated rat kidney, and mean arterial blood pressure in anesthetized rats. PMID:7568074

  7. High-affinity neuropeptide Y receptor antagonists.

    PubMed

    Daniels, A J; Matthews, J E; Slepetis, R J; Jansen, M; Viveros, O H; Tadepalli, A; Harrington, W; Heyer, D; Landavazo, A; Leban, J J; Spaltenstein, A

    1995-09-26

    Neuropeptide Y (NPY) is one of the most abundant peptide transmitters in the mammalian brain. In the periphery it is costored and coreleased with norepinephrine from sympathetic nerve terminals. However, the physiological functions of this peptide remain unclear because of the absence of specific high-affinity receptor antagonists. Three potent NPY receptor antagonists were synthesized and tested for their biological activity in in vitro, ex vivo, and in vivo functional assays. We describe here the effects of these antagonists inhibiting specific radiolabeled NPY binding at Y1 and Y2 receptors and antagonizing the effects of NPY in human erythroleukemia cell intracellular calcium mobilization perfusion pressure in the isolated rat kidney, and mean arterial blood pressure in anesthetized rats.

  8. Endothelin receptor antagonism prevents hypoxia-induced mortality and morbidity in a mouse model of sickle-cell disease

    PubMed Central

    Sabaa, Nathalie; de Franceschi, Lucia; Bonnin, Philippe; Castier, Yves; Malpeli, Giorgio; Debbabi, Haythem; Galaup, Ariane; Maier-Redelsperger, Micheline; Vandermeersch, Sophie; Scarpa, Aldo; Janin, Anne; Levy, Bernard; Girot, Robert; Beuzard, Yves; Leboeuf, Christophe; Henri, Annie; Germain, Stéphane; Dussaule, Jean-Claude; Tharaux, Pierre-Louis

    2008-01-01

    Patients with sickle-cell disease (SCD) suffer from tissue damage and life-threatening complications caused by vasoocclusive crisis (VOC). Endothelin receptors (ETRs) are mediators of one of the most potent vasoconstrictor pathways in mammals, but the relationship between vasoconstriction and VOC is not well understood. We report here that pharmacological inhibition of ETRs prevented hypoxia-induced acute VOC and organ damage in a mouse model of SCD. An in vivo ultrasonographic study of renal hemodynamics showed a substantial increase in endothelin-mediated vascular resistance during hypoxia/reoxygenation-induced VOC. This increase was reversed by administration of the dual ETR antagonist (ETRA) bosentan, which had pleiotropic beneficial effects in vivo. It prevented renal and pulmonary microvascular congestion, systemic inflammation, dense rbc formation, and infiltration of activated neutrophils into tissues with subsequent nitrative stress. Bosentan also prevented death of sickle-cell mice exposed to a severe hypoxic challenge. These findings in mice suggest that ETRA could be a potential new therapy for SCD, as it may prevent acute VOC and limit organ damage in sickle-cell patients. PMID:18382768

  9. Celecoxib offsets the negative renal influences of cyclosporine via modulation of the TGF-β1/IL-2/COX-2/endothelin ET(B) receptor cascade.

    PubMed

    El-Gowelli, Hanan M; Helmy, Maged W; Ali, Rabab M; El-Mas, Mahmoud M

    2014-03-01

    Endothelin (ET) signaling provokes nephrotoxicity induced by the immunosuppressant drug cyclosporine A (CSA). We tested the hypotheses that (i): celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, counterbalances renal derangements caused by CSA in rats and (ii) the COX-2/endothelin ET(B) receptor signaling mediates the CSA-celecoxib interaction. Ten-day treatment with CSA (20 mg/kg/day) significantly increased biochemical indices of renal function (serum urea, creatinine), inflammation (interleukin-2, IL-2) and fibrosis (transforming growth factor-β₁, TGF-β₁). Histologically, CSA caused renal tubular atrophy along with interstitial fibrosis. These detrimental renal effects of CSA were largely reduced in rats treated concurrently with celecoxib (10 mg/kg/day). We also report that cortical glomerular and medullary tubular protein expressions of COX-2 and ET(B) receptors were reduced by CSA and restored to near-control values in rats treated simultaneously with celecoxib. The importance of ET(B) receptors in renal control and in the CSA-celecoxib interaction was further verified by the findings (i) most of the adverse biochemical, inflammatory, and histopathological profiles of CSA were replicated in rats treated with the endothelin ETB receptor antagonist BQ788 (0.1 mg/kg/day, 10 days), and (ii) the BQ788 effects, like those of CSA, were alleviated in rats treated concurrently with celecoxib. Together, the data suggest that the facilitation of the interplay between the TGF-β1/IL-2/COX-2 pathway and the endothelin ET(B) receptors constitutes the cellular mechanism by which celecoxib ameliorates the nephrotoxic manifestations of CSA in rats.

  10. Pharmacological analysis of calcium antagonist receptors

    SciTech Connect

    Reynolds, I.J.

    1987-01-01

    This work focuses on two aspects of the action of calcium antagonist drugs, namely, the interaction of drugs with receptors for verapamil-like calcium antagonists, and the interactions of drugs with voltage-sensitive calcium fluxes in rat brain synaptosomes. From binding studies I have found that the ligand of choice for labeling the verapamil receptor is (-)(/sup 3/H)desmethoxy-verapamil. This drug labels potently, reversibly and stereoselectively two receptors in membranes prepared from rat brain and rabbit skeletal muscle tissues. In equilibrium studies dihydropyridine calcium antagonists interact in a non-competitive fashion, while many non-DHPs are apparently competitive. In-depth kinetic studies in skeletal muscle membranes indicate that the two receptors are linked in a negative heterotropic fashion, and that low-affinity binding of (-) (/sup 3/H)desmethoxy-verapamil may be to the diltiazem receptor. However, these studies were not able to distinguish between the hypothesis that diltiazem binds to spatially separate, allosterically coupled receptors, and the hypothesis that diltiazem binds to a subsite of the verapamil receptor.

  11. Emerging cardiovascular indications of mineralocorticoid receptor antagonists.

    PubMed

    Parviz, Yasir; Iqbal, Javaid; Pitt, Bertram; Adlam, David; Al-Mohammad, Abdallah; Zannad, Faiez

    2015-04-01

    Mineralocorticoid receptor (MR) antagonism is a well-established treatment modality for patients with hypertension, heart failure, and left ventricular systolic dysfunction (LVSD) post-myocardial infarction (MI). There are emerging data showing potential benefits of MR antagonists in other cardiovascular conditions. Studies have shown association between MR activation and the development of myocardial fibrosis, coronary artery disease, metabolic syndrome, and cerebrovascular diseases. This review examines the preclinical and clinical data of MR antagonists for novel indications including heart failure with preserved ejection fraction (HFPEF), pulmonary arterial hypertension (PAH), arrhythmia, sudden cardiac death, valvular heart disease, metabolic syndrome, renal disease, and stroke. MR antagonists are not licensed for these conditions yet; however, emerging data suggest that indication for MR antagonists are likely to broaden; further studies are warranted.

  12. Endothelin-1 and ET receptors impair left ventricular function by mediated coronary arteries dysfunction in chronic intermittent hypoxia rats.

    PubMed

    Wang, Jin-Wei; Li, Ai-Ying; Guo, Qiu-Hong; Guo, Ya-Jing; Weiss, James W; Ji, En-Sheng

    2017-01-01

    Obstructive sleep apnea (OSA) results in cardiac dysfunction and vascular endothelium injury. Chronic intermittent hypoxia (CIH), the main characteristic of OSAS, is considered to be mainly responsible for cardiovascular system impairment. This study is aimed to evaluate the role of endothelin-1(ET-1) system in coronary injury and cardiac dysfunction in CIH rats. In our study, Sprague-Dawley rats were exposed to CIH (FiO2 9% for 1.5 min, repeated every 3 min for 8 h/d, 7 days/week for 3 weeks). After 3 weeks, the left ventricular developed pressure (LVDP) and coronary resistance (CR) were measured with the langendorff mode in isolated hearts. Meanwhile, expressions of ET-1 and ET receptors were detected by immunohistochemical and western blot, histological changes were also observed to determine effects of CIH on coronary endothelial cells. Results suggested that decreased LVDP level combined with augmented coronary resistance was exist in CIH rats. CIH could induce endothelial injury and endothelium-dependent vasodilatation dysfunction in the coronary arteries. Furthermore, ET-1 and ETA receptor expressions in coronary vessels were increased after CIH exposure, whereas ETB receptors expression was decreased. Coronary contractile response to ET-1 in both normoxia and CIH rats was inhibited by ETA receptor antagonist BQ123. However, ETB receptor antagonist BQ788 enhanced ET-1-induced contractile in normoxia group, but had no significant effects on CIH group. These results indicate that CIH-induced cardiac dysfunction may be associated with coronary injury. ET-1 plays an important role in coronary pathogenesis of CIH through ETA receptor by mediating a potent vasoconstrictor response. Moreover, decreased ETB receptor expression that leads to endothelium-dependent vasodilatation decline, might be also participated in coronary and cardiac dysfunction.

  13. Trypanosoma cruzi invades host cells through the activation of endothelin and bradykinin receptors: a converging pathway leading to chagasic vasculopathy

    PubMed Central

    Andrade, Daniele; Serra, Rafaela; Svensjö, Erik; Lima, Ana Paula C; Ramos Junior, Erivan S; Fortes, Fabio S; Morandini, Ana Carolina F; Morandi, Verônica; Soeiro, Maria de N; Tanowitz, Herbert B; Scharfstein, Julio

    2012-01-01

    BACKGROUND AND PURPOSE Independent studies in experimental models of Trypanosoma cruzi appointed different roles for endothelin-1 (ET-1) and bradykinin (BK) in the immunopathogenesis of Chagas disease. Here, we addressed the hypothesis that pathogenic outcome is influenced by functional interplay between endothelin receptors (ETAR and ETBR) and bradykinin B2 receptors (B2R). EXPERIMENTAL APPROACH Intravital microscopy was used to determine whether ETR/B2R drives the accumulation of rhodamine-labelled leucocytes in the hamster cheek pouch (HCP). Inflammatory oedema was measured in the infected BALB/c paw of mice. Parasite invasion was assessed in CHO over-expressing ETRs, mouse cardiomyocytes, endothelium (human umbilical vein endothelial cells) or smooth muscle cells (HSMCs), in the presence/absence of antagonists of B2R (HOE-140), ETAR (BQ-123) and ETBR (BQ-788), specific IgG antibodies to each GPCRs; cholesterol or calcium-depleting drugs. RNA interference (ETAR or ETBR genes) in parasite infectivity was investigated in HSMCs. KEY RESULTS BQ-123, BQ-788 and HOE-140 reduced leucocyte accumulation in HCP topically exposed to trypomastigotes and blocked inflammatory oedema in infected mice. Acting synergistically, ETAR and ETBR antagonists reduced parasite invasion of HSMCs to the same extent as HOE-140. Exogenous ET-1 potentiated T. cruzi uptake by HSMCs via ETRs/B2R, whereas RNA interference of ETAR and ETBR genes conversely reduced parasite internalization. ETRs/B2R-driven infection in HSMCs was reduced in HSMC pretreated with methyl-β-cyclodextrin, a cholesterol-depleting drug, or in thapsigargin- or verapamil-treated target cells. CONCLUSIONS AND IMPLICATIONS Our findings suggest that plasma leakage, a neutrophil-driven inflammatory response evoked by trypomastigotes via the kinin/endothelin pathways, may offer a window of opportunity for enhanced parasite invasion of cardiovascular cells. LINKED ARTICLE This paper is commented on by D'Orléans-Juste et al

  14. NMDA Receptor Antagonists for Treatment of Depression

    PubMed Central

    Ates-Alagoz, Zeynep; Adejare, Adeboye

    2013-01-01

    Depression is a psychiatric disorder that affects millions of people worldwide. Individuals battling this disorder commonly experience high rates of relapse, persistent residual symptoms, functional impairment, and diminished well-being. Medications have important utility in stabilizing moods and daily functions of many individuals. However, only one third of patients had considerable improvement with a standard antidepressant after 2 months and all patients had to deal with numerous side effects. The N-methyl-d-aspartate (NMDA) receptor family has received special attention because of its critical role in psychiatric disorders. Direct targeting of the NMDA receptor could result in more rapid antidepressant effects. Antidepressant-like effects of NMDA receptor antagonists have been demonstrated in different animal models. MK-801 (a use-dependent channel blocker), and CGP 37849 (an NMDA receptor antagonist) have shown antidepressant properties in preclinical studies, either alone or combined with traditional antidepressants. A recent development is use of ketamine clinically for refractory depression. The purpose of this review is to examine and analyze current literature on the role of NMDA receptor antagonists for treatment of depression and whether this is a feasible route in drug discovery. PMID:24276119

  15. Medicinal Chemistry of Competitive Kainate Receptor Antagonists

    PubMed Central

    2010-01-01

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1−5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure−activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

  16. Medicinal chemistry of competitive kainate receptor antagonists.

    PubMed

    Larsen, Ann M; Bunch, Lennart

    2011-02-16

    Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1-5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure-activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field.

  17. Risk Factors in Normal-Tension Glaucoma and High-Tension Glaucoma in relation to Polymorphisms of Endothelin-1 Gene and Endothelin-1 Receptor Type A Gene

    PubMed Central

    Wróbel-Dudzińska, Dominika; Kosior-Jarecka, Ewa; Łukasik, Urszula; Kocki, Janusz; Witczak, Agnieszka; Mosiewicz, Jerzy; Żarnowski, Tomasz

    2015-01-01

    The aim of the research is to analyse the influence of polymorphisms of endothelin-1 gene and endothelin-1 receptor type A gene on the clinical condition of patients with primary open angle glaucoma. Methods. 285 Polish patients took part in the research (160 normal-tension glaucoma and 125 high-tension glaucoma). DNA was isolated by standard methods and genotype distributions of four polymorphisms in genes encoding endothelin-1 (K198N) and endothelin-1 receptor type A polymorphisms (C1222T, C70G, and G231A) were determined. Genotype distributions were compared between NTG and HTG groups. The clinical condition of participants was examined for association with polymorphisms. Results. A similar frequency of occurrence of the polymorphic varieties of the studied genes was observed in patients with NTG and HTG. There is no relation between NTG risk factors and examined polymorphisms. NTG patients with TT genotype of K198N polymorphism presented with the lowest intraocular pressure in comparison to GG + GT genotype (p = 0.03). In NTG patients with CC genotype of C1222T polymorphism (p = 0.028) and GG of C70G polymorphism (p = 0.03) the lowest values of mean blood pressure were observed. Conclusions. The studied polymorphic varieties (K198N, C1222T) do have an influence on intraocular pressure as well as arterial blood pressure in NTG patients. PMID:26697209

  18. Agonists and antagonists for P2 receptors

    PubMed Central

    Jacobson, Kenneth A.; Costanzi, Stefano; Joshi, Bhalchandra V.; Besada, Pedro; Shin, Dae Hong; Ko, Hyojin; Ivanov, Andrei A.; Mamedova, Liaman

    2015-01-01

    Recent work has identified nucleotide agonists selective for P2Y1, P2Y2 and P2Y6 receptors and nucleotide antagonists selective for P2Y1, P2Y12 and P2X1 receptors. Selective non-nucleotide antagonists have been reported for P2Y1, P2Y2, P2Y6, P2Y12, P2Y13, P2X2/3/P2X3 and P2X7 receptors. For example, the dinucleotide INS 37217 (Up4dC) potently activates the P2Y2 receptor, and the non-nucleotide antagonist A-317491 is selective for P2X2/3/P2X3 receptors. Nucleotide analogues in which the ribose moiety is substituted by a variety of novel ring systems, including conformation-ally locked moieties, have been synthesized as ligands for P2Y receptors. The focus on conformational factors of the ribose-like moiety allows the inclusion of general modifications that lead to enhanced potency and selectivity. At P2Y1,2,4,11 receptors, there is a preference for the North conformation as indicated with (N)-methanocarba analogues. The P2Y1 antagonist MRS2500 inhibited ADP-induced human platelet aggregation with an IC50 of 0.95 nM. MRS2365, an (N)-methanocarba analogue of 2-MeSADP, displayed potency (EC50) of 0.4 nM at the P2Y1 receptor, with >10 000-fold selectivity in comparison to P2Y12 and P2Y13 receptors. At P2Y6 receptors there is a dramatic preference for the South conformation. Three-dimensional structures of P2Y receptors have been deduced from structure activity relationships (SAR), mutagenesis and modelling studies. Detailed three-dimensional structures of P2X receptors have not yet been proposed. PMID:16805423

  19. Muscarinic Receptor Antagonists: Effects on Pulmonary Function

    PubMed Central

    Buels, Kalmia S.

    2014-01-01

    In healthy lungs, muscarinic receptors control smooth muscle tone, mucus secretion, vasodilation, and inflammation. In chronic obstructive pulmonary disease (COPD) and asthma, cholinergic mechanisms contribute to increased bronchoconstriction and mucus secretion that limit airflow. This chapter reviews neuronal and nonneuronal sources of acetylcholine in the lung and the expression and role of M1, M2, and M3 muscarinic receptor subtypes in lung physiology. It also discusses the evidence for and against the role of parasympathetic nerves in asthma, and the current use and therapeutic potential of muscarinic receptor antagonists in COPD and asthma. PMID:22222705

  20. The endothelin B receptor plays a crucial role in the adhesion of neutrophils to the endothelium in sickle cell disease

    PubMed Central

    Koehl, Bérengère; Nivoit, Pierre; El Nemer, Wassim; Lenoir, Olivia; Hermand, Patricia; Pereira, Catia; Brousse, Valentine; Guyonnet, Léa; Ghinatti, Giulia; Benkerrou, Malika; Colin, Yves; Le Van Kim, Caroline; Tharaux, Pierre-Louis

    2017-01-01

    Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ETB receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ETB receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ETB function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ETB axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ETB, may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients. PMID:28385784

  1. Celecoxib offsets the negative renal influences of cyclosporine via modulation of the TGF-β1/IL-2/COX-2/endothelin ET{sub B} receptor cascade

    SciTech Connect

    El-Gowelli, Hanan M.; Helmy, Maged W.; Ali, Rabab M.; El-Mas, Mahmoud M.

    2014-03-01

    Endothelin (ET) signaling provokes nephrotoxicity induced by the immunosuppressant drug cyclosporine A (CSA). We tested the hypotheses that (i): celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, counterbalances renal derangements caused by CSA in rats and (ii) the COX-2/endothelin ET{sub B} receptor signaling mediates the CSA-celecoxib interaction. Ten-day treatment with CSA (20 mg/kg/day) significantly increased biochemical indices of renal function (serum urea, creatinine), inflammation (interleukin-2, IL-2) and fibrosis (transforming growth factor-β{sub 1}, TGF-β{sub 1}). Histologically, CSA caused renal tubular atrophy along with interstitial fibrosis. These detrimental renal effects of CSA were largely reduced in rats treated concurrently with celecoxib (10 mg/kg/day). We also report that cortical glomerular and medullary tubular protein expressions of COX-2 and ET{sub B} receptors were reduced by CSA and restored to near-control values in rats treated simultaneously with celecoxib. The importance of ET{sub B} receptors in renal control and in the CSA-celecoxib interaction was further verified by the findings (i) most of the adverse biochemical, inflammatory, and histopathological profiles of CSA were replicated in rats treated with the endothelin ET{sub B} receptor antagonist BQ788 (0.1 mg/kg/day, 10 days), and (ii) the BQ788 effects, like those of CSA, were alleviated in rats treated concurrently with celecoxib. Together, the data suggest that the facilitation of the interplay between the TGF-β1/IL-2/COX-2 pathway and the endothelin ET{sub B} receptors constitutes the cellular mechanism by which celecoxib ameliorates the nephrotoxic manifestations of CSA in rats. - Highlights: • Celecoxib abolishes nephrotoxic manifestations of CSA in rats. • Blockade of ETB receptors by BQ788 mimicked the nephrotoxic effects of CSA. • CSA or BQ788 reduces renal protein expression of COX-2 and endothelin ETB receptors. • Enhanced TGFβ1/IL-2/COX2/ETB

  2. Long-Term Endothelin-A Receptor Antagonism Provides Robust Renal Protection in Humanized Sickle Cell Disease Mice.

    PubMed

    Kasztan, Malgorzata; Fox, Brandon M; Speed, Joshua S; De Miguel, Carmen; Gohar, Eman Y; Townes, Tim M; Kutlar, Abdullah; Pollock, Jennifer S; Pollock, David M

    2017-03-27

    Sickle cell disease (SCD)-associated nephropathy is a major source of morbidity and mortality in patients because of the lack of efficacious treatments targeting renal manifestations of the disease. Here, we describe a long-term treatment strategy with the selective endothelin-A receptor (ETA) antagonist, ambrisentan, designed to interfere with the development of nephropathy in a humanized mouse model of SCD. Ambrisentan preserved GFR at the level of nondisease controls and prevented the development of proteinuria, albuminuria, and nephrinuria. Microscopy studies demonstrated prevention of podocyte loss and structural alterations, the absence of vascular congestion, and attenuation of glomerulosclerosis in treated mice. Studies in isolated glomeruli showed that treatment reduced inflammation and oxidative stress. At the level of renal tubules, ambrisentan treatment prevented the increased excretion of urinary tubular injury biomarkers. Additionally, the treatment strategy prevented tubular brush border loss, diminished tubular iron deposition, blocked the development of interstitial fibrosis, and prevented immune cell infiltration. Furthermore, the prevention of albuminuria in treated mice was associated with preservation of cortical megalin expression. In a separate series of identical experiments, combined ETA and ETB receptor antagonism provided only some of the protection observed with ambrisentan, highlighting the importance of exclusively targeting the ETA receptor in SCD. Our results demonstrate that ambrisentan treatment provides robust protection from diverse renal pathologies in SCD mice, and suggest that long-term ETA receptor antagonism may provide a strategy for the prevention of renal complications of SCD.

  3. Control of Endothelin-A Receptor Expression by Progesterone Is Enhanced by Synergy With Gata2

    PubMed Central

    Zhang, Yanping; Knutsen, Gregory R.; Brown, Matthew D.

    2013-01-01

    The endothelin-A receptor (Ednra) is involved in several physiological, pathological, and developmental pathways. Known for its function in vasoconstriction after being activated by endothelin-1, Ednra also controls cephalic neural crest cell development and appears to play a role in several pathologies, including cancer and periodontitis. However, the mechanisms regulating Ednra expression have not been identified despite its important functions. In this study, we investigated the role progesterone plays in Ednra gene expression in vivo and in vitro. In mice, pregnancy promotes Ednra expression in the heart, kidney, lung, uterus, and placenta, and the up-regulation is mediated by progesterone. We determined that the conserved region between −5.7 and −4.2 kb upstream of the mouse Ednra gene is necessary for the progesterone response. We also found that progesterone mediates Ednra activation through progesterone receptor B activation by its recruitment to PRE6, one of the 6 progesterone response elements found in that locus. However, gene activation by means of a GATA2 site was also necessary for the progesterone response. The Gata2 transcription factor enhances the progesterone response mediated by the progesterone receptor B. Together these results indicate that progesterone regulates Ednra expression by synergizing with Gata2 activity, a previously unknown mechanism. This mechanism may have an impact on pathologies involving the endothelin signaling. PMID:23592430

  4. Mutations in the Endothelin Receptor Type A Cause Mandibulofacial Dysostosis with Alopecia

    PubMed Central

    Gordon, Christopher T.; Weaver, K. Nicole; Zechi-Ceide, Roseli Maria; Madsen, Erik C.; Tavares, Andre L.P.; Oufadem, Myriam; Kurihara, Yukiko; Adameyko, Igor; Picard, Arnaud; Breton, Sylvain; Pierrot, Sébastien; Biosse-Duplan, Martin; Voisin, Norine; Masson, Cécile; Bole-Feysot, Christine; Nitschké, Patrick; Delrue, Marie-Ange; Lacombe, Didier; Guion-Almeida, Maria Leine; Moura, Priscila Padilha; Garib, Daniela Gamba; Munnich, Arnold; Ernfors, Patrik; Hufnagel, Robert B.; Hopkin, Robert J.; Kurihara, Hiroki; Saal, Howard M.; Weaver, David D.; Katsanis, Nicholas; Lyonnet, Stanislas; Golzio, Christelle; Clouthier, David E.; Amiel, Jeanne

    2015-01-01

    The endothelin receptor type A (EDNRA) signaling pathway is essential for the establishment of mandibular identity during development of the first pharyngeal arch. We report four unrelated individuals with the syndrome mandibulofacial dysostosis with alopecia (MFDA) who have de novo missense variants in EDNRA. Three of the four individuals have the same substitution, p.Tyr129Phe. Tyr129 is known to determine the selective affinity of EDNRA for endothelin 1 (EDN1), its major physiological ligand, and the p.Tyr129Phe variant increases the affinity of the receptor for EDN3, its non-preferred ligand, by two orders of magnitude. The fourth individual has a somatic mosaic substitution, p.Glu303Lys, and was previously described as having Johnson-McMillin syndrome. The zygomatic arch of individuals with MFDA resembles that of mice in which EDNRA is ectopically activated in the maxillary prominence, resulting in a maxillary to mandibular transformation, suggesting that the p.Tyr129Phe variant causes an EDNRA gain of function in the developing upper jaw. Our in vitro and in vivo assays suggested complex, context-dependent effects of the EDNRA variants on downstream signaling. Our findings highlight the importance of finely tuned regulation of EDNRA signaling during human craniofacial development and suggest that modification of endothelin receptor-ligand specificity was a key step in the evolution of vertebrate jaws. PMID:25772936

  5. A novel radiologand [[sup 125]I]BQ-3020 selective for endothelin (ET[sub B]) receptors

    SciTech Connect

    Ihara, Masaki; Saeki, Toshihiko; Fukuroda, Takahiro; Kimura, Sachiyo; Ozaki, Satoshi; Yano, Mitsuo ); Patel, A.C. )

    1992-01-01

    A linear endothelin (ET) analog, N-acetyl-LeuMetAspLysGluAlaValTryPheAlaHisLeuAspIleIleTrp (BQ-3020), is highly selective for ET[sub B] receptors. BQ-3020 displaces [[sup 125]I]ET-1 binding to ET[sub B] receptors in porcine cerebellar membranes at a concentration 4,700 times lower than that of ET[sub A] receptors on aortic vascular smooth muscle cells (VSMC). BQ-3929 as well as ET-1 and ET-3 elicits vasoconstriction in the rabbit pulmonary artery. The ET[sub A] antagonist BB-123 failed to inhibit this BQ-3020-induced vasocontraction. Futhermore, BQ-3929 elicits endothelium-dependent vasodilation. These data indicate that BQ-3020 has ET[sub B]agonistic activity. The radioligand [[sup 125]I]BQ-3020 binds to cerebellar membranes at single high affinity sites, whereas it scarcely binds to VSMC. [[sup 125]I]BQ-3020 binding to the cerebellum was displaced by BQ-3020, ET-1 and ET-3 in a nonselective manner. However, the binding of [[sup 125]I]BQ-3020 was insensitive to the ET[sub A] antagonist BQ-123 and other bioactive peptides. Both [[sup 125]I]ET-1 and [[sup 125]I]BQ-3020 show slow onset and offset binding kinetics to ET[sub B] receptors. These data indicate that the radioligand [[sup 125]I]BQ-3020 selectively labels ET[sub B] receptors and that the slow binding kinetics of ET-1 are dependent on the peptide sequence from Leu[sup 6] to Trp[sup 21], but not on the structure formed by its two disulfide bridges.

  6. Salvianolic Acid A, as a Novel ETA Receptor Antagonist, Shows Inhibitory Effects on Tumor in Vitro

    PubMed Central

    Zhang, Qiao; Wang, Shifeng; Yu, Yangyang; Sun, Shengnan; Zhang, Yuxin; Zhang, Yanling; Yang, Wei; Li, Shiyou; Qiao, Yanjiang

    2016-01-01

    Endothelin-1 (ET-1) autocrine and paracrine signaling modulate cell proliferation of tumor cells by activating its receptors, endothelin A receptor (ETAR) and endothelin B receptor (ETBR). Dysregulation of ETAR activation promotes tumor development and progression. The potential of ETAR antagonists and the dual-ETAR and ETBR antagonists as therapeutic approaches are under preclinical and clinical studies. Salvianolic acid A (Sal A) is a hydrophilic polyphenolic derivative isolated from Salvia miltiorrhiza Bunge (Danshen), which has been reported as an anti-cancer and cardio-protective herbal medicine. In this study, we demonstrate that Sal A inhibits ETAR activation induced by ET-1 in both recombinant and endogenous ETAR expression cell lines. The IC50 values were determined as 5.7 µM in the HEK293/ETAR cell line and 3.14 µM in HeLa cells, respectively. Furthermore, our results showed that Sal A suppressed cell proliferation and extended the doubling times of multiple cancer cells, including HeLa, DU145, H1975, and A549 cell lines. In addition, Sal A inhibited proliferation of DU145 cell lines stimulated by exogenous ET-1 treatment. Moreover, the cytotoxicity and cardio-toxicity of Sal A were assessed in human umbilical vein endothelial cells (HUVEC) and Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs), which proved that Sal A demonstrates no cytotoxicity or cardiotoxicity. Collectively, our findings indicate that Sal A is a novel anti-cancer candidate through targeting ETAR. PMID:27490540

  7. Development of Kappa Opioid Receptor Antagonists

    PubMed Central

    Carroll, F. Ivy; Carlezon, William A.

    2013-01-01

    Kappa opioid receptors (KORs) belong to the G-protein coupled class of receptors (GPCRs). They are activated by the endogenous opioid peptide dynorphin (DYN) and expressed at particularly high levels within brain areas implicated in modulation of motivation, emotion, and cognitive function. Chronic activation of KORs in animal models has maladaptive effects including increases in behaviors that reflect depression, the propensity to engage in drug-seeking behavior, and drug craving. The fact that KOR activation has such a profound influence on behaviors often triggered by stress has led to interest in selective KOR antagonists as potential therapeutic agents. This perspective provides a description of preclinical research conducted in the development of several different classes of selective KOR antagonists, a summary of the clinical studies conducted thus far, and recommendations for the type of work needed in the future to determine if these agents would be useful as pharmacotherapies for neuropsychiatric illness. PMID:23360448

  8. Collecting duct-specific knockout of the endothelin B receptor causes hypertension and sodium retention.

    PubMed

    Ge, Yuqiang; Bagnall, Alan; Stricklett, Peter K; Strait, Kevin; Webb, David J; Kotelevtsev, Yuri; Kohan, Donald E

    2006-12-01

    Collecting duct (CD)-derived endothelin-1 (ET-1) inhibits renal Na reabsorption and its deficiency increases blood pressure (BP). The role of CD endothelin B (ETB) receptors in mediating these effects is unknown. CD-specific knockout of the ETB receptor was achieved using an aquaporin-2 promoter-Cre recombinase transgene and the loxP-flanked ETB receptor gene (CD ETB KO). Systolic BP in mice with CD-specific knockout of the ETB receptor, ETA receptor (CD ETA KO) and ET-1 (CD ET-1 KO), and their respective controls were compared during normal- and high-salt diet. On a normal-sodium diet, CD ETB KO mice had elevated BP, which increased further during high salt feeding. However, the degree of hypertension in CD ETB KO mice and the further increase in BP during salt feeding were lower than that of CD ET-1 KO mice, whereas CD ETA KO mice were normotensive. CD ETB KO mice had impaired sodium excretion following acute sodium loading. Aldosterone and plasma renin activity were decreased in CD ETB KO mice on normal- and high-sodium diets, while plasma and urinary ET-1 levels did not differ from controls. In conclusion, the CD ETB receptor partially mediates the antihypertensive and natriuretic effects of ET-1. CD ETA and ETB receptors do not fully account for the antihypertensive and natriuretic effects of CD-derived ET-1, suggesting paracrine effects of this peptide.

  9. 25 years of endothelin research: the next generation.

    PubMed

    Emoto, Noriaki; Vignon-Zellweger, Nicolas; Lopes, Rhéure Alves Moreira; Cacioppo, Joseph; Desbiens, Louisane; Kamato, Danielle; Leurgans, Thomas; Moorhouse, Rebecca; Straube, Julia; Wurm, Raphael; Heiden, Susi; Ergul, Adviye; Yanagisawa, Masashi; Barton, Matthias

    2014-11-24

    In the past three decades, endothelin and endothelin receptor antagonists have received great scientific and clinical interest, leading to the publication of more than 27,000 scientific articles since its discovery. The Thirteenth International Conference on Endothelin (ET-13) was held on September 8-11, 2013, at Tokyo Campus of the University of Tsukuba in Japan. Close to 300 scientists from 25 countries from around the world came to Tokyo to celebrate the anniversary of the discovery of the endothelin peptide discovered 25 years ago at the University of Tsukuba. This article summarizes some of the highlights of the conference, the anniversary celebration ceremony, and particularly the participation of next generation of endothelin researchers in endothelin science and the anniversary celebration. As a particular highlight, next generation endothelin researchers wrote a haiku (a traditional form of Japanese poetry originating from consisting of no more than three short verses and 27 on, or Japanese phonetic units) to describe the magic of endothelin science which they presented to the conference audience at the anniversary ceremony. The text of each haiku - both in its original language together with the English translation - is part of this article providing in an exemplary fashion how poetry can be bridged with science. Finally, we give an outlook towards the next 25 years of endothelin research.

  10. Endothelin-converting enzyme inhibitors: their application in cardiovascular diseases.

    PubMed

    Cerdeira, Ana Sofia; Brás-Silva, Carmen; Leite-Moreira, Adelino F

    2008-03-01

    Endothelin, a potent vasoconstrictor first described in 1988 by Yanagisawa, is an important regulator of cardiovascular function. Hyperactivation of the endothelin system has been implicated in the pathogenesis of various cardiovascular disorders including myocardial infarction, restenosis, hypertension, heart failure and Chagas cardiopathy. Various attempts have been made to suppress this axis. Although promising, the results of clinical trials on endothelin receptor antagonists have been disappointing. There is growing interest in blockade of endothelin formation. Several selective and non-selective endothelin-converting enzyme (ECE) inhibitors have been developed, the latter with the possibility of simultaneously blocking angiotensin-converting enzyme and neutral endopeptidase, combining inhibition more than one axis. This article reviews the different ECE inhibitors, with particular emphasis on their potential clinical application in cardiovascular diseases.

  11. Endothelin-1 (ET-1) stimulates carboxy terminal Smad2 phosphorylation in vascular endothelial cells by a mechanism dependent on ET receptors and de novo protein synthesis.

    PubMed

    Sharifat, Narges; Mohammad Zadeh, Ghorban; Ghaffari, Mohammad-Ali; Dayati, Parisa; Kamato, Danielle; Little, Peter J; Babaahmadi-Rezaei, Hossein

    2017-01-01

    G protein-coupled receptor (GPCR) agonists through their receptors can transactivate protein tyrosine kinase receptors such as epidermal growth factor receptor and serine/threonine kinase receptors most notably transforming growth factor (TGF)-β receptor (TβRI). This signalling mechanism represents a major expansion in the cellular outcomes attributable to GPCR signalling. This study addressed the role and mechanisms involved in GPCR agonist, endothelin-1 (ET-1)-mediated transactivation of the TβRI in bovine aortic endothelial cells (BAECs). The in-vitro model used BAECs. Signalling intermediate phospho-Smad2 in the carboxy terminal was detected and quantified by Western blotting. ET-1 treatment of BAECs resulted in a time and concentration-dependent increase in pSmad2C. Peak phosphorylation was evident with 100 nm treatment of ET-1 at 4-6 h. TβRI antagonist, SB431542 inhibited ET-1-mediated pSmad2C. In the presence of bosentan, a mixed ETA and ETB receptor antagonist ET-1-mediated pSmad2C levels were inhibited. The ET-mediated pSmad2C was blocked by the protein synthesis inhibitor, cycloheximide. In BAECs, ET-1 via the ETB receptor is involved in transactivation of the TβRI. The transactivation-dependent response is dependent upon de novo protein synthesis. © 2016 Royal Pharmaceutical Society.

  12. Decreased endothelin receptor B expression in large primary uveal melanomas is associated with early clinical metastasis and short survival

    PubMed Central

    Smith, S L; Damato, B E; Scholes, A G M; Nunn, J; Field, J K; Heighway, J

    2002-01-01

    The most devastating aspect of cancer is the metastasis of tumour cells to organs distant from the original tumour site. The major problem facing oncologists treating uveal melanoma, the most common cancer of the eye, is metastatic disease. To lower mortality, it is necessary to increase our understanding of the molecular genetic alterations involved in this process. Using suppression subtractive hybridisation, we have analysed differential gene expression between four primary tumours from patients who have developed clinical metastasis and four primary tumours from patients with no evidence of metastasis to date. We have identified endothelin receptor type B as differentially expressed between these tumours and confirmed this observation using comparative multiplex RT–PCR. In a further 33 tumours, reduced endothelin receptor type B expression correlated with death from metastatic disease. Reduced expression also correlated with other known prognostic indicators, including the presence of epithelioid cells, chromosome 3 allelic imbalance and chromosome 8q allelic imbalance. Endothelin receptor type B expression was also reduced in four out of four primary small cell lung carcinomas compared to normal bronchial epithelium. We also show that the observed down-regulation of endothelin receptor type B in uveal melanoma was not due to gene deletion. Our findings suggest a role for endothelin receptor type B in the metastasis of uveal melanoma and, potentially, in the metastasis of other neural crest tumours. British Journal of Cancer (2002) 87, 1308–1313. doi:10.1038/sj.bjc.6600620 www.bjcancer.com © 2002 Cancer Research UK PMID:12439722

  13. Activation of purinergic receptors (P2) in the renal medulla promotes endothelin-dependent natriuresis in male rats.

    PubMed

    Gohar, Eman Y; Speed, Joshua S; Kasztan, Malgorzata; Jin, Chunhua; Pollock, David M

    2016-08-01

    Renal endothelin-1 (ET-1) and purinergic signaling systems regulate Na(+) reabsorption in the renal medulla. A link between the renal ET-1 and purinergic systems was demonstrated in vitro, however, the in vivo interaction between these systems has not been defined. To test whether renal medullary activation of purinergic (P2) receptors promotes ET-dependent natriuresis, we determined the effect of increased medullary NaCl loading on Na(+) excretion and inner medullary ET-1 mRNA expression in anesthetized adult male Sprague-Dawley rats in the presence and absence of purinergic receptor antagonism. Isosmotic saline (NaCl; 284 mosmol/kgH2O) was infused into the medullary interstitium (500 μl/h) during a 30-min baseline urine collection period, followed by isosmotic or hyperosmotic saline (1,800 mosmol/kgH2O) for two further 30-min urine collection periods. Na(+) excretion was significantly increased during intramedullary infusion of hyperosmotic saline. Compared with isosmotic saline, hyperosmotic saline infused into the renal medulla caused significant increases in inner medullary ET-1 mRNA expression. Renal intramedullary infusion of the P2 receptor antagonist suramin inhibited the increase in Na(+) excretion and inner medullary ET-1 mRNA expression induced by NaCl loading in the renal medulla. Activation of medullary P2Y2/4 receptors by infusion of UTP increased urinary Na(+) excretion. Combined ETA and ETB receptor blockade abolished the natriuretic response to intramedullary infusion of UTP. These data demonstrate that activation of medullary P2 receptors promotes ET-dependent natriuresis in male rats, suggesting that the renal ET-1 and purinergic signaling systems interact to efficiently facilitate excretion of a NaCl load.

  14. Investigation of orexin-2 selective receptor antagonists: Structural modifications resulting in dual orexin receptor antagonists.

    PubMed

    Skudlarek, Jason W; DiMarco, Christina N; Babaoglu, Kerim; Roecker, Anthony J; Bruno, Joseph G; Pausch, Mark A; O'Brien, Julie A; Cabalu, Tamara D; Stevens, Joanne; Brunner, Joseph; Tannenbaum, Pamela L; Wuelfing, W Peter; Garson, Susan L; Fox, Steven V; Savitz, Alan T; Harrell, Charles M; Gotter, Anthony L; Winrow, Christopher J; Renger, John J; Kuduk, Scott D; Coleman, Paul J

    2017-03-15

    In an ongoing effort to explore the use of orexin receptor antagonists for the treatment of insomnia, dual orexin receptor antagonists (DORAs) were structurally modified, resulting in compounds selective for the OX2R subtype and culminating in the discovery of 23, a highly potent, OX2R-selective molecule that exhibited a promising in vivo profile. Further structural modification led to an unexpected restoration of OX1R antagonism. Herein, these changes are discussed and a rationale for selectivity based on computational modeling is proposed.

  15. Validation of endothelin B receptor antibodies reveals two distinct receptor-related bands on Western blot.

    PubMed

    Barr, Travis P; Kornberg, Daniel; Montmayeur, Jean-Pierre; Long, Melinda; Reichheld, Stephen; Strichartz, Gary R

    2015-01-01

    Antibodies are important tools for the study of protein expression but are often used without full validation. In this study, we used Western blots to characterize antibodies targeted to the N or C terminal (NT or CT, respectively) and the second or third intracellular loop (IL2 or IL3, respectively) of the endothelin B receptor (ETB). The IL2-targeted antibody accurately detected endogenous ETB expression in rat brain and cultured rat astrocytes by labeling a 50-kDa band, the expected weight of full-length ETB. However, this antibody failed to detect transfected ETB in HEK293 cultures. In contrast, the NT-targeted antibody accurately detected endogenous ETB in rat astrocyte cultures and transfected ETB in HEK293 cultures by labeling a 37-kDa band but failed to detect endogenous ETB in rat brain. Bands detected by the CT- or IL3-targeted antibody were found to be unrelated to ETB. Our findings show that functional ETB can be detected at 50 or 37kDa on Western blot, with drastic differences in antibody affinity for these bands. The 37-kDa band likely reflects ETB processing, which appears to be dependent on cell type and/or culture condition. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Rational discovery of novel nuclear hormone receptor antagonists

    NASA Astrophysics Data System (ADS)

    Schapira, Matthieu; Raaka, Bruce M.; Samuels, Herbert H.; Abagyan, Ruben

    2000-02-01

    Nuclear hormone receptors (NRs) are potential targets for therapeutic approaches to many clinical conditions, including cancer, diabetes, and neurological diseases. The crystal structure of the ligand binding domain of agonist-bound NRs enables the design of compounds with agonist activity. However, with the exception of the human estrogen receptor-, the lack of antagonist-bound "inactive" receptor structures hinders the rational design of receptor antagonists. In this study, we present a strategy for designing such antagonists. We constructed a model of the inactive conformation of human retinoic acid receptor- by using information derived from antagonist-bound estrogen receptor-α and applied a computer-based virtual screening algorithm to identify retinoic acid receptor antagonists. Thus, the currently available crystal structures of NRs may be used for the rational design of antagonists, which could lead to the development of novel drugs for a variety of diseases.

  17. Involvement of α₂-adrenoceptors, imidazoline, and endothelin-A receptors in the effect of agmatine on morphine and oxycodone-induced hypothermia in mice.

    PubMed

    Bhalla, Shaifali; Andurkar, Shridhar V; Gulati, Anil

    2013-10-01

    Potentiation of opioid analgesia by endothelin-A (ET(A)) receptor antagonist, BMS182874, and imidazoline receptor/α₂-adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂-adrenoceptors, imidazoline, and ET(A) receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂-adrenoceptors, imidazoline, and ET(A) receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂-adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET(A) receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine-induced hypothermia. Agmatine-induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine-induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂-adrenoceptors are involved in agmatine-induced reversal of oxycodone hypothermia. Our findings also suggest that ET(A) receptors may be involved in blockade of oxycodone hypothermia by agmatine.

  18. Mineralocorticoid receptor antagonists and endothelial function

    PubMed Central

    Maron, Bradley A.; Leopold, Jane A.

    2010-01-01

    Hyperaldosteronism has been associated with endothelial dysfunction and impaired vascular reactivity in patients with hypertension or congestive heart failure. The mineralocorticoid receptor (MR) antagonists spironolactone and eplerenone have been shown to reduce morbidity and mortality, in part, by ameliorating the adverse effects of aldosterone on vascular function. Although spironolactone and eplerenone are increasingly utilized in patients with cardiovascular disease, widespread clinical use is limited by the development of gynecomastia with spironolactone and hyperkalemia with both agents. This suggests that the development of newer agents with favorable side effect profiles is warranted. PMID:18729003

  19. Endothelin receptor a blockade is an ineffective treatment for adriamycin nephropathy.

    PubMed

    Tan, Roderick J; Zhou, Lili; Zhou, Dong; Lin, Lin; Liu, Youhua

    2013-01-01

    Endothelin is a vasoconstricting peptide that plays a key role in vascular homeostasis, exerting its biologic effects via two receptors, the endothelin receptor A (ETA) and endothelin receptor B (ETB). Activation of ETA and ETB has opposing actions, in which hyperactive ETA is generally vasoconstrictive and pathologic. Selective ETA blockade has been shown to be beneficial in renal injuries such as diabetic nephropathy and can improve proteinuria. Atrasentan is a selective pharmacologic ETA blocker that preferentially inhibits ETA activation. In this study, we evaluated the efficacy of ETA blockade by atrasentan in ameliorating proteinuria and kidney injury in murine adriamycin nephropathy, a model of human focal segmental glomerulosclerosis. We found that ETA expression was unaltered during the course of adriamycin nephropathy. Whether initiated prior to injury in a prevention protocol (5 mg/kg/day, i.p.) or after injury onset in a therapeutic protocol (7 mg/kg or 20 mg/kg three times a week, i.p.), atrasentan did not significantly affect the initiation and progression of adriamycin-induced albuminuria (as measured by urinary albumin-to-creatinine ratios). Indices of glomerular damage were also not improved in atrasentan-treated groups, in either the prevention or therapeutic protocols. Atrasentan also failed to improve kidney function as determined by serum creatinine, histologic damage, and mRNA expression of numerous fibrosis-related genes such as collagen-I and TGF-β1. Therefore, we conclude that selective blockade of ETA by atrasentan has no effect on preventing or ameliorating proteinuria and kidney injury in adriamycin nephropathy.

  20. Vascular endothelial cells mediate mechanical stimulation-induced enhancement of endothelin hyperalgesia via activation of P2X2/3 receptors on nociceptors.

