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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Blood rheological properties were studied in 21 patients suffering from essential hypertension (EHT), degree I-II according to WHO criteria. These patients were diagnosed "de novo". The whole blood filterability (WBF), blood viscosity (BV) at 230 s-1 and 23 s-1, red cell deformability (FI), erythrocyte aggregation in autologous (MEA) and normal plasma (MEAc), fibrinogen (Fbg) and hematocrit (Ht) have been evaluated. In the hypertensive patients we have found decreased WBF, greater BV and FI in comparison with the control group (p less than 0.001). Likewise, MEA and Fbg were increased, though the differences were less significant (p less than 0.01). The evaluation of Ht did not show any differences between the two groups. The results suggest that in the newly diagnosed EHT, clear hemorheological alterations occur, both in plasma and in the erythrocytes, which could play a role in the pathogenesis of the aforementioned disease.
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PMID:Hemorheological alterations in mild essential hypertension. 141 93

1. The vascular pharmacology, physiological relevance and pathophysiological roles of the endothelium-derived vasoconstrictor peptide endothelin-1 have been unclear. These issues were investigated, in vivo in man, using infusion of drugs into the brachial artery or dorsal hand vein, with responses measured by forearm plethysmography and the hand vein displacement technique respectively. 2. Endothelin-1 is a potent and sustained constrictor of resistance and capacitance vessels in vivo in man, acting through both subtypes (ETA and ETB) of endothelin receptors. Endothelin-1 stimulates generation of vasodilator prostaglandins, but not of nitric oxide, that act to oppose its direct constrictor actions. Venoconstriction to endothelin-1 is blocked more effectively by K(+)-channel openers than by Ca(2+)-channel antagonists, suggesting a novel cellular mechanism of action for this peptide. 3. The forearm vasculature is able to convert the precursor big endothelin-1 to the mature peptide, endothelin-1, thus demonstrating the local presence of 'endothelin-converting enzyme' in man. Local inhibition of this enzyme, or blockade of ETA receptors, causes slow-onset forearm vasodilatation, suggesting that endogenously generated endothelin-1 contributes to basal resistance vessel tone in man. 4. Venoconstriction to endothelin-1 is selectively enhanced in patients with untreated essential hypertension. Endothelin-1 also potentiates sympathetically mediated vasoconstriction, but only in hypertensive subjects. 5. Endogenous generation of endothelin-1 plays a fundamental physiological role in the maintenance of basal vascular tone. Endothlin-converting enzyme inhibitors and endothelin receptor antagonists possess novel vasodilator properties and should represent a major therapeutic advance in cardiovascular disease.
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PMID:Endothelins as regulators of vascular tone in man. 761 9

ENDOTHELIUM-DERIVED NITRIC OXIDE: The endothelium is a source of vasoactive factors among which the most relevant are nitric oxide and endothelin. Nitric oxide is synthesized from L-arginine by a family of nitric oxide synthases and is a widespread biological mediator. It is implicated in many physiological and pathophysiological processes, including a variety of cardiovascular diseases like hypertension. NITRIC OXIDE AND HYPERTENSION: The release of nitric oxide seems to be modulated by changes in blood pressure. However, the role of nitric oxide in hypertension is still controversial and seems to vary depending on the stage of the disease and the model studied. In spontaneous hypertension, the production of nitric oxide is increased but inefficacious, probably because of increased inactivation or scavenging. In the heart the production of nitric oxide seems to be increased, probably as a compensatory mechanism against hypertension. In salt-induced hypertension, nitric oxide production may be impaired. In human hypertension, pharmacological experiments reveal an impaired nitric oxide dilator mechanism. In pulmonary hypertension, the use of nitric oxide gas inhalation has been proposed as a future therapy for this condition. ENDOTHELIN: Endothelin-1 is a potent vasoconstrictor peptide produced and released from endothelial cells. In isolated blood vessels, endothelin causes profound contraction. The hemodynamic effects of endothelin can be explained by the activation of two endothelin receptors, ETA and ETB. The relationship between endothelin and hypertension is not clear. Although plasma endothelin levels are normal in most patients with essential hypertension, the hypertensive blood vessel wall may contract more profoundly in response to the peptide; hence, endothelin antagonists may have antihypertensive effects in patients with hypertension.
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PMID:Endothelium-derived vasoactive factors in hypertension: nitric oxide and endothelin. 857 87

