UMLS:C0020538 - FACTA Search

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Query: UMLS:C0020538 (hypertension)
170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelin-1 has been shown to contribute to basal vascular tone in man. Since endothelin-1 is a potent vasoconstrictor putatively involved in hypertension, we have compared the contractile responses of endothelin-1 and noradrenaline in relation to potassium chloride in subcutaneous resistance arteries from subjects with established essential hypertension with matched controls. Furthermore, with RT-PCR, the occurrence of mRNA for the ETA and ET(B) receptors was shown in the tunica media layer of subcutaneous arteries in controls and hypertensives. The maximum contractile response to endothelin-1 was significantly higher in the subcutaneous arteries of the hypertensives (by 88% with no change in potency) as compared to controls. The responses to noradrenaline, acetylcholine and potassium chloride did not differ between the groups. This selective increase in the contractile response to endothelin-1 might contribute to the development of essential hypertension.
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PMID:Selective increase of the contractile response to endothelin-1 in subcutaneous arteries from patients with essential hypertension. 1041 77

Endothelins build a peptide family composed of three isoforms, each of them containing 21 amino acids. Endothelin-1 is the isoform mainly responsible for any cardiovascular action and therefore the sole scope of this review. Endothelin-1 is the most potent endogenous vasoconstrictor known; in addition it acts as a potent (co)mitogen. There is a substantial body of experimental evidence that endothelin-1 may contribute not only to sustained vasoconstriction, but also to remodeling within the cardiovascular system. Thus, with the help of endothelin receptor antagonists (available for a few years) the involvement of mainly ETA receptors in structural diseases such as heart failure, pulmonary hypertension, atherosclerosis, restenosis, systemic hypertension, and chronic renal failure has been shown. These data make endothelin receptor antagonists, and especially those selective for the ETA receptor, promising agents for the treatment of chronic cardiovascular diseases associated with remodeling. Currently several chemically distinct, orally available members of this novel class of therapeutic agents are under clinical investigation.
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PMID:Endothelin-1 and endothelin receptor antagonists in cardiovascular remodeling. 1046 Jun 93

In a subset of hypertensive patients, activity of the sympathetic nervous system (SNS) is enhanced. Hypertension is also associated with an adaptative process where small arteries (lumen < 300 microns) are subjected to structural changes (eutrophic or hypertrophic remodeling). Since, it has been shown that norepinephrine (NE) can induced proliferation of vascular smooth muscle cells, the purpose of the present study was to determine the effect of a chronic treatment with NE, mimicking hyperactivity of SNS, on small artery structure. The role of endothelin (ET) in the process was also evaluated. To achieve these goals, control rats were compared with rats receiving NE 2.5 micrograms/kg/min alone or in combination with LU135252 30 mg/kg/d (ET-receptor antagonist, affinity ETA/ETB approximately equal to 100) for 2 weeks. Blood pressure was measured intra-arterially in conscious rats prior to sacrifice. Geometric parameters of the basilar artery were determined in pressurized and perfused conditions with calcium free Krebs solution. Plasma NE and arterial mesenteric ET levels were determined by HPLC and RIA respectively. Blood pressured was not altered following exogenous administration of NE for 2 weeks. However, media thickness increased while the lumen diameter was reduced at the level of the basilar artery, leading to elevated media:lumen ratio (p < 0.05). This morphological alteration was associated with a significant augmentation of the basilar artery cross-sectional area (CSA). Co-administration of LU135252 with NE prevented partially the increase of M/L while the elevation of CSA was completely blunted. Plasma levels of NE were significantly and similarly elevated in groups receiving NE but, interestingly, mesenteric ET levels were not modified by any treatment. These results suggest that chronic NE administration induced an hypertrophic inward remodeling of small arteries independently from blood pressure, which required the participation of ET as an obligatory intermediate. Furthermore, the local production of ET is probably enhanced transiently in the first days of NE administration and come back to control level at 2 weeks. Thus, early therapy initiation with an ET-receptor antagonist prevents vascular remodeling in conditions of SNS hyperactivity, which may contribute to lower risks of end-organ damage.
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PMID:[Role of endothelin in the hypertrophic remodeling of small arteries induced by exogenous norepinephrine]. 1048 65