    PubMed

    Joseph, Elizabeth K; Green, Paul G; Bogen, Oliver; Alvarez, Pedro; Levine, Jon D

    2013-02-13

    Endothelin-1 (ET-1) is unique among a broad range of hyperalgesic agents in that it induces hyperalgesia in rats that is markedly enhanced by repeated mechanical stimulation at the site of administration. Antagonists to the ET-1 receptors, ET(A) and ET(B), attenuated both initial as well as stimulation-induced enhancement of hyperalgesia (SIEH) by endothelin. However, administering antisense oligodeoxynucleotide to attenuate ET(A) receptor expression on nociceptors attenuated ET-1 hyperalgesia but had no effect on SIEH, suggesting that this is mediated via a non-neuronal cell. Because vascular endothelial cells are both stretch sensitive and express ET(A) and ET(B) receptors, we tested the hypothesis that SIEH is dependent on endothelial cells by impairing vascular endothelial function with octoxynol-9 administration; this procedure eliminated SIEH without attenuating ET-1 hyperalgesia. A role for protein kinase Cε (PKCε), a second messenger implicated in the induction and maintenance of chronic pain, was explored. Intrathecal antisense for PKCε did not inhibit either ET-1 hyperalgesia or SIEH, suggesting no role for neuronal PKCε; however, administration of a PKCε inhibitor at the site of testing selectively attenuated SIEH. Compatible with endothelial cells releasing ATP in response to mechanical stimulation, P2X(2/3) receptor antagonists eliminated SIEH. The endothelium also appears to contribute to hyperalgesia in two ergonomic pain models (eccentric exercise and hindlimb vibration) and in a model of endometriosis. We propose that SIEH is produced by an effect of ET-1 on vascular endothelial cells, sensitizing its release of ATP in response to mechanical stimulation; ATP in turn acts at the nociceptor P2X(2/3) receptor.

  1. Vascular Endothelial Cells Mediate Mechanical Stimulation-Induced Enhancement of Endothelin Hyperalgesia via Activation of P2X2/3 Receptors on Nociceptors

    PubMed Central

    Joseph, Elizabeth K.; Green, Paul G.; Bogen, Oliver; Alvarez, Pedro; Levine, Jon D.

    2013-01-01

    Endothelin-1 (ET-1) is unique amongst a broad range of hyperalgesic agents in that it induces hyperalgesia in rats that is markedly enhanced by repeated mechanical stimulation at the site of administration. Antagonists to the ET-1 receptors, ETA and ETB, attenuated both initial as well as stimulation-induced enhancement of hyperalgesia (SIEH) by endothelin. However, administering antisense oligodeoxynucleotide to attenuate ETA receptor expression on nociceptors attenuated ET-1 hyperalgesia, but had no effect on SIEH suggesting that this is mediated via a non-neuronal cell. Since vascular endothelial cells are both stretch-sensitive and express ETA and ETB receptors, we tested the hypothesis that SIEH is dependent on endothelial cells by impairing vascular endothelial function with octoxynol-9 administration; this procedure eliminated SIEH without attenuating ET-1 hyperalgesia. A role for protein kinase C epsilon (PKCε), a second messenger implicated in the induction and maintenance of chronic pain, was explored. Intrathecal antisense for PKCε did not inhibit either ET-1 hyperalgesia or SIEH, suggesting no role for neuronal PKCε; however, administration of a PKCε inhibitor at the site of testing selectively attenuated SIEH. Compatible with endothelial cells releasing ATP in response to mechanical stimulation, P2X2/3 receptor antagonists eliminated SIEH. The endothelium also appears to contribute to hyperalgesia in two ergonomic pain models (eccentric exercise and hind limb vibration) and in model of endometriosis. We propose that SIEH is produced by an effect of ET-1 on vascular endothelial cells, sensitizing its release of ATP in response to mechanical stimulation; ATP in turn acts at the nociceptor P2X2/3 receptor. PMID:23407944

  2. Up-Regulation of Endothelin Type A Receptor in Human and Rat Radiation Proctitis: Preclinical Therapeutic Approach With Endothelin Receptor Blockade

    SciTech Connect

    Jullien, Nicolash; Blirando, Karl; Milliat, Fabien; Benderitter, Marc; Francois, Agnes

    2009-06-01

    Purpose: Rectum radiation damage and fibrosis are often associated with radiation therapy of pelvic tumors. The endothelin (ET) system has been implicated in several fibrotic diseases but never studied in the context of gastrointestinal radiation damage. This study assessed modifications in ET type 1 (ET-1), ET type A receptor (ET{sub A}), and ET type B receptor (ET{sub B}) localization and/or expression in irradiated human rectal tissue and in a rat model of delayed colorectal injury. We also evaluated the therapeutic potential of long-term ET receptor blockade. Methods and Materials: Routine histological studies of sections of healthy and radiation-injured human rectum tissue were done; the sections were also immunostained for ET{sub A} and ET{sub B} receptors. The rat model involved the delivery of 27 Gy in a single dose to the colons and rectums of the animals. The ET-1/ET{sub A}/ET{sub B} expression and ET{sub A}/ET{sub B} localization were studied at 10 weeks postexposure. The abilities of bosentan and atrasentan to protect against delayed rectal injury were also investigated. Results: The immunolocalization of ET{sub A} and ET{sub B} in healthy human rectums was similar to that in rat rectums. However, strong ET{sub A} immunostaining was seen in the presence of human radiation proctitis, and increased ET{sub A} mRNA levels were seen in the rat following colorectal irradiation. Immunostaining for ET{sub A} was also strongly positive in rats in areas of radiation-induced mucosal ulceration, atypia, and fibroproliferation. However, neither bosentan nor atrasentan prevented radiation damage to the rectum when given long term. The only effect seen for atrasentan was an increased number of sclerotic vessel sections in injured tissues. Conclusions: As the result of the overexpression of ET{sub A}, radiation exposure deregulates the endothelin system through an 'ET{sub A} profile' in the human and rodent rectum. However, therapeutic interventions involving mixed or

  3. HIGH AFFINITY ACYLATING ANTAGONISTS FOR MUSCARINIC RECEPTORS

    PubMed Central

    Baumgold, Jesse; Karton, Yishai; Malka, Naftali; Jacobson, Kenneth A.

    2012-01-01

    Summary The muscarinic antagonists pirenzepine and telenzepine were derivitized as alkylamino derivatives at a site on the molecules corresponding to a region of bulk tolerance in receptor binding. The distal primary amino groups were coupled to the cross-linking reagent meta-phenylene diisothiocyanate, resulting in two isothiocyanate derivatives that were found to inhibit muscarinic receptors irreversibly and in a dose-dependent fashion. Preincubation of rat forebrain membranes with an isothiocyanate derivative followed by radioligand binding using [3H]N-methylscopolamine diminished the Bmax value, but did not affect the Kd value. The receptor binding site was not restored upon repeated washing, indicating that irreversible inhibition had occurred. IC50 values for the irreversible inhibition at rat forebrain muscarinic receptors were 0.15 nM and 0.19 nM, for derivatives of pirenzepine and telenzepine, respectively. The isothiocyanate derivative of pirenzepine was non-selective as an irreversible muscarinic inhibitor, and the corresponding derivative prepared from telenzepine was 5-fold selective for forebrain (mainly m1) vs. heart (m2) muscarinic receptors. PMID:1625525

  4. Endothelin-1 down-regulates matrix metalloproteinase 14 and 15 expression in human first trimester trophoblasts via endothelin receptor type B

    PubMed Central

    Majali-Martinez, Alejandro; Velicky, Philipp; Pollheimer, Jürgen; Knöfler, Martin; Yung, Hong wa; Burton, Graham J.; Tabrizi-Wizsy, Nassim Ghaffari; Lang, Uwe; Hiden, Ursula; Desoye, Gernot; Dieber-Rotheneder, Martina

    2017-01-01

    STUDY QUESTION Does endothelin-1 (ET-1) regulate matrix metalloproteinase (MMP) 14 and 15 production and invasion of human first trimester trophoblasts? SUMMARY ANSWER ET-1 in pathophysiological concentrations down-regulates MMP14 and MMP15 expression via endothelin receptor (ETR) type B and decreases trophoblast migration and invasion. WHAT IS KNOWN ALREADY MMP14 and MMP15 are involved in trophoblast invasion. Impairment of invasion has been linked to pregnancy complications such as pre-eclampsia (PE). ET-1 is up-regulated in PE. STUDY DESIGN, SIZE, DURATION In vitro study using primary human trophoblasts from 50 first trimester placentas (gestational week 7–12). PARTICIPANTS/MATERIALS, SETTING, METHODS Trophoblasts were cultured in the absence or presence of 10–100 nM ET-1. MMP14 and MMP15 mRNA and protein were quantified by RT-qPCR and Western blotting, respectively. Selective antagonists for ETRA (BQ-123) or ETRB (BQ-788) were used to identify ETR subtypes involved. Functional ET-1 effects were tested in first trimester chorionic villous explants and transwell invasion assays. The roles of tumor necrosis factor (TNF)-α (25 ng/ml) and oxygen (1%) in ET-1 regulation of MMP14 and 15 expression were assessed by Western blotting. MAIN RESULTS AND THE ROLE OF CHANCE ET-1 down-regulated MMP14 and MMP15 mRNA (−21% and −26%, respectively, P < 0.05) and protein levels (–18% and –22%, respectively, P < 0.05). This effect was mediated via ETRB. ET-1 decreased trophoblast outgrowth in placental explants (−24%, P < 0.05) and trophoblast invasion (−26%, P ≤ 0.01). TNF-α enhanced ET-1 mediated MMP15 down-regulation (by 10%, P < 0.05), whereas hypoxia abolished the effect of ET-1 on both MMPs. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION Only primary trophoblasts were used in this study. Since trophoblast yield from first trimester placental material is limited, further aspects of MMP14 and 15 regulation could not be characterized. Other anti

  5. Identification of endothelin 2 as an inflammatory factor that promotes central nervous system remyelination

    PubMed Central

    Johnson, Kory R.; Miron, Veronique E.; Zhao, Chao; Harrisingh, Marie C.; Swire, Matthew; Williams, Anna; McFarland, Henry F.

    2013-01-01

    The development of new regenerative therapies for multiple sclerosis is hindered by the lack of potential targets for enhancing remyelination. The study of naturally regenerative processes such as the innate immune response represents a powerful approach for target discovery to solve this problem. By ‘mining’ these processes using transcriptional profiling we can identify candidate factors that can then be tested individually in clinically-relevant models of demyelination and remyelination. Here, therefore, we have examined a previously described in vivo model of the innate immune response in which zymosan-induced macrophage activation in the retina promotes myelin sheath formation by oligodendrocytes generated from transplanted precursor cells. While this model is not itself clinically relevant, it does provide a logical starting point for this study as factors that promote myelination must be present. Microarray analysis of zymosan-treated retinae identified several cytokines (CXCL13, endothelin 2, CCL20 and CXCL2) to be significantly upregulated. When tested in a cerebellar slice culture model, CXCL13 and endothelin 2 promoted myelination and endothelin 2 also promoted remyelination. In studies to identify the receptor responsible for this regenerative effect of endothelin 2, analysis of both remyelination following experimental demyelination and of different stages of multiple sclerosis lesions in human post-mortem tissue revealed high levels of endothelin receptor type B in oligodendrocyte lineage cells. Confirming a role for this receptor in remyelination, small molecule agonists and antagonists of endothelin receptor type B administered in slice cultures promoted and inhibited remyelination, respectively. Antagonists of endothelin receptor type B also inhibited remyelination of experimentally-generated demyelination in vivo. Our work therefore identifies endothelin 2 and the endothelin receptor type B as a regenerative pathway and suggests that

  6. Requirement of cortical actin organization for bombesin, endothelin, and EGF receptor internalization.

    PubMed

    Lunn, J A; Wong, H; Rozengurt, E; Walsh, J H

    2000-12-01

    The role of actin organization in occupancy-induced receptor internalization remains poorly defined. Here we report that treatment of mouse Swiss 3T3 cells with latrunculin A, a potent inhibitor of actin polymerization (including cortical actin), inhibited the internalization of the endogenous bombesin/gastrin-releasing peptide (GRP) receptor, as judged by uptake of (125)I-labeled GRP or fluorescent Cy3-labeled bombesin. In contrast, cells pretreated with cytochalasin D showed minimal inhibition of bombesin/GRP receptor internalization. Similarly, pretreatment of Swiss 3T3 cells with the potent Rho-kinase inhibitor HA-1077, at concentrations (10-20 microM) that abrogated bombesin-mediated stress fiber formation, did not significantly alter receptor-mediated internalization of (125)I-GRP. These results indicate that bombesin/GRP receptor internalization depends on latrunculin A-sensitive cortical actin rather than on rapidly turning over actin stress fibers that are disrupted by either cytochalasin D or HA-1077. The rates and total levels of internalization of the endogenously expressed endothelin A receptor and epidermal growth factor receptor were also markedly reduced by latrunculin A in Swiss 3T3 cells. The potency of latrunculin A for inhibiting G protein-coupled receptor endocytosis was comparable to that for reducing internalization of the epidermal growth factor tyrosine kinase receptor. We conclude that cortical actin structures, disrupted by latrunculin A, are necessary for occupancy-induced receptor internalization in animal cells.

  7. The endothelin B receptor plays a crucial role in the adhesion of neutrophils to the endothelium in sickle cell disease.

    PubMed

    Koehl, Bérengère; Nivoit, Pierre; El Nemer, Wassim; Lenoir, Olivia; Hermand, Patricia; Pereira, Catia; Brousse, Valentine; Guyonnet, Léa; Ghinatti, Giulia; Benkerrou, Malika; Colin, Yves; Le Van Kim, Caroline; Tharaux, Pierre-Louis

    2017-07-01

    Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ETB receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ETB receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ETB function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ETB axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ETB, may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients. Copyright© 2017 Ferrata Storti Foundation.

  8. The heart as an extravascular target of endothelin-1 in ...

    EPA Pesticide Factsheets

    Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease and cardiac dysfunction have been explored, though linkage with specific factors or genes remains limited. Given evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction, the present review highlights the emerging role of endothelins as mediators of cardiac dysfunction following particulate matter exposure. Endothelin-1 is a small multifunctional protein expressed in the pulmonary and cardiovascular system, known for its ability to constrict blood vessels. Although endothelin-1 can also directly and indirectly (via secondary signaling events) modulate cardiac contractility, heart rate, and rhythm, research on the role of endothelins in the context of air pollution has tended to focus on the vascular effects. The plausibility of endothelin as a mechanism underlying particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. Extravascular effects of endothelin on the heart could better explain one mechanism by which particulate matter exposure may lead to cardiac dysfunction. We propose and support the novel hypothesis that autocrine/paracrine signaling systems, such as endothelins, mediate cardiac

  9. The heart as an extravascular target of endothelin-1 in ...

    EPA Pesticide Factsheets

    Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease and cardiac dysfunction have been explored, though linkage with specific factors or genes remains limited. Given evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction, the present review highlights the emerging role of endothelins as mediators of cardiac dysfunction following particulate matter exposure. Endothelin-1 is a small multifunctional protein expressed in the pulmonary and cardiovascular system, known for its ability to constrict blood vessels. Although endothelin-1 can also directly and indirectly (via secondary signaling events) modulate cardiac contractility, heart rate, and rhythm, research on the role of endothelins in the context of air pollution has tended to focus on the vascular effects. The plausibility of endothelin as a mechanism underlying particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. Extravascular effects of endothelin on the heart could better explain one mechanism by which particulate matter exposure may lead to cardiac dysfunction. We propose and support the novel hypothesis that autocrine/paracrine signaling systems, such as endothelins, mediate cardiac

  10. Endothelin-1 induces proliferation of human lung fibroblasts and IL-11 secretion through an ET(A) receptor-dependent activation of MAP kinases.

    PubMed

    Gallelli, Luca; Pelaia, Girolamo; D'Agostino, Bruno; Cuda, Giovanni; Vatrella, Alessandro; Fratto, Donatella; Gioffrè, Vincenza; Galderisi, Umberto; De Nardo, Marilisa; Mastruzzo, Claudio; Salinaro, Elisa Trovato; Maniscalco, Mauro; Sofia, Matteo; Crimi, Nunzio; Rossi, Francesco; Caputi, Mario; Costanzo, Francesco S; Maselli, Rosario; Marsico, Serafino A; Vancheri, Carlo

    2005-11-01

    Endothelin-1 (ET-1) is implicated in the fibrotic responses characterizing interstitial lung diseases, as well as in the airway remodeling process occurring in asthma. Within such a context, the aim of our study was to investigate, in primary cultures of normal human lung fibroblasts (NHLFs), the ET-1 receptor subtypes, and the intracellular signal transduction pathways involved in the proliferative effects of this peptide. Therefore, cells were exposed to ET-1 in the presence or absence of an overnight pre-treatment with either ET(A) or ET(B) selective receptor antagonists. After cell lysis, immunoblotting was performed using monoclonal antibodies against the phosphorylated, active forms of mitogen-activated protein kinases (MAPK). ET-1 induced a significant increase in MAPK phosphorylation pattern, and also stimulated fibroblast proliferation and IL-6/IL-11 release into cell culture supernatants. All these effects were inhibited by the selective ET(A) antagonist BQ-123, but not by the specific ET(B) antagonist BQ-788. The stimulatory influence of ET-1 on IL-11, but not on IL-6 secretion, was prevented by MAPK inhibitors. Therefore, such results suggest that in human lung fibroblasts ET-1 exerts a profibrogenic action via an ET(A) receptor-dependent, MAPK-mediated induction of IL-11 release and cell proliferation.

  11. Nociceptive tolerance is improved by bradykinin receptor B1 antagonism and joint morphology is protected by both endothelin type A and bradykinin receptor B1 antagonism in a surgical model of osteoarthritis

    PubMed Central

    2011-01-01

    Introduction Endothelin-1, a vasoconstrictor peptide, influences cartilage metabolism mainly via endothelin receptor type A (ETA). Along with the inflammatory nonapeptide vasodilator bradykinin (BK), which acts via bradykinin receptor B1 (BKB1) in chronic inflammatory conditions, these vasoactive factors potentiate joint pain and inflammation. We describe a preclinical study of the efficacy of treatment of surgically induced osteoarthritis with ETA and/or BKB1 specific peptide antagonists. We hypothesize that antagonism of both receptors will diminish osteoarthritis progress and articular nociception in a synergistic manner. Methods Osteoarthritis was surgically induced in male rats by transection of the right anterior cruciate ligament. Animals were subsequently treated with weekly intra-articular injections of specific peptide antagonists of ETA and/or BKB1. Hind limb nociception was measured by static weight bearing biweekly for two months post-operatively. Post-mortem, right knee joints were analyzed radiologically by X-ray and magnetic resonance, and histologically by the OARSI histopathology assessment system. Results Single local BKB1 antagonist treatment diminished overall hind limb nociception, and accelerated post-operative recovery after disease induction. Both ETA and/or BKB1 antagonist treatments protected joint radiomorphology and histomorphology. Dual ETA/BKB1 antagonism was slightly more protective, as measured by radiology and histology. Conclusions BKB1 antagonism improves nociceptive tolerance, and both ETA and/or BKB1 antagonism prevents joint cartilage degradation in a surgical model of osteoarthritis. Therefore, they represent a novel therapeutic strategy: specific receptor antagonism may prove beneficial in disease management. PMID:21575197

  12. Dual Endothelin Receptor Blockade Abrogates Right Ventricular Remodeling and Biventricular Fibrosis in Isolated Elevated Right Ventricular Afterload

    PubMed Central

    Nielsen, Eva Amalie; Sun, Mei; Honjo, Osami; Hjortdal, Vibeke E.; Redington, Andrew N.; Friedberg, Mark K.

    2016-01-01

    Background Pulmonary arterial hypertension is usually fatal due to right ventricular failure and is frequently associated with co-existing left ventricular dysfunction. Endothelin-1 is a powerful pro-fibrotic mediator and vasoconstrictor that is elevated in pulmonary arterial hypertension. Endothelin receptor blockers are commonly used as pulmonary vasodilators, however their effect on biventricular injury, remodeling and function, despite elevated isolated right ventricular afterload is unknown. Methods Elevated right ventricular afterload was induced by progressive pulmonary artery banding. Seven rabbits underwent pulmonary artery banding without macitentan; 13 received pulmonary artery banding + macitentan; and 5 did not undergo inflation of the pulmonary artery band (sham-operated controls). Results: Right and left ventricular collagen content was increased with pulmonary artery banding compared to sham-operated controls and ameliorated by macitentan. Right ventricular fibrosis signaling (connective tissue growth factor and endothelin-1 protein levels); extra-cellular matrix remodeling (matrix-metalloproteinases 2 and 9), apoptosis and apoptosis-related peptides (caspases 3 and 8) were increased with pulmonary artery banding compared with sham-operated controls and decreased with macitentan. Conclusion Isolated right ventricular afterload causes biventricular fibrosis, right ventricular apoptosis and extra cellular matrix remodeling, mediated by up-regulation of endothelin-1 and connective tissue growth factor signaling. These pathological changes are ameliorated by dual endothelin receptor blockade despite persistent elevated right ventricular afterload. PMID:26765263

  13. Application of structure-metabolism relationships in the identification of a selective endothelin A antagonist, BMS-193884, with favourable pharmacokinetic properties.

    PubMed

    Humphreys, W G; Obermeier, M T; Barrish, J C; Chong, S; Marino, A M; Murugesan, N; Wang-Iverson, D; Morrison, R A

    2003-11-01

    1. Based on binding affinity, 2'-amino-N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-methylpropyl)[1,1'-biphenyl]-2-sulfonamide (2) was identified as an initial lead in a programme to identify selective endothelin (ET) receptor antagonists. However, the compound was extensively metabolized in preclinical animal species and human in vitro systems due to oxidative biotransformation. 2. To optimize this structural class, the site of metabolism of 2 was determined. This allowed for focussed structure-activity and structure-metabolism studies aimed at finding more metabolically stable analogues that maintained potency. New analogues were screened for their ET binding characteristics and their stability in rat and human liver microsomes. 3. The use of the microsomal stability screen was tested by the determination of the pharmacokinetic parameters of select analogues. A good correlation was found between reduced rates of rat microsomal metabolism and reduced clearance in the rat. 4. N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-oxazolyl)[1,1'-biphenyl]-2-sulfonamide (3) was identified as an analogue with improved in vitro properties and further studies revealed that the compound had improved pharmacokinetic properties. 5. N-[[2'-[[(3,4-dimethyl-5-isoxazolyl)amino]sulfonyl]-4-(2-oxazolyl)[1,1'-biphenyl]-2-yl]methyl]acetamide (4) was subsequently identified as a compound with superior in vitro properties compared with compound 3, but when tested in vivo it had a substantially increased rate of clearance. Further studies demonstrated that the clearance of this closely related structural analogue was not dictated by metabolic processes, but was mediated by transport-mediated direct biliary excretion. 6. The utility of screening for in vitro liver microsomal stability as part of the lead optimization process for compounds with metabolic liabilities was shown. It was also shown that relatively small molecular changes can dramatically change the disposition of closely related analogues and care

  14. Expression of endothelin receptors in frog, chicken, mouse and human pigment cells.

    PubMed

    Scarparo, Ana Cristina; Isoldi, Mauro César; de Lima, Leonardo Henrique Ribeiro Graciani; Visconti, Maria Aparecida; Castrucci, Ana Maria de Lauro

    2007-07-01

    Several reports have shown the participation of vasoactive endothelins (ETs) in the regulation of vertebrate pigment cells. In the present study, we identified ET receptors in pigment cells of vertebrate species by RT-PCR assays, and compared the differential expression of the various subtypes in each species by quantitative PCR. RT-PCR was performed with specific primers for ETC, ETA(X) or ETA in Xenopus laevis melanophores, ETA or ETB(2) in chicken melanocytes, ETA or ETB in murine (B-16, S-91 or Melan-A) or human (SK-Mel 23 or SK-Mel 28) melanoma cells, and the products obtained were confirmed by cloning and sequencing. The results showed the presence of ETA(X), but not ETA mRNA, and confirmed the expression of ETC in X. laevis melanophores. ETA and ETB(2) mRNAs were also demonstrated in chicken melanocytes. ETA and ETB receptor were identified in S-91, B16 and Melan-A murine cells. In human melanoma cells, SK-Mel 23 and SK-Mel 28, we confirmed the presence of ETB mRNA, and also found ETA mRNA. The comparison between the two subtypes present in the pigment cell of each species and among species demonstrated that the expression of ETAs in chicken, mouse, and human melanocytes is negligible, as is the expression of ETA(X) in Xenopus melanophores. The relative expression, as determined by quantitative PCR, was as follows: chicken ETB>SK-Mel 23 ETB>S91 ETB>Xenopus ETC, suggesting that the endothelin system plays a major role in avian and mammalian pigment cell regulation, as compared to lower vertebrates. The phylogenetic analysis revealed that subtype A receptors were probably the most primitive ET receptors, directly deriving from the ancestral type; all the other receptors, B subtypes and C, originated from diverse derivative molecules.

  15. Smooth Muscle Endothelin B Receptors Regulate Blood Pressure but Not Vascular Function or Neointimal Remodeling

    PubMed Central

    Miller, Eileen; Czopek, Alicja; Duthie, Karolina M.; Kirkby, Nicholas S.; van de Putte, Elisabeth E. Fransen; Christen, Sibylle; Kimmitt, Robert A.; Moorhouse, Rebecca; Castellan, Raphael F.P.; Kotelevtsev, Yuri V.; Kuc, Rhoda E.; Davenport, Anthony P.; Dhaun, Neeraj; Webb, David J.

    2017-01-01

    The role of smooth muscle endothelinB (ETB) receptors in regulating vascular function, blood pressure (BP), and neointimal remodeling has not been established. Selective knockout mice were generated to address the hypothesis that loss of smooth muscle ETB receptors would reduce BP, alter vascular contractility, and inhibit neointimal remodeling. ETB receptors were selectively deleted from smooth muscle by crossing floxed ETB mice with those expressing cre-recombinase controlled by the transgelin promoter. Functional consequences of ETB deletion were assessed using myography. BP was measured by telemetry, and neointimal lesion formation induced by femoral artery injury. Lesion size and composition (day 28) were analyzed using optical projection tomography, histology, and immunohistochemistry. Selective deletion of ETB was confirmed by genotyping, autoradiography, polymerase chain reaction, and immunohistochemistry. ETB-mediated contraction was reduced in trachea, but abolished from mesenteric veins, of knockout mice. Induction of ETB-mediated contraction in mesenteric arteries was also abolished in these mice. Femoral artery function was unaltered, and baseline BP modestly elevated in smooth muscle ETB knockout compared with controls (+4.2±0.2 mm Hg; P<0.0001), but salt-induced and ETB blockade–mediated hypertension were unaltered. Circulating endothelin-1 was not altered in knockout mice. ETB-mediated contraction was not induced in femoral arteries by incubation in culture medium or lesion formation, and lesion size was not altered in smooth muscle ETB knockout mice. In the absence of other pathology, ETB receptors in vascular smooth muscle make a small but significant contribution to ETB-dependent regulation of BP. These ETB receptors have no effect on vascular contraction or neointimal remodeling. PMID:28028193

  16. Smooth Muscle Endothelin B Receptors Regulate Blood Pressure but Not Vascular Function or Neointimal Remodeling.

    PubMed

    Miller, Eileen; Czopek, Alicja; Duthie, Karolina M; Kirkby, Nicholas S; van de Putte, Elisabeth E Fransen; Christen, Sibylle; Kimmitt, Robert A; Moorhouse, Rebecca; Castellan, Raphael F P; Kotelevtsev, Yuri V; Kuc, Rhoda E; Davenport, Anthony P; Dhaun, Neeraj; Webb, David J; Hadoke, Patrick W F

    2017-02-01

    The role of smooth muscle endothelinB (ETB) receptors in regulating vascular function, blood pressure (BP), and neointimal remodeling has not been established. Selective knockout mice were generated to address the hypothesis that loss of smooth muscle ETB receptors would reduce BP, alter vascular contractility, and inhibit neointimal remodeling. ETB receptors were selectively deleted from smooth muscle by crossing floxed ETB mice with those expressing cre-recombinase controlled by the transgelin promoter. Functional consequences of ETB deletion were assessed using myography. BP was measured by telemetry, and neointimal lesion formation induced by femoral artery injury. Lesion size and composition (day 28) were analyzed using optical projection tomography, histology, and immunohistochemistry. Selective deletion of ETB was confirmed by genotyping, autoradiography, polymerase chain reaction, and immunohistochemistry. ETB-mediated contraction was reduced in trachea, but abolished from mesenteric veins, of knockout mice. Induction of ETB-mediated contraction in mesenteric arteries was also abolished in these mice. Femoral artery function was unaltered, and baseline BP modestly elevated in smooth muscle ETB knockout compared with controls (+4.2±0.2 mm Hg; P<0.0001), but salt-induced and ETB blockade-mediated hypertension were unaltered. Circulating endothelin-1 was not altered in knockout mice. ETB-mediated contraction was not induced in femoral arteries by incubation in culture medium or lesion formation, and lesion size was not altered in smooth muscle ETB knockout mice. In the absence of other pathology, ETB receptors in vascular smooth muscle make a small but significant contribution to ETB-dependent regulation of BP. These ETB receptors have no effect on vascular contraction or neointimal remodeling. © 2016 The Authors.

  17. Cannabinoid receptor antagonists: pharmacological opportunities, clinical experience, and translational prognosis.

    PubMed

    Janero, David R; Makriyannis, Alexandros

    2009-03-01

    The endogenous cannabinoid (CB) (endocannabinoid) signaling system is involved in a variety of (patho)physiological processes, primarily by virtue of natural, arachidonic acid-derived lipids (endocannabinoids) that activate G protein-coupled CB1 and CB2 receptors. A hyperactive endocannabinoid system appears to contribute to the etiology of several disease states that constitute significant global threats to human health. Consequently, mounting interest surrounds the design and profiling of receptor-targeted CB antagonists as pharmacotherapeutics that attenuate endocannabinoid transmission for salutary gain. Experimental and clinical evidence supports the therapeutic potential of CB1 receptor antagonists to treat overweight/obesity, obesity-related cardiometabolic disorders, and substance abuse. Laboratory data suggest that CB2 receptor antagonists might be effective immunomodulatory and, perhaps, anti-inflammatory drugs. One CB1 receptor antagonist/inverse agonist, rimonabant, has emerged as the first-in-class drug approved outside the United States for weight control. Select follow-on agents (taranabant, otenabant, surinabant, rosonabant, SLV-319, AVE1625, V24343) have also been studied in the clinic. However, rimonabant's market withdrawal in the European Union and suspension of rimonabant's, taranabant's, and otenabant's ongoing development programs have highlighted some adverse clinical side effects (especially nausea and psychiatric disturbances) of CB1 receptor antagonists/inverse agonists. Novel CB1 receptor ligands that are peripherally directed and/or exhibit neutral antagonism (the latter not affecting constitutive CB1 receptor signaling) may optimize the benefits of CB1 receptor antagonists while minimizing any risk. Indeed, CB1 receptor-neutral antagonists appear from preclinical data to offer efficacy comparable to or better than that of prototype CB1 receptor antagonists/inverse agonists, with less propensity to induce nausea. Continued

  18. Differential regulation of oxidative stress and cytokine production by endothelin ETA and ETB receptors in superoxide anion-induced inflammation and pain in mice.

    PubMed

    Fattori, Victor; Serafim, Karla G G; Zarpelon, Ana C; Borghi, Sergio M; Pinho-Ribeiro, Felipe A; Alves-Filho, José C; Cunha, Thiago M; Cunha, Fernando Q; Casagrande, Rúbia; Verri, Waldiceu A

    2017-03-01

    The present study investigated whether endothelin-1 acts via ETA or ETB receptors to mediate superoxide anion-induced pain and inflammation. Mice were treated with clazosentan (ETA receptor antagonist) or BQ-788 (ETB receptor antagonist) prior to stimulation with the superoxide anion donor, KO2. Intraplantar treatment with 30 nmol of clazosentan or BQ-788 reduced mechanical hyperalgesia (47% and 42%), thermal hyperalgesia (68% and 76%), oedema (50% and 30%); myeloperoxidase activity (64% and 32%), and overt-pain like behaviours, such as paw flinching (42% and 42%) and paw licking (38% and 62%), respectively. Similarly, intraperitoneal treatment with 30 nmol of clazosentan or BQ-788 reduced leukocyte recruitment to the peritoneal cavity (58% and 32%) and abdominal writhing (81% and 77%), respectively. Additionally, intraplantar treatment with clazosentan or BQ-788 decreased spinal (45% and 41%) and peripheral (47% and 47%) superoxide anion production as well as spinal (47% and 47%) and peripheral (33% and 54%) lipid peroxidation, respectively. Intraplantar treatment with clazosentan, but not BQ-788, reduced spinal (71%) and peripheral (51%) interleukin-1 beta as well as spinal (59%) and peripheral (50%) tumor necrosis factor-alpha production. Therefore, the present study unveils the differential mechanisms by which ET-1, acting on ETA or ETB receptors, regulates superoxide anion-induced inflammation and pain.

  19. Effects of environmental salinity on gill endothelin receptor expression in the killifish, Fundulus heteroclitus.

    PubMed

    Hyndman, Kelly A; Evans, David H

    2009-01-01

    We recently determined that rapid changes in environmental salinity alter endothelin-1 (EDN1) mRNA levels in the euryhaline killifish, Fundulus heteroclitus, so we hypothesized that EDN1 may be a local regulator of gill ion transport in teleost fishes. The purpose of the present study was to examine the effects of changes in environmental salinity on the gill endothelin receptors: EDNRA, EDNRB, and EDNRC. Using quantitative real-time PCR, we determined that after a fresh water (FW) to seawater (SW) transfer, there is a two to threefold increase in gill EDNRA and EDNRB mRNA levels. Likewise, we found a two to three fold increase in gill EDNRA and EDNRB protein concentration. In addition, killifish that have acclimated to FW for 30 days had significantly lower EDNRA mRNA and protein levels than SW killifish. ENDRA were immunolocalized to the mitochondrion-rich cells of the killifish gill, suggesting that EDN1 signaling cascades may affect MRC function. EDNRB were found throughout the gill vasculature and on lamellar pillar cells. We previously immunolocalized EDN1 to the pillar cell suggesting that EDN1 acts as an autocrine signaling molecule and potentially regulates pillar cell tone and lamellar perfusion. We conclude that EDN1 is physiologically active in the teleost gill, and regulated by environmental salinity. Future functional studies examining the physiological role of this system are necessary to completely understand EDN1 in the fish gill.

  20. The heart as an extravascular target of endothelin-1 in particulate matter-induced cardiac dysfunction.

    PubMed

    Chan, Elizabeth A W; Buckley, Barbara; Farraj, Aimen K; Thompson, Leslie C

    2016-09-01

    Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease have been explored, although linkage with specific factors or genes remains limited. These hypotheses may or may not also lead to particulate matter-induced cardiac dysfunction. Evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction has increased interest in the emerging role of endothelins as mediators of cardiac function following particulate matter exposure. Endothelin-1, a well-described small peptide expressed in the pulmonary and cardiovascular systems, is best known for its ability to constrict blood vessels, although it can also induce extravascular effects. Research on the role of endothelins in the context of air pollution has largely focused on vascular effects, with limited investigation of responses resulting from the direct effects of endothelins on cardiac tissue. This represents a significant knowledge gap in air pollution health effects research, given the abundance of endothelin receptors found on cardiac tissue and the ability of endothelin-1 to modulate cardiac contractility, heart rate, and rhythm. The plausibility of endothelin-1 as a mediator of particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. The present review examines the possibility that endothelin-1 release caused by exposure to PM directly modulates extravascular effects on the heart, deleteriously altering cardiac function. Published by Elsevier Inc.

  1. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists

    PubMed Central

    Khanfar, Mohammad A.; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures. PMID:27303254

  2. Multiple Targeting Approaches on Histamine H3 Receptor Antagonists.

    PubMed

    Khanfar, Mohammad A; Affini, Anna; Lutsenko, Kiril; Nikolic, Katarina; Butini, Stefania; Stark, Holger

    2016-01-01

    With the very recent market approval of pitolisant (Wakix®), the interest in clinical applications of novel multifunctional histamine H3 receptor antagonists has clearly increased. Since histamine H3 receptor antagonists in clinical development have been tested for a variety of different indications, the combination of pharmacological properties in one molecule for improved pharmacological effects and reduced unwanted side-effects is rationally based on the increasing knowledge on the complex neurotransmitter regulations. The polypharmacological approaches on histamine H3 receptor antagonists on different G-protein coupled receptors, transporters, enzymes as well as on NO-signaling mechanism are described, supported with some lead structures.

  3. Molecular modeling, quantum polarized ligand docking and structure-based 3D-QSAR analysis of the imidazole series as dual AT1 and ETA receptor antagonists

    PubMed Central

    Singh, Khuraijam Dhanachandra; Muthusamy, Karthikeyan

    2013-01-01

    Aim: Both endothelin ETA receptor antagonists and angiotensin AT1 receptor antagonists lower blood pressure in hypertensive patients. A dual AT1 and ETA receptor antagonist may be more efficacious antihypertensive drug. In this study we identified the mode and mechanism of binding of imidazole series of compounds as dual AT1 and ETA receptor antagonists. Methods: Molecular modeling approach combining quantum-polarized ligand docking (QPLD), MM/GBSA free-energy calculation and 3D-QSAR analysis was used to evaluate 24 compounds as dual AT1 and ETA receptor antagonists and to reveal their binding modes and structural basis of the inhibitory activity. Pharmacophore-based virtual screening and docking studies were performed to identify more potent dual antagonists. Results: 3D-QSAR models of the imidazole compounds were developed from the conformer generated by QPLD, and the resulting models showed a good correlation between the predicted and experimental activity. The visualization of the 3D-QSAR model in the context of the compounds under study revealed the details of the structure-activity relationship: substitution of methoxymethyl and cyclooctanone might increase the activity against AT1 receptor, while substitution of cyclohexone and trimethylpyrrolidinone was important for the activity against ETA receptor; addition of a trimethylpyrrolidinone to compound 9 significantly reduced its activity against AT1 receptor but significantly increased its activity against ETA receptor, which was likely due to the larger size and higher intensities of the H-bond donor and acceptor regions in the active site of ETA receptor. Pharmacophore-based virtual screening followed by subsequent Glide SP, XP, QPLD and MM/GBSA calculation identified 5 potential lead compounds that might act as dual AT1 and ETA receptor antagonists. Conclusion: This study may provide some insights into the development of novel potent dual ETA and AT1 receptor antagonists. As a result, five compounds are

  4. Endothelin ETB1 receptor agonism as a new therapeutic strategy in pulmonary arterial hypertension and chronic heart failure.

    PubMed

    Ramirez, Giuseppe A

    2013-11-01

    Pulmonary arterial hypertension and post-ischemic chronic heart failure are highly prevalent diseases with high morbidity and mortality rates due to chronic vascular injury and extensive remodeling responses at the level of the vessel walls. Endothelins play a central role in this setting, through a complex signaling system that mainly affects endothelial and vascular smooth muscle cells. ETA and ETB2 endothelin receptors are thought to mediate pro-ischemic responses, while ETB1 receptor activity could account for the overall protective effect of ETB signaling in physiology. The pharmacologic modulation of the endothelin system has mainly focused on the dual non-selective blockade of ETA and ETB endothelin receptors or to the selective blockade of ETA-related pathways to date. Good clinical results were achieved in the setting of pulmonary hypertension but no advantage has been demonstrated for heart failure. Restoring and enhancing the physiological protective role of ETB1-signaling with concomitant blockade of ETB2 could possibly improve the efficacy of current therapies in the setting of pulmonary arterial hypertension and post-ischemic chronic heart failure. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Selective endothelinA receptor antagonism with sitaxsentan for pulmonary arterial hypertension associated with connective tissue disease

    PubMed Central

    Girgis, Reda E; Frost, Adaani E; Hill, Nicholas S; Horn, Evelyn M; Langleben, David; McLaughlin, Vallerie V; Oudiz, Ronald J; Robbins, Ivan M; Seibold, James R; Shapiro, Shelley; Tapson, Victor F; Barst, Robyn J

    2007-01-01

    Introduction Endothelin receptor antagonism has become an important component in the treatment of pulmonary arterial hypertension (PAH) associated with connective tissue disease (CTD). The purpose of this study was to analyse the safety and effectiveness of sitaxsentan, a selective antagonist of the ETA receptor, in a cohort of patients with PAH and CTD. Short‐term clinical and haemodynamic effects and longer‐term follow‐up data are presented. Methods A post hoc subgroup analysis was performed on 42 patients who had PAH associated with CTD, out of a group of 178 patients enrolled in a 12‐week, double‐blind, randomised clinical trial of sitaxsentan versus placebo. Data from 33 patients assigned to sitaxsentan 100 mg or 300 mg daily were pooled and compared with nine placebo‐treated patients. There were 41 patients entered into the blinded extension study, in which all patients received either 100 mg or 300 mg sitaxsentan once daily. Results Patients treated with sitaxsentan had a mean (SD) increase in 6 minute walk distance of 20 (5) m from baseline to week 12 (p = 0.037), whereas the placebo group had a decrease of 38 (84) m, resulting in a placebo‐subtracted treatment effect of 58 m (p = 0.027). Parallel improvements in quality of life and haemodynamics were also observed. No patient discontinued their drug during the 12‐week trial. In the blinded extension study (median treatment duration 26 weeks), more patients were in functional class I–II than in III–IV (p<0.001) at the end of the study compared with the start of active therapy. Elevation of hepatic transaminase levels occurred in two patients. Conclusions Sitaxsentan appears to be efficacious in patients with PAH associated with CTD. PMID:17472992

  6. Discovery of Novel Triazole-Based Opioid Receptor Antagonists

    PubMed Central

    Zhang, Qiang; Keenan, Susan M.; Peng, Youyi; Nair, Anil C.; Yu, Seong Jae; Howells, Richard D.; Welsh, William J.

    2009-01-01

    We report the computer-aided design, chemical synthesis, and biological evaluation of a novel family of δ opioid receptor (DOR) antagonists containing a 1,2,4-triazole core structure that are structurally distinct from other known opioid receptor active ligands. Among those δ antagonists sharing this core structure, 8 exhibited strong binding affinity (Ki = 50 nM) for the DOR and appreciable selectivity for δ over μ and opioid receptors (δ/μ = 80; δ/κ > 200). PMID:16821764

  7. Minimally Modified LDL Upregulates Endothelin Type A Receptors in Rat Coronary Arterial Smooth Muscle Cells

    PubMed Central

    Li, Jie; Cao, Lei; Xu, Cang-Bao; Wang, Jun-Jie

    2013-01-01

    Minimally modified low-density lipoprotein (mmLDL) is a risk factor for cardiovascular disease. The present study investigated the effects of mmLDL on the expression of endothelin type A (ETA) receptors in coronary arteries. Rat coronary arteries were organ-cultured for 24 h. The contractile responses were recorded using a myographic system. ETA receptor mRNA and protein expressions were determined using real-time PCR and western blotting, respectively. The results showed that organ-culturing in the presence of mmLDL enhanced the arterial contractility mediated by the ETA receptor in a concentration-dependent and time-dependent manner. Culturing with mmLDL (10 μg/mL) for 24 h shifted the concentration-contractile curves toward the left significantly with increased Emax of 228% ± 20% from control of 100% ± 10% and significantly increased ETA receptor mRNA and protein levels. Inhibition of the protein kinase C, extracellular signal-related kinases 1 and 2 (ERK1/2), or NF-κB activities significantly attenuated the effects of mmLDL. The c-Jun N-terminal kinase inhibitor or the p38 pathway inhibitor, however, had no such effects. The results indicate that mmLDL upregulates the ETA receptors in rat coronary arterial smooth muscle cells mainly via activating protein kinase C, ERK1/2, and the downstream transcriptional factor, NF-κB. PMID:23861561

  8. Cyclosporine A-induced increase in glomerular cyclic GMP in rats and the involvement of the endothelinB receptor

    PubMed Central

    Tack, Ivan; Marin-Castano, Encarna; Bascands, Jean-Loup; Pecher, Christiane; Ader, Jean-Louis; Girolami, Jean-Pierre

    1997-01-01

    A transient two fold increase in the cyclic GMP content was observed in rat freshly isolated glomeruli 6 to 9 h after a single subcutaneous injection of 20 mg kg−1 cyclosporine A (CsA) in conscious animals. In vitro stimulation with endothelin 3 (ET-3) of isolated glomeruli obtained from CsA-untreated rats resulted in a dose-dependent increase in cyclic GMP content. The increase observed with 10 nM ET-3 was similar to that observed in glomeruli isolated 9 h after in vivo CsA administration. The rise in glomerular cyclic GMP content after in vivo CsA injection was prevented by in vivo treatment with L-NAME (10 mg kg−1) or by in vitro calcium deprivation of the incubation medium. The stimulating effects of CsA on glomerular cyclic GMP content were inhibited by in vivo administration of the ETB receptor antagonist BQ-788 (2 mg kg−1) but not by the ETA receptor antagonist BQ-123 (2 mg kg−1). The maximum increase in glomerular cyclic GMP content induced in vitro by acetylcholine (100 μM) and by ET-3 (100 nM) was slightly lower (approximately by 20–25%, P<0.05) in glomeruli from CsA-treated rats than in glomeruli from untreated rats. In contrast, the maximum increase achieved with 1 μM sodium nitroprusside was similar in both groups. A single subcutaneous injection of CsA did not significantly alter the glomerular mRNA expression of constitutive endothelial NO synthase (eNOS), as evaluated by RT–PCR, whereas the mRNA expression of the inducible NO synthase (iNOS), which follows pretreatment with lipopolysaccharide, was prevented. These results indicate that in vivo administration of a single dose of cyclosporine A transiently increases the cyclic GMP content of freshly isolated glomeruli, and that activation of ETB receptors and stimulation of the NO pathway are involved in this process. Furthermore, a single administration of CsA does not impair eNOS mRNA expression and only slightly reduces NO-dependent glomerular cyclic GMP

  9. Role of epidermal growth factor receptor transactivation in endothelin-1-induced enhanced expression of Gi protein and proliferation in A10 vascular smooth muscle cells.

    PubMed

    Gomez Sandoval, Yessica-Haydee; Lévesque, Louis-Olivier; Li, Yuan; Anand-Srivastava, Madhu B

    2013-03-01

    We have recently shown that vasoactive peptides such as angiotensin II (Ang II) and endothelin-1 (ET-1) increase the expression of Gi proteins and the proliferation of A10 vascular smooth muscle cells (VSMC) through mitogen-activated protein (MAP) kinase-phosphoinositide (PI) 3-kinase pathways. This study was intended to examine the implication of epidermal growth factor receptor (EGFR) activation in ET-1-induced enhanced expression of Gi proteins and proliferation of A10 VSMC, and to further investigate the underlying mechanisms responsible for these increases. Cell proliferation was determined by [(3)H]thymidine incorporation and the expression of Gi proteins; extracellular signal-regulated kinases 1 and 2 (ERK1/2) and EGFR phosphorylation was determined by Western blotting. Treatment of A10 VSMC with ET-1 enhanced the expression of Gi proteins, which was attenuated by BQ123 and BQ788, antagonists of ET(A) and ET(B) receptor respectively. In addition, ET-1 enhanced the phosphorylation of EGFR in A10 VSMC, which was restored to the control levels by EGFR inhibitor and ETA and ETB receptor antagonists. Furthermore, ET-1 also augmented the proliferation and ERK1/2 phosphorylation of A10 VSMC, which were restored to the control levels by inhibition of EGFR. These data suggest that ET-1 transactivates EGFR, which, through MAP kinase signaling, may contribute to the enhanced expression of Gi proteins and thus increased proliferation of A10 VSMC.

