UMLS:C0020538 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

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

The aim of this study was to evaluate the effect of synthetic human/porcine endothelin (ET-1) on mean arterial blood pressure (MAP) in pregnant and non-pregnant rats and to compare this to the effects of two well characterized agonists, angiotensin II (AII), and vasopressin (VP). On day 14 of gestation (parturition day 22) polyethylene catheters were chronically implanted in the abdominal aorta for monitoring of MAP and in the vena cava for administration of drugs. Pressor responsiveness was measured in conscious freely moving animals on day 20 and again on the 7th day post-partum. All three agonists increased MAP in a dose related manner. However, whereas the sensitivity of pregnant rats (P) to AII and VP was significantly blunted compared to postpartal (PP) measurements, the MAP responses to ET-1 were the same in both groups. Moreover, the combined administration of ET-1 at a subpressor dose (0.05 pmol/100 g bw) and AII or VP at effective doses significantly potentiated (particularly in P) the pressor effects of AII and VP. These results demonstrate that ET-1 and possibly other vasoactive substances of endothelial origin, override the compensatory mechanism of normal pregnancy with respect to the blunted responsiveness to AII and VP. Such a mechanism may be of particular relevance in the evolution of pregnancy-induced hypertension.
...
PMID:Pressor responsiveness to endothelin is not attenuated in gravid rats. 225 May 62

Previous work has shown that the plasma levels of the potent vasoactive peptide endothelin (ET) are increased in pathophysiological conditions with increased pulmonary vascular resistance and it has been speculated that ET may play some part in hypoxic pulmonary hypertension. We have therefore evaluated the effects of ET-infusion in the porcine pulmonary circulation after hypoxia-induced hypertension. Pits under general anaesthesia were artificially ventilated through an endotracheal tube and hypoxia was induced by decreasing the fraction inhaled O2 from 0.21 to 0.10. Haemodynamic parameters were continuously recorded using a Swan-Ganz catheter in combination with thermodilution for cardiac output measurements. ET-1 or ET-3 was given as an i.v. infusion through the Swan-Ganz catheter in the right ventricle. Hypoxia induced a reproducible increase in pulmonary vascular resistance (PVR), mean pulmonary artery pressure (MPAP) and right ventricular stroke work (RVSW) while the systemic vascular resistance (SVR) slightly decreased. Cumulative infusion of ET-1 (10, 25 and 50 ng kg-1 min-1) dose-dependently decreased MPAP and PVR; at a higher dose (100 ng kg-1 min-1), the PVR returned to the level observed at hypoxia. ET-infusions at 50 and 100 ng kg-1 min-1 evoked an increase in SVR and a decrease in cardiac output (CO) and stroke volume (SV). RVSW also gradually decreased during ET-1 infusion. Infusion of ET-3 evoked effects similar to those of ET-1 infusions, although the response to ET-3 was not that rapid in onset. In a second series of animals, repeated 15 min periods of hypoxia evoked a stable, reproducible response with a consistent increase in PVR, MPAP and RVSW which returned to baseline values during normoxia. Infusion of ET-1 (25 ng kg-1 min-1) evoked a rapidly developing decrease in PVR and MPAP which was quickly normalized upon cessation of the ET-infusion. ET-1 infusion at this concentration did not per se influence the haemodynamic parameters during normoxia. It is concluded that in the pig, short-term ET-infusion reduces the pulmonary hypertension associated with acute hypoxia.
...
PMID:Endothelin infusion reduces hypoxic pulmonary hypertension in pigs in vivo. 748 75