The renin-angiotensin-aldosterone (RAA) system and the endothelin (ET) system entail the most potent vasopressor mechanisms identified to date. Although they were studied in depth in relation to arterial hypertension and cardiovascular diseases, limited information on their interrelationships in causing hypertension and related target organ damage exists. The identification of consensus sequences for jun in the regulatory region of the preproendothelin-1 (ppET-1) gene raised the possibility of its transcriptional regulation by angiotensin II (Ang II). This was confirmed by the finding that stimulation with Ang II of cultured vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) induced expression of the ppET-1 gene and synthesis of ET-1. Endogenously produced ET-1 was found to contribute to the hypertrophic response of cardiomyocytes to Ang II and thereby to cardiac hypertrophy. Furthermore, ET-1 exerts multifaceted effects on the RAA system, such as dose-dependent inhibition of renin synthesis, and stimulation of aldosterone secretion. The finding of abundant specific ET-1 receptors in the adrenocortical zona glomerulosa (ZG) suggested a direct secretagogue effect of ET-1. In rats, ETB receptors mediate such an effect, whilst in humans, both ETA and ETB receptor subtypes intervene in regulating the transcription of the aldosterone synthase gene. In addition, ET-1 stimulates DNA synthesis and proliferation of ZG cells via ETA receptors and, therefore, might play a role in cell turnover of the normal adrenal cortex and in the onset of adrenal tumours. Studies on the in vivo interactions between ETs and the RAA system have given conflicting results, insofar as some suggested a participation of ET-1 in the pressor and cellular effects of exogenously administered Ang II, whereas others did not in the transgenic TGR(Ren 2m)27 rats and in the two-kidney, one clip.
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PMID:Interactions between endothelin-1 and the renin-angiotensin-aldosterone system. 1069 Mar 21

Endothelin (ET) -1 is a potent vasoconstrictor and promitogenic peptide produced by the vascular endothelium. The ET system is activated in atherosclerosis and in most cardiovascular conditions associated with increased vascular tone and remodelling. There are two ET-receptor (ET-R) subtypes: the ETA-Rs mediate smooth muscle vasoconstriction and proliferation, and the more complex ETB-Rs have antagonistic actions - they serve a dual role of clearance and vasodilation in the endothelium, while in smooth muscle cells they also provoke vasoconstriction. Selective ETA-R and nonselective ETA/B-R antagonists are entering the clinical development phase. These agents have shown their effectiveness in the therapy of various models of heart failure, pulmonary hypertension, systemic hypertension and ischemia-reperfusion and in the prevention of restenosis. In patients with congestive heart failure, short term ET-antagonist (ET-R) therapy provides hemodynamic and symptomatic improvement. Because of the dual role of the ETB-R, nonselective antagonists may provide greater or fewer benefits than selective ETA-R antagonists: a lack of direct comparison of the two categories of agents, however, does not allow this distinction at present. In the evaluation of this new class of therapeutic agents, particular attention should be paid to potency and receptor selectivity of a compound, the alterations in ETA-R and ETB-R activity brought on by pathological conditions, the proportions of ETA versus ETB-R of the target system, and finally, the net importance of the possible protective role of the endothelial ETB versus the deleterious effects of the smooth muscle ETB-R.
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PMID:Endothelin receptor antagonists and their developing role in cardiovascular therapeutics. 1093 9

Endothelins (ET) comprise a group of substances which are produced and have regulatory functions in different systems of the organism. The main cardiovascular ET is ET-1 which is so far the most potent vasoconstrictor substance. In the pathophysiology of cardiac insufficiency ET-1 promotes cardiac hypertrophy, is involved in vasoconstriction, delayed relaxation and reduced left ventricular contractility. The ET-1 level correlates with pulmonary vascular hypertension. By vasoconstriction of renal arteries ET leads to volume retention. Big-ET is a very efficient neurohumoral marker in the diagnosis of developed cardiac failure which can lead to more accurate prognostic stratification. ET-1 is probably important for assessment of the diagnosis of cardiac insufficiency only in severe cardiac failure. The favourable effect of ET block in cardiac insufficiency was proved for the non-selective ETA/ETB blocker and selective ETA blocker. The selective ETB blocker has an adverse haemodynamic effect in treatment of heart failure but by suppression of aldosterone it can prevent fluid retention. In the treatment of cardiac failure blockers of endothelin converting enzyme seem perspective as they reduce adversely activated neurohumoral factors.
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PMID:[Endothelins and chronic cardiac insufficiency]. 1095 66

We assessed the role of angiotensin (Ang) II type 1 receptor (AT1) and endothelin type A and B (ETA & ETB) receptor in cardiovascular hypertrophy associated with angiotensin II-induced hypertension (200 ng/kg.min s.c. for 10 or 17 days). Antagonism of AT1 receptors was obtained by oral administration of losartan (10 or 30 mg/kg.day) and blockade of ETA and ETB receptors was obtained by oral administration of bosentan (30 mg/kg.day). Losartan and bosentan were administered 24 h before and during the 10 days of angiotensin II (prevention) or they were given after the development of hypertension i.e. from day 10 to 17 of angiotensin II (treatment). Tail-cuff pressure (TCP) was measured before and at the end of the period of administration of antagonists. At the end of experiments, cross sectional area (CSA, mm2) of the carotid was measured after perfusion and fixation at 100 mmHg and heart weight index (HWI, mg/g body weight) was determined. Results are mean +/- SEM. [table: see text] In addition to its blood pressure lowering effect, both doses of losartan prevented and reversed the cardiovascular hypertrophy induced by angiotensin II. Similarly, bosentan prevented and reversed the effect of angiotensin II on cardiovascular structure independently of arterial pressure. These results indicate that the effect of angiotensin II on blood pressure, heart and carotid structure is exclusively mediated by AT1 receptors. The influence of bosentan suggests that endothelin plays an important role in local action of angiotensin II independently of blood pressure level.
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PMID:[Cardiac and vascular hypertrophy in hypertension due to angiotensin II. Effect of losartan and bosentan]. 1098 42