  10. Selective endothelin receptor blockade in resistant hypertension: results of the DORADO trial.

    PubMed

    Grassi, Guido

    2011-01-01

    Effective treatment of resistant hypertension still remains an unmet goal of antihypertensive drug treatment. The DORADO trial recently evaluated the efficacy and safety profile of the selective endothelin receptor blocker darusentan in almost 400 hypertensive patients treated with more than four antihypertensive drugs (including a diuretic) but without effective blood pressure control. The trial results show that > 50% of patients treated with the drug exhibit clinical blood pressure < 140/90 mmHg and well-controlled ambulatory blood pressure values. Darusentan, however, was associated with a high incidence of peripheral edema and fluid retention, a side effect that may reduce the safety profile of the drug and its tolerability. Although these data are promising, the drug requires further evaluation, with particularly regard to the long term.

  11. Submucosal microinfusion of endothelin and adrenaline mobilizes ECL-cell histamine in rat stomach, and causes mucosal damage: a microdialysis study.

    PubMed

    Bernsand, M; Ericsson, P; Bjorkqvist, M; Zhao, C-M; Hakanson, R; Norlen, P

    2003-10-01

    Rat stomach ECL cells release histamine in response to gastrin. Submucosal microinfusion of endothelin or adrenaline, known to cause vasoconstriction and gastric lesions, mobilized striking amounts of histamine. While the histamine response to gastrin is sustainable for hours, that to endothelin and adrenaline was characteristically short-lasting (1-2 h). The aims of this study were to identify the cellular source of histamine mobilized by endothelin and adrenaline, and examine the differences between the histamine-mobilizing effects of gastrin, and of endothelin and adrenaline. Endothelin, adrenaline or gastrin were administered by submucosal microinfusion. Gastric histamine mobilization was monitored by microdialysis. Local pretreatment with the H1-receptor antagonist mepyramine and the H2-receptor antagonist ranitidine did not prevent endothelin- or adrenaline-induced mucosal damage. Submucosal microinfusion of histamine did not cause damage. Acid blockade by ranitidine or omeprazole prevented the damage, suggesting that acid back diffusion contributes. Gastrin raised histidine decarboxylase (HDC) activity close to the probe, without affecting the histamine concentration. Endothelin and adrenaline lowered histamine by 50-70%, without activating HDC. Histamine mobilization declined upon repeated administration. Endothelin reduced the number of histamine-immunoreactive ECL cells locally, and reduced the number of secretory vesicles. Thus, unlike gastrin, endothelin (and adrenaline) is capable of exhausting ECL-cell histamine. Microinfusion of alpha-fluoromethylhistidine (known to deplete ECL cells but not mast cells of histamine) reduced the histamine-mobilizing effect of endothelin by 80%, while 1-week pretreatment with omeprazole enhanced it, supporting the involvement of ECL cells. Somatostatin or the prostanoid misoprostol inhibited gastrin-, but not endothelin-stimulated histamine release, suggesting that endothelin and gastrin mobilize histamine via

  12. Down-regulation of endothelin receptors in the ventrolateral medulla of spontaneously hypertensive rats

    SciTech Connect

    Gulati, A.; Rebello, S. )

    1991-01-01

    The binding of ({sup 125}I) sarafotoxin 6b (SRT 6b) and ({sup 125}I) endothelin-1 (ET-1) to endothelin (ET) receptors of neuronal membranes prepared from cerebral cortex and ventrolateral medulla of 8 week old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats was determined. ({sup 125}I) SRT 6b bound to the membranes of cerebral cortex and ventrolateral medulla at a single high affinity site. The binding of ({sup 125}I) SRT 6b in the cerebral cortex was found to be similar in SHR and WKY rats. However, in the ventrolateral medulla ({sup 125}I) SRT 6b binding was found to be significantly lower in SHR as compared to WKY rats. The decreased binding was due to decrease (48%) in the B{sub max} values in SHR rats as compared to WKY rats. The K{sub d} values were similar in SHR and WKY rats. ({sup 125}I) ET-1 also bound to the membranes of cerebral cortex and ventrolateral medulla at a single high affinity site. The binding of ({sup 125}I) ET-1 in the cerebral cortex was found to be similar in SHR and WKY rats. However, in the ventrolateral medulla ({sup 125}I) ET-1 binding was found to be significantly lower in SHR as compared to WKY rats. The decreased binding was due to 36% decrease in the B{sub max} values in SHR rats as compared to WKY rats. The K{sub d} values were similar in SHR and WKY rats. It is concluded that the population of ET receptors is less in the ventrolateral medulla of SHR rats and may be contributing to the regulation of blood pressure.

  13. Constitutive ALK5-Independent c-Jun N-Terminal Kinase Activation Contributes to Endothelin-1 Overexpression in Pulmonary Fibrosis: Evidence of an Autocrine Endothelin Loop Operating through the Endothelin A and B Receptors

    PubMed Central

    Shi-Wen, Xu; Rodríguez-Pascual, Fernando; Lamas, Santiago; Holmes, Alan; Howat, Sarah; Pearson, Jeremy D.; Dashwood, Michael R.; du Bois, Roland M.; Denton, Christopher P.; Black, Carol M.; Abraham, David J.; Leask, Andrew

    2006-01-01

    The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor β (TGF-β) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-β induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-β are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis. PMID:16809784

  14. Prenatal Oxycodone Exposure Alters CNS Endothelin Receptor Expression in Neonatal Rats.

    PubMed

    Devarapalli, M; Leonard, M; Briyal, S; Stefanov, G; Puppala, B L; Schweig, L; Gulati, A

    2016-05-01

    Prenatal opioid exposure such as oxycodone is linked to significant adverse effects on the developing brain. Endothelin (ET) and its receptors are involved in normal development of the central nervous system. Opioid tolerance and withdrawal are mediated through ET receptors. It is possible that adverse effect of oxycodone on the developing brain is mediated through ET receptors. We evaluated brain ETA and ETB receptor expression during postnatal development in rats with prenatal oxycodone exposure. Timed pregnant Sprague-Dawley rats received either oxycodone or placebo throughout gestation. After birth, male rat pups were sacrificed on postnatal day (PND) 1, 7, 14 or 28. Brain ETA and ETB receptor expression was determined by Western blot analysis. Oxycodone pups compared to placebo demonstrated congenital malformations of the face, mouth, and vertebrae at the time of birth [4/69 (5.7%) vs. 0/60 (0%); respectively] and intrauterine growth retardation [10/69 (15%) vs. 2/60 (3.3%); respectively]. On PND 28, oxycodone pups compared to placebo had lower body and kidney weight. ETA receptor expression in the oxycodone group was significantly higher compared to placebo on PND 1 (p=0.035), but was similar on PND 7, 14, or 28. ETB receptor expression decreased in oxycodone compared to placebo on PND 1 and 7 (p=0.001); and increased on PND 28 (p=0.002), but was similar on PND 14. Oxycodone-exposed rat pups had lower birth weight and postnatal weight gain and greater congenital malformations. ETB receptor expression is altered in the brain of oxycodone-treated rat pups indicating a possible delay in CNS development.

  15. Common genetic variation in the type A endothelin-1 receptor is associated with ambulatory blood pressure: a family study.

    PubMed

    Rahman, T; Baker, M; Hall, D H; Avery, P J; Keavney, B

    2008-04-01

    The endothelins are among the most potent vasoconstrictors known. Pharmacological inhibition of endothelin receptors lowers blood pressure (BP). It is unknown whether naturally occurring genetic variation in the endothelin receptors influences BP. We have evaluated the type A endothelin receptor (EDNRA) as a candidate gene for hypertension in a large family study. A total of 1425 members of 248 families selected via a proband with hypertension were studied. Ambulatory BP monitoring was conducted using the A&D TM2421 device. Four haplotype-tagging single nucleotide polymorphisms (SNPs) spanning the EDNRA gene were typed. There was evidence of association between genotype at the rs5335 (C+70G) SNP and night systolic blood pressure (+1.24% (s.e. 0.64) per G allele; P=0.05); night diastolic blood pressure (+1.64% (s.e. 0.71) per G allele; P=0.021) and night mean BP (+1.51% (s.e. 0.64) per G allele; P=0.017). Borderline significant trends in the same direction were seen for daytime BPs. Proportions of hypertensives in each of the three genotype groups were C/C 34.7%, C/G 37.9%, G/G 42.4% yielding an odds ratio for hypertension per G allele of 1.19 (95% confidence interval 1.00-1.41; P=0.05). In conclusion, the rs5335 (C+70G) polymorphism of the EDNRA gene has small effects on the risk of hypertension. Natural variation in other genes in the endothelin-signalling pathway should be explored to identify additional influences on BP regulation.

  16. Endothelin receptor-specific control of endoplasmic reticulum stress and apoptosis in the kidney

    PubMed Central

    De Miguel, Carmen; Hamrick, William C.; Hobbs, Janet L.; Pollock, David M.; Carmines, Pamela K.; Pollock, Jennifer S.

    2017-01-01

    Endothelin-1 (ET-1) promotes renal damage during cardiovascular disease; yet, the molecular mechanisms involved remain unknown. Endoplasmic reticulum (ER) stress, triggered by unfolded protein accumulation in the ER, contributes to apoptosis and organ injury. These studies aimed to determine whether the ET-1 system promotes renal ER stress development in response to tunicamycin. ETB deficient (ETB def) or transgenic control (TG-con) rats were used in the presence or absence of ETA receptor antagonism. Tunicamycin treatment similarly increased cortical ER stress markers in both rat genotypes; however, only ETB def rats showed a 14–24 fold increase from baseline for medullary GRP78, sXBP-1, and CHOP. Pre-treatment of TG-con rats with the ETA blocker ABT-627 for 1 week prior to tunicamycin injection significantly reduced the ER stress response in cortex and medulla, and also inhibited renal apoptosis. Pre-treatment with ABT-627 failed to decrease renal ER stress and apoptosis in ETB def rats. In conclusion, the ET-1 system is important for the development of tunicamycin-induced renal ER stress and apoptosis. ETA receptor activation induces renal ER stress genes and apoptosis, while functional activation of the ETB receptor has protective effects. These results highlight targeting the ETA receptor as a therapeutic approach against ER stress-induced kidney injury. PMID:28230089

  17. Phenylacetamides as selective alpha-1A adrenergic receptor antagonists.

    PubMed

    Patane, M A; DiPardo, R M; Newton, R C; Price, R P; Broten, T P; Chang, R S; Ransom, R W; Di Salvo, J; Nagarathnam, D; Forray, C; Gluchowski, C; Bock, M G

    2000-08-07

    A novel class of potent and selective alpha-1a receptor antagonists has been identified. The structures of these antagonists were derived from truncating the 4-aryl dihydropyridine subunit present in known alpha-1a antagonists. The design principles which led to the discovery of substituted phenylacetamides, the synthesis and SAR of key analogues, and the results of select in vitro and in vivo studies are described.

  18. Prostanoid receptor antagonists: development strategies and therapeutic applications

    PubMed Central

    Jones, RL; Giembycz, MA; Woodward, DF

    2009-01-01

    Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP1, EP2 …) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP1, TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP2). While some antagonists are structurally related to the natural agonist, most recent compounds are ‘non-prostanoid’ (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD2 (acting on DP1 and DP2 receptors) and PGE2 (on EP1 and EP4 receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage. PMID:19624532

  19. CXCR2 receptor antagonists: a medicinal chemistry perspective.

    PubMed

    Dwyer, Michael P; Yu, Younong

    2014-01-01

    Dysregulated leukocyte recruitment is believed to be a key contributor to various acute and chronic inflammatory disorders which can lead to serious pathological consequences. Chemokines are small molecular weight proteins that have been shown to be imperative in the direction of leukocytes to the sites of inflammation. In humans, several of these chemokines (CXCL8 and CXCL1) are elevated in inflammatory disorders such as asthma, arthritis, and chronic obstructive pulmonary disease (COPD). These chemokines modulate their downstream effects thru G-protein coupled receptors, such as CXCR2, making the identification of small-molecule antagonists of this receptor attractive towards developing novel therapies to treat inflammatory conditions. Since the first report of a CXCR2 receptor antagonist in 1998, there has been a considerable effort conducted mainly in the pharmaceutical industry to identify novel classes of CXCR2 receptor antagonists. Over a dozen distinct classes of CXCR2 receptor antagonists have been reported in the literature to date with a number of these compounds having reached mid-stage clinical trials. This review will provide a broad overview the medicinal chemistry efforts over the past 15 years towards the identification of CXCR2 receptor antagonists. The discussion will focus upon the early preclinical space covering the structure activity relationships (SAR), pharmacology, as well in preclinical in vivo evaluation for the different series of CXCR2 receptor antagonists. In addition, the available clinical data for the most advanced compounds in the clinic will be discussed and along with a perspective of the area moving forward.

  20. Overexpression of Endothelin-A-receptor in breast cancer: regulation by estradiol and cobalt-chloride induced hypoxia.

    PubMed

    Wülfing, Pia; Götte, Martin; Sonntag, Barbara; Kersting, Christian; Schmidt, Hartmut; Wülfing, Christian; Buerger, Horst; Greb, Robert; Böcker, Werner; Kiesel, Ludwig

    2005-04-01

    Previous studies have demonstrated the potential significance of Endothelin (ET)-1 and its receptors, ETAR and ETBR, in the development and progression of breast cancer. The objective of this study was to assess the expression levels and potential regulation of the "ET axis" in human non-neoplastic and neoplastic breast tissue as well as in various human breast cancer cell lines. Expression of ET-1, ETAR and ETBR was evaluated in 31 neoplastic and 7 non-neoplastic breast tissue samples and in six human breast cancer cell lines using conventional and quantitative real-time RT-PCR, Western blotting and immunohistochemistry. The effects of 17beta-estradiol (E2) and cobalt-chloride (CoCl2) treatment on ET-1, ETAR and ETBR expression were studied in vitro. ETAR mRNA expression levels were found to be statistically significantly higher in breast cancer specimens than in non-neoplastic breast tissue (p<0.001). For ET-1 and ETBR mRNA expression, no significant difference was observed between the two groups. All cell lines exhibited expression of ET-1 and ETAR mRNA, whereas none showed significant ETBR mRNA expression. We observed a strong and reproducible induction of ETAR mRNA and protein expression by E2 and CoCl2 in MDA-MB-468 and BT-474 cells and in MDA-MB-453 and SK-BR-3 cells with a maximum increase after 8 and 16 h of treatment, respectively, while MCF-7 and HBL-100 cells showed a constitutive expression pattern. The present data suggest a novel mechanism in the regulation of ETAR expression in breast cancer. Based on these findings, a combination of ETAR-antagonists with adjuvant endocrine treatment seems to be a reasonable therapeutic strategy.

  1. Vasopressin-receptor antagonist therapy in patients with hyponatraemia.

    PubMed

    Vachharajani, Tushar; Vachharajani, Vidula

    2007-07-01

    Hyponatraemia often complicates the treatment of underlying conditions in patients who are seriously ill. Arginine vasopressin receptor antagonists block the action of arginine vasopressin and correct sodium and water imbalance in patients with euvolaemic or hypervolaemic hyponatraemia.

  2. Identification and developmental analysis of endothelin receptor type-A expressing cells in the mouse kidney.

    PubMed

    Kitazawa, Taro; Sato, Takahiro; Nishiyama, Koichi; Asai, Rieko; Arima, Yuichiro; Uchijima, Yasunobu; Kurihara, Yukiko; Kurihara, Hiroki

    2011-10-01

    The endothelin (Edn) system plays pleiotropic roles in renal function and various disease processes through two distinct G protein-coupled receptors, Edn receptors type-A (Ednra) and type-B (Ednrb). However, difficulties in the accurate identification of receptor-expressing cells in situ have made it difficult to dissect their diverse action in renal (patho)physiology. We have recently established mouse lines in which lacZ and EGFP are 'knocked-in' to the Ednra locus to faithfully mark Ednra-expressing cells. Here we analyzed these mice for their expression in the kidney to characterize Ednra-expressing cells. Ednra expression was first observed in undifferentiated mesenchymal cells around the ureteric bud at E12.5. Thereafter, Ednra expression was widely observed in vascular smooth muscle cells, JG cells and mesenchymal cells in the interstitium. After growth, the expression became confined to vascular smooth muscle cells, pericytes and renin-producing JG cells. By contrast, most cells in the nephron and vascular endothelial cells did not express Ednra. These results indicate that Ednra expression may be linked with non-epithelial fate determination and differentiation of metanephric mesenchyme. Ednra-lacZ/EGFP knock-in mice may serve as a useful tool in studies on renal function and pathophysiology of various renal diseases.

  3. Twisting integrin receptors increases endothelin-1 gene expression in endothelial cells

    NASA Technical Reports Server (NTRS)

    Chen, J.; Fabry, B.; Schiffrin, E. L.; Wang, N.; Ingber, D. E. (Principal Investigator)

    2001-01-01

    A magnetic twisting stimulator was developed based on the previously published technique of magnetic twisting cytometry. Using ligand-coated ferromagnetic microbeads, this device can apply mechanical stresses with varying amplitudes, duration, frequencies, and waveforms to specific cell surface receptors. Biochemical and biological responses of the cells to the mechanical stimulation can be assayed. Twisting integrin receptors with RGD (Arg-Gly-Asp)-containing peptide-coated beads increased endothelin-1 (ET-1) gene expression by >100%. In contrast, twisting scavenger receptors with acetylated low-density lipoprotein-coated beads or twisting HLA antigen with anti-HLA antibody-coated beads did not lead to alterations in ET-1 gene expression. In situ hybridization showed that the increase in ET-1 mRNA was localized in the cells that were stressed with the RGD-coated beads. Blocking stretch-activated ion channels with gadolinium, chelating Ca2+ with EGTA, or inhibiting tyrosine phosphorylation with genistein abolished twist-induced ET-1 mRNA elevation. Abolishing cytoskeletal tension with an inhibitor of the myosin ATPase, with an inhibitor of myosin light chain kinase, or with an actin microfilament disrupter blocked twisted-induced increases in ET-1 expression. Our results are consistent with the hypothesis that the molecular structural linkage of integrin-cytoskeleton is an important pathway for stress-induced ET-1 gene expression.

  4. Twisting integrin receptors increases endothelin-1 gene expression in endothelial cells

    NASA Technical Reports Server (NTRS)

    Chen, J.; Fabry, B.; Schiffrin, E. L.; Wang, N.; Ingber, D. E. (Principal Investigator)

    2001-01-01

    A magnetic twisting stimulator was developed based on the previously published technique of magnetic twisting cytometry. Using ligand-coated ferromagnetic microbeads, this device can apply mechanical stresses with varying amplitudes, duration, frequencies, and waveforms to specific cell surface receptors. Biochemical and biological responses of the cells to the mechanical stimulation can be assayed. Twisting integrin receptors with RGD (Arg-Gly-Asp)-containing peptide-coated beads increased endothelin-1 (ET-1) gene expression by >100%. In contrast, twisting scavenger receptors with acetylated low-density lipoprotein-coated beads or twisting HLA antigen with anti-HLA antibody-coated beads did not lead to alterations in ET-1 gene expression. In situ hybridization showed that the increase in ET-1 mRNA was localized in the cells that were stressed with the RGD-coated beads. Blocking stretch-activated ion channels with gadolinium, chelating Ca2+ with EGTA, or inhibiting tyrosine phosphorylation with genistein abolished twist-induced ET-1 mRNA elevation. Abolishing cytoskeletal tension with an inhibitor of the myosin ATPase, with an inhibitor of myosin light chain kinase, or with an actin microfilament disrupter blocked twisted-induced increases in ET-1 expression. Our results are consistent with the hypothesis that the molecular structural linkage of integrin-cytoskeleton is an important pathway for stress-induced ET-1 gene expression.

  5. Endothelin receptor A -231 G>A polymorphism: no linkage to primary pediatric headache.

    PubMed

    Lisi, Veronica; Garbo, Greta; Battistella, PierAntonio; Miccichè, Flavia; Stecca, Anna; Terrazzino, Salvatore; Franzoi, Malida; Tripoli, Elisa; Leon, Alberta; Clementi, Maurizio

    2006-03-01

    To assess whether the biallelic -231 G>A polymorphism of the endothelin type A receptor (EDNRA) gene, previously shown to be a marker of increased risk for developing migraine, has a role in the susceptibility to primary pediatric headache. Several studies suggest that endothelin has a role in migraine. A recent association study has shown that the biallelic -231 G>A polymorphism of the EDNRA gene is associated to migraine in an elderly population. A total of 126 consecutive unrelated pediatric patients affected by primary headache, classified according to the International Headache Society criteria in migraine (migraine with aura, n = 3; migraine without aura, n = 80), and tension-type headache (episodic tension-type headache, n = 36; chronic tension-type headache, n = 7) patients, were recruited to the study. Sixty-seven healthy blood donors were used as a control group. Genomic DNA was extracted from buccal swabs or blood samples and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for the above-mentioned polymorphism. Allele and genotype frequencies for primary headache patients were analyzed in comparison with the control group. No significant differences were found in the distribution of the EDNRA -231 G>A polymorphic variant when considering both genotype (migraine chi2 = 2.78, P = .25; tension-type headache chi2 = 3.58, P = .17) and allelic frequencies (migraine chi2 = 1.48, P = .22; tension-type headache chi2 = 0.39, P = .56). Furthermore, no significant genotype-related difference was found in relation to clinical features, such as age at onset, frequency, and length of the attacks. Our study shows that the -231 G>A polymorphism in the EDNRA gene is neither associated with primary juvenile headache nor significantly correlated with main clinical features characteristic of the headache pathology in pediatric settings.

  6. The application of the human beta-globin gene locus control region and murine erythroleukemia cell system to the expression and pharmacological characterization of human endothelin receptor subtypes.

    PubMed

    Davies, A; Whiting, E; Bath, C; Tang, E; Brennand, J

    1995-06-01

    The cDNAs encoding both A and B subtypes of the human endothelin receptor have been inserted into mammalian cell expression vectors that utilize the human globin gene, locus control region. These constructs have been introduced into murine erythroleukemia cells and inducible high level expression of the receptors has been achieved (approximately 1.5-pM/mg membrane protein and approximately 13,500 binding sites/cell for both receptor subtypes). Cell lines expressing these receptors were obtained on a rapid time scale (3-4 weeks), facilitated by the need for the analysis of only small numbers of cell clones/receptor (approximately 6). Competitive binding assays with endothelin-1 gave IC50s of 130 +/- 30 pM for endothelin-A receptor and 160 +/- 30 pM for endothelin-B receptor. Similar studies with the different isoforms of endothelin, sarafatoxin-S6b and -S6c, BQ123 and BQ3020, all gave the expected selectivity profiles. The IC50s for all compounds were in close agreement with those reported for native receptors. Thus, this expression system, which has several advantages over other described expression systems, is capable of rapidly providing large quantities of receptor for detailed pharmacological analyses or drug screening. In addition, the expressed receptors display the expected pharmacological profiles in the absence of any complicating, competing interactions from other subtypes or binding sites.

  7. Endothelin-1 stimulates human adipocyte lipolysis through the ET A receptor.

    PubMed

    Eriksson, A K S; van Harmelen, V; Stenson, B M; Aström, G; Wåhlén, K; Laurencikiene, J; Rydén, M

    2009-01-01

    Levels of the vascular peptide endothelin-1 (ET-1) are significantly elevated in obesity. Adipose tissue-derived ET-1 attenuates insulin-mediated antilipolysis in human visceral adipocytes through the activation of the ET receptor B (ET(B)R), thereby linking ET-1 to insulin resistance. Whether ET-1 has direct effects on lipolysis in human adipocytes is not known. Endothelin-1 receptor (ETR) mRNA expression was determined by quantitative PCR in 130 non-obese and obese subjects. ET-1 mRNA in different adipose tissue regions was also assessed. ETR protein expression was analyzed by western blotting in 37 subjects. The effect of ET-1 on lipolysis was assessed in freshly isolated adipocytes and in vitro differentiated adipocytes from human donors. Freshly isolated human adipocytes incubated with different concentrations of ET-1 showed no acute effect on lipolysis. In contrast, a 24 h incubation in primary cultures of human adipocytes resulted in a significant 50% increase in lipolysis. This effect was concentration dependent and could be mimicked by an agonist of the ET(A) receptor but not with a selective ET(B)R agonist. Adipocyte differentiation was not affected by any of the agonists. In subcutaneous (s.c.) adipose tissue from 19 non-obese and 18 obese subjects, the protein expression of ET(A)R was significantly higher in obese subjects whereas there was no difference in ET(B)R expression. Interestingly, the differences in protein expression were not observed at the mRNA level as ET(A)R expression was similar between lean and obese subjects. Long-term but not acute incubation of human adipocytes with ET-1 results in a significant increase in lipolysis. This appears to be mediated through the activation of ET(A)R, demonstrating a yet another receptor-specific effect of ET-1. In addition, the protein expression of ET(A)R is increased in s.c. adipose tissue in obesity, possibly through post-transcriptional mechanisms. An increased effect of ET-1 could be a mechanism

  8. [Angiotensin II receptor antagonists: different or equivalent?].

    PubMed

    Mounier-Vehier, C; Devos, P

    ARA-II: Angiotensin II receptor antagonists (ARA-II) belong to a recent class of antihypertensive drugs whose mechanism of action is similar to converting enzyme inhibitors (CEI). ARA-II are particularly interesting due to the excellent clinical and biological tolerance, similar to placebo, and their antihypertensive efficacy, comparable with classical drug classes. PUBLISHED TRIALS: A meta-analysis, published by Conlin in the American Journal of Hypertension, suggests that ARA-II, specifically losartan, valsartan, irbesartan and candesartan, have an equipotent blood pressure lowering effect. The careful lecture of this meta-analysis however discloses a faulty methodology from which no valid conclusion can be drawn. Since this early publication, several other comparative studies have been published. These multicentric, randomized double-blind studies enrolled a sufficient number of patients and demonstrated a clinical difference between certain ARA-II at usual dosages. CLINICAL PRACTICE: These studies do have an impact on everyday practice. For the practitioner, the goal is to obtain and then maintain a long-term and optimal reduction in the blood pressure level (reduction or prevention of target-organ disorders and cardiovascular complications of high blood pressure). This reduction in the cardiovascular risk will also depend directly on tolerance and compliance to the antihypertensive treatment. This element must also be considered in assessing treatment efficacy, independent of the blood pressure lowering effect. The results of several other studies will be published in 2001-2003. These large-scale studies on ARA-II related morbidity and mortality will be most useful in determining the role of these drugs in different therapeutic strategies compared with other drug classes.

  9. Transforming growth factor-beta receptor requirements for the induction of the endothelin-1 gene.

    PubMed

    Castañares, Cristina; Redondo-Horcajo, Mariano; Magan-Marchal, Noemi; Lamas, Santiago; Rodriguez-Pascual, Fernando

    2006-06-01

    Expression of the endothelin (ET)-1 gene is subject to complex regulation by numerous factors, among which the cytokine transforming growth factor-beta (TGF-beta) is one of the most important. TGF-beta action is based on the activation of the Smad signaling pathway. Smad proteins activate transcription of the gene by cooperation with activator protein-1 (AP-1) at specific sites on the ET-1 promoter. Smad signaling pathway is initiated by binding of the cytokine to a heteromeric complex of type I and type II receptors. Signal is then propagated to the nucleus by specific members of the Smad family. Most cell types contain a type I receptor known as ALK5. However, endothelial cells are unique because they coexpress an additional type I receptor named ALK1. These forms do not constitute redundant receptors with the same function, but they actually activate different Smad-mediated expression programs that lead to specific endothelial phenotypes. TGF-beta/ALK5/Smad3 pathway is associated to a mature endothelium because it leads to inhibition of cell migration/proliferation. Conversely, TGF-beta/ALK1/Smad5 activates both processes and is more related to the angiogenic state. We have analyzed the TGF-beta receptor subtype requirements for the activation of the ET-1 gene. For that purpose, we have overexpressed type I receptor and Smad isoforms in endothelial cells and analyzed the effect on ET-1 expression. Our experiments indicate that TGF-beta induces ET-1 expression preferentially through the activation of the ALK5/Smad3 pathway and, therefore, the expression of the vaso-constrictor may be associated to a quiescent and mature endothelial phenotype.

  10. Antagonists of the kappa opioid receptor.

    PubMed

    Urbano, Mariangela; Guerrero, Miguel; Rosen, Hugh; Roberts, Edward

    2014-05-01

    The research community has increasingly focused on the development of OPRK antagonists as pharmacotherapies for the treatment of depression, anxiety, addictive disorders and other psychiatric conditions produced or exacerbated by stress. Short-acting OPRK antagonists have been recently developed as a potential improvement over long-acting prototypic ligands including nor-BNI and JDTic. Remarkably the short-acting LY2456302 is undergoing phase II clinical trials for the augmentation of the antidepressant therapy in treatment-resistant depression. This Letter reviews relevant chemical and pharmacological advances in the identification and development of OPRK antagonists.

  11. Endothelin in cerebral vasospasm. Clinical and experimental results.

    PubMed

    Zimmermann, M

    1997-06-01

    Since their discovery in 1988, endothelins have attracted scientific interest because of their extremely potent and long lasting vasoconstrictive effects. In the clinical part of the study plasma and cerebrospinal fluid (CSF) concentrations of big endothelin-1, endothelin-1 and endothelin-3 in patients with aneurysmal subarachnoid hemorrhage (SAH) were measured serially for 2 weeks after the onset of SAH. Big endothelin-1 was the predominant peptide present in CSF. The CSF concentrations of big ET-1, ET-1 and ET-3 were significantly higher in older than in younger patients. In patients with cerebral vasospasm postoperative concentrations of endothelins in the CSF remained at or were increased above levels measured before surgery. The volume of hematoma in the basal cisterns was predictive of the concentrations of endothelins in CSF. In the experimental study the efficacy of the orally active endothelin-receptor-antagonist RO 47-0203 for the prevention of cerebral vasospasm after experimental SAH, using the canine two-hemorrhage model, was investigated. Twenty-eight beagle dogs were used in this laboratory experiment. Fourteen animals each were assigned to the treatment and to the control group. In the treatment group each dog received two single doses of 30 mg/kg RO 47-0203 orally per day. The diameter of the basilar artery decreased from 1.36 +/- 0.17 mm at day 1 to 1.19 +/- 0.23 mm at day 8 in the treatment group while in the control group the vessel diameter decreased from 1.48 +/- 0.19 mm at day 1 to 1.02 +/- 0.22 mm at day 8. These results corresponded to a decrease of vessel diameter of 13.1% +/- 11.2% in the treatment group and a decrease of vessel diameter of 30.7% +/- 12.4% in the control group (p < 0.001). Concentrations of endothelin-1 in CSF significantly increased with time after SAH. These results underline the important role of endothelin in the development of cerebral vasospasm, and gives for the first time evidence that prevention of cerebral

  12. Action of AT1 receptor antagonists on angiotensin II-induced tone in human isolated subcutaneous resistance arteries.

    PubMed

    Garcha, R S; Sever, P S; Hughes, A D

    1999-08-01

    1. Human isolated subcutaneous arteries were studied under isometric conditions in a myograph. 2. Addition of angiotensin II (AII) induced a concentration-dependent increase in tone in isolated arteries. The active metabolite of candesartan (CV 11974), losartan and the active metabolite of losartan, E-3174 antagonized AII-induced tone in a non-competitive manner, but the AT2 selective antagonist, PD123319, was without effect on responses to AII. The effects of candesartan, losartan and E-3174 were analysed using a classical model of non-competitive antagonism and a two-state receptor model. 3. Mechanical removal of the endothelium; pre-incubation with Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME); pre-incubation with indomethacin, a cyclo-oxygenase inhibitor; or pre-incubation with BQ 485, an endothelin antagonist; had no significant effect on contractions induced by AII. 4. Our results suggest AII contracts human isolated resistance arteries by an action on AT1 receptors and does not involve release of endothelial factors. Use of a two-state receptor model successfully described the action of the AT1 antagonists without sacrificing assumptions regarding the competitive nature of binding of these antagonists.

  13. Methamphetamine induces the release of endothelin.

    PubMed

    Seo, Jeong-Woo; Jones, Susan M; Hostetter, Trisha A; Iliff, Jeffrey J; West, G Alexander

    2016-02-01

    Methamphetamine is a potent psychostimulant drug of abuse that increases release and blocks reuptake of dopamine, producing intense euphoria, factors that may contribute to its widespread abuse. It also produces severe neurotoxicity resulting from oxidative stress, DNA damage, blood-brain barrier disruption, microgliosis, and mitochondrial dysfunction. Intracerebral hemorrhagic and ischemic stroke have been reported after intravenous and oral abuse of methamphetamine. Several studies have shown that methamphetamine causes vasoconstriction of vessels. This study investigates the effect of methamphetamine on endothelin-1 (ET-1) release in mouse brain endothelial cells by ELISA. ET-1 transcription as well as endothelial nitric oxide synthase (eNOS) activation and transcription were measured following methamphetamine treatment. We also examine the effect of methamphetamine on isolated cerebral arteriolar vessels from C57BL/6 mice. Penetrating middle cerebral arterioles were cannulated at both ends with a micropipette system. Methamphetamine was applied extraluminally, and the vascular response was investigated. Methamphetamine treatment of mouse brain endothelial cells resulted in ET-1 release and a transient increase in ET-1 message. The activity and transcription of eNOS were only slightly enhanced after 24 hr of treatment with methamphetamine. In addition, methamphetamine caused significant vasoconstriction of isolated mouse intracerebral arterioles. The vasoconstrictive effect of methamphetamine was attenuated by coapplication of the endothelin receptor antagonist PD145065. These findings suggest that vasoconstriction induced by methamphetamine is mediated through the endothelin receptor and may involve an endothelin-dependent pathway. © 2015 Wiley Periodicals, Inc.

  14. Endothelin receptor subtype A blockade does not affect the haemodynamic recovery from haemorrhage during xenon/remifentanil or isoflurane/remifentanil anaesthesia in dogs.

    PubMed

    Francis, Roland C E; Höhne, Claudia; Klein, Adrian; Kaisers, Udo X; Pickerodt, Philipp A; Boemke, Willehad

    2010-05-01

    To test the compensatory role of endothelin-1 when acute blood loss is superimposed on anaesthesia, by characterizing the effect of systemic endothelin receptor subtype A (ET(A)) blockade on the haemodynamic and hormonal responses to haemorrhage in dogs anaesthetized with xenon/remifentanil (X/R) or isoflurane/remifentanil (I/R). Prospective experimental randomized controlled study. Six female Beagle dogs, 13.4 +/- 1.3 kg. Animals were anaesthetized with remifentanil 0.5 microg kg(-1) minute(-1) plus either 0.8% isoflurane (I/R) or 63% xenon (X/R), with and without (Control) the systemic intravenous endothelin receptor subtype A antagonist atrasentan (four groups, n = 6 each). After 60 minutes of baseline anaesthesia, the dogs were bled (20 mL kg(-1)) over 5 minutes and hypovolemia was maintained for 1 hour. Continuous haemodynamic monitoring was performed via femoral and pulmonary artery catheters; vasoactive hormones were measured before and after haemorrhage. In Controls, systemic vascular resistance (SVR), vasopressin and catecholamine plasma concentrations were higher with X/R than with I/R anaesthesia at pre-haemorrhage baseline. The peak increase after haemorrhage was higher during X/R than during I/R anaesthesia (SVR 7420 +/- 867 versus 5423 +/- 547 dyne seconds cm(-5); vasopressin 104 +/- 23 versus 44 +/- 6 pg mL(-1); epinephrine 2956 +/- 310 versus 177 +/- 99 pg mL(-1); norepinephrine 862 +/- 117 versus 195 +/- 33 pg mL(-1), p < 0.05). Haemorrhage reduced central venous pressure from 3 +/- 1 to 1 +/- 1 cm H(2)O (I/R, ns) and from 8 +/- 1 to 5 +/- 1 cm H(2)O (X/R, p < 0.05), but did not reduce mean arterial pressure, nor cardiac output. Atrasentan did not alter the haemodynamic and hormonal response to haemorrhage during either anaesthetic protocol. Selective ET(A) receptor blockade with atrasentan did not impair the haemodynamic and hormonal compensation of acute haemorrhage during X/R or I/R anaesthesia in dogs.

  15. Recent advances in CB1 cannabinoid receptor antagonists.

    PubMed

    Lange, Jos H M; Kruse, Chris G

    2004-07-01

    Cannabinoid CB1 receptor antagonists are currently the subject of intensive research due to their highly promising therapeutic prospects. Novel chemical entities having CB1 antagonistic properties have recently been disclosed by several pharmaceutical companies and some academic research groups, some of which are close structural analogs of the leading compound rimonabant (SR-141716A; Sanofi-Synthélabo). A considerable number of these CB1 antagonists are bioisosteres that are derived from rimonabant by the replacement of the pyrazole moiety with an alternative heterocycle. As well as these achiral compounds, Solvay Pharmaceuticals have disclosed a novel class of chiral pyrazolines that are potent and CB1/CB2 subtype-selective cannabinoid receptor antagonists, in which the interactions with the CB1 receptor are highly stereoselective.

  16. Solution structures and molecular interactions of selective melanocortin receptor antagonists.

    PubMed

    Lee, Chul-Jin; Yun, Ji-Hye; Lim, Sung-Kil; Lee, Weontae

    2010-12-01

    The solution structures and inter-molecular interaction of the cyclic melanocortin antagonists SHU9119, JKC363, HS014, and HS024 with receptor molecules have been determined by NMR spectroscopy and molecular modeling. While SHU9119 is known as a nonselective antagonist, JKC363, HS014, and HS024 are selective for the melanocortin subtype-4 receptor (MC4R) involved in modulation of food intake. Data from NMR and molecular dynamics suggest that the conformation of the Trp9 sidechain in the three MC4R-selective antagonists is quite different from that of SHU9119. This result strongly supports the concept that the spatial orientation of the hydrophobic aromatic residue is more important for determining selectivity than the presence of a basic, "arginine-like" moiety responsible for biological activity. We propose that the conformation of hydrophobic residues of MCR antagonists is critical for receptor-specific selectivity.

  17. Endothelin receptor B polymorphism associated with lethal white foal syndrome in horses.

    PubMed

    Santschi, E M; Purdy, A K; Valberg, S J; Vrotsos, P D; Kaese, H; Mickelson, J R

    1998-04-01

    Overo lethal white syndrome (OLWS) is an inherited syndrome of foals born to American Paint Horse parents of the overo coat-pattern lineage. Affected foals are totally or almost totally white and die within days from complications due to intestinal aganglionosis. Related conditions occur in humans and rodents in which mutations in the endothelin receptor B (EDNRB) gene are responsible. EDNRB is known to be involved in the developmental regulation of neural crest cells that become enteric ganglia and melanocytes. In this report we identify a polymorphism in the equine EDNRB gene closely associated with OLWS. This Ile to Lys substitution at codon 118 is located within the first transmembrane domain of this seven-transmembrane domain G-protein-coupled receptor protein. All 22 OLWS-affected foals examined were homozygous for the Lys118 EDNRB allele, while all available parents of affected foals were heterozygous. All but one of the parents also had an overo white body-spot phenotype. Solid-colored control horses of other breeds were homozygous for the Ile118 EDNRB allele. Molecular definition of the basis for OLWS in Paint Horses provides a genetic test for the presence of the Lys118 EDNRB allele and adds to our understanding of the basis for coat color patterns in the horse.

  18. NK-1 receptor antagonists: a new paradigm in pharmacological therapy.

    PubMed

    Muñoz, M; Coveñas, R

    2011-01-01

    The neuropeptide substance P (SP) shows a widespread distribution in both the central and peripheral nervous systems and it is known that after binding to the neurokinin-1 (NK-1) receptors, SP regulates many biological functions in the central nervous system such as emotional behaviour, stress, depression, anxiety, emesis, migraine, alcohol addiction and neurodegeneration. SP has been also implicated in pain, inflammation, hepatotoxicity and in virus proliferation, and it plays an important role in cancer (e.g., tumour cell proliferation, angiogenesis, and the migration of tumour cells for invasion and metastasis). By contrast, it is known that after binding to NK-1 receptors, NK-1 receptor antagonists specifically inhibit the above-mentioned biological functions mediated by SP. Thus, these antagonists exert an anxyolitic, antidepressant, antiemetic, antimigraine, antialcohol addiction or neuroprotector effect in the central nervous system, and they play a role in analgesic, antiinflammatory, hepatoprotector processes and in antivirus proliferation. Regarding cancer, NK-1 receptor antagonists exert an antitumour action (inducing tumour cell death by apoptosis), and induce antiangiogenesis and inhibit the migration of tumour cells. It is also known that NK-1 receptors have a widespread distribution and that they are overexpressed in tumour cells. Thus, NK-1 receptor antagonists are molecularly targeted agents. In general, current drugs have a single therapeutic effect, although less commonly they may exert several. However, the data reported above indicate that NK-1 receptor antagonists are promising drugs, exerting many therapeutic effects (the action of such antagonists is dose-dependent and, depending on the concentration, has more positive effects). In this review, we update the multiple therapeutic effects exerted by NK-1 receptor antagonists.

  19. Protein kinase mediated upregulation of endothelin A, endothelin B and 5-hydroxytryptamine 1B/1D receptors during organ culture in rat basilar artery

    PubMed Central

    Hansen-Schwartz, Jacob; Svensson, Carl-Lennart; Xu, Cang-Bao; Edvinsson, Lars

    2002-01-01

    Organ culture has been shown to upregulate both endothelin (ET) and 5-hydroxytryptamine 1B/1D (5-HT1B/1D) receptors in rat cerebral arteries. The purpose of the present study was to investigate the involvement of protein kinases, especially protein kinases C (PKC) and A (PKA) in this process. The effect of inhibiting protein kinases during organ culture with staurosporine (unspecific protein kinase inhitor), RO 31-7549 (specific inhibitor of classical PKC's) and H 89 (specific inhibitor of PKA) was examined using in vitro pharmacological examination of cultured vessel segments with ET-1 (unspecific ETA and ETB agonist), S6c (specific ETB agonist) and 5-CT (5-HT1 agonist). Levels of mRNA coding for the ETA, ETB, 5-HT1B and 5-HT1D receptors were analysed using real-time RT–PCR. Classical PKC's are critically involved in the appearance of the ETB receptor; co-culture with RO 31-7549 abolished the contractile response (6.9±1.8%) and reduced the ETB receptor mRNA by 44±4% as compared to the cultured control. Correlation between decreased ETB receptor mRNA and abolished contractile function indicates upstream involvement of PKC. Inhibition of PKA generally had an enhancing effect on the induced changes giving rise to a 7–25% increase in Emax in response to ET-1, S6c and 5-CT as compared to the cultured control. Staurosporine inhibited the culture induced upregulation of the response of both the ETA and the 5-HT1B/1D receptors, but had no significant effect on the mRNA levels of these receptors. This lack of correlation indicates an additional downstream involvement of protein kinases. PMID:12183337

  20. Combining Elements from Two Antagonists of Formyl Peptide Receptor 2 Generates More Potent Peptidomimetic Antagonists.

    PubMed

    Skovbakke, Sarah Line; Holdfeldt, André; Nielsen, Christina; Hansen, Anna Mette; Perez-Gassol, Iris; Dahlgren, Claes; Forsman, Huamei; Franzyk, Henrik

    2017-08-24

    Structural optimization of a peptidomimetic antagonist of formyl peptide receptor 2 (FPR2) was explored by an approach involving combination of elements from the two most potent FPR2 antagonists described: a Rhodamine B-conjugated 10-residue gelsonin-derived peptide (i.e., PBP10, RhB-QRLFQVKGRR-OH) and the palmitoylated α-peptide/β-peptoid hybrid Pam-(Lys-βNspe)6-NH2. This generated an array of hybrid compounds from which a new subclass of receptor-selective antagonists was identified. The most potent representatives displayed activity in the low nanomolar range. The resulting stable and potent FPR2-selective antagonists (i.e., RhB-(Lys-βNphe)n-NH2; n = 4-6) are expected to become valuable tools in further elucidation of the physiological role of FPR2 in health and disease.

  1. Effect of short-term hyperinsulinemia on the localization and expression of endothelin receptors A and B in lamellar tissue of the forelimbs of horses

    PubMed Central

    Gauff, Felicia C.; Patan-Zugaj, Bianca; Licka, Theresia F.

