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  • 1
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 35, No. 1 ( 2000-01), p. 329-336
    Abstract: Abstract —In the C57BL/6J mice model, we investigated whether obesity affects the function or expression of components of the tissue renin-angiotensin system and whether endothelin (ET)-1 contributes to these changes. ACE activity (nmol · L His-Leu · mg protein −1 ) was measured in lung, kidney, and liver in control (receiving standard chow) and obese animals treated for 30 weeks with a high-fat, low cholesterol diet alone or in combination with LU135252 , an orally active ET A receptor antagonist. ACE mRNA expression was measured in the kidney, and the effects of LU135252 on purified human ACE were determined. Aortic and renal tissue ET-1 protein content was measured, and the vascular contractility to angiotensin II was assessed. Obesity was associated with a tissue-specific increase in ACE activity in the kidney (55±4 versus 33±3 nmol/L) but not in the lung (34±2 versus 32±2 nmol/L). Long-term LU135252 treatment completely prevented this activation (13.3±0.3 versus 55±4 nmol/L, P 〈 0.05) independent of ACE mRNA expression, body weight, or renal ET-1 protein but did not affect pulmonary or hepatic ACE activity. Obesity potentiated contractions in response to angiotensin II in the aorta (from 6±2% to 33±5% KCl) but not in the carotid artery (4±1% to 3.6±1% KCl), an effect that was completely prevented with LU135252 treatment (6±0.4% versus 33±5% KCl). No effect of LU135252 on purified ACE was observed. Thus, obesity is associated with the activation of renal ACE in vivo independent of its mRNA expression and enhanced vascular contractility to angiotensin II. These effects are regulated by ET in an organ-specific manner, providing novel mechanisms by which ET antagonists may exert organ protection.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2000
    detail.hit.zdb_id: 2094210-2
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  • 2
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 1997
    In:  Hypertension Vol. 29, No. 1 ( 1997-01), p. 435-441
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 29, No. 1 ( 1997-01), p. 435-441
    Abstract: Angiotensin II, a constrictor and mitogen of vascular smooth muscle cells, affects the release of endothelium-derived factors such as nitric oxide or endothelin-1. This study investigated the influence of endothelin-1, using the selective endothelin A receptor antagonist LU135252 , on blood pressure and endothelial function in angiotensin II-induced hypertension in the rat. Two weeks of angiotensin II administration (200 ng/kg per minute) increased systolic blood pressure (+35±5 mm Hg; tail-cuff method) compared with placebo ( P 〈 .05). LU135252 alone did not affect systolic pressure but lowered the angiotensin II-induced pressure increase ( P 〈 .05). In isolated aortic rings, endothelium-dependent relaxations to acetylcholine were reduced in the angiotensin II group ( P 〈 .05 versus placebo) and improved by concomitant chronic LU135252 treatment ( P 〈 .05 versus angiotensin II). Blood pressure elevation strongly correlated with impaired endothelium-dependent relaxations to acetylcholine ( r =−.967). LU135252 did not affect endothelium-independent relaxations to sodium nitroprusside, which were diminished after angiotensin II treatment ( P 〈 .05). In quiescent rings, chronic angiotensin II administration enhanced endothelium-dependent contractions to acetylcholine, which were reduced by LU135252 ( P 〈 .05). Impaired contractions to endothelin-1 and norepinephrine in the angiotensin II group were normalized after treatment with LU135252 ( P 〈 .05). Thus, chronic therapy with LU135252 partially prevents angiotensin II-induced hypertension and the alternations of the endothelial function observed in this experimental model.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1997
    detail.hit.zdb_id: 2094210-2
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  • 3
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 1998
    In:  Journal of Cardiovascular Pharmacology Vol. 31 ( 1998), p. S265-S268
    In: Journal of Cardiovascular Pharmacology, Ovid Technologies (Wolters Kluwer Health), Vol. 31 ( 1998), p. S265-S268
    Type of Medium: Online Resource
    ISSN: 0160-2446
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1998
    detail.hit.zdb_id: 2049700-3
    SSG: 15,3
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  • 4
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 1997
    In:  Circulation Vol. 96, No. 5 ( 1997-09-02), p. 1593-1597
    In: Circulation, Ovid Technologies (Wolters Kluwer Health), Vol. 96, No. 5 ( 1997-09-02), p. 1593-1597
    Abstract: Background In vitro studies on vascular smooth muscle cells suggest that endothelin has a stimulating effect on cellular proliferation. This study was designed to determine the endogenous effect of endothelin on angiotensin II–induced hypertrophy of small arteries in vivo. Methods and Results Two weeks of angiotensin II administration (200 ng·kg −1 ·min −1 ) increased media thickness, media/lumen ratio, and cross-sectional area of basilar and small mesenteric arteries, confirming the proliferative properties of angiotensin II. The tissue levels of endothelin-1 were elevated in mesenteric arteries after angiotensin II administration. The administration of the selective and specific ET A -receptor antagonist LU135252 (50 mg·kg −1 ·d −1 ) in combination with angiotensin II prevented the changes of vascular geometry and partially reduced the increase in blood pressure induced by angiotensin II. Indeed, part of the effect on the vascular structure of the endothelin-receptor antagonist seemed pressure-independent. Conclusions Our results therefore demonstrate that angiotensin II increases the production of endothelin in the blood vessel wall that, via ET A receptors, mediates changes in vascular structure of the cerebral and mesenteric circulation. Endothelin antagonists may therefore be of value to reduce blood pressure and to prevent vascular structural changes in conditions of increased activity of the renin-angiotensin system.