The purpose of this study was to characterize the receptor(s) and second messenger systems involved in prostacyclin (prostaglandin [PG] I2) synthesis elicited by endothelin (ET)-1 in the rat aorta. PGI2 synthesis, measured as immunoreactive 6-keto-PGF1 alpha, was assessed in aortic rings exposed to endothelin receptor agonists in the presence and absence of selective ETA and ETB receptor antagonists. ET-1, which has equal affinity for both endothelin receptor subtypes, and ET-3, a preferential ETB receptor agonist, enhanced 6-keto-PGF1 alpha synthesis in a time- and concentration-dependent manner. ET-1 was more potent than ET-3 in increasing 6-keto-PGF1 alpha synthesis. Moreover, the selective ETB receptor agonists IRL-1620 and sarafotoxin S6c did not significantly increase 6-keto-PGF1 alpha synthesis. Furthermore, ET-1-induced 6-keto-PGF1 alpha synthesis was attenuated by an ETA receptor antagonist, BQ-123, in a dose-dependent manner but not by an ETB receptor antagonist, BQ-788. Depletion of extracellular Ca2+ or addition of Ca2+ channel blockers (nifedipine, verapamil, SK&F 96365) attenuated ET-1-mediated 6-keto-PGF1 alpha synthesis, while a Ca2+ channel agonist, S(-)-Bay K 8644, potentiated this effect of ET-1. Selective protein kinase C inhibitors (bisindolylmaleimide I, calphostin C) did not alter ET-1-induced 6-keto-PGF1 alpha synthesis. These data suggest that PGI2 synthesis elicited by ET-1 in the rat aorta is mediated primarily through influx of extracellular Ca2+ via activation of an ETA receptor and is independent of protein kinase C.
Hypertension 1995 Dec
PMID:Prostacyclin synthesis elicited by endothelin-1 in rat aorta is mediated by an ETA receptor via influx of calcium and is independent of protein kinase C. 749 63

The role of different endothelin (ET) receptors in the hemodynamic action of ET-1 was investigated with an ETA-receptor antagonist, BQ-123, in anesthetized Wistar rat. BQ-123 (10 mg/kg/0.1 ml) was injected 5 min before ET-1 injection (1 nmol/kg). IV injection of ET-1 induced a short period of hypotension associated with aortic vasodilation, followed by long-lasting hypertension and aortic vasoconstriction. These effects were concomitant with immediate renal and mesenteric vasoconstriction. In the presence of BQ-123, the hypotension and aortic vasodilation induced by ET-1 were prolonged and the subsequent hypertension and aortic constriction were prevented. In the renal vascular bed, BQ-123 did not significantly affect the initial ET-1-induced constriction but markedly shortened its duration. In contrast, in the mesenteric vascular bed, BQ-123 seemed initially to amplify the ET-1-induced constriction, but afterwards slightly reduced it. The hemodynamic response to ET-1 may be mediated at first by ETB receptors, which induce a reduction of systemic blood pressure and regional vasoconstriction. In a second phase, ETA receptors operate to induce a systemic pressor effect and participate with ETB receptors in regional vasoconstriction. Therefore, ETA and ETB receptors may exist in various proportions in different vessels, the renal vascular bed appearing to be richer in ETA receptors than the mesenteric bed. The results, which demonstrate that ETB receptors mediate aortic dilation and regional constriction, are unexpected and suggest the existence of another non-ETA-type receptor and/or a different localization of non-ETA receptors in the vascular wall.
...
PMID:Implication of different endothelin receptors in the vascular action of a hypertensive dose of ET-1 in rat. 750 55

Review article informs about the physiological and pathophysiological effects of the most potent vasoconstrictor agent endothelin (ET). This vasoactive polypeptide (21-aminoacid) has three izoforms (ET-1, ET-2, ET-3) and participates on regulation of the vascular tone and on remodelling of the vascular and myocardial wall. Article is focused on the effects of endothelins on the cardiovascular system, kidney and the central nervous system with respect to their expected role in the initiation and sustaining of disorders and diseases accompanied by the local and general vasconstriction. Findings concerning the role of endothelins in the pathogenesis of arterial hypertension, myocardial infarction, congestive heart failure, atherosclerosis, shock conditions, renal failure, and vasospasm following the subarachnoidhem orrage are discussed.
...
PMID:[Endothelin--a cardiovascular regulatory peptide. II. Outline of its pathophysiologic activity]. 758 20

Studies on the effect of antihypertensive agents on resistance arteries in hypertensive patients have in the past yielded inconclusive results regarding the ability of these drugs to induce a regression toward normal of either the structure or the function of these critically important vessels. We have recently compared the effects of the angiotensin-I-converting enzyme inhibitor cilazapril and of the beta blocker atenolol on the structure and the function of subcutaneous resistance arteries of essential hypertensive patients. The patients were randomly assigned to receive either cilazapril or atenolol for a period of 2 years. The blood pressure was normalized for the duration of the trial by both drugs. The media-to-lumen ratio of resistance arteries, which was significantly increased in all hypertensive patients before starting treatment, was normalized by the 2-year treatment with cilazapril, whereas treatment with atenolol did not result in any change in this vascular parameter. Treatment with cilazapril also returned to normal the contractile responses to several vasoconstrictors, particularly endothelin 1. Endothelium-dependent relaxation responses of blood vessels to acetylcholine were abnormal in hypertensive patients and improved in the cilazapril-treated patients, but remained unchanged in the atenolol-treated ones. We conclude that treatment with the angiotensin-I-converting enzyme inhibitor cilazapril corrects in part the vascular remodeling and the functional abnormalities of resistance arteries of hypertensive patients, whereas treatment with the beta blocker atenolol does not. These results may indicate that treatment with cilazapril and perhaps with other angiotensin-I-converting enzyme inhibitors as well may improve the clinical outcome in hypertension by inducing a regression of abnormal resistance vessel structure and function.
...
PMID:Remodeling of resistance arteries in human hypertension: effects of cilazapril, an angiotensin-I-converting enzyme inhibitor. 761 1