    2014-01-01

    Objective To determine the effect of short-term hyperinsulinemia on the localization and expression of endothelin receptor (ETR)-A and ETR-B in lamellar tissue of the forelimbs of horses. Samples Distal portion of 15 cadaveric forelimbs from healthy adult horses (1 limb/horse) obtained immediately after slaughter at an abattoir. Procedures Each forelimb was assigned to 1 of 3 treatment groups (perfused with autologous blood for 10 hours [control perfusion; n = 5], perfused with an insulin [142 ± 81 μU/mL] perfusate for 10 hours [insulinemic perfusion; 5], or not perfused [unperfused control; 5]). Immunohistochemical evaluation of lamellar tissue was performed to assess localization of ETR-A and ETR-B. Expression of ETR-A and ETR-B was measured semiquantitatively on a scale of 0 to 3 (0 = none, 1 = mild, 2 = moderate, and 3 = high-intensity staining) and quantitatively by means of gray value analysis with imaging software. Results In all specimens, ETR-A and ETR-B were localized in endothelium, smooth muscle cells, axons, and keratinocytes. Quantitative expression of ETR-A in the midportion of the primary epidermal lamellae for the insulinemic perfusion group (149 ± 16) was lower than that for the control perfusion group (158 ± 15). Expression of ETR-B in the primary epidermal lamellae tips for the insulinemic perfusion group (140 ± 29) was higher than that for the control perfusion group (114 ± 8). Conclusions and Clinical Relevance Hyperinsulinemia caused significant changes in endothelin receptor expression, which suggested that ETR antagonists might be beneficial for treatment of laminitis in horses. PMID:24669922

  2. Nonpeptidic urotensin-II receptor antagonists I: in vitro pharmacological characterization of SB-706375

    PubMed Central

    Douglas, Stephen A; Behm, David J; Aiyar, Nambi V; Naselsky, Diane; Disa, Jyoti; Brooks, David P; Ohlstein, Eliot H; Gleason, John G; Sarau, Henry M; Foley, James J; Buckley, Peter T; Schmidt, Dulcie B; Wixted, William E; Widdowson, Katherine; Riley, Graham; Jin, Jian; Gallagher, Timothy F; Schmidt, Stanley J; Ridgers, Lance; Christmann, Lisa T; Keenan, Richard M; Knight, Steven D; Dhanak, Dashyant

    2005-01-01

    SB-706375 potently inhibited [125I]hU-II binding to both mammalian recombinant and ‘native' UT receptors (Ki 4.7±1.5 to 20.7±3.6 nM at rodent, feline and primate recombinant UT receptors and Ki 5.4±0.4 nM at the endogenous UT receptor in SJRH30 cells). Prior exposure to SB-706375 (1 μM, 30 min) did not alter [125I]hU-II binding affinity or density in recombinant cells (KD 3.1±0.4 vs 5.8±0.9 nM and Bmax 3.1±1.0 vs 2.8±0.8 pmol mg−1) consistent with a reversible mode of action. The novel, nonpeptidic radioligand [3H]SB-657510, a close analogue of SB-706375, bound to the monkey UT receptor (KD 2.6±0.4 nM, Bmax 0.86±0.12 pmol mg−1) in a manner that was inhibited by both U-II isopeptides and SB-706375 (Ki 4.6±1.4 to 17.6±5.4 nM) consistent with the sulphonamides and native U-II ligands sharing a common UT receptor binding domain. SB-706375 was a potent, competitive hU-II antagonist across species with pKb 7.29–8.00 in HEK293-UT receptor cells (inhibition of [Ca2+]i-mobilization) and pKb 7.47 in rat isolated aorta (inhibition of contraction). SB-706375 also reversed tone established in the rat aorta by prior exposure to hU-II (Kapp∼20 nM). SB-706375 was a selective U-II antagonist with ⩾100-fold selectivity for the human UT receptor compared to 86 distinct receptors, ion channels, enzymes, transporters and nuclear hormones (Ki/IC50>1 μM). Accordingly, the contractile responses induced in isolated aortae by KCl, phenylephrine, angiotensin II and endothelin-1 were unaltered by SB-706375 (1 μM). In summary, SB-706375 is a high-affinity, surmountable, reversible and selective nonpeptide UT receptor antagonist with cross-species activity that will assist in delineating the pathophysiological actions of U-II in mammals. PMID:15852036

  3. Pharmacophore development for antagonists at α1 adrenergic receptor subtypes

    NASA Astrophysics Data System (ADS)

    Bremner, J. B.; Coban, B.; Griffith, R.

    1996-12-01

    Many receptors, including α1 adrenergic receptors, have a range of subtypes. This offers possibilities for the development of highly selective antagonists with potentially fewer detrimental effects. Antagonists developed for α1A receptors, for example, would have potential in the treatment of benign prostatic hyperplasia. As part of the molecular design process, structural features necessary for the selective affinity for α1A and α1B adrenergic receptors have been investigated. The molecular modelling software (particularly the Apex module) of Molecular Simulations, Inc. was used to develop pharmacophore models for these two subtypes. Low-energy conformations of a set of known antagonists were used as input, together with a classification of the receptor affinity data. The biophores proposed by the program were evaluated and pharmacophores were proposed. The pharmacophore models were validated by testing the fit of known antagonists, not included in the training set. The critical structural feature for selectivity between the α1A and α1B adrenergic receptor sites is the distance between the basic nitrogen atom and the centre of an aromatic ring system. This will be exploited in the design and synthesis of structurally new selective antagonists for these sites.

  4. Prevention of RhoA activation and cofilin-mediated actin polymerization mediates the antihypertrophic effect of adenosine receptor agonists in angiotensin II- and endothelin-1-treated cardiomyocytes.

    PubMed

    Zeidan, Asad; Gan, Xiaohong Tracey; Thomas, Ashley; Karmazyn, Morris

    2014-01-01

    Adenosine receptor activation has been shown to be associated with diminution of cardiac hypertrophy and it has been suggested that endogenously produced adenosine may serve to blunt pro-hypertrophic processes. In the present study, we determined the effects of two pro-hypertrophic stimuli, angiotensin II (Ang II, 100 nM) and endothelin-1 (ET-1, 10 nM) on Ras homolog gene family, member A (RhoA)/Rho-associated, coiled-coil containing protein kinase (ROCK) activation in cultured neonatal rat ventricular myocytes and whether the latter serves as a target for the anti-hypertrophic effect of adenosine receptor activation. Both hypertrophic stimuli potently increased RhoA activity with peak activation occurring 15-30 min following agonist addition. These effects were associated with significantly increased phosphorylation (inactivation) of cofilin, a downstream mediator of RhoA, an increase in actin polymerization, and increased activation and nuclear import of p38 mitogen activated protein kinase. The ability of both Ang II and ET-1 to activate the RhoA pathway was completely prevented by the adenosine A1 receptor agonist N (6)-cyclopentyladenosine, the A2a receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine, the A3 receptor agonist N (6)-(3-iodobenzyl)adenosine-5'-methyluronamide as well as the nonspecific adenosine analog 2-chloro adenosine. All effects of specific receptor agonists were prevented by their respective receptor antagonists. Moreover, all adenosine agonists prevented either Ang II- or ET-1-induced hypertrophy, a property shared by the RhoA inhibitor Clostridium botulinum C3 exoenzyme, the ROCK inhibitor Y-27632 or the actin depolymerizing agent latrunculin B. Our study therefore demonstrates that both Ang II and ET-1 can activate the RhoA pathway and that prevention of the hypertrophic response to both agonists by adenosine receptor activation is mediated by prevention of RhoA stimulation and actin polymerization.

  5. Discovery of Dual ETA/ETB Receptor Antagonists from Traditional Chinese Herbs through in Silico and in Vitro Screening

    PubMed Central

    Wang, Xing; Zhang, Yuxin; Liu, Qing; Ai, Zhixin; Zhang, Yanling; Xiang, Yuhong; Qiao, Yanjiang

    2016-01-01

    Endothelin-1 receptors (ETAR and ETBR) act as a pivotal regulator in the biological effects of ET-1 and represent a potential drug target for the treatment of multiple cardiovascular diseases. The purpose of the study is to discover dual ETA/ETB receptor antagonists from traditional Chinese herbs. Ligand- and structure-based virtual screening was performed to screen an in-house database of traditional Chinese herbs, followed by a series of in vitro bioassay evaluation. Aristolochic acid A (AAA) was first confirmed to be a dual ETA/ETB receptor antagonist based intracellular calcium influx assay and impedance-based assay. Dose-response curves showed that AAA can block both ETAR and ETBR with IC50 of 7.91 and 7.40 μM, respectively. Target specificity and cytotoxicity bioassay proved that AAA is a selective dual ETA/ETB receptor antagonist and has no significant cytotoxicity on HEK293/ETAR and HEK293/ETBR cells within 24 h. It is a feasible and effective approach to discover bioactive compounds from traditional Chinese herbs using in silico screening combined with in vitro bioassay evaluation. The structural characteristic of AAA for its activity was especially interpreted, which could provide valuable reference for the further structural modification of AAA. PMID:26999111

  6. Stimulation of peroxisome-proliferator-activated receptor alpha (PPAR alpha) attenuates cardiac fibrosis and endothelin-1 production in pressure-overloaded rat hearts.

    PubMed

    Ogata, Takehiro; Miyauchi, Takashi; Sakai, Satoshi; Irukayama-Tomobe, Yoko; Goto, Katsutoshi; Yamaguchi, Iwao

    2002-08-01

    Endothelin-1 (ET-1) production is increased in hypertrophied hearts accompanied with fibrosis. ET-1 is a potent mitogen of fibroblasts and ET receptor antagonists are reported to inhibit the proliferation of fibroblasts and cardiac fibrosis. Peroxisome-proliferator-activated receptor alpha (PPAR alpha), one of the nuclear hormone receptors, suppresses activator protein-1 (AP-1), one of the nuclear transcription factors. Activation of PPAR alpha is reported to inhibit thrombin-induced ET-1 production by repressing the AP-1 signalling pathway in vascular endothelial cells. We investigated effects of the PPAR alpha activator fenofibrate (80 mg/kg per day, per os) on mRNA levels of ET-1, collagen type I and type III and histological features of myocardial fibrosis in hypertrophied rat hearts due to pressure-overload by abdominal aortic banding (AB). The treatment with fenofibrate or vehicle was started 7 days before the AB operation. Four days after the AB operation, fenofibrate treatment significantly reduced ET-1 mRNA expression compared with vehicle treatment in AB rat hearts. Collagen type I and type III mRNA expression, and interstitial and perivascular fibrosis were attenuated in the fenofibrate-treated AB rat group. Since the ET-1 gene has AP-1 response elements in the 5'-flanking region, it is suggested that myocardial fibrosis is effectively inhibited by fenofibrate through suppression of AP-1-mediated ET-1 gene augmentation in the pressure-overloaded heart caused by aortic banding in rats.

  7. Inhibition of infarction-induced sympathetic innervation with endothelin receptor antagonism via a PI3K/GSK-3β-dependent pathway.

    PubMed

    Lee, T-M; Chang, Nen-Chung; Lin, Shinn-Zong

    2017-03-01

    Although endothelin (ET)-1 has been shown to upregulate nerve growth factor (NGF) expression, the molecular mechanisms are largely unknown. Phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase (GSK)-3β signal has been implicated in the regulation of NGF. We investigated whether selective ET receptor blockers attenuated cardiac sympathetic reinnervation through restoring PI3K/Akt/GSK-3β activity. After ligation of the left anterior descending artery, male Wistar rats were randomized to either vehicle, atrasentan (an ETA receptor antagonist) or A-192621 (an ETB receptor antagonist) for 4 weeks. Sympathetic hyperinnervation after infarction was confirmed by myocardial norepinephrine measurement and immunofluorescent analysis. Post infarction was associated with increased reactive oxygen species (ROS), as measured by myocardial superoxide levels and dihydroethidine fluorescence staining. This was paralleled by a significant upregulation of NGF expression on mRNA and protein levels in the vehicle-treated rats, which reduced after administering atrasentan, not A-192621. Arrhythmic scores in the vehicle-treated rats were significantly higher than those treated with atrasentan. In an in vivo study atrasentan-induced decreased NGF was associated with activation of PI3K/Akt signaling pathway, which was further confirmed by the ex vivo study showing the restoration of NGF levels after coadministration of PI3K inhibitors (wortmannin and LY294002). Lithium chloride, an inhibitor of GSK-3β, did not provide additional attenuated NGF levels compared with atrasentan alone. Finally, atrasentan-attenuated NGF levels were reversed in the presence of peroxynitrite generator. ETA receptor antagonism is a mediator to attenuate sympathetic hyperinnervation probably through restoration of PI3K/Akt/GSK-3β/ROS signaling pathway, a potential pharmacological target for arrhythmias after infarction.

  8. Long-Term Effect of Endothelin Receptor Antagonism With Bosentan on the Morbidity and Mortality of Patients With Severe Chronic Heart Failure: Primary Results of the ENABLE Trials.

    PubMed

    Packer, Milton; McMurray, John J V; Krum, Henry; Kiowski, Wolfgang; Massie, Barry M; Caspi, Avi; Pratt, Craig M; Petrie, Mark C; DeMets, David; Kobrin, Isaac; Roux, Sebastien; Swedberg, Karl

    2017-05-01

    The objective of this clinical trial was to evaluate the long-term effect of endothelin receptor antagonism with bosentan on the morbidity and mortality of patients with severe chronic heart failure. Endothelin may play a role in heart failure, but short-term clinical trials with endothelin receptor antagonists have reported disappointing results. Long-term trials are lacking. In 2 identical double-blind trials, we randomly assigned 1,613 patients with New York Heart Association functional class IIIb to IV heart failure and an ejection fraction <35% to receive placebo or bosentan (target dose 125 mg twice daily) for a median of 1.5 years. The primary outcome for each trial was clinical status at 9 months (assessed by the hierarchical clinical composite); the primary outcome across the 2 trials was death from any cause or hospitalization for heart failure. Bosentan did not influence clinical status at 9 months in either trial (p = 0.928 and p = 0.263). In addition, 321 patients in the placebo group and 312 patients in the bosentan group died or were hospitalized for heart failure (hazard ratio [HR]: 1.01; 95% confidence interval [CI]: 0.86 to 1.18; p = 0.90). The bosentan group experienced fluid retention within the first 2 to 4 weeks, as evidenced by increased peripheral edema, weight gain, decreases in hemoglobin, and an increased risk of hospitalization for heart failure, despite intensification of background diuretics. During follow-up, 173 patients died in the placebo group and 160 patients died in the bosentan group (HR: 0.94; 95% CI: 0.75 to 1.16). About 10% of the bosentan group showed meaningful increases in hepatic transaminases, but none had acute or chronic liver failure. Bosentan did not improve the clinical course or natural history of patients with severe chronic heart failure and but caused early and important fluid retention. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  9. Inhibition of Biosynthesis of Human Endothelin B Receptor by the Cyclodepsipeptide Cotransin*

    PubMed Central

    Westendorf, Carolin; Schmidt, Antje; Coin, Irene; Furkert, Jens; Ridelis, Ingrid; Zampatis, Dimitris; Rutz, Claudia; Wiesner, Burkhard; Rosenthal, Walter; Beyermann, Michael; Schülein, Ralf

    2011-01-01

    The specific inhibition of the biosynthesis of target proteins is a relatively novel strategy in pharmacology and is based mainly on antisense approaches (e.g. antisense oligonucleotides or RNA interference). Recently, a novel class of substances was described acting at a later step of protein biosynthesis. The cyclic heptadepsipeptides CAM741 and cotransin were shown to inhibit selectively the biosynthesis of a small subset of secretory proteins by preventing stable insertion of the nascent chains into the Sec61 translocon complex at the endoplasmic reticulum membrane (Besemer, J., Harant, H., Wang, S., Oberhauser, B., Marquardt, K., Foster, C. A., Schreiner, E. P., de Vries, J. E., Dascher-Nadel, C., and Lindley, I. J. (2005) Nature 436, 290–293; Garrison, J. L., Kunkel, E. J., Hegde, R. S., and Taunton, J. (2005) Nature 436, 285–289). These peptides act in a signal sequence-discriminatory manner, which explains their selectivity. Here, we have analyzed the cotransin sensitivity of various G protein-coupled receptors in transfected HEK 293 cells. We show that the biosynthesis of the human endothelin B receptor (ETBR) is highly sensitive to cotransin, in contrast to that of the other G protein-coupled receptors analyzed. Using a novel biosynthesis assay based on fusions with the photoconvertible Kaede protein, we show that the IC50 value of cotransin action on ETBR biosynthesis is 5.4 μm and that ETBR signaling could be completely blocked by treating cells with 30 μm cotransin. Taken together, our data add an integral membrane protein, namely the ETBR, to the small group of cotransin-sensitive proteins. PMID:21808059

  10. Triterpenes from Alisma orientalis act as androgen receptor agonists, progesterone receptor antagonists, and glucocorticoid receptor antagonists.

    PubMed

    Lin, Hsiang-Ru

    2014-08-01

    Alisma orientalis, a well-known traditional medicine, exerts numerous pharmacological effects including anti-diabetes, anti-hepatitis, and anti-diuretics but its bioactivity is not fully clear. Androgen receptor (AR), progesterone receptor (PR), and glucocorticoid receptor (GR) are three members of nuclear receptor superfamily that has been widely targeted for developing treatments for essential diseases including prostate cancer and breast cancer. In this study, two triterpenes, alisol M 23-acetate and alisol A 23-acetate from Alisma orientalis were determined whether they may act as androgen receptor (AR), progesterone receptor (PR), or glucocorticoid receptor (GR) modulators. Indeed, in the transient transfection reporter assays, alisol M 23-acetate and alisol A 23-acetate transactivated AR in dose-dependent manner, while they transrepressed the transactivation effects exerted by agonist-activated PR and GR. Through molecular modeling docking studies, they were shown to respectively interact with AR, PR, or GR ligand binding pocket fairly well. All these results indicate that alisol M 23-acetate and alisol A 23-acetate from Alisma orientalis might possess therapeutic effects through their modulation of AR, PR, and GR pathways. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  12. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  13. Novel arylpiperazines as selective alpha1-adrenergic receptor antagonists.

    PubMed

    Li, X; Murray, W V; Jolliffe, L; Pulito, V

    2000-05-15

    A novel series of arylpiperazines has been synthesized and identified as antagonists of alpha1a adrenergic receptor (alpha1a-AR) implicated in benign prostatic hyperplasia. These compounds selectively bind to membrane bound alpha1a-AR with K(i)s as low as 0.66 nM. As such, these potentially represent a viable treatment for BPH without the side effects associated with known alpha1-adrenergic antagonists.

  14. Thermodynamic analysis of antagonist and agonist interactions with dopamine receptors.

    PubMed

    Duarte, E P; Oliveira, C R; Carvalho, A P

    1988-03-01

    The binding of [3H]spiperone to dopamine D-2 receptors and its inhibition by antagonists and agonists were examined in microsomes derived from the sheep caudate nucleus, at temperatures between 37 and 1 degree C, and the thermodynamic parameters of the binding were evaluated. The affinity of the receptor for the antagonists, spiperone and (+)-butaclamol, decreased as the incubation temperature decreased; the affinity for haloperidol did not further decrease at temperatures below 15 degrees C. The binding of the antagonists was associated with very large increases in entropy, as expected for hydrophobic interactions. The enthalpy and entropy changes associated with haloperidol binding were dependent on temperature, in contrast to those associated with spiperone and (+)-butaclamol. The magnitude of the entropy increase associated with the specific binding of the antagonists did not correlate with the degree of lipophilicity of these drugs. The data suggest that, in addition to hydrophobic forces, other forces are also involved in the antagonist-dopamine receptor interactions, and that a conformational change of the receptor could occur when the antagonist binds. Agonist binding data are consistent with a two-state model of the receptor, a high-affinity state (RH) and a low-affinity state (RL). The affinity of dopamine binding to the RH decreased with decreasing temperatures below 20 degrees C, whereas the affinity for the RL increased at low temperatures. In contrast, the affinity of apomorphine for both states of receptor decreased as the temperature decreased from 30 to 8 degrees C. A clear distinction between the energetics of high-affinity and low-affinity agonist binding was observed. The formation of the high-affinity complex was associated with larger increases in enthalpy and entropy than the interaction with the low-affinity state was. The results suggest that the interaction of the receptor with the G-proteins, induced or stabilized by the binding of

  15. Electroporation-aided DNA immunization generates polyclonal antibodies against the native conformation of human endothelin B receptor.

    PubMed

    Allard, Bertrand; Priam, Fabienne; Deshayes, Frédérique; Ducancel, Frédéric; Boquet, Didier; Wijkhuisen, Anne; Couraud, Jean-Yves

    2011-09-01

    Endothelin B receptor (ET(B)R) is a G protein-coupled receptor (GPCR) specific for endothelin peptides (including endothelin-1, ET1), which mediates a variety of key physiological functions in normal tissues, such as modulation of vasomotor tone, tissue differentiation, or cell proliferation. Moreover, ET(B)R, overexpressed in various cancer cells including melanoma, has been implicated in the growth and progression of tumors, as well as in controlling T cell homing to tumors. To gather information on receptor structure and function, antibodies are generally considered choice molecular probes, but generation of such reagents against the native conformation of GPCRs is a real technical challenge. Here, we show that electroporation-aided genetic immunization, coupled to cardiotoxin pretreatment, is a simple and very efficient method to raise large amounts of polyclonal antibodies highly specific for native human ET(B)R (hET(B)R), as assessed by both flow cytometry analysis of different stably transfected cell lines and a new and rapid cell-based enzyme-linked immunosorbent assay that we also describe. The antibodies recognized two major epitopes on hET(B)R, mapped within the N-terminal extracellular domain. They were used to reveal hET(B)R on membranes of three different human melanoma cell lines, by flow cytometry and confocal microscopy, a method that we show is more relevant than mRNA polymerase chain reaction in assessing receptor expression. In addition, ET-1 partially competed with antibodies for receptor binding. The strategy described here, thus, efficiently generated new immunological tools to further analyze the role of ET(B)R under both normal and pathological conditions, including cancers. Above all, it can now be used to raise monoclonal antibodies against hET(B)R and, more generally, against GPCRs that constitute, by far, the largest reservoir of potential pharmacological targets.

  16. Mixed antagonistic effects of bilobalide at rho1 GABAC receptor.

    PubMed

    Huang, S H; Duke, R K; Chebib, M; Sasaki, K; Wada, K; Johnston, G A R

    2006-01-01

    Bilobalide was found to be a moderately potent antagonist with a weak use-dependent effect at recombinant human rho(1) GABA(C) receptors expressed in Xenopus oocytes using two-electrode voltage clamp methodology. Antagonism of bilobalide at homomeric rho(1) GABA(C) receptors appeared to be mixed. At low concentration, bilobalide (3 microM) caused a parallel right shift and surmountable GABA maximal response of the GABA dose-response curve characteristic of a competitive antagonist. At high concentrations, bilobalide (10-100 microM) caused nonparallel right shifts and reduced maximal GABA responses of GABA dose-response curves characteristic of a noncompetitive antagonist. The potency of bilobalide appears to be dependent on the concentrations of GABA and was more potent at lower GABA concentrations. The mechanism of action of bilobalide at rho(1) GABA(C) receptors appears to be similar to that of the chloride channel blocker picrotoxinin.

  17. Third Generation Mineralocorticoid Receptor Antagonists; Why We Need a Fourth

    PubMed Central

    Gomez-Sanchez, Elise

    2015-01-01

    The first mineralocorticoid receptor (MR) antagonist, spironolactone, was developed almost 60 years ago to treat primary aldosteronism and pathological edema. Its use waned in part due to its lack of selectivity. Subsequently knowledge of the scope of MR function was expanded along with clinical evidence of the therapeutic importance of MR antagonists to prevent the ravages of inappropriate MR activation. Forty-two years elapsed between the first and MR-selective second generation of MR antagonists. Fifteen years later, despite serious shortcomings of the existing antagonists, a third generation antagonist has yet to be marketed. Progress has been slowed by the lack of appreciation of the large variety of cell types that express the MR and its diverse cell-type-specific actions, as well as its uniquely complex interactions actions at the molecular level. New MR antagonists should preferentially target the inflammatory and fibrotic effects of MR and perhaps its excitatory effects on sympathetic nervous system, but not the renal tubular epithelium or neurons of the cortex and hippocampus. This review briefly describes efforts to develop a third generation MR antagonist and why fourth generation antagonists and selective agonists based on structural determinants of tissue and ligand-specific MR activation should be contemplated. PMID:26466326

  18. Drug discovery and chemokine receptor antagonists: eppur si muove!

    PubMed

    Terricabras, Emma; Benjamim, Claudia; Godessart, Nuria

    2004-11-01

    The blockade of leukocyte migration has been demonstrated to be a valid option for the treatment of several autoimmune diseases. Chemokines play an active role in regulating cell infiltration into inflammatory sites and disrupting chemokine-receptor interactions has emerged as an alternative therapeutic approach. Pharmaceutical companies have developed an intense activity in the drug discovery of chemokine receptor antagonists in the last 10 years. Potent and selective compounds have been obtained and some of them are currently being evaluated in the clinic. The success of these trials will demonstrate whether the blockade of a single receptor is of therapeutic benefit. Alternative approaches, such as pan-receptor antagonists or inhibitors of the signalling pathways evoked by chemokines, are also being explored. In the meantime, new relationships between chemokines and receptors will be revealed, increasing our knowledge of such a fascinating field.

  19. Myocardial ischemia-reperfusion enhances transcriptional expression of endothelin-1 and vasoconstrictor ETB receptors via the protein kinase MEK-ERK1/2 signaling pathway in rat

    PubMed Central

    Kruse, Lars Schack; Berchtold, Lukas Adrian; Grell, Anne-Sofie; Warfvinge, Karin; Edvinsson, Lars

    2017-01-01

    Background Coronary artery remodelling and vasospasm is a complication of acute myocardial ischemia and reperfusion. The underlying mechanisms are complex, but the vasoconstrictor peptide endothelin-1 is suggested to have an important role. This study aimed to determine whether the expression of endothelin-1 and its receptors are regulated in the myocardium and in coronary arteries after experimental ischemia-reperfusion. Furthermore, we evaluated whether treatment with a specific MEK1/2 inhibitor, U0126, modified the expression and function of these proteins. Methods and findings Sprague-Dawley rats were randomly divided into three groups: sham-operated, ischemia-reperfusion with vehicle treatment and ischemia-reperfusion with U0126 treatment. Ischemia was induced by ligating the left anterior descending coronary artery for 30 minutes followed by reperfusion. U0126 was administered before ischemia and repeated 6 hours after start of reperfusion. The contractile properties of isolated coronary arteries to endothelin-1 and sarafotoxin 6c were evaluated using wire-myography. The gene expression of endothelin-1 and endothelin receptors were measured using qPCR. Distribution and localization of proteins (pERK1/2, prepro-endothelin-1, endothelin-1, and endothelin ETA and ETB receptors) were analysed by Western blot and immunohistochemistry. We found that pERK1/2 was significantly augmented in the ischemic area 3 hours after ischemia-reperfusion; this correlated with increased ETB receptor and ET-1 gene expressions in ischemic myocardium and in coronary arteries. ETB receptor-mediated vasoconstriction was observed to be increased in coronary arteries 24 hours after ischemia-reperfusion. Treatment with U0126 reduced pERK1/2, expression of ET-1 and ETB receptor, and ETB receptor-mediated vasoconstriction. Conclusions These findings suggest that the MEK-ERK1/2 signaling pathway is important for regulating endothelin-1 and ETB receptors in myocardium and coronary arteries

  20. Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

    SciTech Connect

    Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino; Collins, Jon L.; Galardi, Cristin M.; Gampe, Robert T.; Hyatt, Stephen M.; Merrihew, Susan L.; Moore, John T.; Oplinger, Jeffrey A.; Reid, Paul R.; Spearing, Paul K.; Stanley, Thomas B.; Stewart, Eugene L.; Willson, Timothy M.

    2010-08-12

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  1. Systemic and renal effects of an ETA receptor subtype-specific antagonist in healthy subjects

    PubMed Central

    Schmetterer, Leopold; Dallinger, Susanne; Bobr, Barbara; Selenko, Nicole; Eichler, Hans-Georg; Wolzt, Michael

    1998-01-01

    Endothelins (ETs) might play a pathophysiological role in a variety of vascular diseases. The aim of the present study was to characterize the effects of BQ-123, a specific ETA receptor antagonist on systemic and renal haemodynamics in healthy subjects. This was done at baseline and during infusion of exogenous ET-1.The study was performed in a balanced, randomized, placebo-controlled, double blind 4 way cross-over design in 10 healthy male subjects. Subjects received co-infusions of ET-1 (2.5 ng kg−1 min−1 for 120 min) or placebo and BQ-123 (15 μg min−1 for 60 min and subsequently 60 μg min−1 for 60 min) or placebo. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were assessed by the para-aminohippurate (PAH) and the inulin plasma clearance method, respectively.BQ-123 alone had no renal or systemic haemodynamic effect. ET-1 significantly reduced RPF (−24%, P<0.001) and GFR (−12%, P=0.034). These effects were abolished by co-infusion of either dose of BQ-123 (RPF: P=0.0012; GFR: P=0.020).BQ-123 reversed the renal haemodynamic effects induced by exogenous ET-1 in vivo. This indicates that vasoconstriction in the kidney provoked by ET-1 is predominantly mediated by the ETA receptor subtype. PMID:9692778

  2. [Inhibitory effect of angiotensin II receptor antagonist on the contraction and growth of hepatic stellate cells].

    PubMed

    Baik, Soon Koo; Jo, Ho Sung; Suk, Ki Tae; Kim, Jung Min; Lee, Byong Jun; Choi, Yeun Jong; Kim, Hyun Soo; Lee, Dong Ki; Kwon, Sang Ok; Lee, Keon Il; Cha, Seung Kyu; Park, Kyu Sang; Kong, In Deok

    2003-08-01

    This study aimed to investigate the effects of angiotensin II (ANG II) and its receptor antagonist (losartan) on the contraction and growth of HSCs. HSCs were isolated from Sprague Dawley rat and cultured at various conditions as follows: control, pretreatment of 10(-5) M ANG II, pretreatment of 10(-5) M endothelin, and pretreatment of 10(-5) M ANG II and 10(-6) M losartan. We conducted morphologic analysis with cellular area and length by image analysis system to estimate cell growth in each group. In addition, we measured the change of intracellular calcium currents via electrophysiological methods to evaluate the contractile effect of ANG II and losartan on HSCs. At the fifth day of incubation, the mean cellular area of ANG II-pretreated group and ANG II with losartan-pretreated group were 704.68+/-22.6 micro m2 and 332.90+/-32.6 micro m2, respectively. This difference was statistically significant (p<0.05). ANG II induced an increase in the intracellular calcium current by 22.0+/-3.0% compared with basal current level (p<0.05). However, when losartan was pretreated, ANG II did not cause a significant increase in calcium current (3.1+/-0.8%, p>0.05). ANG II accelerates the contraction and growth of HSCs, while its receptor blocker, losartan, inhibits the contraction and growth of HSCs.

  3. Protective effect of Et-1 receptor antagonist bosentan on paracetamol induced acute liver toxicity in rats.

    PubMed

    Yayla, Muhammed; Halici, Zekai; Unal, Bunyami; Bayir, Yasin; Akpinar, Erol; Gocer, Fatma

    2014-03-05

    Paracetamol is one of the first rank drugs which cause hepatic damage during drug intoxications. Endothelin (ET) which is known as one of the most potent vasoactive agent has been shown to contribute in the pathophysiology of various diseases. We hypothesized that bosentan, which is a non-selective ET-1 receptor antagonist, can prevent liver damage. This study included 49 female rats. Groups; I: Healthy group, II: Paracetamol (2 g/kg orally). Groups 3, 4 and 5 received NAC 140 mg/kg (2 doses), BOS 45 mg/kg and BOS 90 mg/kg orally, respectively. 1 h after administration of pretreatment drugs, Groups 3, 4, 5 were given paracetamol. VI: received BOS 90 mg/kg. VII: received 140 mg/kg NAC (2 doses). According to biochemical results, TNF-α, ALT and AST levels were statistically increased in the paracetamol group, these parameters were improved in the bosentan groups. Paracetamol administration decreased SOD activity, GSH level and increased level of MDA in the liver, while bosentan administration significantly improved these parameters. In immunohistochemical staining ET-1 receptor expression was excessively increased in paracetamol group, but not in bosentan groups when compared to healthy control. All these results suggest that bosentan exerted protective effects against experimentally induced paracetamol toxicity in liver.

  4. Endothelin-1 Induces Contraction of Female Rat Internal Pudendal and Clitoral Arteries through ETA Receptor and Rho-Kinase Activation

    PubMed Central

    Allahdadi, Kyan J.; Hannan, Johanna L.; Tostes, Rita C.; Webb, R. Clinton

    2011-01-01

    Introduction Endothelin-1 (ET-1), a potent vasoconstrictor peptide, acts mainly through the Gprotein-coupled ETA receptor (ETAR). Increased vascular ET-1 production and constrictor sensitivity have been observed in various cardiovascular diseases, including hypertension, as well as erectile dysfunction. The internal pudendal artery (IPA) supplies blood to the vagina and clitoris. Inadequate blood flow through the IPA may lead to insufficient vaginal engorgement and clitoral tumescence. Aim Characterize the effects of ET-1 on the IPA and clitoral artery (CA). Methods IPA and CA from female Sprague Dawley rats (225–250 g) were mounted in myograph chambers. Arterial segments were submitted to increasing concentrations of ET-1 (10-10-10-6 M). Segments were incubated with the ETAR antagonist, atrasentan (10-8 M) or the Rho-kinase inhibitor, Y-27632 (10-6 M) 30 minutes prior to agonist exposure. All Emax values are expressed as % KCl-induced maximal contraction. ETAR, RhoA, and Rho-kinase expression from IPA was evaluated by Western blot. mRNA of preproET-1, ETAR, ETBR, RhoA, and Rho-kinase were measured by real time PCR. Main Outcome Measures ET-1 constrictor sensitivity in IPA and CA, protein expression and messenger RNA levels of ET-1-mediated constriction components. Results ET-1 concentration-dependently contracted IPA (% Contraction and pD2, respectively: 156 ± 18, 8.2 ± 0.1) and CA (163 ± 12, 8.8 ± 0.08), while ETAR antagonism reduced ET-1-mediated contraction (IPA: 104 ± 23, 6.4 ± 0.2; CA: 112 ± 17, 6.6 ± 0.08). Pretreatment with Y-27632 significantly shifted ET-1 pD2 in IPA (108 ± 24, 7.9 ± 0.1) and CA (147 ± 58 and 8.0 ± 0.25). Protein expression of ETAR, ETBR, RhoA, and Rho-kinase were detected in IPA. IPA and CA contained preproET-1, ETAR, ETBR, RhoA, and Rho-kinase message. Conclusion We observed that the IPA and CA are sensitive to ET-1, signaling through the ETAR and Rho-kinase pathway. These data indicate that ET-1 may play a role in vaginal

  5. Endothelin-1 activation of ETB receptors leads to a reduced cellular proliferative rate and an increased cellular footprint

    PubMed Central

    Wilson, Jamie L.; Taylor, Linda; Polgar, Peter

    2012-01-01

    Endothelin-1 (ET-1) is a vasoactive peptide which signals through two G-protein coupled receptors, endothelin receptor A (ETA) and B (ETB). We determined that ET-1 activation of its ETB receptor in stably cDNA transfected CHO cells leads to a 55% reduction in cell number by end-point cell counting and a 35% decrease in cell growth by a real-time cell-substrate impedance-based assay after 24 hours of cell growth. When CHO ETB cells were synchronized in the late G1 cell cycle phase, ET-1 delayed their S phase progression compared to control by 30% as determined by [3H]-thymidine incorporation. On the other hand, no such delay was observed during late G2/M to G1 transit when cells were treated with ET-1 after release from mitotic arrest. Using the cell-substrate impedance-based assay, we observed that ET-1 induces opposing morphological changes in CHO ETA and CHO ETB cells with ETB causing an increase in the cell footprint and ETA a decrease. Likewise, in pulmonary artery smooth muscle cells, which express both ETA and ETB receptors, ET-1 induces an ETA-dependent contraction and an ETB dependent dilation. These results are shedding light on a possible beneficial role for ETB in diseases involving ET-1 dysfunction such as pulmonary hypertension. PMID:22504006

  6. Endothelin receptor type B agonist, IRL-1620, prevents beta amyloid (Aβ) induced oxidative stress and cognitive impairment in normal and diabetic rats.

    PubMed

    Briyal, Seema; Shepard, Cortney; Gulati, Anil

    2014-05-01

    Alzheimer's disease (AD) is a progressive brain disorder leading to impairment of learning and memory. Amyloid β (Aβ) induced oxidative stress has been implicated in the initiation and progression of AD. Endothelin (ET) and its receptors have been considered as therapeutic targets for AD. Recent studies indicate that stimulation of ETB receptors may provide neuroprotection. The purpose of this study was to determine the preventative effect of selectively stimulating ETB receptors on cognitive impairment and oxidative stress in Aβ treated non-diabetic and diabetic (induced by streptozotocin) rats. Rats were concurrently treated with Aβ1-40 (day 1, 7 and 14) and either saline, IRL-1620 (an ETB agonist), and/or BQ788 (an ETB antagonist) daily for 14 days in the lateral cerebral ventricles using sterotaxically implanted cannula; experiments were performed on day 15. Aβ treatment produced a significant (p<0.0001) increase of 360% and 365% in malondialdehyde levels (a marker of lipid peroxidation) in non-diabetic and diabetic rats, respectively, compared to sham group. Antioxidants (superoxide dismutase and reduced glutathione) decreased following Aβ treatment compared to sham group. Treatment with IRL-1620 reversed these effects, indicating that ETB receptor stimulation reduces oxidative stress injury following Aβ treatment. In Morris swim task, Aβ treated rats showed impairment in spatial memory. Rats treated with IRL-1620 significantly reduced the cognitive impairment induced by Aβ. BQ788 treatment completely blocked IRL-1620 induced reduction in oxidative stress and cognitive impairment. Results of the present study demonstrate that IRL-1620 improved both acquisition (learning) and retention (memory) on water maze task and reduced oxidative stress parameters. It can be speculated that ETB receptor stimulation prevents cognitive impairment and may be useful in neurodegenerative diseases. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Endothelin-1 contributes to endothelial dysfunction and enhanced vasoconstriction through augmented superoxide production in penile arteries from insulin-resistant obese rats: role of ETA and ETB receptors

    PubMed Central

    Sánchez, A; Martínez, P; Muñoz, M; Benedito, S; García-Sacristán, A; Hernández, M; Prieto, D

    2014-01-01

    Background and Purpose We assessed whether endothelin-1 (ET-1) inhibits NO and contributes to endothelial dysfunction in penile arteries in a model of insulin resistance-associated erectile dysfunction (ED). Experimental Approach Vascular function was assessed in penile arteries, from obese (OZR) and lean (LZR) Zucker rats, mounted in microvascular myographs. Changes in basal and stimulated levels of superoxide (O2−) were detected by lucigenin-enhanced chemiluminescence and ET receptor expression was determined by immunohistochemistry. Key Results ET-1 stimulated acute O2− production that was blunted by tempol and the NADPH oxidase inhibitor, apocynin, but markedly enhanced in obese animals. ET-1 inhibited the vasorelaxant effects of ACh and of the NO donor S-nitroso-N-acetyl-DL-penicillamine in arteries from both LZR and OZR. Selective ETA (BQ123) or ETB receptor (BQ788) antagonists reduced both basal and ET-1-stimulated superoxide generation and reversed ET-1-induced inhibition of NO-mediated relaxations in OZR, while only BQ-123 antagonized ET-1 actions in LZR. ET-1-induced vasoconstriction was markedly enhanced by NO synthase blockade and reduced by endothelium removal and apocynin. In endothelium-denuded penile arteries, apocynin blunted augmented ET-1-induced contractions in OZR. Both ETA and ETB receptors were expressed in smooth muscle and the endothelial layer and up-regulated in arteries from OZR. Conclusions and Implications ET-1 stimulates ETA-mediated NADPH oxidase-dependent ROS generation, which inhibits endothelial NO bioavailability and contributes to ET-1-induced contraction in healthy penile arteries. Enhanced vascular expression of ETB receptors contributes to augmented ROS production, endothelial dysfunction and increased vasoconstriction in erectile tissue from insulin-resistant obese rats. Hence, antagonism of ETB receptors might improve the ED associated with insulin-resistant states. PMID:25091502

  8. Combination decongestion therapy in hospitalized heart failure: loop diuretics, mineralocorticoid receptor antagonists and vasopressin antagonists.

    PubMed

    Vaduganathan, Muthiah; Mentz, Robert J; Greene, Stephen J; Senni, Michele; Sato, Naoki; Nodari, Savina; Butler, Javed; Gheorghiade, Mihai

    2015-01-01

    Congestion is the most common reason for admissions and readmissions for heart failure (HF). The vast majority of hospitalized HF patients appear to respond readily to loop diuretics, but available data suggest that a significant proportion are being discharged with persistent evidence of congestion. Although novel therapies targeting congestion should continue to be developed, currently available agents may be utilized more optimally to facilitate complete decongestion. The combination of loop diuretics, natriuretic doses of mineralocorticoid receptor antagonists and vasopressin antagonists represents a regimen of currently available therapies that affects early and persistent decongestion, while limiting the associated risks of electrolyte disturbances, hemodynamic fluctuations, renal dysfunction and mortality.

  9. miR-30a inhibits endothelin A receptor and chemoresistance in ovarian carcinoma

    PubMed Central

    Rosanò, Laura; Tocci, Piera; Semprucci, Elisa; Di Castro, Valeriana; Caprara, Valentina; Ferrandina, Gabriella; Sacconi, Andrea; Blandino, Giovanni; Bagnato, Anna

    2016-01-01

    Drug resistance remains the major clinical barrier to successful treatment in epithelial ovarian carcinoma (EOC) patients, and the evidence of microRNA involvement in drug resistance has been recently emerging. Endothelin-1 (ET-1)/ETA receptor (ETAR) axis is aberrantly activated in chemoresistant EOC cells and elicits pleiotropic effects promoting epithelial-to-mesenchymal transition (EMT) and the acquisition of chemoresistance. However, the relationship between ETAR and miRNA is still unknown. Hence, in this study we evaluated whether dysregulation of miRNA might enhance ETAR expression in sensitive and resistant EOC cells. Based on bioinformatic tools, we selected putative miRNA able to recognize the 3′UTR of ETAR. An inverse correlation was observed between the expression levels of miR-30a and ETAR in both EOC cell lines and tumor samples. miR-30a was found to specifically bind to the 3′UTR of ETAR mRNA, indicating that ETAR is a direct target of miR-30a. Overexpression of miR-30a decreased Akt and mitogen activated protein kinase signaling pathway activation, cell proliferation, invasion, plasticity, EMT marker levels, and vascular endothelial growth factor release. Interestingly, ectopic expression of miR-30a re-sensitized platinum-resistant EOC cells to cisplatinum-induced apoptosis. Consistently, resistant EOC xenografts overexpressing miR-30a resulted in significantly less tumor growth than controls. Together our study provides a new perspective on the regulatory mechanism of ETAR gene. Interestingly, our findings highlight that blockade of ETAR regulatory axis is the mechanism underlying the tumor suppressor function of miR-30a in chemoresistant EOC cells. PMID:26675258

  10. Enhanced Chronic Pain Management Utilizing Chemokine Receptor Antagonists

    DTIC Science & Technology

    2016-08-01

    treatment; Analgesia; Nociception; Antinociception; Inflammation ; Chemokines; Chemokine receptor antagonists; Opioid analgesics; Animal models of pain...multiplex quantitative analysis of protein levels of these molecules. 2. KEYWORDS: Pain treatment; Analgesia; Nociception; Antinociception; Inflammation ...with a circulating water bath (Model 9500, Fisher Scientific; Pittsburgh, PA). Rats were held over the bath with their tails submerged

  11. [Medical economics evaluation of 5-HT3 receptor antagonist drugs].

    PubMed

    Utsunomiya, Junpei; Hirano, Shigeki; Fukui, Aiko; Funabashi, Kazuaki; Deguchi, Yuko; Yamada, Susumu; Naito, Kazuyuki

    2010-10-01

    At Komaki City Hospital, the drug cost in connection with cancer chemotherapy was re-examined as part of improved management along with the introduction of DPC in July 2008. With due attention to the 5-HT3 receptor antagonists, both the change from injections to oral drugs and the change from brand-name drugs to generic drugs were tried between July 2008 and June 2009. After that, in order to examine the economic impact of these changes, we investigated and analyzed the number of medications, the cost of medicine purchased, and the average drug cost per medication of the 5-HT3 receptor antagonists between April 2008 and September 2009. As a result, the cost of 5-HT3 receptor antagonists purchased decreased greatly, and the impact of the improvement was mainly due to the change to oral drugs, and partially to the change to generic drugs. Therefore, from the viewpoint of hospital economic improvement in DPC, it was thought that the change to oral drugs(5-HT3 receptor antagonists)is given top priority.

  12. Novel benzopolycyclic amines with NMDA receptor antagonist activity.

    PubMed

    Valverde, Elena; Sureda, Francesc X; Vázquez, Santiago

    2014-05-01

    A new series of benzopolycyclic amines active as NMDA receptor antagonists were synthesized. Most of them exhibited increased activity compared with related analogues previously published. All the tested compounds were more potent than clinically approved amantadine and one of them displayed a lower IC50 value than memantine, an anti-Alzheimer's approved drug.

  13. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects.

  14. Significance of the Melanocortin 1 and Endothelin B Receptors in Melanocyte Homeostasis and Prevention of Sun-Induced Genotoxicity

    PubMed Central

    Swope, Viki B.; Abdel-Malek, Zalfa A.

    2016-01-01

    The membrane bound melanocortin 1 receptor (MC1R), and the endothelin B receptor (ENDBR) are two G-protein coupled receptors that play important roles in constitutive regulation of melanocytes and their response to ultraviolet radiation (UVR), the main etiological factor for melanoma. The human MC1R is a Gs protein-coupled receptor, which is activated by its agonists α-melanocyte stimulating hormone (α-melanocortin; α-MSH) and adrenocorticotropic hormone (ACTH). The ENDBR is a Gq coupled-receptor, which is activated by Endothelin (ET)-3 during embryonic development, and ET-1 postnatally. Pigmentation and the DNA repair capacity are two major factors that determine the risk for melanoma. Activation of the MC1R by its agonists stimulates the synthesis of eumelanin, the dark brown photoprotective pigment. In vitro studies showed that α-MSH and ET-1 interact synergistically in the presence of basic fibroblast growth factor to stimulate human melanocyte proliferation and melanogenesis, and to inhibit UVR-induced apoptosis. An important function of the MC1R is reduction of oxidative stress and activation of DNA repair pathways. The human MC1R is highly polymorphic, and MC1R variants, particularly those that cause loss of function of the expressed receptor, are associated with increased melanoma risk independently of pigmentation. These variants compromise the DNA repair and antioxidant capacities of human melanocytes. Recently, activation of ENDBR by ET-1 was reported to reduce the induction and enhance the repair of UVR-induced DNA photoproducts. We conclude that α-MSH and ET-1 and their cognate receptors MC1R and ENDBR reduce the risk for melanoma by maintaining genomic stability of melanocytes via modulating the DNA damage response to solar UVR. Elucidating the response of melanocytes to UVR should improve our understanding of the process of melanomagenesis, and lead to effective melanoma chemoprevention, as well as therapeutic strategies. PMID:27582758

  15. Small molecule antagonists for chemokine CCR3 receptors.

    PubMed

    Willems, Lianne I; Ijzerman, Ad P

    2010-09-01

    The chemokine receptor CCR3 is believed to play a role in the development of allergic diseases such as asthma, atopic dermatitis, and allergic rhinitis. Despite the conflicting results that have been reported regarding the importance of eosinophils and CCR3 in allergic inflammation, inhibition of this receptor with small molecule antagonists is thought to provide a valuable approach for the treatment of these diseases. This review describes the structure-activity relationships (SAR) of small molecule CCR3 antagonists as reported in the scientific and patent literature. Various chemical classes of small molecule CCR3 antagonists have been described so far, including (bi)piperidine and piperazine derivatives, N-arylalkylpiperidine urea derivatives and (N-ureidoalkyl)benzylpiperidines, phenylalanine derivatives, morpholinyl derivatives, pyrrolidinohydroquinazolines, arylsulfonamides, amino-alkyl amides, imidazole- and pyrimidine-based antagonists, and bicyclic diamines. The (N-ureidoalkyl)benzylpiperidines are the best studied class in view of their generally high affinity and antagonizing potential. For many of these antagonists subnanomolar IC(50) values were reported for binding to CCR3 along with the ability to effectively inhibit intracellular calcium mobilization and eosinophil chemotaxis induced by CCR3 agonist ligands in vitro.