    Type of Medium: Online Resource
    ISSN: 0009-7322 , 1524-4539
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1997
    detail.hit.zdb_id: 1466401-X
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  • 5
    In: Biochemical and Biophysical Research Communications, Elsevier BV, Vol. 238, No. 3 ( 1997-09), p. 861-865
    Type of Medium: Online Resource
    ISSN: 0006-291X
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1997
    detail.hit.zdb_id: 1461396-7
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 2000
    In:  Journal of Cardiovascular Pharmacology Vol. 35 ( 2000), p. S55-S59
    In: Journal of Cardiovascular Pharmacology, Ovid Technologies (Wolters Kluwer Health), Vol. 35 ( 2000), p. S55-S59
    Type of Medium: Online Resource
    ISSN: 0160-2446
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2000
    detail.hit.zdb_id: 2049700-3
    SSG: 15,3
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  • 7
    Online Resource
    Online Resource
    Ovid Technologies (Wolters Kluwer Health) ; 1997
    In:  Hypertension Vol. 30, No. 4 ( 1997-10), p. 905-911
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 30, No. 4 ( 1997-10), p. 905-911
    Abstract: Abstract The involvement of endothelin in salt-induced hypertension is unclear. In the Dahl rat model, we studied the effects of a selective endothelin-subtype A (ET A ) receptor antagonist, LU135252 , on blood pressure, vascular structure, and function. Dahl salt-sensitive and salt-resistant rats were treated for 8 weeks with 4% NaCl alone or in combination with LU135252 taken orally (60 mg/kg per day). The geometry and reactivity of basilar and mesenteric arteries were studied in vitro under perfused and pressurized conditions using a video dimension analyzer. Chronic salt administration increased systolic blood pressure by 37±3 mm Hg and media-lumen ratio of the basilar and mesenteric arteries in salt-sensitive rats ( P 〈 .05). These structural changes were caused by eutrophic remodeling in basilar and hypertrophic remodeling in mesenteric arteries. Endothelium-dependent relaxations to acetylcholine and contractions to endothelin-1 were impaired in mesenteric arteries of salt-sensitive rats on a high NaCl diet. LU135252 prevented part of the increase in systolic blood pressure and structural and functional alterations but increased plasma endothelin 1 levels ( P 〈 .05 versus salt-treated, salt-sensitive rats). LU135252 had no effect on these parameters in salt-resistant rats. These findings suggest that the long-term pressor effect of salt administration is mediated in part by the action of endogenous endothelin acting via ET A receptors. Thus, chronic ET A receptor blockade may be useful therapeutically to lower arterial pressure and prevent endothelial dysfunction and hypertrophic remodeling of resistance arteries in salt-sensitive forms of hypertension.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1997
    detail.hit.zdb_id: 2094210-2
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  • 8
    In: Hypertension, Ovid Technologies (Wolters Kluwer Health), Vol. 31, No. 1 ( 1998-01), p. 499-504
    Abstract: Sodium plays an important role in the pathogenesis and therapy of hypertension, a major risk factor for cardiovascular disease. This study investigated the involvement of endothelin in vascular alterations in salt-induced Dahl hypertension. Salt-sensitive (DS) and salt-resistant (DR) Dahl rats were treated with a high-sodium diet (NaCl 4%) with or without ET A receptor antagonist LU135252 for two months, and effects of treatments on systolic blood pressure, vascular endothelin-1 (ET-1) protein content, aortic hypertrophy, and vascular reactivity of isolated aortic rings were studied. In DS rats, a high-sodium diet increased systolic pressure (190±4 versus 152±2 mm Hg, P 〈 .05) and