Systemic hypertension has been reported to develop, or to worsen, in 20-30% of patients treated with recombinant human erythropoietin (r-HuEPO) worldwide. The greatest increases in blood pressure affect day-time systolic and night-time diastolic blood pressure. Hypertension may develop in some patients as early as 2 weeks and in others as late as 4 months after the start of r-HuEPO treatment. In haemodialysis patients with systemic hypotension, r-HuEPO usually induces a 10% increase in blood pressure, with no significant change in the frequency of hypotensive episodes. Several risk factors for the development, or worsening, of hypertension after r-HuEPO therapy have been identified. They include the presence of pre-existing hypertension, rapid increase in haematocrit, a low baseline haematocrit before r-HuEPO administration, high doses and i.v. route of administration, the presence of native kidneys, a genetic predisposition to hypertension, and possibly a younger age. There are several potential mechanisms by which r-HuEPO therapy may increase blood pressure in haemodialysis patients. They include increased blood viscosity; the loss of hypoxic vasodilation; the activation of neurohumoral systems (catecholamines, the renin-angiotensin system); and especially a direct vascular effect. This last mechanism is supported by several data, and many factors may be involved in its pathogenesis (an increased cell calcium uptake; an imbalance in local vasoactive agents, with increased synthesis of ET-1; a mitogenic effect; and a platelet-dependent mechanism).
...
PMID:Erythropoietin and systemic hypertension. 764 10

1. The effects of the non-selective endothelin (ET) receptor (ETA/ETB) antagonist, bosentan, on sciatic nerve dysfunction in experimental diabetes were investigated. 2. Rats with 5-6 weeks untreated streptozotocin-diabetes exhibited characteristic slowed motor nerve conduction velocity (mean +/- s.d., 36.6 +/- 3.4 m s-1) and nerve laser Doppler flux (197 +/- 64 arbitrary units) compared to age-matched control animals (42.7 +/- 2.4 m s-1 and 398 +/- 77 arbitrary units, respectively). Preventative treatment of diabetic rats with bosentan at 100 mg kg-1 day-1 p.o. attenuated both these deficits (39.7 +/- 3.0 m s-1 and 305 +/- 56 arbitrary units, respectively) without affecting mean arterial pressure. 3. In control and untreated diabetic rats, ET-1, 1 nmol kg-1 i.v., caused an initial hypotension (duration, 30 +/- 13 and 26 +/- 9 s, respectively; change in mean arterial pressure, -27 +/- 13 and -25 +/- 7 mmHg, respectively) followed by prolonged hypertension (change in mean arterial pressure, 52 +/- 18 and 31 +/- 5 mmHg, respectively). Effectiveness of the chronic bosentan treatment was demonstrated by inhibition of the hypotensive response to ET-1 in treated diabetic rats (duration, 5 +/- 2 s; change in mean arterial pressure, -4 +/- 2 mmHg) although the hypertension was unaltered (change in mean arterial pressure, 32 +/- 9 mmHg). 4. Acute i.v. administration of 10 mg kg-1 bosentan caused variable and transient rises in nerve laser Doppler flux in control (78 +/- 63 arbitrary units) and untreated diabetic rats (93 +/- 77 arbitrary units). Acute bosentan blocked the hypotensive response to subsequent ET-1 administration and attenuated the later hypertension (change in mean arterial pressure, 21 +/-9 mmHg in control, 29 +/- 10 mmHg in diabetic).5. Our results indicate that oral treatment of diabetic rats with an ET receptor antagonist can improves ciatic nerve perfusion and conduction, suggesting that the vasoconstrictor action of endogenous ET may contribute to peripheral nerve dysfunction in experimental diabetes.
...
PMID:Effects of endothelin receptor antagonism with bosentan on peripheral nerve function in experimental diabetes. 767 Jul 40