  16. Prevention of cultured rat stellate cell transformation and endothelin-B receptor upregulation by retinoic acid.

    PubMed

    Chi, Xuedong; Anselmi, Kristin; Watkins, Simon; Gandhi, Chandrashekhar R

    2003-06-01

    1 Physiologically, perisinusoidal hepatic stellate cells (HSC) are quiescent and store retinoids. During liver injury and in cell culture, HSC transform into proliferating myofibroblast-like cells that express alpha-smooth muscle actin (alpha-sma) and produce excessive amounts of extracellular matrix. During transformation (also known as activation), HSC are depleted of the retinoid stores, and their expression of the endothelin-1 (ET-1) system is increased. ET-1 causes contraction of transformed HSC and is implicated in their proliferation and fibrogenic activity. In order to understand the association between retinoids, ET-1 and the activation of HSC, we investigated the effect of 13-cis-retinoic acid on the transformation of cultured HSC and the expression of ET-1 system. 2 HSC derived from normal rat liver were maintained for 10-12 days in a medium supplemented with 5% serum and containing 2.5 micro M retinoic acid without or with 50 nM ET-1 (ETA+ETB agonist) or sarafotoxin S6c (ETB agonist). In another set of experiments, cells treated for 10-12 days with vehicle (ethanol) or retinoic acid were challenged with ET-1 or sarafotoxin S6c, and various determinations were made at 24 h. 3 Retinoic acid inhibited transformation and proliferation of HSC as assessed by morphological characteristics, expression of alpha-sma, bromodeoxyuridine incorporation and cell count. Retinoic acid also prevented upregulation of ETB receptors without affecting ET-1 or ETA expression. Total protein synthesis ([(3)H]leucine incorporation), collagen alpha types I mRNA expression and collagen synthesis ([(3)H]proline incorporation) were lower in retinoic acid-treated cells. Although ET-1-treated cells were morphologically similar to the control cells, their expression of alpha-smooth muscle actin was significantly inhibited. The presence of retinoic acid in the medium during treatment with ET-1 caused further reduction in the expression of alpha-smooth muscle actin. ET-1 and sarafotoxin

  17. Superoxide-dependent hypertension in male and female endothelin B receptor-deficient rats.

    PubMed

    Sullivan, Jennifer C; Pollock, Jennifer S; Pollock, David M

    2006-06-01

    Evidence for endothelin (ET) involvement in the control of fluid volume balance and arterial pressure has been derived in part from the observations that rats lacking the ET(B) receptor develop hypertension when placed on a high-salt (HS) diet. The present study was designed to determine the effect of superoxide on salt-induced hypertension in male and female ET(B)-deficient (sl/sl) and wild-type control (wt) rats. After 14 days on a HS (8% NaCl) diet, female sl/sl rats had significantly elevated arterial pressure (183 +/- 2 mm Hg, tail cuff) compared with female wt rats (134 +/- 2 mm Hg). The response to a HS diet was lower in male sl/sl rats (166 +/- 6 mm Hg) yet was significantly greater than that in male wt controls (135 +/- 3 mm Hg). Separate groups of male and female sl/sl and wt rats were given tempol (1 mM in drinking water) during HS treatment. Arterial pressures were 149 +/- 5 mm Hg in male and 143 +/- 3 mm Hg in female sl/sl rats treated with tempol, values that were similar to those of controls on a normal salt diet. After 14 days, however, male and female sl/ sl rats recovered from the blood pressure-lowering effects of tempol. On Day 15, arterial pressures in female sl/sl rats on a HS diet were 160 +/- 6 mm Hg and 177 +/- 6 mm Hg in tempol-treated and untreated groups, respectively. In male sl/sl rats, arterial pressures were 155 +/- 3 mm Hg and 165 +/- 5 mm Hg in tempol-treated and untreated groups, respectively. On Day 15, no differences among groups with or without tempol were observed in plasma thiobarbituric acid-reactive substance (TBARS) concentrations or in urinary excretion of TBARS. Plasma ET-1 concentrations were significantly higher in female vs. male sl/sl rats. These results indicate that the early stages of salt-dependent hypertension produced by ET(B) receptor deficiency are dependent on superoxide and that the elevated pressure in the female rats may be due to elevated circulating levels of ET-1.

  18. Characterizing the role of endothelin-1 in the progression of cardiac hypertrophy in aryl hydrocarbon receptor (AhR) null mice

    SciTech Connect

    Lund, Amie K.; Goens, M. Beth; Nunez, Bethany A.; Walker, Mary K. . E-mail: mkwalker@unm.edu

    2006-04-15

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor characterized to play a role in detection and adaptation to environmental stimuli. Genetic deletion of AhR results in hypertension, and cardiac hypertrophy and fibrosis, associated with elevated plasma angiotensin II (Ang II) and endothelin-1 (ET-1), thus AhR appears to contribute to cardiovascular homeostasis. In these studies, we tested the hypothesis that ET-1 mediates cardiovascular pathology in AhR null mice via ET{sub A} receptor activation. First, we determine the time courses of cardiac hypertrophy, and of plasma and tissue ET-1 expression in AhR wildtype and null mice. AhR null mice exhibited increases in heart-to-body weight ratio and age-related expression of cardiac hypertrophy markers, {beta}-myosin heavy chain ({beta}-MHC), and atrial natriuretic factor (ANF), which were significant at 2 months. Similarly, plasma and tissue ET-1 expression was significantly elevated at 2 months and increased further with age. Second, AhR null mice were treated with ET{sub A} receptor antagonist, BQ-123 (100 nmol/kg/day), for 7, 28, or 58 days and blood pressure, cardiac fibrosis, and cardiac hypertrophy assessed, respectively. BQ-123 for 7 days significantly reduced mean arterial pressure in conscious, catheterized mice. BQ-123 for 28 days significantly reduced the histological appearance of cardiac fibrosis. Treatment for 58 days significantly reduced cardiac mass, assessed by heart weight, echocardiography, and {beta}-MHC and ANF expression; and reduced cardiac fibrosis as determined by osteopontin and collagen I mRNA expression. These findings establish ET-1 and the ET{sub A} receptor as primary determinants of hypertension and cardiac pathology in AhR null mice.

  19. Scaffold variations in amine warhead of histamine H₃ receptor antagonists.

    PubMed

    Wingen, Kerstin; Stark, Holger

    2013-12-01

    The histamine H₃ receptor (H₃R) is involved in numerous regulatory neurotransmission processes and there-fore, is a prominent target for centrally occurring disease with some promising clinical candidates. Previous research resulted in the identification of a core pharmacophore blueprint for H₃R antagonists/inverse agonists, which when inserted in a molecule, mostly ensures acceptable affinity. Nevertheless, variations of scaffold and peripheral areas can increase potency and pharmacokinetic profile of drug candidates. The variations in amine scaffolds of antagonists for this aminergic GPCR are of special importance.

  20. Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist

    NASA Astrophysics Data System (ADS)

    Johnson, David G.; Ulichny Goebel, Camy; Hruby, Victor J.; Bregman, Marvin D.; Trivedi, Dev

    1982-02-01

    The glucagon analog [l-Nα-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.

  1. Aldosterone Inactivates the Endothelin-B Receptor via a Cysteinyl Thiol Redox Switch to Decrease Pulmonary Endothelial Nitric Oxide Levels and Modulate Pulmonary Arterial Hypertension

    PubMed Central

    Maron, Bradley A.; Zhang, Ying-Yi; White, Kevin; Chan, Stephen Y.; Handy, Diane E.; Mahoney, Christopher E.; Loscalzo, Joseph; Leopold, Jane A.

    2012-01-01

    Background Pulmonary arterial hypertension (PAH) is characterized, in part, by decreased endothelial nitric oxide (NO•) production and elevated levels of endothelin-1. Endothelin-1 is known to stimulate endothelial nitric oxide synthase (eNOS) via the endothelin-B receptor (ETB), suggesting that this signaling pathway is perturbed in PAH. Endothelin-1 also stimulates adrenal aldosterone synthesis; in systemic blood vessels, hyperaldosteronism induces vascular dysfunction by increasing endothelial reactive oxygen species (ROS) generation and decreasing NO• levels. We hypothesized that aldosterone modulates PAH by disrupting ETB-eNOS signaling through a mechanism involving increased pulmonary endothelial oxidant stress. Methods and Results In rats with PAH, elevated endothelin-1 levels were associated with elevated aldosterone levels in plasma and lung tissue and decreased lung NO• metabolites in the absence of left heart failure. In human pulmonary artery endothelial cells (HPAECs), endothelin-1 increased aldosterone levels via PGC-1α/steroidogenesis factor-1-dependent upregulation of aldosterone synthase. Aldosterone also increased ROS production, which oxidatively modified cysteinyl thiols in the eNOS-activating region of ETB to decrease endothelin-1-stimulated eNOS activity. Substitution of ETB-Cys405 with alanine improved ETB-dependent NO• synthesis under conditions of oxidant stress, confirming that Cys405 is a redox sensitive thiol that is necessary for ETB-eNOS signaling. In HPAECs, mineralocorticoid receptor antagonism with spironolactone decreased aldosterone-mediated ROS generation and restored ETB-dependent NO• production. Spironolactone or eplerenone prevented or reversed pulmonary vascular remodeling and improved cardiopulmonary hemodynamics in two animal models of PAH in vivo. Conclusions Our findings demonstrate that aldosterone modulates an ETB cysteinyl thiol redox switch to decrease pulmonary endothelium-derived NO• and promote PAH

  2. Endothelin-1 Induces Proteinuria by Heparanase-Mediated Disruption of the Glomerular Glycocalyx.

    PubMed

    Garsen, Marjolein; Lenoir, Olivia; Rops, Angelique L W M M; Dijkman, Henry B; Willemsen, Brigith; van Kuppevelt, Toin H; Rabelink, Ton J; Berden, Jo H M; Tharaux, Pierre-Louis; van der Vlag, Johan

    2016-12-01

    Diabetic nephropathy (DN) is the leading cause of CKD in the Western world. Endothelin receptor antagonists have emerged as a novel treatment for DN, but the mechanisms underlying the protective effect remain unknown. We previously showed that both heparanase and endothelin-1 are essential for the development of DN. Here, we further investigated the role of these proteins in DN, and demonstrated that endothelin-1 activates podocytes to release heparanase. Furthermore, conditioned podocyte culture medium increased glomerular transendothelial albumin passage in a heparanase-dependent manner. In mice, podocyte-specific knockout of the endothelin receptor prevented the diabetes-induced increase in glomerular heparanase expression, consequent reduction in heparan sulfate expression and endothelial glycocalyx thickness, and development of proteinuria observed in wild-type counterparts. Our data suggest that in diabetes, endothelin-1 signaling, as occurs in endothelial activation, induces heparanase expression in the podocyte, damage to the glycocalyx, proteinuria, and renal failure. Thus, prevention of these effects may constitute the mechanism of action of endothelin receptor blockers in DN. Copyright © 2016 by the American Society of Nephrology.

  3. The calcium channel antagonist benidipine reduces plasma and cardiac endothelin-1 levels in type II diabetic rat model.

    PubMed

    Jesmin, Subrina; Sakuma, Ichiro; Hattori, Yuichi; Kitabatake, Akira; Miyauchi, Takashi

    2004-11-01

    Cardiovascular complications are the central feature of type 2 diabetes mellitus, and insulin resistance is an early clinical manifestation of type 2 diabetes mellitus. Calcium channel blockers are widely used to treat cardiovascular diseases in diabetic patients; however, it remains unknown how endothelin-1 (ET-1) is altered and associated with cardiac lesions at the insulin-resistant early stage of type 2 diabetes mellitus, and, if so, whether calcium channel blockers can reverse such alterations. We examined plasma and cardiac expression of ET-1 in male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a spontaneous model of human type 2 diabetes mellitus. At 8 weeks of age, OLETF rats were treated for 12 weeks with a long acting calcium channel blocker, benidipine (3 mg/kg per day p.o.) (BEN, n = 15), or with vehicle (OLETF, n = 15), and age-matched genetic control, male Long-Evans Tokushima Otsuka (LETO) rats were also used (n = 15). Blood pressure was significantly higher in OLETF than LETO rats, and benidipine treatment of OLETF rats for 12 weeks did not reduce their blood pressure significantly. Plasma and cardiac levels of ET-1 were significantly higher in OLETF compared with LETO rats (both P < 0.01), and were reversed after benidipine treatment. Our results suggest that ET-1 plays a pivotal role in the pathogenesis of cardiac complications at the insulin-resistant stage of diabetes mellitus, and that benidipine treatment may have a beneficial effect on these complications.

  4. Fasting influences steroidogenesis, vascular endothelial growth factor (VEGF) levels and mRNAs expression for VEGF, VEGF receptor type 2 (VEGFR-2), endothelin-1 (ET-1), endothelin receptor type A (ET-A) and endothelin converting enzyme-1 (ECE-1) in newly formed pig corpora lutea.

    PubMed

    Galeati, Giovanna; Forni, Monica; Spinaci, Marcella; Zannoni, Augusta; Govoni, Nadia; Ribeiro, Luciana A; Seren, Eraldo; Tamanini, Carlo

    2005-04-01

    This study was designed to verify whether fasting influences vascular endothelial growth factor (VEGF) production and VEGF, VEGF receptor-2 (VEGFR-2) as well as endothelin (ET) system members (endothelin converting enzyme-1, ECE-1; ET-1; endothelin receptor type A, ET-A) mRNA expression in pig corpora lutea; furthermore, we wanted to assess whether fasting affects steroidogenesis in luteal cells. Eight prepubertal gilts were induced to ovulate and were randomly assigned to two groups: (A) n = 4, normally fed; and (B) n = 4, fasted for 72 h starting 3 days after ovulation. At the end of fasting, ovaries were removed from all the animals and corpora lutea (CLs) were collected. VEGF and steroid levels in luteal tissue were determined by ELISA and RIA, respectively; VEGF, VEGFR-2, ET-1, ET-A and ECE-1 mRNAs expression was measured by real-time PCR. VEGF protein levels were similar in the two groups, while all steroid (progesterone, testosterone, estradiol 17beta) concentrations were significantly (P < 0.001) higher in CLs collected from fasted animals compared with those from normally fed gilts. VEGF, VEGFR-2, ET-1 and ECE-1 (but not ET-A) mRNA expression was significantly lower (P < 0.05) in fasted versus normally fed animals. The overall conclusion is that all the parameters studied are affected by feed restriction, but the mechanisms activated at luteal level are possibly not fully adequate to compensate for nutrient shortage.

  5. μ Opioid receptor: novel antagonists and structural modeling

    NASA Astrophysics Data System (ADS)

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-02-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

  6. μ Opioid receptor: novel antagonists and structural modeling

    PubMed Central

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-01-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates. PMID:26888328

  7. Antagonistic action of pitrazepin on human and rat GABAA receptors

    PubMed Central

    Demuro, Angelo; Martinez-Torres, Ataulfo; Francesconi, Walter; Miledi, Ricardo

    1999-01-01

    Pitrazepin, 3-(piperazinyl-1)-9H-dibenz(c,f) triazolo(4,5-a)azepin is a piperazine antagonist of GABA in a variety of electrophysiological and in vitro binding studies involving GABA and glycine receptors. In the present study we have investigated the effects of pitrazepin, and the GABAA antagonist bicuculline, on membrane currents elicited by GABA in Xenopus oocytes injected with rat cerebral cortex mRNA or cDNAs encoding α1β2 or α1β2γ2S human GABAA receptor subunits.The three types of GABAA receptors expressed were reversibly antagonized by bicuculline and pitrazepin in a concentration-dependent manner. GABA dose-current response curves for the three types of receptors were shifted to the right, in a parallel manner, by increasing concentrations of pitrazepin.Schild analyses gave pA2 values of 6.42±0.62, n=4, 6.41±1.2, n=5 and 6.21±1.24, n=6, in oocytes expressing rat cerebral cortex, α1β2 or α1β2γ2S human GABAA receptors respectively (values are given as means±s.e.mean), and the Hill coefficients were all close to unity. All this is consistent with the notion that pitrazepin acts as a competitive antagonist of these GABAA receptors; and that their antagonism by pitrazepin is not strongly dependent on the subunit composition of the receptors here studied.Since pitrazepin has been reported to act also at the benzodiazepine binding site, we studied the effect of the benzodiazepine antagonist Ro 15-1788 (flumazenil) on the inhibition of α1β2γ2S receptors by pitrazepin. Co-application of Ro 15-1788 did not alter the inhibiting effect of pitrazepin. Moreover, pitrazepin did not antagonize the potentiation of GABA-currents by flunitrazepam. All this suggests that pitrazepin does not affect the GABA receptor-chloride channel by interacting with the benzodiazepine receptor site. PMID:10369456

  8. Targeted activation of endothelin-1 exacerbates hypoxia-induced pulmonary hypertension

    SciTech Connect

    Satwiko, Muhammad Gahan; Ikeda, Koji; Nakayama, Kazuhiko; Yagi, Keiko; Hocher, Berthold; Hirata, Ken-ichi; Emoto, Noriaki

    2015-09-25

    Pulmonary arterial hypertension (PAH) is a fatal disease that eventually results in right heart failure and death. Current pharmacologic therapies for PAH are limited, and there are no drugs that could completely cure PAH. Enhanced activity of endothelin system has been implicated in PAH severity and endothelin receptor antagonists have been used clinically to treat PAH. However, there is limited experimental evidence on the direct role of enhanced endothelin system activity in PAH. Here, we investigated the correlation between endothelin-1 (ET-1) and PAH using ET-1 transgenic (ETTG) mice. Exposure to chronic hypoxia increased right ventricular pressure and pulmonary arterial wall thickness in ETTG mice compared to those in wild type mice. Of note, ETTG mice exhibited modest but significant increase in right ventricular pressure and vessel wall thickness relative to wild type mice even under normoxic conditions. To induce severe PAH, we administered SU5416, a vascular endothelial growth factor receptor inhibitor, combined with exposure to chronic hypoxia. Treatment with SU5416 modestly aggravated hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial vessel wall thickening in ETTG mice in association with increased interleukin-6 expression in blood vessels. However, there was no sign of obliterative endothelial cell proliferation and plexiform lesion formation in the lungs. These results demonstrated that enhanced endothelin system activity could be a causative factor in the development of PAH and provided rationale for the inhibition of endothelin system to treat PAH. - Highlights: • Role of endothelin-1 in pulmonary arterial hypertension (PAH) was investigated. • The endothelin-1 transgenic (ETTG) and wild type (WT) mice were analyzed. • ETTG mice spontaneously developed PAH under normoxia conditions. • SU5416 further aggravated PAH in ETTG mice. • Enhanced endothelin system activity could be a causative factor in

  9. Endothelin mediated contraction of equine laminar veins.

    PubMed

    Keen, J A; Hillier, C; McGorum, B C; Nally, J E

    2008-07-01

    Endothelin-1 (ET-1) may be a key mediator in the pathogenesis of laminitis, but endothelin-mediated responses in the venous microcirculation of the equine foot have yet to be fully characterised. To characterise the response of equine laminar veins to ET-1 and evaluate the ET-1 receptor subtypes that mediate this response. Small veins (150-500 microns) draining the equine digital laminae from healthy horses and ponies subjected to euthanasia at an abattoir were investigated using wire myography. Concentration response curves were constructed for ET-1 in the presence of ETA (BQ123) and ETB (BQ788) receptor antagonists, and L-NAME, a nitric oxide synthase blocker. The selective ETB receptor agonist BQ3020 was investigated alone and following incubation with L-NAME, with or without BQ788. Endothelin-1 contraction of laminar veins was significantly inhibited by BQ123 but not by BQ788. In the presence of L-NAME, sensitivity of laminar veins to ET-1 was enhanced 4-fold, and further addition of BQ788 did not alter this increased sensitivity. BQ3020 induced no venoconstriction; however, in the presence of L-NAME, it caused contraction of veins with approximately 30% of the efficacy of ET-1. The action of BQ3020 in the presence of L-NAME was abolished by BQ788. Both ETA and ETB receptors are involved in the net tonic response to ET-1 in normal laminar veins. A population of ETB receptors may be present on the vascular endothelium and on smooth muscle of laminar veins, and the action of ET-1 at these 2 sites is likely to be approximately equal and opposite. Our results clarify the function of the ET-1 receptor subtypes in laminar veins from healthy horses. Further study of ET-1 receptors in laminitic horses is therefore warranted.

  10. Endothelin B Receptors on Primary Chicken Müller Cells and the Human MIO-M1 Müller Cell Line Activate ERK Signaling via Transactivation of Epidermal Growth Factor Receptors

    PubMed Central

    Harun-Or-Rashid, Mohammad; Konjusha, Dardan; Galindo-Romero, Caridad

    2016-01-01

    Injury to the eye or retina triggers Müller cells, the major glia cell of the retina, to dedifferentiate and proliferate. In some species they attain retinal progenitor properties and have the capacity to generate new neurons. The epidermal growth factor receptor (EGFR) system and extracellular signal-regulated kinase (ERK) signaling are key regulators of these processes in Müller cells. The extracellular signals that modulate and control these processes are not fully understood. In this work we studied whether endothelin receptor signaling can activate EGFR and ERK signaling in Müller cells. Endothelin expression is robustly upregulated at retinal injury and endothelin receptors have been shown to transactivate EGFRs in other cell types. We analyzed the endothelin signaling system in chicken retina and cultured primary chicken Müller cells as well as the human Müller cell line MIO-M1. The Müller cells were stimulated with receptor agonists and treated with specific blockers to key enzymes in the signaling pathway or with siRNAs. We focused on endothelin receptor mediated transactivation of EGFRs by using western blot analysis, quantitative reverse transcriptase PCR and immunocytochemistry. The results showed that chicken Müller cells and the human Müller cell line MIO-M1 express endothelin receptor B. Stimulation by the endothelin receptor B agonist IRL1620 triggered phosphorylation of ERK1/2 and autophosphorylation of (Y1173) EGFR. The effects could be blocked by Src-kinase inhibitors (PP1, PP2), EGFR-inhibitor (AG1478), EGFR-siRNA and by inhibitors to extracellular matrix metalloproteinases (GM6001), consistent with a Src-kinase mediated endothelin receptor response that engage ligand-dependent and ligand-independent EGFR activation. Our data suggest a mechanism for how injury-induced endothelins, produced in the retina, may modulate the Müller cell responses by Src-mediated transactivation of EGFRs. The data give support to a view in which endothelins

  11. Endothelin B Receptors on Primary Chicken Müller Cells and the Human MIO-M1 Müller Cell Line Activate ERK Signaling via Transactivation of Epidermal Growth Factor Receptors.

    PubMed

    Harun-Or-Rashid, Mohammad; Konjusha, Dardan; Galindo-Romero, Caridad; Hallböök, Finn

    2016-01-01

    Injury to the eye or retina triggers Müller cells, the major glia cell of the retina, to dedifferentiate and proliferate. In some species they attain retinal progenitor properties and have the capacity to generate new neurons. The epidermal growth factor receptor (EGFR) system and extracellular signal-regulated kinase (ERK) signaling are key regulators of these processes in Müller cells. The extracellular signals that modulate and control these processes are not fully understood. In this work we studied whether endothelin receptor signaling can activate EGFR and ERK signaling in Müller cells. Endothelin expression is robustly upregulated at retinal injury and endothelin receptors have been shown to transactivate EGFRs in other cell types. We analyzed the endothelin signaling system in chicken retina and cultured primary chicken Müller cells as well as the human Müller cell line MIO-M1. The Müller cells were stimulated with receptor agonists and treated with specific blockers to key enzymes in the signaling pathway or with siRNAs. We focused on endothelin receptor mediated transactivation of EGFRs by using western blot analysis, quantitative reverse transcriptase PCR and immunocytochemistry. The results showed that chicken Müller cells and the human Müller cell line MIO-M1 express endothelin receptor B. Stimulation by the endothelin receptor B agonist IRL1620 triggered phosphorylation of ERK1/2 and autophosphorylation of (Y1173) EGFR. The effects could be blocked by Src-kinase inhibitors (PP1, PP2), EGFR-inhibitor (AG1478), EGFR-siRNA and by inhibitors to extracellular matrix metalloproteinases (GM6001), consistent with a Src-kinase mediated endothelin receptor response that engage ligand-dependent and ligand-independent EGFR activation. Our data suggest a mechanism for how injury-induced endothelins, produced in the retina, may modulate the Müller cell responses by Src-mediated transactivation of EGFRs. The data give support to a view in which endothelins

  12. Aryl biphenyl-3-ylmethylpiperazines as 5-HT7 receptor antagonists.

    PubMed

    Kim, Jeeyeon; Kim, Youngjae; Tae, Jinsung; Yeom, Miyoung; Moon, Bongjin; Huang, Xi-Ping; Roth, Bryan L; Lee, Kangho; Rhim, Hyewhon; Choo, Il Han; Chong, Youhoon; Keum, Gyochang; Nam, Ghilsoo; Choo, Hyunah

    2013-11-01

    The 5-HT7 receptor (5-HT7 R) is a promising therapeutic target for the treatment of depression and neuropathic pain. The 5-HT7 R antagonist SB-269970 exhibited antidepressant-like activity, whereas systemic administration of the 5-HT7 R agonist AS-19 significantly inhibited mechanical hypersensitivity and thermal hyperalgesia. In our efforts to discover selective 5-HT7 R antagonists or agonists, aryl biphenyl-3-ylmethylpiperazines were designed, synthesized, and biologically evaluated against the 5-HT7 R. Among the synthesized compounds, 1-([2'-methoxy-(1,1'-biphenyl)-3-yl]methyl)-4-(2-methoxyphenyl)piperazine (28) was the best binder to the 5-HT7 R (pKi =7.83), and its antagonistic property was confirmed by functional assays. The selectivity profile of compound 28 was also recorded for the 5-HT7 R over other serotonin receptor subtypes, such as 5-HT1 R, 5-HT2 R, 5-HT3 R, and 5-HT6 R. In a molecular modeling study, the 2-methoxyphenyl moiety attached to the piperazine ring of compound 28 was proposed to be essential for the antagonistic function.

  13. Optimization of amide-based EP3 receptor antagonists.

    PubMed

    Lee, Esther C Y; Futatsugi, Kentaro; Arcari, Joel T; Bahnck, Kevin; Coffey, Steven B; Derksen, David R; Kalgutkar, Amit S; Loria, Paula M; Sharma, Raman

    2016-06-01

    Prostaglandin E receptor subtype 3 (EP3) antagonism may treat a variety of symptoms from inflammation to cardiovascular and metabolic diseases. Previously, most EP3 antagonists were large acidic ligands that mimic the substrate, prostaglandin E2 (PGE2). This manuscript describes the optimization of a neutral small molecule amide series with improved lipophilic efficiency (LipE) also known as lipophilic ligand efficiency (LLE) ((a) Nat. Rev. Drug Disc.2007, 6, 881; (b) Annu. Rep. Med. Chem.2010, 45, 380).

  14. Human glucagon receptor antagonists based on alkylidene hydrazides.

    PubMed

    Ling, Anthony; Plewe, Michael; Gonzalez, Javier; Madsen, Peter; Sams, Christian K; Lau, Jesper; Gregor, Vlad; Murphy, Doug; Teston, Kimberly; Kuki, Atsuo; Shi, Shenghua; Truesdale, Larry; Kiel, Dan; May, John; Lakis, James; Anderes, Kenna; Iatsimirskaia, Eugenia; Sidelmann, Ulla G; Knudsen, Lotte B; Brand, Christian L; Polinsky, Alex

    2002-02-25

    A series of alkylidene hydrazide derivatives containing an alkoxyaryl moiety was optimized. The resulting hydrazide-ethers were competitive antagonists at the human glucagon receptor. Pharmacokinetic experiments showed fast clearance of most of the compounds tested. A representative compound [4-hydroxy-3-cyanobenzoic acid (4-isopropylbenzyloxy-3,5-dimethoxymethylene)hydrazide] with an IC50 value of 20 nM was shown to reduce blood glucose levels in fasted rats.

  15. Endothelin-1 activation of ETB receptors leads to a reduced cellular proliferative rate and an increased cellular footprint

    SciTech Connect

    Wilson, Jamie L.; Taylor, Linda; Polgar, Peter

    2012-06-10

    Endothelin-1 (ET-1) is a vasoactive peptide which signals through two G-protein coupled receptors, endothelin receptor A (ETA) and B (ETB). We determined that ET-1 activation of its ETB receptor in stably cDNA transfected CHO cells leads to a 55% reduction in cell number by end-point cell counting and a 35% decrease in cell growth by a real-time cell-substrate impedance-based assay after 24 h of cell growth. When CHO ETB cells were synchronized in the late G1 cell cycle phase, ET-1 delayed their S phase progression compared to control by 30% as determined by [{sup 3}H]-thymidine incorporation. On the other hand, no such delay was observed during late G2/M to G1 transit when cells were treated with ET-1 after release from mitotic arrest. Using the cell-substrate impedance-based assay, we observed that ET-1 induces opposing morphological changes in CHO ETA and CHO ETB cells with ETB causing an increase in the cell footprint and ETA a decrease. Likewise, in pulmonary artery smooth muscle cells, which express both ETA and ETB receptors, ET-1 induces an ETA-dependent contraction and an ETB dependent dilation. These results are shedding light on a possible beneficial role for ETB in diseases involving ET-1 dysfunction such as pulmonary hypertension. -- Highlights: Black-Right-Pointing-Pointer ET- hinders cell proliferation in CHO cells transfected with ETB. Black-Right-Pointing-Pointer ET-1 also decreases the rate of DNA synthesis in CHO ETB cells. Black-Right-Pointing-Pointer JNK and PI3K appear to be involved in this reduction of DNA synthesis. Black-Right-Pointing-Pointer ETB activation in CHO ETB cells and hSMCs leads to dilatory morphological changes. Black-Right-Pointing-Pointer In CHO ETA and hSMCs, ETA activation leads to constrictive morphological changes.

  16. Can angiotensin receptor antagonists prevent restenosis after stent placement?

    PubMed

    Peters, Stefan

    2002-01-01

    Restenosis rates after coronary stent implantation in complex lesions are between 30 and 50%. Neointimal hyperplasia promoted by complex interaction between cellular and acellular elements, such as cytokines and growth factors, is thought to be the primary process responsible for restenosis. The risk of in-stent restenosis is increased in patients with a history of restenosis after percutaneous transluminal coronary angioplasty, in long lesions, in total occlusions, in patients with diabetes mellitus, in small vessels, in the proximal parts of the left anterior descending coronary artery and in cases of stent oversizing. In-stent restenosis represents a serious economic burden on society because treatment strategies include expensive approaches such as cutting-balloon angioplasty, rotational atherectomy and brachytherapy. A number of pharmacological agents, including ACE inhibitors, have been unsuccessful in preventing restenosis. Alternative procedures such as brachytherapy, radioactive stents and drug-eluting stents are under evaluation. Although sirolimus- or paclitaxel-eluting stents have been associated with very low restenosis rates over durations of 6 to 12 months, the long-term efficacy and tolerability of this approach is currently being investigated. Although ACE inhibitors have failed in reducing restenosis rates, the selective angiotensin II type 1 (AT(1)) receptor antagonist valsartan has shown encouraging results in the single-center Valsartan for Prevention of Restenosis after Stenting of Type B2/C lesions trial (ValPREST). The ValPREST trial is the first randomized, placebo-controlled study to have evaluated the effect of an angiotensin receptor antagonist on in-stent restenosis in a moderate number of patients. Compared with ACE inhibitors, angiotensin receptor blockers exert additional effects on the pathophysiological processes which lead to restenosis. Angiotensin receptor antagonists may affect several mechanisms involved in neointimal

  17. A synthetic peptide derivative that is a cholecystokinin receptor antagonist.

    PubMed

    Lignon, M F; Galas, M C; Rodriguez, M; Laur, J; Aumelas, A; Martinez, J

    1987-05-25

    So far, there are no known peptidic effective receptor antagonists of both peripheral and central effects of cholecystokinin (CCK). Here, we describe a synthetic peptide derivative of CCK, t-butyloxycarbonyl-Tyr(SO3-)-Met-Gly-D-Trp-Nle-Asp 2-phenylethyl ester 1 (where Nle is norleucine), which is a potent CCK receptor antagonist. In rat and guinea pig dispersed pancreatic acini, this peptide derivative did not alter amylase secretion, but was able to antagonize the stimulation caused by cholecystokinin-related agonists. It caused a parallel rightward shift in the dose-response curve for the stimulation of amylase secretion with half-maximal inhibition of CCK-8-stimulated amylase release at a concentration of about 0.1 microM. Compound 1 was able to inhibit the binding of labeled CCK-9 (the C-terminal nonapeptide of CCK) to rat and guinea pig pancreatic acini (IC50 = 5 X 10(-8) M) as well as to guinea pig cerebral cortical membranes (IC50 = 5 X 10(-7) M). These results indicate that Compound 1 is a potent competitive CCK receptor antagonist.

  18. Discovery of new muscarinic acetylcholine receptor antagonists from Scopolia tangutica

    PubMed Central

    Du, Nana; Liu, Yanfang; Zhang, Xiuli; Wang, Jixia; Zhao, Jianqiang; He, Jian; Zhou, Han; Mei, Lijuan; Liang, Xinmiao

    2017-01-01

    Scopolia tangutica (S. tangutica) is a traditional Chinese medicinal plant used for antispasmodics, anesthesia, analgesia and sedation. Its pharmacological activities are mostly associated with the antagonistic activity at muscarinic acetylcholine receptors (mAchRs) of several known alkaloids such as atropine and scopolamine. With our recent identification of four hydroxycinnamic acid amides from S. tangutica, we hypothesized that this plant may contain previously unidentified alkaloids that may also contribute to its in vivo effect. Herein, we used a bioassay-guided multi-dimension separation strategy to discover novel mAchR antagonists from S. tangutica. The core of this approach is to use label-free cell phenotypic assay to first identify active fractions, and then to guide purification of active ligands. Besides four tropanes and six cinnamic acid amides that have been previously isolated from S. tangutica, we recently identified two new tropanes, one new cinnamic acid amide, and nine other compounds. Six tropane compounds purified from S. tangutica for the first time were confirmed to be competitive antagonists of muscarinic receptor 3 (M3), including the two new ones 8 and 12 with IC50 values of 1.97 μM and 4.47 μM, respectively. Furthermore, the cinnamic acid amide 17 displayed 15-fold selectivity for M1 over M3 receptors. These findings will be useful in designing lead compounds for mAchRs and elucidating mechanisms of action of S. tangutica. PMID:28387362

  19. [5-HT3 receptor antagonist als analgetics in rheumatic diseases].

    PubMed

    Müller, W; Fiebich, B L; Stratz, T

    2006-10-01

    Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

  20. A prototypical Sigma-1 receptor antagonist protects against brain ischemia.

    PubMed

    Schetz, John A; Perez, Evelyn; Liu, Ran; Chen, Shiuhwei; Lee, Ivan; Simpkins, James W

    2007-11-21

    Previous studies indicate that the Sigma-1 ligand 4-phenyl-1-(4-phenylbutyl) piperidine (PPBP) protects the brain from ischemia. Less clear is whether protection is mediated by agonism or antagonism of the Sigma-1 receptor, and whether drugs already in use for other indications and that interact with the Sigma-1 receptor might also prevent oxidative damage due to conditions such as cerebral ischemic stroke. The antipsychotic drug haloperidol is an antagonist of Sigma-1 receptors and in this study it potently protects against oxidative stress-related cell death in vitro at low concentrations. The protective potency of haloperidol and a number of other butyrophenone compounds positively correlate with their affinity for a cloned Sigma-1 receptor, and the protection is mimicked by a Sigma-1 receptor-selective antagonist (BD1063), but not an agonist (PRE-084). In vivo, an acute low dose (0.05 mg/kg s.c.) of haloperidol reduces by half the ischemic lesion volume induced by a transient middle cerebral artery occlusion. These in vitro and in vivo pre-clinical results suggest that a low dose of acutely administered haloperidol might have a novel application as a protective agent against ischemic cerebral stroke and other types of brain injury with an ischemic component.

  1. Endothelin-1 contributes to the Frank-Starling response in hypertrophic rat hearts.

    PubMed

    Piuhola, Jarkko; Szokodi, István; Kinnunen, Pietari; Ilves, Mika; deChâtel, Rudolf; Vuolteenaho, Olli; Ruskoaho, Heikki

    2003-01-01

    Endothelin-1 is involved in mechanical load-induced cardiac growth processes; it also has effects on contractility. The interaction of endothelin-1 and the Frank-Starling response is unknown. The present study aimed to characterize the role of endothelin-1 in the regulation of the Frank-Starling response, one of the major mechanisms regulating cardiac contractile force, in both normal and hypertrophied hearts. Nontransgenic rat hearts and hypertrophic hearts of hypertensive double transgenic rats harboring human angiotensinogen and renin genes were studied in a Langendorff isolated heart setup with a liquid-filled balloon inside the left ventricle used to measure contractile parameters. The rats were studied at compensated phase, before showing any signs of heart failure. Compensated hypertrophy in double transgenic rat hearts resulted in improved contractility at a given level of preload when compared with nontransgenic rat hearts. Hearts of both rat lines showed preserved Frank-Starling responses, that is, increased contractile function in response to increased end-diastolic pressure. The mixed endothelin A/B receptor antagonist bosentan attenuated the Frank-Starling response by 53% (P<0.01) in the double transgenic hearts but not in nontransgenic hearts. The diastolic parameters remained unaffected. The left ventricles of the double transgenic rat hearts showed an 82% higher level of endothelin type A receptor mRNA and a 25% higher level of immunoreactive endothelin-1 compared with nontransgenic rat hearts. The type 1 angiotensin II receptor antagonist CV-11974 had no significant effect on contractile function in response to load in either strain. These results show that endogenous endothelin-1 contributes to the Frank-Starling response in hypertrophied rat hearts by affecting systolic performance.

  2. Effects of combined endothelin A receptor and renin-angiotensin system blockade on the course of end-organ damage in 5/6 nephrectomized Ren-2 hypertensive rats.

    PubMed

    Vaněčková, Ivana; Kujal, Petr; Husková, Zuzana; Vaňourková, Zdeňka; Vernerová, Zdenka; Certíková Chábová, Věra; Skaroupková, Petra; Kramer, Herbert J; Tesař, Vladimír; Červenka, Luděk

    2012-01-01

    Our previous studies in rats with ablation nephrectomy have shown similar cardiorenal protective effects of renin-angiotensin system (RAS)-dependent treatment (combination of angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker) and RAS-independent treatment (combination of α- and β-adrenoreceptor antagonist and diuretics). Moreover, selective blockade of endothelin (ET) receptor type A (ET(A)) improved survival rate and attenuated hypertension and organ damage in Ren-2 transgenic rats. Therefore, we were interested in whether ET(A) receptor blockade could have additive effects to the classical blockade of the RAS. Transgenic rats underwent 5/6 renal ablation at the age of 2 months and were treated for 20 weeks with RAS blockers alone (angiotensin II receptor blocker - losartan, and angiotensin-converting enzyme inhibitor - trandolapril), ET(A) receptor blocker alone (atrasentan) or with the combination of RAS and ET(A) receptor blockade. RAS blockade normalized blood pressure and improved survival. It decreased cardiac hypertrophy and proteinuria as well as tissue angiotensin II and ET-1 levels. In contrast, ET(A) receptor blockade only partially improved survival rate, reduced blood pressure, attenuated the development of cardiac hypertrophy and transiently reduced proteinuria. However, no additive cardio- and renoprotective effects of ET(A) and RAS blockade were noted at the end of the study. Copyright © 2012 S. Karger AG, Basel.

  3. Decreased expression of messenger RNAs encoding endothelin receptors and neutral endopeptidase 24.11 in endometrial cancer.

    PubMed Central

    Pekonen, F.; Nyman, T.; Ammälä, M.; Rutanen, E. M.

    1995-01-01

    In this study, we used reverse transcriptase-polymerase chain reaction (RT-PCR) to compare the expression of mRNAs encoding endothelin-1 (ET-1), endothelin receptors type A (ETA-R) and type B (ETB-R) and ET-1-degrading enzyme neutral endopeptidase 24.11 (NEP) in 15 endometrial cancer tissues and 13 normal endometrial tissues. The relative levels of ET-1 mRNA in endometrial cancer tissues did not differ from those in normal endometrium. Both ETA-R and ETB-R mRNA levels were significantly lower in endometrial cancer tissue than in normal endometrium (P < 0.001). The complete lack of NEP mRNA in endometrial cancer tissues was in marked contrast to results from normal endometrium (P < 0.001). In conclusion, differential expression of mRNAs encoding ET-R and NEP in normal endometrium and endometrial cancer suggests that ET action is altered in endometrial cancer compared with normal endometrium. Images Figure 2 PMID:7819049

  4. The endothelin receptor-B is required for the migration of neural crest-derived melanocyte and enteric neuron precursors.

    PubMed

    Lee, Hyung-Ok; Levorse, John M; Shin, Myung K

    2003-07-01

    Mutations in the genes encoding endothelin receptor-B (Ednrb) and its ligand endothelin-3 (Edn3) affect the development of two neural crest-derived cell types, melanocytes and enteric neurons. EDNRB signaling is exclusively required between E10.5 and E12.5 during the migratory phase of melanoblast and enteric neuroblast development. To determine the fate of Ednrb-expressing cells during this critical period, we generated a strain of mice with the bacterial beta-galactosidase (lacZ) gene inserted downstream of the endogenous Ednrb promoter. The expression of the lacZ gene was detected in melanoblasts and precursors of the enteric neuron system (ENS), as well as other neural crest cells and nonneural crest-derived lineages. By comparing Ednrb(lacZ)/+ and Ednrb(lacZ)/Ednrb(lacZ) embryos, we determined that the Ednrb pathway is not required for the initial specification and dispersal of melanoblasts and ENS precursors from the neural crest progenitors. Rather, the EDNRB-mediated signaling is required for the terminal migration of melanoblasts and ENS precursors, and this pathway is not required for the survival of the migratory cells.

  5. Endothelin-1, but not angiotensin II, induces afferent arteriolar myosin diphosphorylation as a potential contributor to prolonged vasoconstriction.

    PubMed

    Takeya, Kosuke; Wang, Xuemei; Kathol, Iris; Loutzenhiser, Kathy; Loutzenhiser, Rodger; Walsh, Michael P

    2015-02-01

    Bolus administration of endothelin-1 elicits long-lasting renal afferent arteriolar vasoconstriction, in contrast to transient constriction induced by angiotensin II. Vasoconstriction is generally evoked by myosin regulatory light chain (LC20) phosphorylation at Ser19 by myosin light chain kinase (MLCK), which is enhanced by Rho-associated kinase (ROCK)-mediated inhibition of myosin light chain phosphatase (MLCP). LC20 can be diphosphorylated at Ser19 and Thr18, resulting in reduced rates of dephosphorylation and relaxation. Here we tested whether LC20 diphosphorylation contributes to sustained endothelin-1 but not transient angiotensin II-induced vasoconstriction. Endothelin-1 treatment of isolated arterioles elicited a concentration- and time-dependent increase in LC20 diphosphorylation at Thr18 and Ser19. Inhibition of MLCK or ROCK reduced endothelin-1-evoked LC20 mono- and diphosphorylation. Pretreatment with an ETB but not an ETA receptor antagonist abolished LC20 diphosphorylation, and an ETB receptor agonist induced LC20 diphosphorylation. In contrast, angiotensin II caused phosphorylation exclusively at Ser19. Thus, endothelin-1 and angiotensin II induce afferent arteriolar constriction via LC20 phosphorylation at Ser19 due to calcium activation of MLCK and ROCK-mediated inhibition of MLCP. Endothelin-1, but not angiotensin II, induces phosphorylation of LC20 at Thr18. This could contribute to the prolonged vasoconstrictor response to endothelin-1.

  6. Endothelin A (ET(A)) receptors are involved in augmented adrenergic vasoconstriction and blunted nitric oxide-mediated relaxation of penile arteries from insulin-resistant obese zucker rats.

    PubMed

    Sánchez, Ana; Contreras, Cristina; Martínez, Pilar; Muñoz, Mercedes; Martínez, Ana Cristina; García-Sacristán, Albino; Hernández, Medardo; Prieto, Dolores

    2014-06-01

    Endothelin 1 (ET-1) levels and receptors are up-regulated in the erectile tissue of diabetic patients and animal models of erectile dysfunction (ED). The present study assessed the role of ET-1 receptors in the impaired adrenergic vasoconstriction and nitrergic relaxation of penile arteries from a rat model of insulin resistance. The effect of ET receptor antagonists was evaluated on the contractile responses to electrical field stimulation (EFS) of penile arteries from obese Zucker rats (OZRs) compared with lean Zucker rats (LZRs). ET receptor expression was determined by immunohistochemistry. Changes in neural nitrergic relaxation and adrenergic vasoconstriction and the expression of ET receptors in perivascular nerves were assessed. ET-1 (10(-10)  M) enhanced EFS-induced vasoconstriction, and treatment with the adrenergic neurotoxin guanethidine reduced the contractions induced by ET-1 in penile arteries from both LZRs and OZRs, thus supporting the hypothesis that ET-1 releases noradrenaline from adrenergic nerves. ET-1 antagonized neural nitric oxide (NO)-mediated relaxant responses in LZR arteries, antagonizing relaxations induced by the NO donor S-nitroso-N-acetylpenicillamine to a larger extent in arteries from OZRs. ET(A) and ET(B) receptors were expressed in perivascular fibers colocalized with the neuronal marker protein gene product 9.5 in penile arteries from OZRs. The ET(A) receptor antagonist BQ-123 reversed the enhancing effect of ET-1 on the vasoconstriction elicited by EFS and the ET-1-induced inhibition of nitrergic relaxations in LZRs, restoring them to control levels in penile arteries of OZRs. ET-1 enhances adrenergic vasoconstriction through presynaptic ET(A) receptors and antagonizes neural NO-mediated relaxation through postsynaptic smooth muscle ET(A) receptors in penile arteries from OZRs, which likely contributes to the augmented vasoconstriction and blunted nitrergic relaxation of erectile tissue under conditions of insulin resistance

  7. Functionalized Congeners of P2Y1 Receptor Antagonists:

    SciTech Connect

    de Castro, Sonia; Maruoka, Hiroshi; Hong, Kunlun; Kilbey, II, S Michael; Costanzi, Stefano; Hechler, Béatrice; Gachet, Christian; Harden, T. Kendall; Jacobson, Kenneth A.