aortic ET-1 protein content (4.2-fold, P 〈 .0001) and induced aortic hypertrophy as assessed by tissue weight ( P 〈 .0001). Sodium diet markedly reduced NO-mediated endothelium-dependent relaxations to acetylcholine (49±4% versus 81±4%, P 〈 .0001) and contractions to ET-1 (92±7 versus 136±8% of KCl, P =.0011). ET-1 tissue levels were highly and inversely correlated with endothelium-dependent relaxations ( r =0.931, P 〈 .0001) and contractions to ET ( r =0.77, P =.0007). LU135252 treatment reduced systolic blood pressure only in part (168±3 versus 190±4 mm Hg. P 〈 .05) but normalized sodium-induced changes of vascular reactivity, tissue ET-1 protein content, and vascular structure ( P 〈 .001 versus sodium). None of these effects were observed in DR rats. These results suggest that ET-1 acts as a local mediator of vascular dysfunction and aortic hypertrophy in Dahl salt-induced hypertension. ET A receptor antagonism may have therapeutic potential for lowering vascular ET-1 content, improving endothelial function, and preventing structural changes in salt-sensitive hypertension.
    Type of Medium: Online Resource
    ISSN: 0194-911X , 1524-4563
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1998
    detail.hit.zdb_id: 2094210-2
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  • 9
    In: Nephrology Dialysis Transplantation, Oxford University Press (OUP), Vol. 16, No. 6 ( 2001-06-01), p. 1176-1182
    Type of Medium: Online Resource
    ISSN: 1460-2385 , 0931-0509
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2001
    detail.hit.zdb_id: 1465709-0
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  • 10
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 24 ( 1998-11-24), p. 14367-14372
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 24 ( 1998-11-24), p. 14367-14372
    Abstract: This study investigated whether endothelin-1 (ET-1), a potent vasoconstrictor, which also stimulates cell proliferation, contributes to endothelial dysfunction and atherosclerosis. Apolipoprotein E (apoE)-deficient mice and C57BL/6 control mice were treated with a Western-type diet to accelerate atherosclerosis with or without ET A receptor antagonist LU135252 (50 mg/kg/d) for 30 wk. Systolic blood pressure, plasma lipid profile, and plasma nitrate levels were determined. In the aorta, NO-mediated endothelium-dependent relaxation, atheroma formation, ET receptor-binding capacity, and vascular ET-1 protein content were assessed. In apoE-deficient but not C57BL/6 mice, severe atherosclerosis developed within 30 wk. Aortic ET-1 protein content ( P 〈 0.0001) and binding capacity for ET A receptors was increased as compared with C57BL/6 mice. In contrast, NO-mediated, endothelium-dependent relaxation to acetylcholine (56 ± 3 vs. 99 ± 2%, P 〈 0.0001) and plasma nitrate were reduced (57.9 ± 4 vs. 93 ± 10 μmol/liter, P 〈 0.01). Treatment with the ET A receptor antagonist LU135252 for 30 wk had no effect on the lipid profile or systolic blood pressure in apoE-deficient mice, but increased NO-mediated endothelium-dependent relaxation (from 56 ± 3 to 93 ± 2%, P 〈 0.0001 vs. untreated) as well as circulating nitrate levels (from 57.9 ± 4 to 80 ± 8.3 μmol/liter, P 〈 0.05). Chronic ET A receptor blockade reduced elevated tissue ET-1 levels comparable with those found in C57BL/6 mice and inhibited atherosclerosis in the aorta by 31% without affecting plaque morphology or ET receptor-binding capacity. Thus, chronic ET A receptor blockade normalizes NO-mediated endothelial dysfunction and reduces atheroma formation independent of plasma cholesterol and blood pressure in a mouse model of human atherosclerosis. ET A receptor blockade may have therapeutic potential in patients with atherosclerosis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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