Endothelins (ET) are a family of peptides with potent biological properties. Endothelial cells produce exclusively ET-1 while other tissues produce ET-2 and ET-3. The production of ET requires an increase in intracellular Ca2+. This increase can be induced by physical chemicals (i.e. hypoxia) or receptor-operated stimuli (i.e. thrombin, angiotensin II, arginine vasopressin, transforming growth factor beta 1, interleukin-1). Most of ET is released abluminally towards vascular smooth muscle and less luminally. The main vascular effect of ET are vasodilation (transient), profound and sustained vasoconstriction as well as proliferation of vascular smooth muscle. These biological effects are mediated by distinct receptors. Three ET receptors have been cloned, i.e. ETA-, ETB- and ETC-receptors. In vascular tissue ETA-receptors are expressed on vascular smooth muscle and responsible for vasoconstriction. ETB-receptors are expressed on endothelium and linked to nitric oxide and/or prostacyclin release. Activation of these receptors explains the transient vasodilation with intraluminal application of ET. Vascular smooth muscle cells can express ETB-receptors which contribute to ET-induced vasoconstriction particularly at lower concentrations. The role of the recently cloned ETC-receptor in the vasculature is still uncertain. ET production is increased (as judged from circulating plasma levels) in vascular disease and atherosclerosis in particular, in myocardial infarction and heart failure, pulmonary hypertension and renal disease. ET production is increased in arterial hypertension remains controversial. Non-peptidic ET antagonists have been developed which either block ETA- receptors or ETA- and ETB-receptors simultaneously. The advantage of ETA-receptors is that they leave the endothelium-dependent vasodilation to ET (via ETB-receptor) intact. However, ETB-mediated contraction remains unaffected by these antagonists. In contrast ETA-/ETB-antagonists fully prevent ET-induced vasoconstriction, however, they also inhibit the endothelial effects of the peptide. ET antagonists interfere with the effects of ET in isolated vascular tissue (including that obtained from humans) as well as in vivo. In humans, ETA as well as ETA-/ETB-antagonists inhibit endothelin-induced vasoconstriction. Hence in summary ET are a family of potent peptides with profound effects in the vasculature. Several studies suggest a role of ET in cardiovascular disease. The newly developed ET-antagonists are potent and selective tools to delineate the (patho-)physiological roles of ET and may become a new class of cardiovascular drugs.
...
PMID:Endothelin and endothelin antagonists: pharmacology and clinical implications. 771 86

Adrenomedullin recently has been found to potently stimulate cAMP formation in cultured rat vascular smooth muscle cells (VSMCs). In the present study, we examined the effect of adrenomedullin on the production of a vasoconstrictive and growth-promoting peptide, endothelin-1, after stimulation with a clotting enzyme, thrombin, and a potent mitogen, platelet-derived growth factor (PDGF), in cultured rat VSMCs. Thrombin and PDGF stimulated endothelin-1 production in a dose-dependent manner. Rat adrenomedullin significantly inhibited thrombin- and PDGF-stimulated endothelin-1 production in a dose-dependent manner between 10(-7) and 10(-9) mol/L. Inhibition by rat adrenomedullin of thrombin- and PDGF-stimulated endothelin-1 production was paralleled by an increase in the cellular level of cAMP. Human adrenomedullin also inhibited thrombin- and PDGF-stimulated endothelin-1 production and increased cAMP levels. The addition of 8-bromo-cAMP, a cAMP analogue, reduced thrombin- and PDGF-induced endothelin-1 production. Furthermore, forskolin, a potent activator of adenylate cyclase, reduced thrombin- and PDGF-induced endothelin-1 production. In contrast, basal production of endothelin-1 was not altered by rat or human adrenomedullin. These results indicate that adrenomedullin inhibits not basal but thrombin- and PDGF-induced ET-1 production in cultured VSMCs probably through a cAMP-dependent process. Taken together with the finding that adrenomedullin is synthesized in and secreted from vascular endothelial cells, adrenomedullin may modulate vascular tone as a paracrine regulator partially through the inhibition of VSMC endothelin-1 production in some pathophysiological states.
Hypertension 1995 Jun
PMID:Inhibition of endothelin production by adrenomedullin in vascular smooth muscle cells. 776 61

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>