    2010-01-01

    The P2Y{sub 1} receptor is a prothrombotic G protein-coupled receptor (GPCR) activated by ADP. Preference for the North (N) ring conformation of the ribose moiety of adenine nucleotide 3',5'-bisphosphate antagonists of the P2Y{sub 1} receptor was established by using a ring-constrained methanocarba (a bicyclo[3.1.0]hexane) ring as a ribose substitute. A series of covalently linkable N{sup 6}-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphates containing extended 2-alkynyl chains was designed, and binding affinity at the human (h) P2Y{sub 1} receptor determined. The chain of these functionalized congeners contained hydrophilic moieties, a reactive substituent, or biotin, linked via an amide. Variation of the chain length and position of an intermediate amide group revealed high affinity of carboxylic congener 8 (K{sub i} 23 nM) and extended amine congener 15 (K{sub i} 132 nM), both having a 2-(1-pentynoyl) group. A biotin conjugate 18 containing an extended {epsilon}-aminocaproyl spacer chain exhibited higher affinity than a shorter biotinylated analogue. Alternatively, click coupling of terminal alkynes of homologous 2-dialkynyl nucleotide derivatives to alkyl azido groups produced triazole derivatives that bound to the P2Y{sub 1} receptor following deprotection of the bisphosphate groups. The preservation of receptor affinity of the functionalized congeners was consistent with new P2Y{sub 1} receptor modeling and ligand docking. Attempted P2Y{sub 1} antagonist conjugation to PAMAM dendrimer carriers by amide formation or palladium-catalyzed reaction between an alkyne on the dendrimer and a 2-iodopurine-derivatized nucleotide was unsuccessful. A dialkynyl intermediate containing the chain length favored in receptor binding was conjugated to an azide-derivatized dendrimer, and the conjugate inhibited ADP-promoted human platelet aggregation. This is the first example of attaching a strategically functionalized P2Y receptor antagonist to a PAMAM dendrimer to

  8. Muscarinic Receptor Agonists and Antagonists: Effects on Cancer

    PubMed Central

    2012-01-01

    Many epithelial and endothelial cells express a cholinergic autocrine loop in which acetylcholine acts as a growth factor to stimulate cell growth. Cancers derived from these tissues similarly express a cholinergic autocrine loop and ACh secreted by the cancer or neighboring cells interacts with M3 muscarinic receptors expressed on the cancer cells to stimulate tumor growth. Primary proliferative pathways involve MAPK and Akt activation. The ability of muscarinic agonists to stimulate, and M3 antagonists to inhibit tumor growth has clearly been demonstrated for lung and colon cancer. The ability of muscarinic agonists to stimulate growth has been shown for melanoma, pancreatic, breast, ovarian, prostate and brain cancers, suggesting that M3 antagonists will also inhibit growth of these tumors as well. As yet no clinical trials have proven the efficacy of M3 antagonists as cancer therapeutics, though the widespread clinical use and low toxicity of M3 antagonists support the potential role of these drugs as adjuvants to current cancer therapies. PMID:22222710

  9. Characterization of a novel non-steroidal glucocorticoid receptor antagonist

    SciTech Connect

    Li, Qun-Yi; Zhang, Meng; Hallis, Tina M.; DeRosier, Therese A.; Yue, Jian-Min; Ye, Yang; Mais, Dale E.; Wang, Ming-Wei

    2010-01-15

    Selective antagonists of the glucocorticoid receptor (GR) are desirable for the treatment of hypercortisolemia associated with Cushing's syndrome, psychic depression, obesity, diabetes, neurodegenerative diseases, and glaucoma. NC3327, a non-steroidal small molecule with potent binding affinity to GR (K{sub i} = 13.2 nM), was identified in a high-throughput screening effort. As a full GR antagonist, NC3327 greatly inhibits the dexamethasone (Dex) induction of marker genes involved in hepatic gluconeogenesis, but has a minimal effect on matrix metalloproteinase 9 (MMP-9), a GR responsive pro-inflammatory gene. Interestingly, the compound recruits neither coactivators nor corepressors to the GR complex but competes with glucocorticoids for the interaction between GR and a coactivator peptide. Moreover, NC3327 does not trigger GR nuclear translocation, but significantly blocks Dex-induced GR transportation to the nucleus, and thus appears to be a 'competitive' GR antagonist. Therefore, the non-steroidal compound, NC3327, may represent a new class of GR antagonists as potential therapeutics for a variety of cortisol-related endocrine disorders.

  10. NMDA receptor antagonists extend the sensitive period for imprinting.

    PubMed

    Parsons, C H; Rogers, L J

    2000-03-01

    Filial imprinting in the domestic chick occurs during a sensitive period of development. The exact timing of this period can vary according to the methods used to measure imprinting. Using our imprinting paradigm, we have shown that normal, dark-reared chicks lose the ability to imprint after the second day post-hatching. Further, we reported that chicks treated 10 h after hatching with a mixture of the noncompetitive NMDA receptor antagonist ketamine (55 mg/kg) and the alpha(2)-adrenergic receptor agonist xylazine (6 mg/kg) were able to imprint on day 8 after hatching, whereas controls treated with saline did not imprint. We now show that the effect of the ketamine-xylazine mixture can be mimicked by treating chicks with ketamine alone or with another noncompetitive NMDA receptor antagonist, MK-801 (5 mg/kg). Treating chicks with a single dose of ketamine (55 mg/kg) or with a single dose of xylazine (6 mg/kg) failed to produce the effect on the sensitive period. However, prolonging the action of ketamine by treating chicks with two doses of ketamine (at 10 and 12 h after hatching) did allow imprinting on day 8. In contrast, prolonging the action of xylazine had no effect on the sensitive period for imprinting. Chicks treated with MK-801 were also able to imprint on day 8. Thus, we have evidence that the NMDA receptor system is involved in the mechanisms that control the sensitive period for imprinting.

  11. Cinnamophilin, a novel thromboxane A2 receptor antagonist, isolated from Cinnamomum philippinense.

    PubMed

    Yu, S M; Ko, F N; Wu, T S; Lee, J Y; Teng, C M

    1994-04-11

    The pharmacological activity of cinnamophilin ((8R,8'S)-4,4'-dihydroxy-3,3'-dimethoxy-7-oxo-8,8'-neolignan), isolated from Cinnamomum philippinense, was studied in isolated rat aorta, guinea-pig trachea and rabbit platelets. Cinnamophilin was found to be a thromboxane A2 receptor blocking agent in these tissues as revealed by its competitive antagonism of the U-46619 (9,11-dideoxymethanoepoxy-9 alpha,11 alpha-prostaglandin F2 alpha)-induced contraction of rat aorta and guinea-pig trachea and aggregation of rabbit platelets with pA2 values of 7.3 +/- 0.2, 5.2 +/- 0.1 and 6.3 +/- 0.3, respectively. Protection against the irreversible vasoconstriction of rat aorta caused by U-46619 (0.05 microM) was obtained by cinnamophilin (10 microM) but not by caffeine (25 mM). Cinnamophilin (1-15 microM) also possessed voltage-dependent Ca2+ channel blocking action, judging from its antagonism of the high K+ (60 mM)- and Bay K 8644 (0.1 microM)-induced contraction in rat thoracic aorta. Cinnamophilin (30 microM) produced a slight relaxation of noradrenaline (3 microM)-induced tonic contractions, and this relaxing effect was abolished in the presence of nifedipine (1 microM). Nifedipine (10 microM) sufficient to inhibit high K(+)-induced contractions failed to attenuate the contractile response to U-46619. A high concentration of cinnamophilin (100 microM) did not affect the aortic contraction induced by endothelin-1, angiotensin II, carbachol or serotonin. Neither cAMP nor cGMP in rat aorta was increased by cinnamophilin. These results indicate that cinnamophilin is a selective thromboxane A2 receptor antagonist especially in rat aorta, and also possesses voltage-dependent Ca2+ channel blocking properties.

  12. Renal endothelin system and excretory function in Wistar-Kyoto and Long-Evans rats.

    PubMed

    Girchev, R; Bäcker, A; Markova, P; Kramer, H J

    2006-01-01

    The role of the kidney endothelin system in the renal regulation of fluid and electrolyte excretion was investigated in Wistar-Kyoto (WKY) and Long-Evans (LE) rats in which we found previously marked differences in the renal excretory responses to endothelin A receptor blockade. The selective endothelin A and B receptor antagonists BQ-123 (16.4 nmol kg(-1) min(-1)) and BQ-788 (25 nmol kg(-1) min(-1)) were infused i.v. for 50 min in conscious chronically instrumented WKY and LE rats and their renal function and renal endothelin system were studied. Without effects on glomerular filtration rate or renal blood flow, BQ-123 and BQ-788 decreased by more than 50% (P < 0.01) both urine flow rate and electrolyte excretion in WKY rats but only urine flow rate (P < 0.05) in LE rats. Endothelin-1 content, preproET-1/GPDH mRNA ratio, B(max) and K(d) of total endothelin receptors in renal cortex did not differ between the two strains. In contrast, plasma endothelin-1 concentration (0.58 +/- 0.04 vs. 1.05 +/- 0.01 femtomol mL(-1); P < 0.01), renal papillary ET-1 concentration (68 +/- 5 vs. 478 +/- 62 fmol mg(-1) protein; P < 0.01) and preproET-1/GPDH mRNA ratio (0.65 +/- 0.09 vs. 0.88 +/- 0.05; P < 0.05) as well as total endothelin receptor number in renal papilla (B(max) 5.3 +/- 0.4 vs. and 9.0 +/- 1.2 pmol mg(-1) protein; P < 0.05) were markedly lower in LE than in WKY rats. In vitro studies showed that in both strains ET(B) receptors on renal cortical membranes amounted between 65% and 67% and on papillary membranes between 85% and 88%. The present data show that the selective ET(A) or ET(B) receptor blockade differentially affects tubular water and salt handling, which becomes apparent in conditions of low renal papillary endothelin receptor number and tissue endothelin-1 concentration.

  13. Vasopressin receptor antagonists, heart failure, and polycystic kidney disease.

    PubMed

    Torres, Vicente E

    2015-01-01

    The synthesis of nonpeptide orally bioavailable vasopressin antagonists devoid of agonistic activity (vaptans) has made possible the selective blockade of vasopressin receptor subtypes for therapeutic purposes. Vaptans acting on the vasopressin V2 receptors (aquaretics) have attracted attention as a possible therapy for heart failure and polycystic kidney disease. Despite a solid rationale and encouraging preclinical testing, aquaretics have not improved clinical outcomes in randomized clinical trials for heart failure. Additional clinical trials with select population targets, more flexible dosing schedules, and possibly a different drug type or combination (balanced V1a/V2 receptor antagonism) may be warranted. Aquaretics are promising for the treatment of autosomal dominant polycystic kidney disease and have been approved in Japan for this indication. More studies are needed to better define their long-term safety and efficacy and optimize their utilization.

  14. Crystal Structure of Antagonist Bound Human Lysophosphatidic Acid Receptor 1

    PubMed Central

    Chrencik, Jill E.; Roth, Christopher B.; Terakado, Masahiko; Kurata, Haruto; Omi, Rie; Kihara, Yasuyuki; Warshaviak, Dora; Nakade, Shinji; Asmar-Rovira, Guillermo; Mileni, Mauro; Mizuno, Hirotaka; Griffith, Mark T.; Rodgers, Caroline; Han, Gye Won; Velasquez, Jeffrey; Chun, Jerold; Stevens, Raymond C.

    2015-01-01

    Summary Lipid biology continues to emerge as an area of significant therapeutic interest, particularly as the result of an enhanced understanding of the wealth of signaling molecules with diverse physiological properties. This growth in knowledge is epitomized by lysophosphatidic acid (LPA), which functions through interactions with six cognate G protein-coupled receptors. Herein we present three crystal structures of LPA1 in complex with antagonist tool compounds selected and designed through structural and stability analysis. Structural analysis combined with molecular dynamics identified a basis for ligand access to the LPA1 binding pocket from the extracellular space contrasting with the proposed access for the sphingosine 1-phosphate receptor. Characteristics of the LPA1 binding pocket raise the possibility of promiscuous ligand recognition of phosphorylated endocannabinoids. Cell-based assays confirmed this hypothesis, linking the distinct receptor systems through metabolically related ligands with potential functional and therapeutic implications for treatment of disease. PMID:26091040

  15. Selective Endothelin-B Receptor Stimulation Increases Vascular Endothelial Growth Factor in the Rat Brain during Postnatal Development.

    PubMed

    Leonard, M G; Prazad, P; Puppala, B; Gulati, A

    2015-11-01

    Endothelin, vascular endothelial growth factor and nerve growth factor play important roles in development of the central nervous system. ET(B) receptors have been shown to promote neurovascular remodeling in the adult ischemic brain through an increase in VEGF and NGF. It is possible that ET(B) receptors may be involved in postnatal development of the brain through VEGF and NGF. In the present study, the brains of male rat pups on postnatal days 1, 7, 14 and 28 were analyzed for expression of ET(B) receptors, VEGF and NGF. In order to determine the effect of ET(B) receptor stimulation, a separate group of pups were administered saline or ET(B) receptor agonist, IRL-1620, on day 21, and their brains were analyzed on day 28. The intensity of ET(B) receptor and VEGF staining in the vasculature as well as the number of blood vessels of normal pups increased with age and was significantly higher on postnatal day 14 compared to day 1 and day 7. In contrast, both ET(B) and NGF staining intensity in the cortex and subventricular zones decreased (P<0.01) at postnatal day 14 compared to earlier time points. Stimulation of ET(B) receptors resulted in a significant increase in VEGF and ET(B) intensity both in the vasculature and the brain (P<0.05), however, IRL-1620 did not produce any change in NGF expression. Results indicate that ET(B) receptors appear to play a role in the development of the CNS and selective stimulation of ET(B) receptors enhances VEGF but not NGF in the postnatal rat brain. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    PubMed Central

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  17. Potential Clinical Implications of the Urotensin II Receptor Antagonists.

    PubMed

    Tsoukas, Philip; Kane, Emilie; Giaid, Adel

    2011-01-01

    Urotensin II (UII) binds to its receptor, UT, playing an important role in the heart, kidneys, pancreas, adrenal gland, and central nervous system. In the vasculature, it acts as a potent endothelium-independent vasoconstrictor and endothelium-dependent vasodilator. In disease states, however, this constriction-dilation equilibrium is disrupted. There is an upregulation of the UII system in heart disease, metabolic syndrome, and kidney failure. The increase in UII release and UT expression suggest that UII system may be implicated in the pathology and pathogenesis of these diseases by causing an increase in acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) activity leading to smooth muscle cell proliferation and foam cell infiltration, insulin resistance (DMII), as well as inflammation, high blood pressure, and plaque formation. Recently, UT antagonists such as SB-611812, palosuran, and most recently a piperazino-isoindolinone based antagonist have been developed in the hope of better understanding the UII system and treating its associated diseases.

  18. Thromboxane prostanoid receptors enhance contractions, endothelin-1, and oxidative stress in microvessels from mice with chronic kidney disease.

    PubMed

    Wang, Cheng; Luo, Zaiming; Kohan, Donald; Wellstein, Anton; Jose, Pedro A; Welch, William J; Wilcox, Christopher S; Wang, Dan

    2015-05-01

    Cardiovascular disease is frequent in chronic kidney disease and has been related to angiotensin II, endothelin-1 (ET-1), thromboxane A2, and reactive oxygen species (ROS). Because activation of thromboxane prostanoid receptors (TP-Rs) can generate ROS, which can generate ET-1, we tested the hypothesis that chronic kidney disease induces cyclooxygenase-2 whose products activate TP-Rs to enhance ET-1 and ROS generation and contractions. Mesenteric resistance arterioles were isolated from C57/BL6 or TP-R+/+ and TP-R-/- mice 3 months after SHAM-operation (SHAM) or surgical reduced renal mass (RRM, n=6/group). Microvascular contractions were studied on a wire myograph. Cellular (ethidium: dihydroethidium) and mitochondrial (mitoSOX) ROS were measured by fluorescence microscopy. Mice with RRM had increased excretion of markers of oxidative stress, thromboxane, and microalbumin; increased plasma ET-1; and increased microvascular expression of p22(phox), cyclooxygenase-2, TP-Rs, preproendothelin and endothelin-A receptors, and increased arteriolar remodeling. They had increased contractions to U-46,619 (118 ± 3 versus 87 ± 6, P<0.05) and ET-1 (108 ± 5 versus 89 ± 4, P<0.05), which were dependent on cellular and mitochondrial ROS, cyclooxygenase-2, and TP-Rs. RRM doubled the ET-1-induced cellular and mitochondrial ROS generation (P<0.05). TP-R-/- mice with RRM lacked these abnormal structural and functional microvascular responses and lacked the increased systemic and the increased microvascular oxidative stress and circulating ET-1. In conclusion, RRM leads to microvascular remodeling and enhanced ET-1-induced cellular and mitochondrial ROS and contractions that are mediated by cyclooxygenase-2 products activating TP-Rs. Thus, TP-Rs can be upstream from enhanced ROS, ET-1, microvascular remodeling, and contractility and may thereby coordinate vascular dysfunction in chronic kidney disease.

  19. Management of digital vasculopathy in systemic sclerosis: benefits of multiple courses of endothelin-1 receptor antagonists

    PubMed Central

    Ngcozana, Tanaka; Ong, Voon; Denton, Christopher Paul

    2014-01-01

    Two patients with scleroderma and recurrent digital ulcers (DUs) were treated with bosentan for 6 months. Treatment was associated with a reduction in the number of new DUs; however, DUs recurred on treatment discontinuation. This case report illustrates the positive response of digital vasculopathy to bosentan and describes the benefits of multiple bosentan treatment courses in these patients. PMID:24682137

  20. Pharmacokinetics of the novel dual endothelin receptor antagonist macitentan in subjects with hepatic or renal impairment.

    PubMed

    Sidharta, Patricia N; Lindegger, Nicolas; Ulč, Ivan; Dingemanse, Jasper

    2014-03-01

    Macitentan is under development for the treatment of pulmonary arterial hypertension (PAH). Patients with PAH may suffer from comorbidities such as renal or hepatic impairment. Two prospective, single-center, open-label studies evaluated the pharmacokinetics of macitentan and its metabolites (pharmacologically active ACT-132577 and inactive ACT-373898) in healthy subjects and in subjects with mild, moderate, and severe hepatic impairment or severe renal function impairment (SRFI). After administering a single oral dose of 10 mg macitentan the pharmacokinetic parameters including area under the curve from zero to infinity (AUC∞) were derived from plasma concentration-time profiles. Exposure to macitentan and ACT-132577 was lower in hepatically impaired versus healthy subjects, with no correlation with the degree of hepatic impairment. Exposure to ACT-373898 was lower in subjects with moderate hepatic impairment only. Plasma concentration-time profiles for macitentan and ACT-132577 (active) were similar in healthy subjects and subjects with SRFI. AUC∞ of ACT-373898 (inactive) was 7.3-fold higher in subjects with SRFI versus healthy subjects. No safety concerns were raised in either study. Based on these observations, pharmacokinetic alterations of macitentan due to hepatic or renal function impairment are not considered clinically relevant and no dose adjustment is necessary in these patients. © 2013, The American College of Clinical Pharmacology.

  1. Endothelin-1 inhibits endothelin-converting enzyme-1 expression in cultured rat pulmonary endothelial cells.

    PubMed

    Naomi, S; Iwaoka, T; Disashi, T; Inoue, J; Kanesaka, Y; Tokunaga, H; Tomita, K

    1998-01-27

    The lung expresses large amounts of endothelin-converting enzyme-1 (ECE-1), which catalyzes a step in the biosynthesis of potent vasoactive endothelin-1 (ET-1) from the inactive intermediate big ET-1. Because there has been no report concerning a possible relationship between ET-1 and ECE-1, we investigated the effects of ET-1 on ECE-1 expression in cultured rat pulmonary endothelial cells. ECE-1 messenger RNA (mRNA) and protein expression in cultured endothelial cells were assayed by Northern and Western blotting, respectively. Incubation with ET-1 for 6 hours caused a significant decrease in ECE-1 mRNA expression. The action of ET-1 on ECE-1 mRNA expression was antagonized by pretreatment with BQ788, a specific ETB receptor antagonist, but not by pretreatment with BQ123, a specific ETA receptor antagonist. The expression of ECE-1 protein was also inhibited at 6 hours after incubation with ET-1. The effects of ET-1 on ECE-1 mRNA and protein expression were shown to be mimicked by ionomycin, a calcium ionophore, but not by 12-O-tetradecanoylphorbol 13-acetate, a protein kinase C activator. The present results demonstrate that ET-1 suppressed ECE-1 protein levels by inhibiting ECE-1 mRNA expression through the ETB receptor, suggesting the existence of a feedback action of ET-1 on ECE-1 in pulmonary endothelial cells.

  2. Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity

    SciTech Connect

    Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

    1985-04-01

    The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of /sup 125/I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain.

  3. Safety profile of mineralocorticoid receptor antagonists: Spironolactone and eplerenone.

    PubMed

    Lainscak, Mitja; Pelliccia, Francesco; Rosano, Giuseppe; Vitale, Cristiana; Schiariti, Michele; Greco, Cesare; Speziale, Giuseppe; Gaudio, Carlo

    2015-12-01

    Spironolactone was first developed over 50 years ago as a potent mineralocorticoid receptor antagonist with undesirable side effects; it was followed a decade ago by eplerenone, which is less potent but much more mineralocorticoid receptor-specific. From a marginal role as a potassium-sparing diuretic, spironolactone has been shown to be an extraordinarily effective adjunctive agent in the treatment of progressive heart failure. Also, spironolactone is safe and protective in arterial hypertension, particularly in patients with so-called resistant hypertension. Eplerenone is the second oral aldosterone antagonist available for the treatment of arterial hypertension and heart failure. Treatment with eplerenone has been associated with decreased blood pressure and improved survival for patients with heart failure and reduced left ventricular ejection fraction. Due to the selectivity of eplerenone for the aldosterone receptor, severe adverse effects such as gynecomastia and vaginal bleeding seem to be less likely in patients who take eplerenone than in those who take spironolactone. The most common and potentially dangerous side effect of spironolactone--hyperkalemia--is also observed with eplerenone but the findings from clinical trials do not indicate more hyperkalemia induced drug withdrawals. Treatment with eplerenone should be initiated at a dosage of 25mg once daily and titrated to a target dosage of 50mg once daily preferably within 4 weeks. Serum potassium levels and renal function should be assessed prior to initiating eplerenone therapy, and periodic monitoring is recommended, especially in patients at high risk of developing hyperkalemia.

  4. Endothelin-like action of Pausinystalia yohimbe aqueous extract on vascular and renal regional hemodynamics in Sprague Dawley rats.

    PubMed

    Ajayi, A A; Newaz, M; Hercule, H; Saleh, M; Bode, C O; Oyekan, A O

    2003-12-01

    The bark of the African tree Pausinystalia yohimbe has been used as a food additive with aphrodisiac and penile erection enhancing properties. The effect of an aqueous extract of P. yohimbe (CCD-X) on renal circulation was assessed in order to test the hypothesis that it possesses additional effects on nitric oxide production and/or endothelin-1 (ET-1)-like actions. In vivo studies with CCD-X in Sprague Dawley rats demonstrated a dose-dependent (1-1000 ng/kg) increase in mean blood pressure (p < 0.001) and an increase in medullary blood flow (MBF) (p < 0.001). Both the pressor action and renal medullary vasodilation were blocked by endothelinA (ETA) receptor antagonist BMS182874 and endothelinB (ETB) receptor antagonist BQ788 in combination. L-Nomega-nitro-l-arginine methyl ester (L-NAME; 10 mg/kg) also inhibited the increase in MBF induced by CCD-X. In vitro studies in isolated perfused kidney and in pressurized renal microvessels confirmed the dose-dependent vasoconstrictor action of this extract. ETA receptor antagonist BQ610 and ETB receptor antagonist BQ788 separately and significantly attenuated the renal vasoconstrictor actions of the extract (p < 0.001 ANOVA). These preliminary observations indicate that, in addition to the alpha-adrenergic antagonist actions that characterize yohimbine, CCD-X possesses endothelin-like actions and affects nitric oxide (NO) production in renal circulation. These findings suggest a strong possibility of post-receptor cross-talk between alpha2-adrenoceptors and endothelin, as well as a direct effect of alpha2-adrenoceptors on renal NO production.

  5. Internalization of the chemokine receptor CCR4 can be evoked by orthosteric and allosteric receptor antagonists.

    PubMed

    Ajram, Laura; Begg, Malcolm; Slack, Robert; Cryan, Jenni; Hall, David; Hodgson, Simon; Ford, Alison; Barnes, Ashley; Swieboda, Dawid; Mousnier, Aurelie; Solari, Roberto

    2014-04-15

    The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to β-arrestin and stimulated GTPγS binding however CCL17 did not couple to β-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.

  6. Endothelin-B Receptors and Left Ventricular Dysfunction after Regional versus Global Ischaemia-Reperfusion in Rat Hearts.

    PubMed

    Bibli, Sofia-Iris; Toli, Eleni V; Vilaeti, Agapi D; Varnavas, Varnavas C; Baltogiannis, Giannis G; Papalois, Apostolos; Kyriakides, Zenon S; Kolettis, Theofilos M

    2012-01-01

    Background. Endothelin-1 (ET-1) is implicated in left ventricular dysfunction after ischaemia-reperfusion. ETA and ETB receptors mediate diverse actions, but it is unknown whether these actions depend on ischaemia type and duration. We investigated the role of ETB receptors after four ischaemia-reperfusion protocols in isolated rat hearts. Methods. Left ventricular haemodynamic variables were measured in the Langendorff-perfused model after 40- and 20-minute regional or global ischaemia, followed by 30-minute reperfusion. Wild-type (n = 39) and ETB-deficient (n = 41) rats were compared. Infarct size was measured using fluorescent microspheres after regional ischaemia-reperfusion. Results. Left ventricular dysfunction was more prominent in ETB-deficient rats, particularly after regional ischaemia. Infarct size was smaller (P = 0.006) in wild-type (31.5 ± 4.4%) than ETB-deficient (45.0 ± 7.3%) rats after 40 minutes of regional ischaemia-reperfusion. Although the recovery of left ventricular function was poorer after 40-minute ischaemia-reperfusion, end-diastolic pressure in ETB-deficient rats was higher after 20 than after 40 minutes of regional ischaemia-reperfusion. Conclusion. ETB receptors exert cytoprotective effects in the rat heart, mainly after regional ischaemia-reperfusion. Longer periods of ischaemia suppress the recovery of left ventricular function after reperfusion, but the role of ETB receptors may be more important during the early phases.

  7. Endothelin-B Receptors and Left Ventricular Dysfunction after Regional versus Global Ischaemia-Reperfusion in Rat Hearts

    PubMed Central

    Bibli, Sofia-Iris; Toli, Eleni V.; Vilaeti, Agapi D.; Varnavas, Varnavas C.; Baltogiannis, Giannis G.; Papalois, Apostolos; Kyriakides, Zenon S.; Kolettis, Theofilos M.

    2012-01-01

    Background. Endothelin-1 (ET-1) is implicated in left ventricular dysfunction after ischaemia-reperfusion. ETA and ETB receptors mediate diverse actions, but it is unknown whether these actions depend on ischaemia type and duration. We investigated the role of ETB receptors after four ischaemia-reperfusion protocols in isolated rat hearts. Methods. Left ventricular haemodynamic variables were measured in the Langendorff-perfused model after 40- and 20-minute regional or global ischaemia, followed by 30-minute reperfusion. Wild-type (n = 39) and ETB-deficient (n = 41) rats were compared. Infarct size was measured using fluorescent microspheres after regional ischaemia-reperfusion. Results. Left ventricular dysfunction was more prominent in ETB-deficient rats, particularly after regional ischaemia. Infarct size was smaller (P = 0.006) in wild-type (31.5 ± 4.4%) than ETB-deficient (45.0 ± 7.3%) rats after 40 minutes of regional ischaemia-reperfusion. Although the recovery of left ventricular function was poorer after 40-minute ischaemia-reperfusion, end-diastolic pressure in ETB-deficient rats was higher after 20 than after 40 minutes of regional ischaemia-reperfusion. Conclusion. ETB receptors exert cytoprotective effects in the rat heart, mainly after regional ischaemia-reperfusion. Longer periods of ischaemia suppress the recovery of left ventricular function after reperfusion, but the role of ETB receptors may be more important during the early phases. PMID:22844633

  8. Role of Endothelin in Uteroplacental Circulation and Fetal Vascular Function

    PubMed Central

    Paradis, Alexandra; Zhang, Lubo

    2014-01-01

    Endothelins are 21-amino acid peptides involved in vascular homeostasis. Three types of peptide have been identified, with endothelin-1 (ET-1) being the most potent vasoconstrictor currently known. Two endothelin receptor sub-types are found in various tissues, including the brain, heart, blood vessel, lung, and placenta. The ETA-receptor is associated with vasoconstriction in vascular smooth muscle. Conversely, the ETB-receptor can elicit a vasoconstrictor effect in vascular smooth muscle and a vasodilator effect via its action in endothelial cells. Both receptors play a key role in maintaining circulatory homeostasis and vascular function. Changes in ET-1 expression are found in various disease states, and overexpression of ET-1 is observed in hypertension and preeclampsia in pregnancy. Placental localization of ET-1 implies a key role in regulating the uteroplacental circulation. Additionally, ET-1 is important in the fetal circulation and is involved in the pulmonary circulation and closure of the ductus arteriosus after birth, as well as fetal growth constriction in utero. ET receptor antagonists and nitric oxide donors may provide therapeutic potential in treating conditions associated with overexpression of ET and hypertension. PMID:24063378

  9. Role of endothelin in uteroplacental circulation and fetal vascular function.

    PubMed

    Paradis, Alexandra; Zhang, Lubo

    2013-09-01

    Endothelins are 21-amino acid peptides involved in vascular homeostasis. Three types of peptide have been identified, with endothelin-1 (ET-1) being the most potent vasoconstrictor currently known. Two endothelin receptor subtypes are found in various tissues, including the brain, heart, blood vessel, lung, and placenta. The ETA-receptor is associated with vasoconstriction in vascular smooth muscle. Conversely, the ETB-receptor can elicit a vasoconstrictor effect in vascular smooth muscle and a vasodilator effect via its action in endothelial cells. Both receptors play a key role in maintaining circulatory homeostasis and vascular function. Changes in ET-1 expression are found in various disease states, and overexpression of ET-1 is observed in hypertension and preeclampsia in pregnancy. Placental localization of ET-1 implies a key role in regulating the uteroplacental circulation. Additionally, ET-1 is important in the fetal circulation and is involved in the pulmonary circulation and closure of the ductus arteriosus after birth, as well as fetal growth constriction in utero. ET receptor antagonists and nitric oxide donors may provide therapeutic potential in treating conditions associated with overexpression of ET and hypertension.

  10. New perspectives on glutamate receptor antagonists as antidepressants.

    PubMed

    Chung, Chihye

    2012-03-01

    Classical antidepressants elevate the monoamine levels in the brain by preventing re-uptake of monoamines after release. Treatment of depression with monoamine re-uptake inhibitors is associated with low clinical efficacy and remission rate due to the delayed onset of therapeutic responses. Therefore, the development of alternative antidepressants is essential for successful treatment of this disease. Recently, glutamate receptor antagonists including ketamine and 2-methyl-6-(phenylethynyl)-pyridine (MPEP) have received wide attention as fast-acting therapeutic alternatives for treatment of depression.

  11. Substituted tetrahydroisoquinolines as selective antagonists for the orexin 1 receptor.

    PubMed

    Perrey, David A; German, Nadezhda A; Gilmour, Brian P; Li, Jun-Xu; Harris, Danni L; Thomas, Brian F; Zhang, Yanan

    2013-09-12

    Increasing evidence implicates the orexin 1 (OX1) receptor in reward processes, suggesting OX1 antagonism could be therapeutic in drug addiction. In a program to develop an OX1 selective antagonist, we designed and synthesized a series of substituted tetrahydroisoquinolines and determined their potency in OX1 and OX2 calcium mobilization assays. Structure-activity relationship (SAR) studies revealed limited steric tolerance and a preference for electron deficiency at the 7-position. Pyridylmethyl groups were shown to be optimal for activity at the acetamide position. Computational studies resulted in a pharmacophore model and confirmed the SAR results. Compound 72 significantly attenuated the development of place preference for cocaine in rats.

  12. Substituted Tetrahydroisoquinolines as Selective Antagonists for the Orexin 1 Receptor

    PubMed Central

    Perrey, David A.; German, Nadezhda A.; Gilmour, Brian P.; Li, Jun-Xu; Harris, Danni L.; Thomas, Brian F.; Zhang, Yanan

    2013-01-01

    Increasing evidence implicates the orexin 1 (OX1) receptor in reward processes, suggesting OX1 antagonism could be therapeutic in drug addiction. In a program to develop an OX1 selective antagonist, we designed and synthesized a series of substituted tetrahydroisoquinolines and determined their potency in OX1 and OX2 calcium mobilization assays. Structure-activity relationship (SAR) studies revealed limited steric tolerance and preference for electron deficiency at the 7-position. Pyridylmethyl groups were shown to be optimal for activity at the acetamide position. Computational studies resulted in a pharmacophore model and confirmed the SAR results. Compound 72 significantly attenuated the development of place preference for cocaine in rats. PMID:23941044

  13. Brain cellular localization of endothelin receptors A and B in a rodent model of diffuse traumatic brain injury.

    PubMed

    Kallakuri, S; Kreipke, C W; Schafer, P C; Schafer, S M; Rafols, J A

    2010-07-14

    Endothelin-1 exerts potent vasoconstrictor and vasodilatory effects through its actions on its receptors A (ETrA) and B (ETrB), respectively. While ETrA and B have classically been thought to be expressed on vascular cell types, more recent evidence suggests that, particularly following brain injury, their expression may be seen in other, non-vascular cell types. To date no studies have comprehensively studied the cellular location of endothelin receptors following traumatic brain injury (TBI). Therefore, this study investigates the cellular localization of ETrA and B in normal and traumatized brains using an impact acceleration device. Adult male Sprague-Dawley rats were subjected to TBI by weight drop (450 g) from either 1.5, a distance known to elicit mild TBI in the absence of changed in cerebral blood flow (CBF) or 2 m, a distance shown to cause a significant reduction in CBF. One set of impacted brains were processed for Western determination of ETrA and B expression. Another set were processed for immunofluorescence (IF). For IF, ETrA and ETrB antibodies were combined with cell markers for neurons, astrocytes, microglia, oligodendrocytes, smooth muscle cells and endothelial cells of blood vessels. While ETrA and B was upregulated after more moderate to severe injury (2 m) overall receptor expression was unchanged in response to mild trauma (1.5 m). Double labeling IF confirmed prominent ETrA and ETrB labeling in NeuN labeled pyramidal neurons and interneurons in sensorymotor cortex (smCx) and hippocampus (hipp) post TBI. ETrA rather than ETrB was preferentially co-localized in vascular smooth muscle cells. After injury, a subpopulation of astrocytes in white matter co-localized ETrA but not ETrB. Localization of either receptor in endothelial cells was sparse. No prominent IF was detected in microglia and oligodendrocytes. Taken together with previous findings in other pathological states that show an apparent shift in the localization of ETrA and B, the

  14. Late-onset endothelin-A receptor blockade reduces podocyte injury in homozygous Ren-2 rats despite severe hypertension.

    PubMed

    Opocenský, Martin; Kramer, Herbert J; Bäcker, Angela; Vernerová, Zdenka; Eis, Václav; Cervenka, Ludek; Certíková Chábová, Vera; Tesar, Vladimír; Vanecková, Ivana

    2006-11-01

    We have recently found in male homozygous hypertensive Ren-2 transgenic rats (TGRs) fed a high-salt diet that early onset selective endothelin (ET) A (ET(A)) or nonselective ET(A)/ET B (ET(B)) receptor blockade improved survival rate and reduced proteinuria, glomerulosclerosis, and cardiac hypertrophy, whereas selective ET(A) receptor blockade also significantly attenuated the rise in blood pressure. Because antihypertensive therapy in general is known to be more efficient when started at early age, our study was performed to determine whether onset of ET receptor blockade at a later age in animals with established hypertension will have similar protective effects as does early-onset therapy. Male homozygous TGRs and age-matched normotensive Hannover Sprague-Dawley rats were fed a high-salt diet between days 51 and 90 of age. TGRs received vehicle (untreated), the selective ET(A) receptor blocker atrasentan (ABT-627), or the nonselective ET(A)/ET(B) receptor blocker bosentan. Survival rates in untreated and bosentan-treated TGRs were 50% and 64%, respectively, whereas with atrasentan, survival rate of TGR was 96%, thus, similar to 93% in Hannover Sprague-Dawley rats. From day 60 on, systolic blood pressure in atrasentan-treated TGRs was transiently lower (P<0.05) than in untreated or bosentan-treated TGRs. Glomerular podocyte injury was substantially reduced with atrasentan treatment independent of severe hypertension and strongly correlated with survival (P<0.001). Our data indicate that in homozygous TGR ET receptors play an important role also in established hypertension. Selective ET(A) receptor blockade not only reduces podocyte injury and end-organ damage but also improves growth and survival independently of hypertension.

  15. Early endothelin-A receptor blockade decreases blood pressure and ameliorates end-organ damage in homozygous Ren-2 rats.

    PubMed

    Vanêcková, Ivana; Kramer, Herbert J; Bäcker, Angela; Vernerová, Zdena; Opocensky, Martin; Cervenka, Ludêk

    2005-10-01

    We have recently found that nonselective endothelin ETA/ETB receptor blockade markedly improves survival rate and ameliorates end-organ damage in male homozygous rats transgenic (TGR) for the mouse Ren-2 renin gene without lowering blood pressure. Because activation of the ETA receptor may be responsible for the detrimental effects of ET in the development of hypertension, this study was performed to determine whether ETA or ETA/ETB receptor blockade exerts these beneficial effects. TGR and age-matched normotensive Hannover Sprague-Dawley rats fed a high-salt diet received either vehicle or bosentan and atrasentan (ABT-627) as nonselective ETA/ETB and selective ETA receptor blockers, respectively, from 29 until 90 days of age. The survival rate of 48% in untreated TGR was significantly (P<0.01) improved to 79% by bosentan and to 92% by ABT-627 (ABT-627 versus bosentan P<0.05). Proteinuria, glomerulosclerosis, and cardiac hypertrophy, as well as ET-1 content in left ventricular tissue, were significantly reduced by bosentan and to a greater degree by ABT-627, which also significantly attenuated the rise in blood pressure (P<0.05). Our data indicate that the ET system, especially via ETA receptors, plays an important role in the development of hypertensive end-organ damage and confirm the concept that the predominant role of ETB receptors within the peripheral vasculature is to mediate the vasorelaxant actions of ET-1. They also demonstrate that selective blockade of ETA receptors is superior to nonselective ETA/ETB in attenuating hypertension, hypertensive organ damage, and survival rate.

  16. Endothelin system in oral squamous carcinoma cells: specific siRNA targeting of ECE-1 blocks cell proliferation.

    PubMed

    Awano, Shuji; Dawson, Louise A; Hunter, Alison R; Turner, Anthony J; Usmani, Badar A

    2006-04-01

    The present study focused on the endothelin axis in human oral squamous cell carcinoma (SCC) cells. We investigated the expression and distribution of endothelin-1 (ET-1), its receptors (endothelin-A receptor (ET(A)R) and endothelin-B receptor (ET(B)R)) and isoforms of its specific converting enzyme (ECE-1a, 1b, 1c) and the report on their relative influences on cell proliferation. We also investigated the effect of an ECE-specific inhibitor (ECE-i) and siRNA targeting of the ECE-1 gene on SCC cell proliferation. We observed the expression of ET-1, ET(A)R, ET(B)R and all endothelin-converting enzyme-1 (ECE-1) isoforms in oral SCC cells, but only the expression of ET-1, ET(B)R and ECE-1 was increased when compared to normal human epidermal keratinocytes. ET-1 alone stimulated proliferation of oral SCC cells. Antagonists of either ET(A)R or ET(B)R inhibited ET-1-mediated proliferation. Decreased ECE-1 expression after ECE siRNA treatment reduced SCC cell proliferation. Antiproliferative effects were also observed by inhibiting ECE activity with ECE-i. In conclusion, the present study demonstrates that modulation of the endothelin system in oral SCC cells might provide a novel therapeutic protocol for oral cancer.

  17. Cangrelor: a novel P2Y12 receptor antagonist.

    PubMed

    Norgard, Nicholas B

    2009-08-01

    Antiplatelet therapy is critical in the prevention of thrombotic complications of acute coronary syndrome and percutaneous coronary interventions. Current antiplatelet agents (aspirin, clopidogrel and glycoprotein IIb/IIIa antagonists) have demonstrated the capacity to reduce major adverse cardiac events. However, these agents have limitations that compromise their clinical utility. The platelet P2Y12 receptor plays a central role in platelet function and is a focus in the development of antiplatelet therapies. Cangrelor is a potent, competitive inhibitor of the P2Y12 receptor that is administered by intravenous infusion and rapidly achieves near complete inhibition of ADP-induced platelet aggregation. This investigational drug has been studied for use during coronary procedures and the management of patients experiencing acute coronary syndrome and is undergoing evaluation for use in the prevention of perioperative stent thrombosis.

  18. Specific endothelin ET(A) receptor antagonism does not modulate insulin-induced hemodynamic effects in the human kidney, eye, or forearm.

    PubMed

    Rab, Anna; Dallinger, Susanne; Polak, Kaija; Pleiner, Johannes; Polska, Elzbieta; Wolzt, Michael; Schmetterer, Leopold

    2004-05-01

    There is evidence that hyperinsulinemia may stimulate endothelin-1 (ET-1) generation or release, which may affect diabetic vascular complications. BQ-123, a specific ET(A) receptor antagonist, was used to investigate if insulin-induced vascular effects are influenced by an acute ET-1 release. Two randomized, placebo-controlled, double-blind, cross-over studies were performed. In protocol 1, 12 healthy subjects received, on separate study days, infusions of BQ-123 (60 microg/min for 30 min) during placebo clamp conditions, BQ-123 during euglycemic hyperinsulinemia (3 mU/kg/min for 390 min), or placebo during euglycemic hyperinsulinemia. Fundus pulsation amplitude (FPA) was measured to assess pulsatile choroidal blood flow, and mean flow velocity (MFV) of the ophtalmic artery was measured by color Doppler imaging. In protocol 2, eight healthy subjects received, on separate study days, intra-arterial infusions of BQ-123 (32 microg/min for 120 min) during placebo or insulin clamp. Forearm blood flow was measured with bilateral plethysmography, expressing the ratio of responses in the intervention arm and in the control arm. Insulin alone increased FPA (+10%, p < 0.001) and forearm blood flow (+19%). BQ-123 increased FPA, MFV, and forearm blood flow ratio in the absence and presence of exogenous insulin, but this effect was not different between normo- and hyperinsulinemic conditions. ET-1 plasma concentrations were not affected by insulin. In conclusion, these data do not support the concept that hyperinsulinemia increases ET-1 generation in healthy subjects. Our results, however, cannot necessarily be extrapolated to diabetic and obese subjects.

  19. Intracrine endothelin signalling evokes IP3-dependent increases in nucleoplasmic Ca2+ in adult cardiac myocytes*

    PubMed Central

    Merlen, Clémence; Farhat, Nada; Luo, Xiaoyan; Chatenet, David; Tadevosyan, Artavazd; Villeneuve, Louis R.; Gillis, Marc-Antoine; Nattel, Stanley; Thorin, Eric; Fournier, Alain; Allen, Bruce G.

    2013-01-01

    Endothelin receptors are present on the nuclear membranes in adult cardiac ventricular myocytes. The objectives of the present study were to determine 1) which endothelin receptor subtype is in cardiac nuclear membranes, 2) if the receptor and ligand traffic from the cell surface to the nucleus, and 3) the effect of increased intracellular ET-1 on nuclear Ca2+ signalling. Confocal microscopy using fluorescently-labeled endothelin analogs confirmed the presence of ETB at the nuclear membrane of rat cardiomyocytes in skinned-cells and isolated nuclei. Furthermore, in both cardiac myocytes and aortic endothelial cells, endocytosed ET:ETB complexes translocated to lysosomes and not the nuclear envelope. Although ETA and ETB can form heterodimers, the presence or absence of ETA did not alter ETB trafficking. Treatment of isolated nuclei with peptide: N-glycosidase F did not alter the electrophoretic mobility of ETB. The absence of N-glycosylation further indicating that these receptors did not originate at the cell surface. Intracellular photolysis of a caged ET-1 analog ([Trp-ODMNB21]ET-1) evoked an increase in nucleoplasmic Ca2+ ([Ca2+]n) that was attenuated by the inositol 1,4,5-trisphosphate receptor inhibitor 2-aminoethoxydiphenyl borate and prevented by pre-treatment with ryanodine. A caged cell-permeable analog of the ETB-selective antagonist IRL-2500 blocked the ability of intracellular cET-1 to increase [Ca2+]n whereas extracellular application of ETA and ETB receptor antagonists did not. These data suggest that 1) the endothelin receptor in the cardiac nuclear membranes is ETB, 2) ETB traffic directly to the nuclear membrane after biosynthesis, 3) exogenous endothelins are not ligands for ETB on nuclear membranes, and 4) ETB associated with the nuclear membranes regulate nuclear Ca2+ signalling. PMID:23756157

  20. Neurokinin-1 Receptor Antagonists in Preventing Postoperative Nausea and Vomiting

    PubMed Central

    Liu, Meng; Zhang, Hao; Du, Bo-Xiang; Xu, Feng-Ying; Zou, Zui; Sui, Bo; Shi, Xue-Yin

    2015-01-01

    Abstract Newly developed neurokinin-1 receptor (NK-1R) antagonists have been recently tried in the prevention of postoperative nausea and vomiting (PONV). This systematic review and meta-analysis was conducted to explore whether NK-1R antagonists were effective in preventing PONV. The PRISMA statement guidelines were followed. Randomized clinical trials (RCTs) that tested the preventive effects of NK-1R antagonists on PONV were identified by searching EMBASE, CINAHL, PubMed, and the Cochrane Library databases followed by screening. Data extraction was performed using a predefined form and trial quality was assessed using a modified Jadad scale. The primary outcome measure was the incidence of PONV. Meta-analysis was performed for studies using similar interventions. Network meta-analysis (NMA) was conducted to compare the anti-vomiting effects of placebo, ondansetron, and aprepitant at different doses. Fourteen RCTs were included. Meta-analysis found that 80 mg of aprepitant could reduce the incidences of nausea (3 RCTs with 224 patients, pooled risk ratio (RR) = 0.60, 95% confidence interval (CI) = 0.47 to 0.75), and vomiting (3 RCTs with 224 patients, pooled RR = 0.13, 95% CI = 0.04 to 0.37) compared with placebo. Neither 40 mg (3 RCTs with 1171 patients, RR = 0.47, 95% CI = 0.37 to 0.60) nor 125 mg (2 RCTs with 1058 patients, RR = 0.32, 95% CI = 0.13 to 0.78) of aprepitant showed superiority over 4 mg of ondansetron in preventing postoperative vomiting. NMA did not find a dose-dependent effect of aprepitant on preventing postoperative vomiting. Limited data suggested that NK-1R antagonists, especially aprepitant were effective in preventing PONV compared with placebo. More large-sampled high-quality RCTs are needed. PMID:25984662

  1. Is All Radiation-Induced Emesis Ameliorated by 5-HT3 Receptor Antagonists

    DTIC Science & Technology

    1992-01-01

    5 - HT3 receptor antagonists ;~// 9-72 Bernard M.I Rabin 0’) and Gregory L. Kingt2) -) Behavioral Sciences and 2 PhYSzo~o~y Dcpiarlrnvni . Arm,. ii - R...RY Exposing ferrets to gamuma rays or X-rays produces vomiting that can be attenuated by 5 - HT3 receptor antagonists and by subdiaphraqmatic vagotomy...Pretreating ferrets with serotonin type-3 ( 5 - HT3 ) receptor antagonists or performing bilateral subdiaphragmatic vagotomy reliably attenuates the

  2. [Single nucleotide polymorphisms in genes of endothelin-1 and receptor A associated to cardiovascular in essential hypertension].