The role of angiotensin-II (Ang-II) and endothelin-1 (ET-1) in the development of hypertension and zona glomerulosa (ZG) hyperfunction in the transgenic rat strain TGR[mREN2]27 (TGR) has been investigated. Male heterozygous TGR were given per os for 4 weeks the Ang-II ATI receptor antagonist irbesartan (50 mg/kg x day) or the mixed ETA/ETB receptor antagonist bosentan (100 mg/kg x day). A group of TGR received a placebo gavage. Irbesartan lowered blood pressure (BP), while bosentan was ineffective. Conversely, both antagonists decreased plasma aldosterone concentration, the volume of ZG and its parenchymal cells, and in vitro aldosterone secretion by capsule-ZG preparations. Collectively, our results allow us to conclude that (i) only Ang-II is involved in the genesis of hypertension in TGR, while both endogenous Ang-II and ET-1 play a role in the genesis of ZG hyperfunction; and (ii) hyperaldosteronism does not contribute significantly to the development of hypertension in TGR.
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PMID:Effects of irbesartan and bosentan on the blood pressure and adrenal zona glomerulosa function in heterozygous transgenic TGR[mREN2]27 rats. 1099 19

The renin-angiotensin system (RAS) and endothelin system may both play a role in the pathogenesis of progressive renal injury. The aims of the present study were 3-fold: first, to explore the possible benefits of dual blockade of the RAS with an ACE inhibitor and an angiotensin type 1(AT1) receptor antagonist; second, to examine the relative efficacy of endothelin A receptor antagonism (ETA-RA) compared with combined endothelin A/B receptor antagonism (ETA/B-RA); and third, to assess whether interruption of both RAS and endothelin system had any advantages over single-system blockade. Subtotally nephrectomized rats were studied as a model of progressive renal injury and randomly assigned to one of the following treatments for 12 weeks: perindopril (ACE inhibitor), irbesartan (AT1 receptor antagonist), BMS193884 (ETA-RA), bosentan (ETA/B-RA), and a combination of irbesartan with either perindopril or BMS193884. Treatment with irbesartan or perindopril was associated with an improved glomerular filtration rate and reductions in blood pressure, urinary protein excretion, glomerulosclerosis, and tubular injury in association with reduced gene expression of transforming growth factor-beta(1) and matrix protein type IV collagen. The combination of irbesartan with perindopril was associated with further reductions in blood pressure and urinary protein excretion. No beneficial effects of either BMS193884 or bosentan were noted. Furthermore, the addition of BMS193884 to irbesartan did not confer any additional benefits. These findings suggest that the RAS but not the endothelin system is a major mediator of progressive renal injury after renal mass reduction and that the combination of an AT1 receptor antagonist with an ACE inhibitor may have advantages over the single agent of RAS blocker treatment.
Hypertension 2000 Oct
PMID:Blockade of the renin-angiotensin and endothelin systems on progressive renal injury. 1135 55

The single oral administration of a mixed endothelin-A-and -B- (ETA/ETB) receptor antagonist, J-104132 (L-753,037) decreased the blood pressure in conscious spontaneously hypertensive rats (SHR), stroke-prone SHR (SHRSP) and Dahl salt-sensitive hypertensive rats fed high-salt diet (DS-H) at doses of 3 and 10 mg/kg, with a duration of approximately 24 h. The magnitude of the antihypertensive effects was greater in DS-H than in SHR and SHRSP Preproendothelin-1 mRNA expression in the kidney and aorta was greater (about twofold) in DS-H than that in nonnotensive Dahl salt-resistant rats fed high-salt diet (DR-H), while there was no difference in preproendothelin-1 mRNA expression between SHR and Wistar Kyoto rats (WKY). An AT1-receptor antagonist, MK-954 (Losartan), also attenuated hypertension in SHR and SHRSP at oral doses of 3 and 10 mg/kg, but bad no effect in DS-H. The concomitant treatment with MK-954 and J-104132 showed additive antihypertensive effects in SHR and SHRSP. In DS-H, MK-954 potentiated the antihypertensive effects of J-104132. From these results, we suggest that: (1) the contribution of endothelin (ET) to the maintenance of hypertension is greater in salt-sensitive hypertensive models than in SHR and SHRSP; (2) the antihypertensive efficacy of ETA/ETB blockade is augmented by AT1-receptor blockade; (3) ET blockers alone or in combination with AT1 antagonists could be useful in the treatment of hypertension for patients who do not respond adequately to renin-angiotensin system inhibitors alone.
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PMID:Antihypertensive effects of a mixed endothelin-A- and -B-receptor antagonist, J-104132, were augmented in the presence of an AT1 -receptor antagonist, MK-954. 1107 14

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