    PubMed

    Tamiozzo, S R; Lassen, O C; Herrera, J; Igarzabal, P; Tabares, S; Sembaj, A

    The endothelin system, for its vasoconstrictor action, is related to the development of essential hypertension (HTAe). The polymorphism analysis of their genes represents a new approach to the study of this disease. We propose to analyze the interaction between stages of essential hypertension (HTAe) and risk factors with polymorphisms 138ex1 ins/del A gene endothelin-1 (ET-1) and H323H receptor gene A ET-1 (ETRA). We included 300 patients of both sexes, unrelated, who consecutively attended the clinic hypertension medical service. Each one underwent a complete physical examination, electrocardiogram, echocardiogram, and Rx thorax. The degree of severity of hypertension was determined in stages. The determination of polymorphisms was performed by amplification followed by cutting by specific restriction enzyme from DNA obtained from peripheral blood. The 46% of patients had HTAe controlled, 17.6% had organ damage or cardiovascular, brain or kidney disease. It was observed that the 4A/4A carriers showed lower frequency of cardiovascular disease, kidney and brain (P<.032; 95% CI: 11.1-21.4). For H323H polymorphism, the evaluation by images showed a higher frequency of the dilations of left auricular (P=.02) and auricular fibrillation (P=.03) between the T/T carrier, a higher frequency of cardiomegaly was detected in C/C patients (P=.04). The genotypes, 4A/4A of the ET-1 gene and the T/T from ETRA gene might be involved in worse outcome of cardiovascular damage. Their identification could help recognize subgroups of the hypertensive patients with different risk. Copyright © 2016 SEH-LELHA. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. Desensitization of ETA endothelin receptor-mediated negative chronotropic response in right atria–species difference and intracellular mechanisms

    PubMed Central

    Ono, Kageyoshi; Sakamoto, Aiji; Masaki, Tomoh; Satake, Motoyoshi

    1998-01-01

    Desensitization of ETA endothelin receptor (ETAR) was compared between the rat and guinea-pig with regard to negative chronotropic response (NC) in the right atria (RA).ET-1 (100 nM) produced distinct NC in the presence of BQ788 (300 nM), and positive chronotropic response (PC) in the presence of BQ123 (1 μM) in both species, showing that ETAR and ETB endothelin receptor (ETBR) mediate NC and PC, respectively.Repetitive applications of ET-1 (50 nM) desensitized PC, and the second application only induced a strong NC in both species. Later applications of ET-1 produced virtually no response in the rat RA, whereas they produced BQ123-sensitive NCs repetitively in guinea-pig RA, exhibiting marked species difference in desensitization of ETAR-mediated NC.Pretreatment with staurosporine (100 nM) prevented desensitization of ETAR in the rat RA altogether. However, phorbol 12-myristate 13-acetate (PMA, 300 nM) failed to induce, but rather hampered, desensitization of ETAR.Partial amino acid sequencing of ETARs, spanning from the 2nd through the 4th intracellular loops, revealed that all the potential Ser/Thr phosphorylation sites, including a protein kinase C (PKC) site, are conserved among guinea-pigs, rats, rabbits, bovines and humans.In guinea pig RA, pretreatment with okadaic acid (1 μg ml−1) and PMA did not facilitate desensitization of ETAR whereas these agents successfully desensitized ETAR during combined stimulation of β-adrenoceptor and ETAR by isoproterenol (300 nM) and ET-1 (100 nM).These results suggest that species differences in desensitization of ETAR are not caused by differences in the site(s) of, but caused by differences in the environment for phosphorylation of the receptor. Desensitization of ETAR appears to require phosphorylation of the receptor by PKC as well as a kinase stimulated by β-adrenoceptor activation. PMID:9831916

  4. Evodiamine as a novel antagonist of aryl hydrocarbon receptor

    SciTech Connect

    Yu, Hui; Tu, Yongjiu; Zhang, Chun; Fan, Xia; Wang, Xi; Wang, Zhanli; Liang, Huaping

    2010-11-05

    Research highlights: {yields} Evodiamine interacted with the AhR. {yields} Evodiamine inhibited the specific binding of [{sup 3}H]-TCDD to the AhR. {yields} Evodiamine acts as an antagonist of the AhR. -- Abstract: Evodiamine, the major bioactive alkaloid isolated from Wu-Chu-Yu, has been shown to interact with a wide variety of proteins and modify their expression and activities. In this study, we investigated the interaction between evodiamine and the aryl hydrocarbon receptor (AhR). Molecular modeling results revealed that evodiamine directly interacted with the AhR. Cytosolic receptor binding assay also provided the evidence that evodiamine could interact with the AhR with the K{sub i} value of 28.4 {+-} 4.9 nM. In addition, we observed that evodiamine suppressed the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced nuclear translocation of the AhR and the expression of CYP1A1 dose-dependently. These results suggested that evodiamine was able to bind to the AhR as ligand and exhibit antagonistic effects.

  5. Classification and virtual screening of androgen receptor antagonists.

    PubMed

    Li, Jiazhong; Gramatica, Paola

    2010-05-24

    Computational tools, such as quantitative structure-activity relationship (QSAR), are highly useful as screening support for prioritization of substances of very high concern (SVHC). From the practical point of view, QSAR models should be effective to pick out more active rather than inactive compounds, expressed as sensitivity in classification works. This research investigates the classification of a big data set of endocrine-disrupting chemicals (EDCs)-androgen receptor (AR) antagonists, mainly aiming to improve the external sensitivity and to screen for potential AR binders. The kNN, lazy IB1, and ADTree methods and the consensus approach were used to build different models, which improve the sensitivity on external chemicals from 57.1% (literature) to 76.4%. Additionally, the models' predictive abilities were further validated on a blind collected data set (sensitivity: 85.7%). Then the proposed classifiers were used: (i) to distinguish a set of AR binders into antagonists and agonists; (ii) to screen a combined estrogen receptor binder database to find out possible chemicals that can bind to both AR and ER; and (iii) to virtually screen our in-house environmental chemical database. The in silico screening results suggest: (i) that some compounds can affect the normal endocrine system through a complex mechanism binding both to ER and AR; (ii) new EDCs, which are nonER binders, but can in silico bind to AR, are recognized; and (iii) about 20% of compounds in a big data set of environmental chemicals are predicted as new AR antagonists. The priority should be given to them to experimentally test the binding activities with AR.

  6. Hypertension in an Animal Model of HELLP Syndrome is Associated With Activation of Endothelin 1.

    PubMed

    Morris, Rachael; Spencer, Shauna-Kay; Kyle, Patrick B; Williams, Jan Michael; Harris, Al'shondra; Owens, Michelle Y; Wallace, Kedra

    2016-01-01

    Women with hypertensive forms of pregnancy such as hemolysis-elevated liver enzymes-low platelet syndrome have increased circulating endothelin 1; however, the relationship between hypertension and endothelin 1 has not been studied. Using an animal model, we sought to determine whether there was an increased activation/dysfunction of endothelin 1, the effect of endothelin 1 receptor-A blockade on hypertension and other manifestations of hemolysis, elevated liver enzymes, and low platelets syndrome. On gestational day 12, timed-pregnant rats were infused with soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEndoglin; 4.7 and 7 µg/kg) via mini-osmotic pumps for 8 days. A subset of rats were treated with receptor-A antagonist (ABT-627, 5mg/kg) for 8 days. Rats with hemolysis-elevated liver enzymes-low platelet syndrome had significantly increased hypertension (P = .0001), circulating endothelin 1 (P = .03), and a significant 3.3- and 7.2-fold increase in preproendothelin messenger RNA (mRNA) expression in the placenta and liver (P = .01 and .04). Urinary protein:creatinine ratio was significantly increased in these animals (P = .0007), and circulating factors from these rats stimulated a significant increase in endothelial cell secretion of endothelin 1 (P = .001) in an in vitro assay. Blockade of the endothelin 1 receptor A significantly decreased hypertension (P = .001), circulating endothelin 1, and interleukin 17 (P = .004 and .003), placental preproendothelin mRNA expression (P = .016), and urinary protein:creatinine ratio (P = .007) in rats with hemolysis-elevated liver enzymes-low platelet syndrome. Blockade of the endothelin 1 receptor A significantly decreased hemolysis (P = .009), liver enzymes (P = .011), and significantly increased platelet levels (P = .03) and decreased circulating CD4+ and CD8+ T lymphocytes (P = .0004 and .0001) in rats infused with sFlt-1 and sEndoglin. These data support the hypothesis that endothelin 1 activation

  7. Guanidinoethyl sulphonate is a glycine receptor antagonist in striatum.

    PubMed

    Sergeeva, Olga A; Chepkova, Aisa N; Haas, Helmut L

    2002-11-01

    1. Guanidinoethyl sulphonate (GES) is an analogue of taurine and an inhibitor of taurine transport. Interactions of GES with GABA(A) and glycine receptors are studied by whole cell recording and fast drug application in isolated striatal neurons of the mouse. 2. We confirm that GES is a weak agonist at GABA(A) receptors, and is able to antagonize GABA-evoked responses. GES did not gate GlyR. 3. GES antagonized glycine responses in a concentration-dependent and surmountable manner. Glycine dose-response curves were shifted to the right by GES (0.5 mM), yielding EC(50)s and Hill coefficients of 62 micro M and 2.5 in control, 154 micro M and 1.3 in the presence of GES. 4. GlyR-mediated taurine responses were competitively antagonized by GES. Taurine dose-response curves, in contrast to the glycine dose-response curves were shifted by GES to the right in a parallel manner. 5. The GlyR-block by GES was not voltage-dependent. 6. In contrast to our findings in the mouse, in rat striatal neurons which lack expression of the alpha3 GlyR subunit, GES shifted the glycine dose-response curve to the right in a parallel way without affecting the maximal response. Subtype-specificity of the GES action at GlyR must await further investigation in artificial expression systems. 7. We conclude that GES is a competitive antagonist at GlyR. The antagonistic action of GES at inhibitory ionotropic receptors can explain its epileptogenic action. Care must be taken with the interpretation of data on GES evoked taurine release.

  8. Identification of New Agonists and Antagonists of the Insect Odorant Receptor Co-Receptor Subunit

    PubMed Central

    Chen, Sisi; Luetje, Charles W.

    2012-01-01

    Background Insects detect attractive and aversive chemicals using several families of chemosensory receptors, including the OR family of olfactory receptors, making these receptors appealing targets for the control of insects. Insect ORs are odorant-gated ion channels, comprised of at least one common subunit (the odorant receptor co-receptor subunit, Orco) and at least one variable odorant specificity subunit. Each of the many ORs of an insect species is activated or inhibited by an unique set of odorants that interact with the variable odorant specificity subunits, making the development of OR directed insect control agents complex and laborious. However, several N-,2-substituted triazolothioacetamide compounds (VUAA1, VU0450667 and VU0183254) were recently shown to act directly on the highly conserved Orco subunit, suggesting that broadly active compounds can be developed. We have explored the chemical space around the VUAA1 structure in order to identify new Orco ligands. Principal Findings We screened ORs from several insect species, using heterologous expression in Xenopus oocytes and an electrophysiological assay, with a panel of 22 compounds structurally related to VUAA1. By varying the nitrogen position in the pyridine ring and altering the moieties decorating the phenyl ring, we identified two new agonists and a series of competitive antagonists. Screening smaller compounds, similar to portions of the VUAA1 structure, also yielded competitive antagonists. Importantly, we show that Orco antagonists inhibit odorant activation of ORs from several insect species. Detailed examination of one antagonist demonstrated inhibition to be through a non-competitive mechanism. Conclusions A similar pattern of agonist and antagonist sensitivity displayed by Orco subunits from different species suggests a highly conserved binding site structure. The susceptibility to inhibition of odorant activation by Orco antagonism is conserved across disparate insect species

  9. NMDA receptor antagonist ketamine impairs feature integration in visual perception.

    PubMed

    Meuwese, Julia D I; van Loon, Anouk M; Scholte, H Steven; Lirk, Philipp B; Vulink, Nienke C C; Hollmann, Markus W; Lamme, Victor A F

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

  10. Orexin receptor antagonists as therapeutic agents for insomnia

    PubMed Central

    Equihua, Ana C.; De La Herrán-Arita, Alberto K.; Drucker-Colin, Rene

    2013-01-01

    Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning. Currently, treatment for insomnia involves a combination of cognitive behavioral therapy (CBTi) and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine (BZD) receptor agonist drugs (GABAA receptor), although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects. Orexin (hypocretin) neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g., impaired cognition, disturbed arousal, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia. PMID:24416019

  11. Orexin receptor antagonists as therapeutic agents for insomnia.

    PubMed

    Equihua, Ana C; De La Herrán-Arita, Alberto K; Drucker-Colin, Rene

    2013-12-25

    Insomnia is a common clinical condition characterized by difficulty initiating or maintaining sleep, or non-restorative sleep with impairment of daytime functioning. Currently, treatment for insomnia involves a combination of cognitive behavioral therapy (CBTi) and pharmacological therapy. Among pharmacological interventions, the most evidence exists for benzodiazepine (BZD) receptor agonist drugs (GABAA receptor), although concerns persist regarding their safety and their limited efficacy. The use of these hypnotic medications must be carefully monitored for adverse effects. Orexin (hypocretin) neuropeptides have been shown to regulate transitions between wakefulness and sleep by promoting cholinergic/monoaminergic neural pathways. This has led to the development of a new class of pharmacological agents that antagonize the physiological effects of orexin. The development of these agents may lead to novel therapies for insomnia without the side effect profile of hypnotics (e.g., impaired cognition, disturbed arousal, and motor balance difficulties). However, antagonizing a system that regulates the sleep-wake cycle may create an entirely different side effect profile. In this review, we discuss the role of orexin and its receptors on the sleep-wake cycle and that of orexin antagonists in the treatment of insomnia.

  12. Bovine pancreatic polypeptide as an antagonist of muscarinic cholinergic receptors

    SciTech Connect

    Pan, G.Z.; Lu, L.; Qian, J.; Xue, B.G.

    1987-03-01

    In dispersed acini from rat pancreas, it was found that bovine pancreatic polypeptide (BPP) and its C-fragment hexapeptide amide (PP-6), at concentrations of 0.1 and 30 ..mu..M, respectively, could significantly inhibit amylase secretion stimulated by carbachol, and this inhibition by BPP was dose dependent. /sup 45/Ca outflux induced by carbachol was also inhibited by BPP or PP-6, but they had no effect on cholecystokinin octapeptide- (CCK-8) or A23187-stimulated /sup 45/Ca outflux. BPP was also capable of displacing the specific binding of (/sup 3/H)-quinuclidinyl benzilate to its receptors, and it possessed a higher affinity (K/sub i/35nM) than carbachol (K/sub i/ 1.8 ..mu..M) in binding with M-receptors. It is concluded from this study that BPP acts as an antagonist of muscarinic cholinergic receptors in rat pancreatic acini. In addition, BPP inhibited the potentiation of amylase secretion caused by the combination of carbachol plus secretin or vasoactive intestinal peptide. This may be a possible explanation of the inhibitory effect of BPP on secretin-induced pancreatic enzyme secretion shown in vivo, since pancreatic enzyme secretion stimulated by secretin under experimental conditions may be the result of potentiation of enzyme release produced by the peptide in combination with a cholinergic stimulant.

  13. Potential Clinical Implications of the Urotensin II Receptor Antagonists

    PubMed Central

    Tsoukas, Philip; Kane, Émilie; Giaid, Adel

    2011-01-01

    Urotensin II (UII) binds to its receptor, UT, playing an important role in the heart, kidneys, pancreas, adrenal gland, and central nervous system. In the vasculature, it acts as a potent endothelium-independent vasoconstrictor and endothelium-dependent vasodilator. In disease states, however, this constriction–dilation equilibrium is disrupted. There is an upregulation of the UII system in heart disease, metabolic syndrome, and kidney failure. The increase in UII release and UT expression suggest that UII system may be implicated in the pathology and pathogenesis of these diseases by causing an increase in acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) activity leading to smooth muscle cell proliferation and foam cell infiltration, insulin resistance (DMII), as well as inflammation, high blood pressure, and plaque formation. Recently, UT antagonists such as SB-611812, palosuran, and most recently a piperazino-isoindolinone based antagonist have been developed in the hope of better understanding the UII system and treating its associated diseases. PMID:21811463

  14. Endothelin-converting enzyme-1 regulates trafficking and signalling of the neurokinin 1 receptor in endosomes of myenteric neurones

    PubMed Central

    Pelayo, Juan-Carlos; Poole, Daniel P; Steinhoff, Martin; Cottrell, Graeme S; Bunnett, Nigel W

    2011-01-01

    Abstract Neuropeptide signalling at the plasma membrane is terminated by neuropeptide degradation by cell-surface peptidases, and by β-arrestin-dependent receptor desensitization and endocytosis. However, receptors continue to signal from endosomes by β-arrestin-dependent processes, and endosomal sorting mediates recycling and resensitization of plasma membrane signalling. The mechanisms that control signalling and trafficking of receptors in endosomes are poorly defined. We report a major role for endothelin-converting enzyme-1 (ECE-1) in controlling substance P (SP) and the neurokinin 1 receptor (NK1R) in endosomes of myenteric neurones. ECE-1 mRNA and protein were expressed by myenteric neurones of rat and mouse intestine. SP (10 nm, 10 min) induced interaction of NK1R and β-arrestin at the plasma membrane, and the SP–NK1R–β-arrestin signalosome complex trafficked by a dynamin-mediated mechanism to ECE-1-containing early endosomes, where ECE-1 can degrade SP. After 120 min, NK1R recycled from endosomes to the plasma membrane. ECE-1 inhibitors (SM-19712, PD-069185) and the vacuolar H+ATPase inhibitor bafilomycin A1, which prevent endosomal SP degradation, suppressed NK1R recycling by >50%. Preincubation of neurones with SP (10 nm, 5 min) desensitized Ca2+ transients to a second SP challenge after 10 min, and SP signals resensitized after 60 min. SM-19712 inhibited NK1R resensitization by >90%. ECE-1 inhibitors also caused sustained SP-induced activation of extracellular signal-regulated kinases, consistent with stabilization of the SP–NK1R–β-arrestin signalosome. By degrading SP and destabilizing endosomal signalosomes, ECE-1 has a dual role in controlling endocytic signalling and trafficking of the NK1R: promoting resensitization of G protein-mediated plasma membrane signalling, and terminating β-arrestin-mediated endosomal signalling. PMID:21878523

  15. Correlation between myometrial receptor affinity, lipophilicity and antagonistic potency of oxytocin analogues in the rat.

    PubMed

    Atke, A; Vilhardt, H; Melin, P

    1988-08-01

    Purified myometrial plasma membrane fractions were prepared from rats treated with oestradiol to induce oestrus. The binding affinities of 11 antagonistic oxytocin analogues to the oxytocin receptor of the plasma membranes were measured. Furthermore, lipophilicity of the peptides was assessed by reversed-phase high pressure liquid chromatography. No significant correlation was found between lipophilicity of the analogues and values for antagonistic potencies or binding affinities. Also, receptor-binding affinity did not correlate with in-vitro antagonistic activity whereas a significant correlation was obtained between binding affinities and in-vivo antagonistic potency for analogues void of partial agonist properties. It is concluded that neither receptor affinity nor lipophilicity in the analogues can predict the potency of the antagonists in vitro. However, receptor affinity was found to be a relatively good predictor of the in-vivo potency, while the usefulness of measuring antagonistic potency in vitro is questioned.

  16. SB-334867-A: the first selective orexin-1 receptor antagonist

    PubMed Central

    Smart, D; Sabido-David, C; Brough, S J; Jewitt, F; Johns, A; Porter, R A; Jerman, J C

    2001-01-01

    The pharmacology of various peptide and non-peptide ligands was studied in Chinese hamster ovary (CHO) cells stably expressing human orexin-1 (OX1) or orexin-2 (OX2) receptors by measuring intracellular calcium ([Ca2+]i) using Fluo-3AM. Orexin-A and orexin-B increased [Ca2+]i in CHO-OX1 (pEC50=8.38±0.04 and 7.26±0.05 respectively, n=12) and CHO-OX2 (pEC50=8.20±0.03 and 8.26±0.04 respectively, n=8) cells. However, neuropeptide Y and secretin (10 pM – 10 μM) displayed neither agonist nor antagonist properties in either cell-line. SB-334867-A (1-(2-Methyylbenzoxanzol-6-yl)-3-[1,5]naphthyridin-4-yl-urea hydrochloride) inhibited the orexin-A (10 nM) and orexin-B (100 nM)-induced calcium responses (pKB=7.27±0.04 and 7.23±0.03 respectively, n=8), but had no effect on the UTP (3 μM)-induced calcium response in CHO-OX1 cells. SB-334867-A (10 μM) also inhibited OX2 mediated calcium responses (32.7±1.9% versus orexin-A). SB-334867-A was devoid of agonist properties in either cell-line. In conclusion, SB-334867-A is a non-peptide OX1 selective receptor antagonist. PMID:11250867

  17. Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise.

    PubMed

    Casey, Darren P; Madery, Brandon D; Pike, Tasha L; Eisenach, John H; Dietz, Niki M; Joyner, Michael J; Wilkins, Brad W

    2009-10-01

    We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols, subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received an intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (alpha-adrenoceptor antagonist) and combined phentolamine and aminophylline administration. Forearm vascular conductance (FVC; in ml x min(-1).100 mmHg(-1)) was calculated from forearm blood flow (in ml/min) and blood pressure (in mmHg). In protocol 1, the change in FVC (DeltaFVC; change from normoxic baseline) during hypoxic exercise with saline was 172 +/- 29 and 314 +/- 34 ml x min(-1) x 100 mmHg(-1) (10% and 20%, respectively). Aminophylline administration did not affect DeltaFVC during hypoxic exercise at 10% (190 +/- 29 ml x min(-1)x100 mmHg(-1), P = 0.4) or 20% (287 +/- 48 ml x min(-1) x 100 mmHg(-1), P = 0.3). In protocol 2, DeltaFVC due to hypoxic exercise with phentolamine infusion was 313 +/- 30 and 453 +/- 41 ml x min(-1) x 100 mmHg(-1) (10% and 20% respectively). DeltaFVC was similar at 10% (352 +/- 39 ml min(-1) x 100 mmHg(-1), P = 0.8) and 20% (528 +/- 45 ml x min(-1) x 100 mmHg(-1), P = 0.2) hypoxic exercise with combined phentolamine and aminophylline. In contrast, DeltaFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans.

  18. Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists.

    PubMed

    Hansen, Kasper B; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L; Yuan, Hongjie; Vance, Katie M; Orr, Anna G; Kvist, Trine; Ogden, Kevin K; Le, Phuong; Vellano, Kimberly M; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T J; Snyder, James P; Bräuner-Osborne, Hans; Traynelis, Stephen F

    2010-06-01

    N-Methyl-D-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca(2+)-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism.

  19. Autoradiographic localization of endothelin-1 binding sites in porcine skin

    SciTech Connect

    Zhao, Y.D.; Springall, D.R.; Wharton, J.; Polak, J.M. )

    1991-01-01

    Autoradiographic techniques and {sup 125}I-labeled endothelin-1 were used to study the distribution of endothelin-1 binding sites in porcine skin. Specific endothelin-1 binding sites were localized to blood vessels (capillaries, deep cutaneous vascular plexus, arteries, and arterioles), the deep dermal and connective tissue sheath of hair follicles, sebaceous and sweat glands, and arrector pili muscle. Specific binding was inhibited by endothelin-2 and endothelin-3 as well as endothelin-1. Non-specific binding was found in the epidermis and the medulla of hair follicles. No binding was found in connective tissue or fat. These vascular binding sites may represent endothelin receptors, in keeping with the known cutaneous vasoconstrictor actions of the peptide. If all binding sites are receptors, the results suggest that endothelin could also regulate the function of sweat glands and may have trophic effects in the skin.

  20. A Novel Bidirectional Interaction between endothelin-3 and Retinoic Acid in Rat Enteric Nervous System Precursors

    PubMed Central

    Gisser, Jonathan M.; Cohen, Ariella R.; Yin, Han; Gariepy, Cheryl E.

    2013-01-01

    Background Signaling through the endothelin receptor B (EDNRB) is critical for the development of the enteric nervous system (ENS) and mutations in endothelin system genes cause Hirschsprung’s aganglionosis in humans. Penetrance of the disease is modulated by other genetic factors. Mutations affecting retinoic acid (RA) signaling also produce aganglionosis in mice. Thus, we hypothesized that RA and endothelin signaling pathways may interact in controlling development of the ENS. Methods Rat immunoselected ENS precursor cells were cultured with the EDNRB ligand endothelin-3, an EDNRB-selective antagonist (BQ-788), and/or RA for 3 or 14 days. mRNA levels of genes related to ENS development, RA- and EDNRB-signaling were measured at 3 days. Proliferating cells and cells expressing neuronal, glial, and myofibroblast markers were quantified. Results Culture of isolated ENS precursors for 3 days with RA decreases expression of the endothelin-3 gene and that of its activation enzyme. These changes are associated with glial proliferation, a higher percentage of glia, and a lower percentage of neurons compared to cultures without RA. These changes are independent of EDNRB signaling. Conversely, EDNRB activation in these cultures decreases expression of RA receptors β and γ mRNA and affects the expression of the RA synthetic and degradative enzymes. These gene expression changes are associated with reduced glial proliferation and a lower percentage of glia in the culture. Over 14 days in the absence of EDNRB signaling, RA induces the formation of a heterocellular plexus replete with ganglia, glia and myofibroblasts. Conclusions A complex endothelin-RA interaction exists that coordinately regulates the development of rat ENS precursors in vitro. These results suggest that environmental RA may modulate the expression of aganglionosis in individuals with endothelin mutations. PMID:24040226

  1. Interleukin-36-receptor antagonist deficiency and generalized pustular psoriasis.

    PubMed

    Marrakchi, Slaheddine; Guigue, Philippe; Renshaw, Blair R; Puel, Anne; Pei, Xue-Yuan; Fraitag, Sylvie; Zribi, Jihen; Bal, Elodie; Cluzeau, Céline; Chrabieh, Maya; Towne, Jennifer E; Douangpanya, Jason; Pons, Christian; Mansour, Sourour; Serre, Valérie; Makni, Hafedh; Mahfoudh, Nadia; Fakhfakh, Faiza; Bodemer, Christine; Feingold, Josué; Hadj-Rabia, Smail; Favre, Michel; Genin, Emmanuelle; Sahbatou, Mourad; Munnich, Arnold; Casanova, Jean-Laurent; Sims, John E; Turki, Hamida; Bachelez, Hervé; Smahi, Asma

    2011-08-18

    Generalized pustular psoriasis is a life-threatening disease of unknown cause. It is characterized by sudden, repeated episodes of high-grade fever, generalized rash, and disseminated pustules, with hyperleukocytosis and elevated serum levels of C-reactive protein, which may be associated with plaque-type psoriasis. We performed homozygosity mapping and direct sequencing in nine Tunisian multiplex families with autosomal recessive generalized pustular psoriasis. We assessed the effect of mutations on protein expression and conformation, stability, and function. We identified significant linkage to an interval of 1.2 megabases on chromosome 2q13-q14.1 and a homozygous missense mutation in IL36RN, encoding an interleukin-36-receptor antagonist (interleukin-36Ra), an antiinflammatory cytokine. This mutation predicts the substitution of a proline residue for leucine at amino acid position 27 (L27P). Homology-based structural modeling of human interleukin-36Ra suggests that the proline at position 27 affects both the stability of interleukin-36Ra and its interaction with its receptor, interleukin-1 receptor-like 2 (interleukin-1 receptor-related protein 2). Biochemical analyses showed that the L27P variant was poorly expressed and less potent than the nonvariant interleukin-36Ra in inhibiting a cytokine-induced response in an interleukin-8 reporter assay, leading to enhanced production of inflammatory cytokines (interleukin-8 in particular) by keratinocytes from the patients. Aberrant interleukin-36Ra structure and function lead to unregulated secretion of inflammatory cytokines and generalized pustular psoriasis. (Funded by Agence Nationale de la Recherche and Société Française de Dermatologie.).

  2. Effect of YM218, a nonpeptide vasopressin V(1A) receptor-selective antagonist, on rat mesangial cell hyperplasia and hypertrophy.

    PubMed

    Tahara, Atsuo; Tsukada, Junko; Tomura, Yuichi; Suzuki, Takeshi; Yatsu, Takeyuki; Shibasaki, Masayuki

    2007-06-01

    Mesangial cell growth constitutes a key feature of progressive glomerular injury. Vasopressin (AVP), a potent peptide vasoconstrictor, acts on mesangial cells through the V(1A) receptors, inducing contraction and cell proliferation. This study examined the effects of YM218, a nonpeptide AVP V(1A) receptor-selective antagonist, on the mitogenic and hypertrophic effects of AVP in rat mesangial cells. When added to mesangial cells whose growth was arrested, AVP concentration-dependently induced hyperplasia and hypertrophy. YM218 potently prevented AVP-induced hyperplasia and hypertrophy of these cells. Furthermore, AVP stimulated endothelin (ET)-1 secretion from mesangial cells in a concentration-dependent manner and this effect was potently inhibited by YM218. ET-1 also induced hyperplasia and hypertrophy in mesangial cells and this effect was completely abolished by ET(A) receptor-selective antagonist YM598. In addition, AVP-induced hyperplasia and hypertrophy were partly inhibited by YM598. These results suggest that AVP may modulate mesangial cell growth not only by its direct action but also through the stimulation of ET-1 secretion. YM218 displays high potency in inhibiting the AVP-induced physiologic responses of mesangial cells via the V(1A) receptors and is a potent pharmacologic probe for investigating the physiologic and pathophysiologic roles of AVP in several renal diseases.

  3. Straub tail reaction in mice treated with σ(1) receptor antagonist in combination with methamphetamine.

    PubMed

    Kitanaka, Junichi; Kitanaka, Nobue; Hall, F Scott; Uhl, George R; Tanaka, Koh-Ichi; Nishiyama, Nobuyoshi; Takemura, Motohiko

    2012-10-30

    Straub tail reaction (STR) was observed in male ddY mice after simultaneous administration with BMY 14802 (a non-specific σ receptor antagonist) and methamphetamine (METH). The intensity and duration of STR depended on the dose of BMY 14802. The tail reaction was inhibited completely by (+)-SKF 10,047 (a putative σ(1) receptor agonist) and partially by PB 28 (a putative σ(2) receptor agonist). The STR was mimicked in mice treated with BD 1047 (a putative σ(1) receptor antagonist), but not SM-21, a putative σ(2) receptor antagonist, in combination with METH. STR evoked with BD 1047 plus METH was inhibited by (+)-SKF 10,047. STR induced by BMY 14802 and METH was abolished by naloxone (a relatively non-selective opioid receptor antagonist) or U-50,488H (a selective κ-agonist), suggesting that the STR may be mediated by activation of opioid receptor system.

  4. Drug discrimination analysis of NMDA receptor channel blockers as nicotinic receptor antagonists in rats.

    PubMed

    Zakharova, E S; Danysz, W; Bespalov, A Y

    2005-04-01

    Antagonists acting at the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors inhibit various phenomena associated with exposures to nicotine (e.g., tolerance, sensitization, dependence, and intravenous self-administration). These effects are often discussed in terms of nicotine-induced glutamate release with subsequent glutamate-dependent stimulation of dopamine metabolism and neuronal plasticity in brain areas critically involved in drug-addiction mechanisms. However, it is also well established that certain types of NMDA receptor antagonists (channel blockers) potently bind to nicotinic receptors and may act as nicotinic receptor antagonists. The present study aimed to evaluate the discriminative-stimulus effects of the NMDA receptor channel blockers (+)MK-801, dextromethorphan, and memantine in rats trained to discriminate nicotine from its vehicle. Adult male Wistar rats were trained to discriminate 0.6 mg/kg nicotine from saline under a two-lever, fixed-ratio 10 schedule of food reinforcement. During test sessions, injections of (+)MK-801 (0.03--0.3 mg/kg, i.p.), dextromethorphan (30 mg/kg, s.c.), or memantine (1--10 mg/kg, i.p.) were co-administered with s.c. nicotine (0.075--0.6 mg/kg; interaction tests) or saline (generalization tests). Additional interaction and generalization tests were conducted with the selective nicotinic receptor antagonists mecamylamine (0.1--3 mg/kg, s.c.) and MRZ 2/621 (0.3--10 mg/kg, i.p.), and the mGlu5 receptor antagonist MPEP (3--10 mg/kg, i.p.). In generalization tests, none of the compounds produced any appreciable levels of substitution for nicotine. The nicotine discriminative-stimulus control was dose dependently attenuated by mecamylamine (ED(50)=0.67 mg/kg) and MRZ 2/621 (ED(50)=9.7 mg/kg). Both agents produced a marked downward shift in the nicotine dose-response curve. Memantine and MPEP slightly attenuated nicotine discriminative-stimulus effects, while (+)MK-801 and dextromethorphan did not affect the

  5. Evaluation of deafness in American Paint Horses by phenotype, brainstem auditory-evoked responses, and endothelin receptor B genotype.

    PubMed

    Magdesian, K Gary; Williams, D Colette; Aleman, Monica; Lecouteur, Richard A; Madigan, John E

    2009-11-15

    To evaluate deafness in American Paint Horses by phenotype, clinical findings, brainstem auditory-evoked responses (BAERs), and endothelin B receptor (EDNBR) genotype. Case series and case-control studies. 14 deaf American Paint Horses, 20 suspected-deaf American Paint Horses, and 13 nondeaf American Paint Horses and Pintos. Horses were categorized on the basis of coat color pattern and eye color. Testing for the EDNBR gene mutation (associated with overo lethal white foal syndrome) and BAERs was performed. Additional clinical findings were obtained from medical records. All 14 deaf horses had loss of all BAER waveforms consistent with complete deafness. Most horses had the splashed white or splashed white-frame blend coat pattern. Other patterns included frame overo and tovero. All of the deaf horses had extensive head and limb white markings, although the amount of white on the neck and trunk varied widely. All horses had at least 1 partially heterochromic iris, and most had 2 blue eyes. Ninety-one percent (31/34) of deaf and suspected-deaf horses had the EDNBR gene mutation. Deaf and suspected-deaf horses were used successfully for various performance events. All nondeaf horses had unremarkable BAER results. Veterinarians should be aware of deafness among American Paint Horses, particularly those with a splashed white or frame overo coat color pattern, blend of these patterns, or tovero pattern. Horses with extensive head and limb markings and those with blue eyes appeared to be at particular risk.

  6. Pharmacogenetic analysis of captopril effects on blood pressure: possible role of the Ednrb (endothelin receptor type B) candidate gene.

    PubMed

    Zicha, J; Dobešová, Z; Zídek, V; Silhavý, J; Simáková, M; Mlejnek, P; Vaněčková, I; Kuneš, J; Pravenec, M

    2014-01-01

    The objective of the current study was to search for genetic determinants associated with antihypertensive effects of angiotensin-converting enzyme (ACE) inhibitor captopril. Linkage and correlation analyses of captopril-induced effects on blood pressure (BP) with renal transcriptome were performed in the BXH/HXB recombinant inbred (RI) strains derived from spontaneously hypertensive rat (SHR) and Brown Norway (BN-Lx) progenitors. Variability of blood pressure lowering effects of captopril among RI strains was continuous suggesting a polygenic mode of inheritance. Linkage analysis of captopril-induced BP effects revealed a significant quantitative trait locus (QTL) on chromosome 15. This QTL colocalized with cis regulated expression QTL (eQTL) for the Ednrb (endothelin receptor type B) gene in the kidney (SHR allele was associated with increased renal expression) and renal expression of Ednrb correlated with captopril-induced BP effects. These results suggest that blood pressure lowering effects of ACE inhibitor captopril may be modulated by the variants at the Ednrb locus.

  7. Histamine and histamine receptor antagonists in cancer biology.

    PubMed

    Blaya, Bruno; Nicolau-Galmés, Francesca; Jangi, Shawkat M; Ortega-Martínez, Idoia; Alonso-Tejerina, Erika; Burgos-Bretones, Juan; Pérez-Yarza, Gorka; Asumendi, Aintzane; Boyano, María D

    2010-07-01

    Histamine has been demonstrated to be involved in cell proliferation, embryonic development, and tumour growth. These various biological effects are mediated through the activation of specific histamine receptors (H1, H2, H3, and H4) that differ in their tissue expression patterns and functions. Although many in vitro and in vivo studies of the modulatory roles of histamine in tumour development and metastasis have been reported, the effect of histamine in the progression of some types of tumours remains controversial; however, recent findings on the role of histamine in the immune system have shed new light on this question. This review focuses on the recent advances in understanding the roles of histamine and its receptors in tumour biology. We report our recent observations of the anti-tumoural effect of H1 histamine antagonists on experimental and human melanomas. We have found that in spite of exogenous histamine stimulated human melanoma cell proliferation, clonogenic ability and migration activity in a dose-dependent manner, the melanoma tumour growth was not modulated by in vivo histamine treatment. On the contrary, terfenadine-treatment in vitro induced melanoma cell death by apoptosis and in vivo terfenadine treatment significantly inhibited tumour growth in murine models. These observations increase our understanding of cancer biology and may inspire novel anticancer therapeutic strategies.

  8. Vasopressin receptor antagonists and their role in clinical medicine.

    PubMed

    Narayen, Girish; Mandal, Surya Narayan

    2012-03-01

    Hyponatremia is the most common electrolyte abnormality in hospitalized patients. Its treatment is based not only on extracellular fluid volume status of patients but also on its pathogenetic mechanisms. Conventional treatment of hyponatremia like fluid restriction, which is useful in euvolemic and hypervolemic hyponatremia, has very poor patient compliance over long term. Vasopressin receptor antagonists (Vaptans) are a new group of nonpeptide drugs which have been used in various clinical conditions with limited success. Whereas conivaptan is to be administered intravenously, the other vaptans like tolvaptan, lixivaptan, and satavaptan are effective as oral medication. They produce aquaresis by their action on vasopressin type 2 (V2R) receptors in the collecting duct and thus increase solute free water excretion. Vaptans are being used as an alternative to fluid restriction in euvolemic and hypervolemic hyponatremic patients. Efficacy of vaptans is now well accepted for management of correction of hyponatremia over a short period. However, its efficacy in improving the long-term morbidity and mortality in patients with chronic hyponatremia due to cirrhosis and heart failure is yet to be established. Vaptans have not become the mainstay treatment of hyponatremia yet.

  9. Management of hyperkalaemia consequent to mineralocorticoid-receptor antagonist therapy.

    PubMed

    Roscioni, Sara S; de Zeeuw, Dick; Bakker, Stephan J L; Lambers Heerspink, Hiddo J

    2012-12-01

    Mineralocorticoid-receptor antagonists (MRAs) reduce blood pressure and albuminuria in patients treated with angiotensin-converting-enzyme inhibitors or angiotensin-II-receptor blockers. The use of MRAs, however, is limited by the occurrence of hyperkalaemia, which frequently occurs in patients older than 65 years with impaired kidney function, and/or diabetes. Patients with these characteristics might still benefit from MRA therapy, however, and should not be excluded from this treatment option. This limitation raises the question of how to optimize the therapeutic use of MRAs in this population of patients. Understanding the individual variability in patients' responses to MRAs, in terms of albuminuria, blood pressure and serum potassium levels, might lead to targeted intervention. MRA use might be restricted to patients with high levels of mineralocorticoid activity, evaluated by circulating renin and aldosterone levels or renal excretion of potassium. In addition, reviewing the patient's diet and concomitant medications might prove useful in reducing the risk of developing subsequent hyperkalaemia. If hyperkalaemia does develop, treatment options exist to decrease potassium levels, including administration of calcium gluconate, insulin, β(2)-agonists, diuretics and cation-exchange resins. In combination with novel aldosterone blockers, these strategies might offer a rationale with which to optimize therapeutic intervention and extend the population of patients who can benefit from use of MRAs.

  10. Inhibition of radiation-induced polyuria by histamine receptor antagonists

    SciTech Connect

    Donlon, M.A.; Melia, J.A.; Helgeson, E.A.; Wolfe, W.W.

    1986-03-01

    In previous studies the authors have demonstrated that gamma radiation results in polyuria, which is preceded by polydypsia. This suggests that the increased thirst elicited by radiation causes increased urinary volume (UV). Histamine, which is released following radiation exposure, also elicits drinking by nonirradiated rats when administered exogenously. In this study the authors have investigated both the role of water deprivation and the effect of histamine receptor antagonists (HRA) on radiation-induced polyuria. Sprague-Dawley rats were housed individually in metabolic cages. Water was allowed ad libitum except in deprivation experiments where water was removed for 24 hr immediately following radiation. Cimetidine (CIM), an H2 HRA, and dexbromopheniramine (DXB), an H1 HRA, were administered i.p. (16 and 1 mg/kg, respectively) 30 min prior to irradiation (950 rads from a cobalt source). UV was determined at 24-hr intervals for 3 days preceding irradiation and 24 hr postirradiation. UV in DXB treated rats was significantly reduced 24 hr postirradiation (CON = 427 +/- 54%; DXB = 247 +/- 39% of preirradiated CON) compared to postirradiation control values. CIM did not affect postirradiation UV. These data suggest that radiation-induced polyuria is caused by polydypsia which is, in part, mediated by histamine induced by an H1 receptor.

  11. Vasopressin receptor antagonists and their role in clinical medicine

    PubMed Central

    Narayen, Girish; Mandal, Surya Narayan

    2012-01-01

    Hyponatremia is the most common electrolyte abnormality in hospitalized patients. Its treatment is based not only on extracellular fluid volume status of patients but also on its pathogenetic mechanisms. Conventional treatment of hyponatremia like fluid restriction, which is useful in euvolemic and hypervolemic hyponatremia, has very poor patient compliance over long term. Vasopressin receptor antagonists (Vaptans) are a new group of nonpeptide drugs which have been used in various clinical conditions with limited success. Whereas conivaptan is to be administered intravenously, the other vaptans like tolvaptan, lixivaptan, and satavaptan are effective as oral medication. They produce aquaresis by their action on vasopressin type 2 (V2R) receptors in the collecting duct and thus increase solute free water excretion. Vaptans are being used as an alternative to fluid restriction in euvolemic and hypervolemic hyponatremic patients. Efficacy of vaptans is now well accepted for management of correction of hyponatremia over a short period. However, its efficacy in improving the long-term morbidity and mortality in patients with chronic hyponatremia due to cirrhosis and heart failure is yet to be established. Vaptans have not become the mainstay treatment of hyponatremia yet. PMID:22470853

  12. Dihydromorphine-peptide hybrids with delta receptor agonistic and mu receptor antagonistic actions

    SciTech Connect

    Smith, C.B.; Medzihradsky, F.; Woods, J.H.

    1986-03-05

    The actions of two morphine derivatives with short peptide side chains were evaluated upon the contraction of the isolated mouse vas deferens and upon displacement of /sup 3/H-etorphine from rat brain membranes. NIH-9833 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-phenylalanyl-L-leucine ethyl ester HCl) was a potent agonist upon the vas deferens. Its EC50 for inhibition of the twitch was 1.2 +/- 0.1 nM. Both naltrexone (10/sup -7/ M) a relatively nonselective opioid antagonist, and ICI-174864 (10/sup -/' M) a highly selective delta receptor antagonist, blocked the actions of NIH-9833 which indicates that this drug is a delta receptor agonist. In contrast, NIH-9835 (N-(6,14-endoetheno-7,8-dihydromorphine-7-alpha-carbonyl)-L-glycyl-L-phenylalanyl-L-leucine ethyl ester HCl), which differs from NIH-9835 by the presence of a single amino acid residue, was devoid of opioid agonistic activity but was a potent antagonist of the inhibitory actions on the vas deferens of morphine and sufentanil. NIH-9833 and NIH-9835 were potent displacers of /sup 3/H-etorphine from rat cerebral membranes with EC50's of 0.58 nM and 1.7 nM, respectively. The observation that addition of a single glycyl group changes a dihydromorphine-peptide analog from a potent delta receptor agonist to an equally potent mu receptor antagonist suggests that the two receptor sites might be structurally quite similar.

  13. Endothelin-induced contraction and mediator release in human bronchus.

    PubMed Central

    Hay, D. W.; Hubbard, W. C.; Undem, B. J.

    1993-01-01

    1. To elucidate the role of acetylcholine and various autacoids in endothelin-1 (ET-1)-induced contraction in human bronchus, the effects of various receptor antagonists were examined. In addition, the ability of ET-1 to stimulate the release of histamine, peptidoleukotrienes and prostanoids was determined. 2. ET-1 was a potent and effective contractile agonist in human bronchus, possessing similar potency and efficacy to leukotriene D4 (LTD4); EC50 (-log M): ET-1 = 7.76 +/- 0.09, n = 7; LTD4 = 8.46 +/- 0.53, n = 7; P > 0.2; maximum response (% 10 microM pre-carbachol): ET-1 = 103.8 +/- 17.4, n = 7; LTD4 = 95.5 +/- 9.3, n = 7; P > 0.6. 3. The cyclo-oxygenase inhibitor, sodium meclofenamate (1 microM) or the potent and selective thromboxane receptor antagonist, SQ 29,548 (1 microM) were without significant effect on ET-1 concentration-response curves. 4. In the presence of sodium meclofenamate (1 microM), the muscarinic receptor antagonist, atropine (1 microM), the platelet activating factor (PAF) receptor antagonist, WEB 2086 (1 microM) or the combination of the H1-histamine receptor antagonist, mepyramine (10 microM) and the leukotriene receptor antagonist, SK&F 104353 (10 microM), were without marked effect on ET-1 concentration-response curves. In addition, the combination of all four receptor antagonists did not antagonize ET-1-induced contraction. 5. ET-1 (0.3 microM) did not stimulate the release of histamine or immunoreactive leukotrienes from human bronchus.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7693285

  14. Use of Enterally Delivered Angiotensin II Type Ia Receptor Antagonists to Reduce the Severity of Colitis

    PubMed Central

    Okawada, Manabu; Koga, Hiroyuki; Larsen, Scott D.; Showalter, Hollis D.; Turbiak, Anjanette J.; Jin, Xiaohong; Lucas, Peter C.; Lipka, Elke; Hillfinger, John; Kim, Jae Seung

    2011-01-01

    Background Renin-angiotensin system blockade reduces inflammation in several organ systems. Having found a fourfold increase in angiotensin II type Ia receptor expression in a dextran sodium sulfate colitis model, we targeted blockade with angiotensin II type Ia receptor antagonists to prevent colitis development. Because hypotension is a major complication of angiotensin II type Ia receptor antagonists use, we hypothesized that use of angiotensin II type Ia receptor antagonists compounds which lack cell membrane permeability, and thus enteric absorption, would allow for direct enteral delivery at far higher concentrations than would be tolerated systemically, yet retain efficacy. Methods Based on the structure of the angiotensin II type Ia receptor antagonist losartan, deschloro-losartan was synthesized, which has extremely poor cell membrane permeability. Angiotensin II type Ia receptor antagonist efficacy was evaluated by determining the ability to block NF-κB activation in vitro. Dextran sodium sulfate colitis was induced in mice and angiotensin II type Ia receptor antagonist efficacy delivered transanally was assessed. Results In vitro, deschloro-losartan demonstrated near equal angiotensin II type Ia receptor blockade compared to losartan as well as another angiotensin II type Ia receptor antagonist, candesartan. In the dextran sodium sulfate model, each compound significantly improved clinical and histologic scores and epithelial cell apoptosis. Abundance of TNF-α, IL-1β, and IL6 mRNA were significantly decreased with each compound. In vitro and in vivo intestinal drug absorption, as well as measures of blood pressure and mucosal and colonic blood flow, showed significantly lower uptake of deschloro-losartan compared to losartan and candesartan. Conclusions This study demonstrated efficacy of high-dose angiotensin II type Ia receptor antagonists in this colitis model. We postulate that a specially designed angiotensin II type Ia receptor antagonist with

  15. Anticonvulsive effect of nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Kuder, Kamil; Subramanian, Dhanasekaran; Shafiullah, Mohamed; Stark, Holger; Lażewska, Dorota; Adem, Abdu; Kieć-Kononowicz, Katarzyna

    2014-06-01

    To determine the potential of histamine H3 receptor (H3R) ligands as new antiepileptic drugs (AEDs), aromatic ether, and diether derivatives (1-12) belonging to the nonimidazole class of ligands, with high in-vitro binding affinity at human H3R, were tested for their in-vivo anticonvulsive activity in the maximal electroshock (MES)-induced and pentylenetetrazole (PTZ)-kindled seizure models in rats. The anticonvulsive effects of a systemic injection of 1-12 on MES-induced and PTZ-kindled seizures were evaluated against the reference AED phenytoin (PHT) and the structurally related H3R antagonist/inverse agonist pitolisant (PIT). Among the most promising ligands 2, 4, 5, and 11, there was a significant and dose-dependent reduction in the duration of tonic hind limb extension (THLE) in MES-induced seizure subsequent to administration of 4 and 5 [(5, 10, and 15 mg/kg, intraperitoneally (i.p.)]. The protective effects observed for the 1-(3-(3-(4-chlorophenyl)propoxy)propyl)-3-methylpiperidine derivative 11 at 10 mg/kg, i.p. were significantly greater than those of PIT, and were reversed by pretreatment with the central nervous system penetrant H1R antagonist pyrilamine (PYR) (10 mg/kg). Moreover, the protective action of the reference AED PHT, at a dose of 5 mg/kg (without considerable protection in the MES model), was significantly augmented when coadministered with derivative 11 (5 mg/kg, i.p.). Surprisingly, pretreatment with derivative 7 (10 mg/kg, i.p.), an ethylphenoxyhexyl-piperidine derivative without considerable protection in the MES model, potently altered PTZ-kindled seizure, significantly prolonged myoclonic latency time, and clearly shortened the total seizure time when compared with control, PHT, and PIT. These interesting results highlight the potential of H3R ligands as new AEDs or as adjuvants to available AED therapeutics.

  16. Heterocyclic 1,7-disubstituted indole sulfonamides are potent and selective human EP3 receptor antagonists.

    PubMed

    Hategan, Georgeta; Polozov, Alexandre M; Zeller, Wayne; Cao, Hua; Mishra, Rama K; Kiselyov, Alex S; Ramirez, Jose; Halldorsdottir, Gudrún; Andrésson, Thornorkell; Gurney, Mark E; Singh, Jasbir

    2009-12-01

    We have developed a pharmacophore model for the EP(3) receptor antagonists based on its endogenous ligand PGE(2). This ligand-based design yielded a series of novel peri-substituted [4.3.0] bicyclic aromatics featuring 1-alklyaryl 7-heterocyclic sulfonamide substituents. The synthesized molecules are potent antagonists of human EP(3) receptor in vitro and show inhibition of rat platelets aggregation. Optimized derivatives display high selectivity over IP, FP, and other EP receptor panels.

  17. Mechanisms of Radiosensitization by the Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models

    DTIC Science & Technology

    2009-04-01

    Neurotensin Receptor Antagonist SR48692 in Prostate Cancer Models PRINCIPAL INVESTIGATOR: Jaroslaw Dziegielewski, Ph.D...Receptor Antagonist 5a. CONTRACT NUMBER SR48692 in Prostate Cancer Models 5b. GRANT NUMBER W81XWH-08-1-0114 5c. PROGRAM ELEMENT NUMBER 6...neurotensin receptor by SR48692 drug could sensitize cancer cells to radiation. SR48692 activity was measured in PC3, C42 and LNCaP prostate cancer

  18. The effects of histamine H3-receptor antagonists on amygdaloid kindled seizures in rats.

    PubMed

    Kakinoki, H; Ishizawa, K; Fukunaga, M; Fujii, Y; Kamei, C

    1998-07-15

    The effects of histamine H3-receptor antagonists, thioperamide, and clobenpropit on amygdaloid kindled seizures were investigated in rats. Both intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) injections of H3-antagonists resulted in a dose-related inhibition of amygdaloid kindled seizures. An inhibition induced by thioperamide was antagonized by an H3-agonist [(R)-alpha-methylhistamine] and H1-antagonists (diphenhydramine and chlorpheniramine). On the other hand, an H2-antagonist (cimetidine and ranitidine) caused no antagonistic effect. Metoprine, an inhibitor of N-methyltransferase was also effective in inhibiting amygdaloid kindled seizure, and this effect was augmented by thioperamide treatment.

  19. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  20. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

    PubMed Central

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%–80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  1. ETA receptor blockade attenuates hypertension and decreases reactive oxygen species in ETB receptor-deficient rats.

    PubMed

    Elmarakby, Ahmed A; Dabbs Loomis, E; Pollock, Jennifer S; Pollock, David M

    2004-11-01

    We hypothesize that endothelin-A receptor stimulation contributes to the elevated blood pressure and superoxide production in endothelin-B receptor-deficient rats on a high salt diet. Experiments were conducted on homozygous endothelin-B-deficient (sl/sl) and wild-type rats (wt) fed a high salt diet (8% NaCl) for 3 weeks. Separate groups were given normal drinking water or water containing the endothelin-A receptor antagonist, ABT-627 (5 mg/kg per day; n = 8-9 in all groups). On a normal salt diet, (sl/sl) rats had a significantly elevated systolic blood pressure compared with wt (138 +/- 3 vs 117 +/- 4 mmHg, respectively; P < 0.05). High salt diet caused a significant increase in systolic blood pressure in (sl/sl) rats compared with wt (158 +/- 2 vs 138 +/- 3 mmHg, respectively; P < 0.05). Endothelin-A receptor blockade decreased systolic blood pressure in (sl/sl) rats on high salt (125 +/- 5 mmHg; P < 0.05 vs without antagonist) without affecting the systolic blood pressure in wt (119 +/- 4 mmHg). Aortic superoxide production (lucigenin chemiluminescence) and plasma 8-isoprostane were elevated in sl/sl rats and were significantly reduced by endothelin-A receptor blockade in sl/sl, but not in wt rats. These findings suggest that endothelin-1, through the endothelin-A receptor, contributes to salt-induced hypertension and vascular superoxide production in endothelin-B-deficient rats.

  2. Development of selective agonists and antagonists of P2Y receptors

    PubMed Central

    Ivanov, Andrei A.; de Castro, Sonia; Harden, T. Kendall; Ko, Hyojin

    2008-01-01

    Although elucidation of the medicinal chemistry of agonists and antagonists of the P2Y receptors has lagged behind that of many other members of group A G protein-coupled receptors, detailed qualitative and quantitative structure–activity relationships (SARs) were recently constructed for several of the subtypes. Agonists selective for P2Y1, P2Y2, and P2Y6 receptors and nucleotide antagonists selective for P2Y1 and P2Y12 receptors are now known. Selective nonnucleotide antagonists were reported for P2Y1, P2Y2, P2Y6, P2Y11, P2Y12, and P2Y13 receptors. At the P2Y1 and P2Y12 receptors, nucleotide agonists (5′-diphosphate derivatives) were converted into antagonists of nanomolar affinity by altering the phosphate moieties, with a focus particularly on the ribose conformation and substitution pattern. Nucleotide analogues with conformationally constrained ribose-like rings were introduced as selective receptor probes for P2Y1 and P2Y6 receptors. Screening chemically diverse compound libraries has begun to yield new lead compounds for the development of P2Y receptor antagonists, such as competitive P2Y12 receptor antagonists with antithrombotic activity. Selective agonists for the P2Y4, P2Y11, and P2Y13 receptors and selective antagonists for P2Y4 and P2Y14 receptors have not yet been identified. The P2Y14 receptor appears to be the most restrictive of the class with respect to modification of the nucleobase, ribose, and phosphate moieties. The continuing process of ligand design for the P2Y receptors will aid in the identification of new clinical targets. PMID:18600475

  3. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    PubMed

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  4. Histamine H4 receptor antagonists as potent modulators of mammalian vestibular primary neuron excitability

    PubMed Central

    Desmadryl, G; Gaboyard-Niay, S; Brugeaud, A; Travo, C; Broussy, A; Saleur, A; Dyhrfjeld-Johnsen, J; Wersinger, E; Chabbert, C

    2012-01-01

    BACKGROUND AND PURPOSE Betahistine, the main histamine drug prescribed to treat vestibular disorders, is a histamine H3 receptor antagonist. Here, we explored the potential for modulation of the most recently cloned histamine receptor (H4 receptor) to influence vestibular system function, using a selective H4 receptor antagonist JNJ 7777120 and the derivate compound JNJ 10191584. EXPERIMENTAL APPROACH RT-PCR was used to assess the presence of H4 receptors in rat primary vestibular neurons. In vitro electrophysiological recordings and in vivo behavioural approaches using specific antagonists were employed to examine the effect of H4 receptor modulation in the rat vestibular system. KEY RESULTS The transcripts of H4 and H3 receptors were present in rat vestibular ganglia. Application of betahistine inhibited the evoked action potential firing starting at micromolar range, accompanied by subsequent strong neuronal depolarization at higher concentrations. Conversely, reversible inhibitory effects elicited by JNJ 10191584 and JNJ 7777120 began in the nanomolar range, without inducing neuronal depolarization. This effect was reversed by application of the selective H4 receptor agonist 4-methylhistamine. Thioperamide, a H3/H4 receptor antagonist, exerted effects similar to those of H3 and H4 receptor antagonists, namely inhibition of firing at nanomolar range and membrane depolarization above 100 µM. H4 receptor antagonists significantly alleviated the vestibular deficits induced in rats, while neither betahistine nor thioperamide had significant effects. CONCLUSIONS AND IMPLICATIONS H4 receptor antagonists have a pronounced inhibitory effect on vestibular neuron activity. This result highlights the potential role of H4 receptors as pharmacological targets for the treatment of vestibular disorders. PMID:22624822

  5. Peripheral 5-HT2-like receptors. Can they be classified with the available antagonists?

    PubMed Central

    Leff, P.; Martin, G. R.

    1986-01-01

    Interactions between 5-hydroxytryptamine (5-HT) and the so-called 5-HT2 receptor antagonists ketanserin, spiperone, trazodone and methysergide were studied in isolated preparations of the rabbit aorta, rat jugular vein, and rat caudal artery. Trazodone and spiperone were apparently simple competitive antagonists since they produced antagonism that was surmountable over the concentration range studied and, in each tissue, their apparent affinity appeared to be independent of the antagonist concentration. Furthermore, concentration-ratios obtained with the two antagonists in combination suggested that antagonism was additive, implying mutual competition with a single population of 5-HT receptors. Ketanserin was a non-surmountable antagonist of 5-HT in the rat caudal artery and methysergide demonstrated surmountable, competitive antagonism only in the rabbit aorta. Antagonist dissociation constants estimated for apparently competitive interactions showed that ketanserin, spiperone and trazodone expressed affinities which differed according to the tissue used. In the case of trazodone, affinity estimates differed by as much as 12 fold. These discrepancies were independent of the 5-HT receptor agonist used and could not be attributed to an inadequate equilibration of the antagonist. These results can be interpreted in two ways: either the receptors in the different tissues are heterogeneous or the antagonists used here must be considered as unreliable probes for the classification of 5-HT2-like receptors. PMID:2943354

  6. A comprehensive patents review on cannabinoid 1 receptor antagonists as antiobesity agents.

    PubMed

    Sharma, Mayank Kumar; Murumkar, Prashant R; Barmade, Mahesh A; Giridhar, Rajani; Yadav, Mange Ram

    2015-01-01

    Obesity is a rapidly expanding worldwide health problem. Various targets are investigated presently for the treatment of obesity, but there remains an unmet need for an effective drug therapy with acceptable efficacy levels and reduced side effects. Targeting peripherally located cannabinoid 1 (CB1) receptors is an attractive strategy as these receptors play a vital role in energy homeostasis. CB1 receptor antagonists constitute one of the most important categories of compounds of interest for the control of obesity. In this review, the authors focus on recent advances (since 2007) in diverse chemical classes of patented compounds belonging to the category of CB1 receptor antagonists. Safer CB1 receptor antagonists for the treatment of obesity can be discovered by developing such compounds that act peripherally. Increasing the polar service area, decreasing the lipophilicity and designing of neutral antagonists and allosteric inhibitors are some interesting strategies that could offer promising results.

  7. Alvimopan: a peripherally acting mu-opioid receptor antagonist.

    PubMed

    Leslie, John B

    2007-09-01

    Postoperative ileus (POI), a transient cessation of coordinated bowel motility after surgery, is an important factor in extending the length of hospital stay. The etiology of POI is multifactorial, and related to both the surgical and anesthetic pathways chosen. Additionally, opioids used to manage non-cancer-related and cancer-related chronic pain may also decrease gastrointestinal (GI) motility resulting in opioid-induced bowel dysfunction (OBD). Postoperative ileus has been associated with prolonged hospital stay and readmission, and thus may increase the overall hospital costs per patient with POI. Alvimopan, a peripherally acting mu-opioid receptor antagonist, accelerated time to GI recovery and reduced postoperative hospital length of stay in phase III POI clinical trials and improved symptoms of OBD compared with placebo in phase II/III clinical trials. The U.S. Food and Drug Administration is currently evaluating alvimopan for the management of POI after bowel resection. Alvimopan may provide clinically meaningful benefits to patients and may lower the economic burden of POI to the healthcare system.

  8. Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure

    PubMed Central

    Sica, Domenic A.

    2015-01-01

    Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered. PMID:27057293

  9. Applicability of DPI formulations for novel neurokinin receptor antagonist.

    PubMed

    Kumon, M; Yabe, Y; Kasuya, Y; Suzuki, M; Kusai, A; Yonemochi, E; Terada, K

    2008-05-22

    A novel triple neurokinin receptor antagonist (TNRA) could have pharmaceutical efficacy for asthma and/or chronic obstructive pulmonary disease. TNRA is potentially developed as inhalation medicine. The aim of this investigation was to evaluate the applicability of dry powder inhaler (DPI) formulation for TNRA. DPI formulation containing lactose was used for this feasibility study. Mechanofusion process for surface modification was applied on lactose particles to prepare four different DPI formulations. The mixture of TNRA and lactose was administered to rats intratracheally using an insufflator. The deposition pattern and blood concentration profile of TNRA were evaluated. Although there was no significant difference in deposition on deep lungs between the four formulations, DPI formulations containing mechanofusion-processed lactose showed longer T(max) and t(1/2) and higher AUC(0-infinity) and MRT compared to that containing intact lactose. On the other hand, the contact angle measurement showed that the mechanofusion process decreased the polar part of the surface energy of the lactose. Therefore, the prolongation of the wetting of the formulated powder mixture seemed to delay the dissolution of TNRA deposited in respiratory tract. It was concluded that DPI formulation containing mechanofusion-processed lactose could be suitable for inhalation of TNRA.

  10. Effects of cholecystokinin receptor antagonist loxiglumide on rat exocrine pancreas.

    PubMed

    Nakano, S; Tachibana, I; Otsuki, M

    1994-07-01

    Effects of long-term administration of the cholecystokinin receptor antagonist loxiglumide on exocrine pancreas were studied in adult rats. Plasma concentrations of loxiglumide at 8 h after a single subcutaneous injection of 50 mg/kg body weight of loxiglumide were 3.2 +/- 0.8 microgram/ml, which were comparable to those at 12 h after oral administration of the same dose (3.7 +/- 0.9 microgram/ml). Eight hours' prior subcutaneous injection of loxiglumide (50 mg/kg body weight) significantly suppressed pancreatic exocrine secretion stimulated by an intravenous bolus injection of 50 ng/kg body weight caerulein compared with the control rats. Based on these results, in the first experiment, loxiglumide at a dose of 50 mg/kg body weight was given subcutaneously three times a day (low dose) for 6 days to adult rats fed a standard laboratory diet. Low dose of loxiglumide significantly decreased pancreatic wet weight (-14%) and pancreatic contents of protein (-26%), trypsin (-38%), and lipase (-68%), while having no significant effect on pancreatic contents of DNA and amylase. In the second experiment, three times higher dose of loxiglumide (150 mg/kg body weight) was given by an orogastric tube twice daily for 6 days. High dose of loxiglumide significantly decreased pancreatic weight (-11%) and contents of protein (-20%) and DNA (-22%), whereas it significantly increased amylase (+92%) and trypsin content (+20%).(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children

    PubMed Central

    Erdem, Semiha Bahceci; Nacaroglu, Hikmet Tekin; Unsal Karkiner, Canan Sule; Gunay, Ilker; Can, Demet

    2015-01-01

    Background: Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well. Objectives: The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma. Patients and Methods: 1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric. Results: Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect. Conclusions: The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals. PMID:26495098

  12. Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children.

    PubMed

    Erdem, Semiha Bahceci; Nacaroglu, Hikmet Tekin; Unsal Karkiner, Canan Sule; Gunay, Ilker; Can, Demet

    2015-10-01

    Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well. The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma. 1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric. Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect. The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals.

  13. Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure.

    PubMed

    Sica, Domenic A

    2015-01-01

    Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered.

  14. Receptors and Channels Targeted by Synthetic Cannabinoid Receptor Agonists and Antagonists

    PubMed Central

    Pertwee, R.G.

    2010-01-01

    It is widely accepted that non-endogenous compounds that target CB1 and/or CB2 receptors possess therapeutic potential for the clinical management of an ever growing number of disorders. Just a few of these disorders are already treated with Δ9-tetrahydrocannabinol or nabilone, both CB1/CB2 receptor agonists, and there is now considerable interest in expanding the clinical applications of such agonists and also in exploiting CB2-selective agonists, peripherally restricted CB1/CB2 receptor agonists and CB1/CB2 antagonists and inverse agonists as medicines. Already, numerous cannabinoid receptor ligands have been developed and their interactions with CB1 and CB2 receptors well characterized. This review describes what is currently known about the ability of such compounds to bind to, activate, inhibit or block non-CB1, non-CB2 G protein-coupled receptors such as GPR55, transmitter gated channels, ion channels and nuclear receptors in an orthosteric or allosteric manner. It begins with a brief description of how each of these ligands interacts with CB1 and/or CB2 receptors. PMID:20166927

  15. Synthesis and pharmacology of willardiine derivatives acting as antagonists of kainate receptors.

    PubMed

    Dolman, Nigel P; Troop, Helen M; More, Julia C A; Alt, Andrew; Knauss, Jody L; Nistico, Robert; Jack, Samantha; Morley, Richard M; Bortolotto, Zuner A; Roberts, Peter J; Bleakman, David; Collingridge, Graham L; Jane, David E

    2005-12-01

    The natural product willardiine (8) is an AMPA receptor agonist while 5-iodowillardiine (10) is a selective kainate receptor agonist. In an attempt to produce antagonists of kainate and AMPA receptors analogues of willardiine with substituents at the N3 position of the uracil ring were synthesized. The N3-4-carboxybenzyl substituted analogue (38c) was found to be equipotent at AMPA and GLUK5-containing kainate receptors in the neonatal rat spinal cord. The N3-2-carboxybenzyl substituted analogue (38a) proved to be a potent and selective GLUK5 subunit containing kainate receptor antagonist when tested on native rat and human recombinant AMPA and kainate receptor subtypes. The GLUK5 kainate receptor antagonist activity was found to reside in the S enantiomer (44a) whereas the R enantiomer (44b) was almost inactive. 5-Iodo substitution of the uracil ring of 44a gave 45, which was found to have enhanced potency and selectivity for GLUK5.

  16. Non-selectivity of new bradykinin antagonists for B1 receptors.

    PubMed

    Rhaleb, N E; Gobeil, F; Regoli, D

    1992-01-01

    Two new B1 receptor antagonists, [Hyp3,Thi5,DTic7,Oic8]desArg9-BK and DArg[Hyp3,Thi5,DTic7,Oic8]desArg9-BK were tested in vitro on the rabbit jugular vein and the guinea pig ileum (preparations containing B2 receptors) and on the rabbit aorta (preparation containing B1 receptors) for pharmacological characterization. The results indicate that both compounds are antagonists on both B1 and B2 receptors, are competitive and discriminate between B2A and B2B receptor subtypes.

  17. Discovery, modeling, and human pharmacokinetics of N-(2-acetyl-4,6-dimethylphenyl)-3-(3,4-dimethylisoxazol-5-ylsulfamoyl)thiophene-2-carboxamide (TBC3711), a second generation, ETA selective, and orally bioavailable endothelin antagonist.

    PubMed

    Wu, Chengde; Decker, E Radford; Blok, Natalie; Bui, Huong; You, Tony J; Wang, Junmei; Bourgoyne, Andree R; Knowles, Vippra; Berens, Kurt L; Holland, George W; Brock, Tommy A; Dixon, Richard A F

    2004-04-08

    Sitaxsentan (1) (Wu et al. J. Med. Chem. 1997, 40, 1690) is our first endothelin antagonist being evaluated in clinical trials. It has demonstrated biological effects in an acute hemodynamic study in CHF (Givertz et al. Circulation 2000, 101, 2922), an open-label 20-patient pulmonary hypertension trial (Barst et al. Chest 2002, 121, 1860-1868), and a 31-patient trial in essential hypertension (Calhoun et al. AHA Scientific Sessions 2000). In a phase 2b/3 pulmonary arterial hypertension trial, once a day treatment of 100 mg of sitaxsentan statistically significantly improved 6-min walk distance and NYHA class at 12 weeks (Barst et al. Am. J. Respir. Crit. Care Med. 2004, 169, 441). We have since reported on our efforts in generating follow-up compounds (Wu et al. J. Med. Chem. 1999, 42, 4485) and recently communicated that an ortho acyl group on the anilino ring enhanced oral absorption in this category of compounds (Wu et al. J. Med. Chem. 2001, 44, 1211). Here we report an expansion of this work by substituting a variety of electron-withdrawing groups at the ortho position and evaluating their effects on oral bioavailability as well as structure-activity relationships. As a result, TBC3711 (7z) was identified as our second endothelin antagonist to enter the clinic due to its good oral bioavailability (approximately 100%) in rats, high potency (ET(A) IC(50) = 0.08 nM), and optimal ET(A)/ET(B) selectivity (441 000-fold). Compound 7z has completed phase-I clinical development and was well tolerated with desirable pharmacokinetics in humans (t(1/2) = 6-7 h, oral availability > 80%).

  18. Endothelin-1 contributes to endothelial dysfunction and enhanced vasoconstriction through augmented superoxide production in penile arteries from insulin-resistant obese rats: role of ET(A) and ET(B) receptors.

    PubMed

    Sánchez, A; Martínez, P; Muñoz, M; Benedito, S; García-Sacristán, A; Hernández, M; Prieto, D

    2014-12-01

    We assessed whether endothelin-1 (ET-1) inhibits NO and contributes to endothelial dysfunction in penile arteries in a model of insulin resistance-associated erectile dysfunction (ED). Vascular function was assessed in penile arteries, from obese (OZR) and lean (LZR) Zucker rats, mounted in microvascular myographs. Changes in basal and stimulated levels of superoxide (O2 (-) ) were detected by lucigenin-enhanced chemiluminescence and ET receptor expression was determined by immunohistochemistry. ET-1 stimulated acute O2 (-) production that was blunted by tempol and the NADPH oxidase inhibitor, apocynin, but markedly enhanced in obese animals. ET-1 inhibited the vasorelaxant effects of ACh and of the NO donor S-nitroso-N-acetyl-DL-penicillamine in arteries from both LZR and OZR. Selective ETA (BQ123) or ETB receptor (BQ788) antagonists reduced both basal and ET-1-stimulated superoxide generation and reversed ET-1-induced inhibition of NO-mediated relaxations in OZR, while only BQ-123 antagonized ET-1 actions in LZR. ET-1-induced vasoconstriction was markedly enhanced by NO synthase blockade and reduced by endothelium removal and apocynin. In endothelium-denuded penile arteries, apocynin blunted augmented ET-1-induced contractions in OZR. Both ETA and ETB receptors were expressed in smooth muscle and the endothelial layer and up-regulated in arteries from OZR. ET-1 stimulates ETA -mediated NADPH oxidase-dependent ROS generation, which inhibits endothelial NO bioavailability and contributes to ET-1-induced contraction in healthy penile arteries. Enhanced vascular expression of ETB receptors contributes to augmented ROS production, endothelial dysfunction and increased vasoconstriction in erectile tissue from insulin-resistant obese rats. Hence, antagonism of ETB receptors might improve the ED associated with insulin-resistant states. © 2014 The British Pharmacological Society.

  19. CGS 8216: receptor binding characteristics of a potent benzodiazepine antagonist.

    PubMed

    Czernik, A J; Petrack, B; Kalinsky, H J; Psychoyos, S; Cash, W D; Tsai, C; Rinehart, R K; Granat, F R; Lovell, R A; Brundish, D E; Wade, R

    1982-01-25

    CGS 8216 is a novel nonbenzodiazepine that inhibited 3H-flunitrazepam (3H-FLU) binding to rat synaptosomal membranes in vitro at subnanomolar concentrations. It prevented the in vivo labeling of brain benzodiazepine receptors by 3H-FLU with the same potency as diazepam when given orally to mice. Pharmacologic tests showed that it was devoid of benzodiazepine-like activity but it antagonized the actions of diazepam in these tests. It did not interact with alpha- or beta- adrenergic, H1-histaminergic or GABA receptors but it inhibited adenosine-activation of cyclic AMP formation. Studies with 3H-CGS 8216 demonstrated that it bound specifically and with high affinity to rat forebrain membranes and was displaced by drugs with an order of potencies similar to that observed when 3H-diazepam and 3H-FLU were used as radioligands. The regional distribution of 3H-CGS 8216 binding sites in the brain was also similar to that of 3H-FLU. Dissociation of 3H-CGS 8216 binding was slow at 0 degrees C but increased with temperature and was almost complete within 1 min at 37 degrees C. Scatchard analyses were linear, yielding KD values of 0.044, 0.11 and 0.18 nM at 0, 25 and 37 degrees C, respectively; the Bmax value did not change appreciably with temperature and was approximately 1000 fmoles/mg protein. Using 3H-FLU, the value for Bmax as well as for the KD increased with temperature. The total number of binding sites determined for 3H-FLU was greater than that for 3H-CGS 8216 at each temperature. CGS 8216 exhibited mixed-type inhibition of 3H-FLU binding. GABA did not stimulate 3H-CGS 8216 binding whereas it enhanced 3H-FLU binding. CGS 8216 may be a useful ligand for probing the antagonist properties of the benzodiazepine receptor and is likely to exhibit interesting therapeutic effects.

  20. Tamoxifen resistant breast cancer: coregulators determine the direction of transcription by antagonist-occupied steroid receptors.

    PubMed

    Takimoto, G S; Graham, J D; Jackson, T A; Tung, L; Powell, R L; Horwitz, L D; Horwitz, K B

    1999-01-01

    Pharmacological antagonists of steroid receptor action had been thought to exert their effects by a passive mechanism driven principally by the ability of the antagonist to compete with agonist for the ligand binding site. However, recent analyses of antagonist-occupied receptor function suggest a more complex picture. Antagonists can be subdivided into two groups, type I, or pure antagonists, and type II, or mixed antagonists that can have variable transcriptional activity based upon differential dimerization and DNA binding properties. This led us to propose that receptor antagonism may not simply be a passive competition for the ligand binding site, but may, in some cases, involve active recruitment of corepressor or coactivator proteins to produce a mixed transcriptional phenotype. We used a yeast two-hybrid screen to identify proteins that interact specifically with antagonist-occupied receptors. Two proteins have been characterized: L7/SPA, a ribosome-associated protein that is localized in both the cytoplasm and nucleus, but with no known extranucleolar nuclear function; and hN-CoR, the human homolog of the mouse thyroid receptor corepressor mN-CoR. In in vivo transcription assays we show that L7/SPA enhances the partial agonist activity of type II mixed antagonists, and that N-CoR and the related corepressor, SMRT, suppresses it. The coregulators do not affect agonists or pure antagonists. Moreover, the net agonist activity seen with mixed antagonists is a function of the ratio of coactivator to corepressor. Based upon these results, we proposed that in breast tumors the inappropriate agonist activity seen with therapeutic antagonists such as tamoxifen is responsible for the hormone-resistant state. To confirm this, we are quantitating coactivator/corepressor ratios in breast tumor cells lines and clinical breast cancers. Results should provide new insights into the mechanisms underlying the progression of breast cancer to hormone resistance, and may

  1. The NK1 receptor antagonist L822429 reduces heroin reinforcement.

    PubMed

    Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

    2013-05-01

    Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects.

  2. The NK1 Receptor Antagonist L822429 Reduces Heroin Reinforcement

    PubMed Central

    Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

    2013-01-01

    Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects. PMID:23303056

  3. Endothelin-1 (ET-1) induces resistance to bortezomib in human multiple myeloma cells via a pathway involving the ETB receptor and upregulation of proteasomal activity.

    PubMed

    Vaiou, Maria; Pangou, Evanthia; Liakos, Panagiotis; Sakellaridis, Nikos; Vassilopoulos, George; Dimas, Konstantinos; Papandreou, Christos

    2016-10-01

    Bortezomib (BTZ) is used for the treatment of multiple myeloma (MM). However, a significant proportion of patients may be refractory to the drug. This study aimed to investigate whether the endothelin (ET-1) axis may act as an escape mechanism to treatment with bortezomib in MM cells. NCI-H929 and RPMI-8226 (human MM cell lines) were cultured with or without ET-1, BTZ, and inhibitors of the endothelin receptors. ET-1 levels were determined by ELISA, while the protein levels of its receptors and of the PI3K and MAPK pathways' components by western blot. Effects of ET-1 on cell proliferation were studied by MTT and on the ubiquitin proteasome pathway by assessing the chymotryptic activity of the 20S proteasome in cell lysates. Endothelin receptors A and B (ETAR and ETBR, respectively) were found to be expressed in both cell lines, with the RPMI-8226 cells that are considered resistant to BTZ, expressing higher levels of ETBR and in addition secreting ET-1. Treatment of the NCI-H929 cells with ET-1 increased proliferation, while co-incubation of these cells with ET-1 and BTZ decreased BTZ efficacy with concomitant upregulation of 20S proteasomal activity. Si-RNA silencing or chemical blockade of ETBR abrogated the protective effects of ET-1. Finally, data suggest that the predominant signaling pathway involved in ET-1/ETBR-induced BTZ resistance in MM cells may be the MAPK pathway. Our data suggest a possible role of the ET-1/ETBR axis in regulating the sensitivity of MM cells to BTZ. Thus, combining bortezomib with strategies to target the ET-1 axis could prove to be a novel promising therapeutic approach in MM.

  4. Endothelin receptor type B gene promoter hypermethylation in salivary rinses independently associates with risk of oral cavity cancer and premalignancy

    PubMed Central

    Pattani, Kavita Malhotra; Zhang, Zhe; Demokan, Semra; Glazer, Chad; Loyo, Myriam; Goodman, Steven; Sidransky, David; Bermudez, Francisco; Jean-Charles, Germain; McCaffrey, Thomas; Padhya, Tapan; Phelan, Joan; Spivakovsky, Silvia; Bowne, Helen Yoo; Goldberg, Judith D.; Rolnitzky, Linda; Robbins, Miriam; Kerr, A. Ross; Sirois, David; Califano, Joseph A.

    2010-01-01

    Endothelin receptor type B (EDNRB) and kinesin family member 1A(KIF1A) are candidate tumor suppressor genes that are inactivated in cancers. In this study we evaluated promoter hypermethylation of EDNRB and KIF1A and their potential use for risk classification in prospectively collected salivary rinses from patients with premalignant/malignant oral cavity lesions. Quantitative methylation-specific PCR(Q-MSP) was performed analyzing methylation status of EDNRB and KIF1A in salivary rinses of 191 patients. We proceeded to determine the association of methylation status with histologic diagnosis and estimate classification accuracy. On univariate analysis, diagnosis of dysplasia/cancer was associated with age and KIF1A or EDNRB methylation. Methylation of EDNRB highly correlated with that of KIF1A(p<0.0001). On multivariable modeling, histologic diagnosis independently associated with EDNRB(p=0.0003) or KIF1A(p=0.027) methylation). A subset of patients analyzed (n=161) without prior biopsy proven malignancy received clinical risk classification based on examination. On univariate analysis, EDNRB and risk classification were associated with diagnosis of dysplasia/cancer, and remained significant on multivariate analysis (EDNRB:p=0.047, risk classification:p=0.008). Clinical risk classification identified dysplasia/cancer with a sensitivity of 71% and specificity of 58%. The sensitivity of clinical risk classification combined with EDNRB methylation improved to 75%. EDNRB methylation in salivary rinses was independently associated with histologic diagnosis of premalignancy and malignancy and may have potential in classifying patients at risk for oral premalignant and malignant lesions in settings without access to a skilled dental practitioner. This may also potentially identify patients with premalignant and malignant lesions that do not meet criteria for high clinical risk based on skilled dental examination. PMID:20798208

  5. Familiar Hypopigmentation Syndrome in Sheep Associated with Homozygous Deletion of the Entire Endothelin Type-B Receptor Gene

    PubMed Central

    Lühken, Gesine; Fleck, Katharina; Pauciullo, Alfredo; Huisinga, Maike; Erhardt, Georg

    2012-01-01

    In humans, rodents and horses, pigmentary anomalies in combination with other disorders, notably intestinal aganglionosis, are associated with variants of the endothelin type-B receptor gene (EDNRB). In an inbred Cameroon sheep flock, five white lambs with light blue eyes were sired from the same ram and died within a few hours up to a few days after birth, some of them with signs of intestinal obstruction. The aim of this study was to investigate if the observed hypopigmentation and a possible lethal condition were associated with a molecular change at the ovine EDNRB locus, and to check if such a genetic alteration also occurs in other Cameroon sheep flocks. Sequence analysis revealed a deletion of about 110 kb on sheep chromosome 10, comprising the entire EDNRB gene, on both chromosomes in the two available hypopigmented lambs and on a single chromosome in the two dams and three other unaffected relatives. This micro-chromosomal deletion was also confirmed by quantitative real-time PCR and by fluorescence in situ hybridization. Genotyping of a total of 127 Cameroon sheep in 7 other flocks by duplex PCR did not identify additional carriers of the deletion. Although both hypopigmented lambs available for post-mortem examination had a considerably dilated cecum and remaining meconium, histopathological examination of intestinal samples showed morphologically normal ganglion cells in appropriate number and distribution. This is to our knowledge the first description of an ENDRB gene deletion and associated clinical signs in a mammalian species different from humans and rodents. In humans and rats it is postulated that the variable presence and severity of intestinal aganglionosis and other features in individuals with EDNRB deletion is due to a variable genetic background and multiple gene interactions. Therefore the here analyzed sheep are a valuable animal model to test these hypotheses in another species. PMID:23300849

  6. Sex differences in endothelin-1-mediated vasoconstrictor tone in middle-aged and older adults.

    PubMed

    Stauffer, Brian L; Westby, Christian M; Greiner, Jared J; Van Guilder, Gary P; Desouza, Christopher A

    2010-02-01

    The prevalence of cardiovascular disease is lower in middle-aged and older women than men. Increased endothelin-1-mediated vasoconstriction has been linked to the etiology of a number of cardiovascular diseases, including atherosclerosis, heart failure, and hypertension. It is unknown whether a sex difference in endothelin-1-mediated vasoconstrictor tone exists in middle-aged and older adults. Therefore, we tested the hypothesis that middle-aged and older men would demonstrate greater ET-1-mediated vasoconstrictor tone than age-matched women. Forearm blood flow in response to intra-arterial infusions of endothelin (ET)-1, BQ-123 (a selective ET(A) receptor antagonist), and BQ-788 (a selective ET(B) receptor antagonist) was assessed by venous occlusion plethysmography in 21 women (age: 58 + or - 1 yr; body mass index: 26.0 + or - 1.0 kg/m(2)) and 25 men (age: 57 + or - 2 yr; body mass index: 26.8 + or - 0.7 kg/m(2)). In response to BQ-123, the increase in forearm blood flow from baseline was significantly higher in the men than the women (24 + or - 5% vs. 9 + or - 5%; P < 0.05). In contrast, the increase in forearm blood flow in response to BQ-123 coinfused with BQ-788 was greater in the women than the men, such that the maximum vasodilation to dual endothelin receptor blockade was similar between men and women (approximately 25%). There was no difference in the vasoconstrictor response to ET-1 between the sexes. These results indicate that middle-aged and older men are under greater ET(A) receptor-mediated vasoconstrictor tone than age-matched women. Since the ET(A) receptor is the predominant receptor subtype in the coronary vasculature, this sex difference in vasoconstrictor tone may be a mechanism contributing to the sex difference in the prevalence of coronary heart disease in middle-aged and older adults.

  7. Discovery of indole alkaloids with cannabinoid CB1 receptor antagonistic activity.

    PubMed

    Kitajima, Mariko; Iwai, Masumi; Kikura-Hanajiri, Ruri; Goda, Yukihiro; Iida, Mitsuru; Yabushita, Hisatoshi; Takayama, Hiromitsu

    2011-04-01

    Three indole alkaloids, voacamine (1), 3,6-oxidovoacangine (2), and a new alkaloid, 5-hydroxy-3,6-oxidovoacangine (3), isolated from Voacanga africana were found to exhibit potent cannabinoid CB1 receptor antagonistic activity. This is the first example of CB1 antagonists derived from natural alkaloids. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Anti-idiotypic antibody: A new strategy for the development of a growth hormone receptor antagonist.

    PubMed

    Lan, Hainan; Zheng, Xin; Khan, Muhammad Akram; Li, Steven

    2015-11-01

    In general, traditional growth hormone receptor antagonist can be divided into two major classes: growth hormone (GH) analogues and anti-growth hormone receptor (GHR) antibodies. Herein, we tried to explore a new class of growth hormone receptor (GHR) antagonist that may have potential advantages over the traditional antagonists. For this, we developed a monoclonal anti-idiotypic antibody growth hormone, termed CG-86. A series of experiments were conducted to characterize and evaluate this antibody, and the results from a competitive receptor-binding assay, Enzyme Linked Immunosorbent Assays (ELISA) and epitope mapping demonstrate that CG-86 behaved as a typical Ab2β. Next, we examined its antagonistic activity using in vitro cell models, and the results showed that CG-86 could effectively inhibit growth hormone receptor-mediated signalling and effectively inhibit growth hormone-induced Ba/F3-GHR638 proliferation. In summary, these studies show that an anti-idiotypic antibody (CG-86) has promise as a novel growth hormone receptor antagonist. Furthermore, the current findings also suggest that anti-idiotypic antibody may represent a novel strategy to produce a new class of growth hormone receptor antagonist, and this strategy may be applied with other cytokines or growth factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Transition strategies from cangrelor to oral platelet P2Y12 receptor antagonists.

    PubMed

    Schneider, David J

    2016-01-01

    Cangrelor is the first parenteral antagonist of the platelet P2Y12 receptor. This direct-acting antagonist of the platelet P2Y12 receptor should be considered an adjunct to a percutaneous coronary intervention in patients who have not been adequately pretreated with platelet P2Y12 receptor antagonists at the time of the procedure. The use of cangrelor requires transition to an oral platelet P2Y12 receptor antagonist. Transition strategies have been developed on the basis of pharmacologic characteristics of platelet P2Y12 receptor antagonists, results of pharmacodynamic studies, and results from clinical trials. Cangrelor blocks the binding to the platelet P2Y12 receptor of the active metabolite of the thienopyridines, clopidogrel and prasugrel. The active metabolite of thienopyridines is present in blood for a short interval after administration. For this reason, clopidogrel should be administered after cangrelor is stopped. Prasugrel can be administered at the end of the cangrelor infusion or up to 30 min before cangrelor is stopped. Ticagrelor is also a reversible direct-acting antagonist of the platelet P2Y12 receptor. Because there is no interaction between ticagrelor and cangrelor, ticagrelor can be administered before or during the infusion of cangrelor.

  10. Sphingosine-1-Phosphate Receptor-2 Antagonists: Therapeutic Potential and Potential Risks

    PubMed Central

    Blankenbach, Kira V.; Schwalm, Stephanie; Pfeilschifter, Josef; Meyer zu Heringdorf, Dagmar

    2016-01-01

    The sphingosine-1-phosphate (S1P) signaling system with its specific G-protein-coupled S1P receptors, the enzymes of S1P metabolism and the S1P transporters, offers a multitude of promising targets for drug development. Until today, drug development in this area has nearly exclusively focused on (functional) antagonists at the S1P1 receptor, which cause a unique phenotype of immunomodulation. Accordingly, the first-in class S1P1 receptor modulator, fingolimod, has been approved for the treatment of relapsing-remitting multiple sclerosis, and novel S1P1 receptor (functional) antagonists are being developed for autoimmune and inflammatory diseases such as psoriasis, inflammatory bowel disease, lupus erythematodes, or polymyositis. Besides the S1P1 receptor, also S1P2 and S1P3 are widely expressed and regulate many diverse functions throughout the body. The S1P2 receptor, in particular, often exerts cellular functions which are opposed to the functions of the S1P1 receptor. As a consequence, antagonists at the S1P2 receptor have the potential to be useful in a contrasting context and different areas of indication compared to S1P1 antagonists. The present review will focus on the therapeutic potential of S1P2 receptor antagonists and discuss their opportunities as well as their potential risks. Open questions and areas which require further investigations will be emphasized in particular. PMID:27445808

  11. Total synthesis of anibamine, a novel natural product as a chemokine receptor CCR5 antagonist.

    PubMed

    Li, Guo; Watson, Karen; Buckheit, Robert W; Zhang, Yan

    2007-05-10

    The total synthesis of anibamine, the first and only natural product known as a chemokine receptor CCR5 antagonist, is reported herein. Anibamine was synthesized from acetylacetone and cyanoacetamide in 10 steps.

  12. Novel morpholine scaffolds as selective dopamine (DA) D3 receptor antagonists.

    PubMed

    Micheli, Fabrizio; Cremonesi, Susanna; Semeraro, Teresa; Tarsi, Luca; Tomelleri, Silvia; Cavanni, Paolo; Oliosi, Beatrice; Perdonà, Elisabetta; Sava, Anna; Zonzini, Laura; Feriani, Aldo; Braggio, Simone; Heidbreder, Christian

    2016-02-15

    A new series of morpholine derivatives has been identified as selective DA D3 receptor antagonists; their in vitro profile and pharmacokinetic data are provided. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. An expedient route to a potent gastrin/CCK-B receptor antagonist (+)-AG-041R.

    PubMed

    Sato, Shigeki; Shibuya, Masatoshi; Kanoh, Naoki; Iwabuchi, Yoshiharu

    2009-10-02

    An enantiocontrolled synthesis of (+)-AG-041R (1), a potent gastrin/CCK-B receptor antagonist, has been achieved employing a chiral rhodium(II)-catalyzed, oxidative intramolecular aza-spiroannulation as the key step.

  14. Crystal structure of human glycine receptor-α3 bound to antagonist strychnine.

    PubMed

    Huang, Xin; Chen, Hao; Michelsen, Klaus; Schneider, Stephen; Shaffer, Paul L

    2015-10-08

    Neurotransmitter-gated ion channels of the Cys-loop receptor family are essential mediators of fast neurotransmission throughout the nervous system and are implicated in many neurological disorders. Available X-ray structures of prokaryotic and eukaryotic Cys-loop receptors provide tremendous insights into the binding of agonists, the subsequent opening of the ion channel, and the mechanism of channel activation. Yet the mechanism of inactivation by antagonists remains unknown. Here we present a 3.0 Å X-ray structure of the human glycine receptor-α3 homopentamer in complex with a high affinity, high-specificity antagonist, strychnine. Our structure allows us to explore in detail the molecular recognition of antagonists. Comparisons with previous structures reveal a mechanism for antagonist-induced inactivation of Cys-loop receptors, involving an expansion of the orthosteric binding site in the extracellular domain that is coupled to closure of the ion pore in the transmembrane domain.

  15. Upregulation of contractile endothelin type B receptors by lipid-soluble cigarette smoking particles in rat cerebral arteries via activation of MAPK

    SciTech Connect

    Sandhu, Hardip; Xu, Cang Bao; Edvinsson, Lars

    2010-11-15

    Cigarette smoke exposure increases the risk of stroke. However, the underlying molecular mechanisms are poorly understood. Endothelin system plays key roles in the pathogenesis of stroke. The present study was designed to examine if lipid-soluble (dimethyl sulfoxide-soluble) cigarette smoke particles (DSP) induces upregulation of contractile endothelin type B (ET{sub B}) receptors in rat cerebral arteries and if activation of mitogen activated protein kinase (MAPK) and nuclear factor-kappaB (NF-{kappa}B) mediate the upregulation of contractile endothelin