The endothelin family consists of three structurally similar isopeptides: ET-1, ET-2, and ET-3. The two receptor subtypes, ETA and ETB, have different receptor affinities for the isopeptides. Stimulation of ETA and ETB receptors results in vasoconstriction, and ETB stimulation also causes vasodilation. These receptors may have profound impact on the etiologies of various diseases, including heart failure and hypertension. Studies with endothelin-receptor antagonists in animals and humans with heart failure show promising short- and long-term results. The place of the agents in the treatment of essential hypertension remains controversial, but they may have a greater role in hypertensive blacks and transplant recipients.
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PMID:The role of endothelin in heart failure and hypertension. 969 45

1. Brachial artery infusion of endothelin (ET)-1 causes transient vasodilatation followed by sustained vasoconstriction of the forearm vascular bed, whereas ET-1 antagonists cause sustained vasodilatation. These data suggest that ET-1 contributes to basal vascular tone. 2. Systemic infusion of ET-1 increases blood pressure and total peripheral vascular resistance and reduces heart rate and cardiac output. The renal and pulmonary circulations are particularly sensitive to the vasoconstrictor effects of ET-1. Systemic infusion of the ETA/B receptor antagonist TAK-044 reduces mean arterial pressure and peripheral vascular resistance. 3. Plasma ET-1 concentrations are not elevated in essential hypertension; however, insulin resistance may be a major determinant of plasma ET-1 concentrations. Vascular sensitivity to ET-1 is normal or may be increased in essential hypertension. 4. Plasma ET-1 concentrations are increased in moderate and severe heart failure and are correlated with clinical and haemodynamic measures of severity. Endothelin-1 contributes to increased vascular tone in cardiac failure. 5. Plasma ET-1 concentrations increase following myocardial infarction and persistent elevation predicts an increased mortality within the subsequent 12 months. 6. Preliminary data suggest that interventions that reduce the activity of the endothelin system may have a beneficial effect in heart failure and myocardial infarction.
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PMID:Endothelin-1 as a mediator in cardiovascular disease. 1006 39

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

Essential hypertension is one of the most important risk factors for cardiovascular diseases. Its pathophysiological mechanism is unknown. Recent data suggests that deformability and aggregation of red blood cells may play an important role in the regulation of blood rheology in hypertension. Simultaneously there are reports suggesting that antihypertensive effects of angiotensin converting enzyme inhibitors (ACEI) could be counteracted by high doses of aspirin. We postulate that these effects could be related to the changes in blood rheology. Accordingly we designed a study to evaluate the effect of low or high dose of aspirin on deformability and aggregability of red blood cells from patients with essential hypertension. Deformability and aggregability of red blood cells were measured by laser diffractometer (Rheodyn SSD, Myrenne GmbH) and computerized automatic aggregometer (MA1 Myrenne GmbH, Germany), respectively. The effects of aspirin on deformability and aggregation of red blood cells were studied ex vivo in whole blood from three groups of patients with essential hypertension (group I: 10 patients receiving placebo, group II: 23 patients receiving 75 mg/day p.o. aspirin for 3 days, and group III: 23 patients receiving 300 mg/day p.o. aspirin for 3 days). Subjects in all groups received the same combination of antihypertensive agents consisting of: one of ACEI (enalapril or perindopril), one of beta-antagonists (metoprolol or bisoprolol), and diuretic agent (indapamid). In patients receiving high dose of aspirin (300 mg/day) we observed that erythrocyte aggregability was 25% higher than in the placebo group (MEA = 25.8 +/- 6 SD, vs MEA = 20.6 +/- 3 SD, p < 0.05). Aspirin had no effects on deformability of erythrocytes or on arterial blood pressure. High doses of aspirin or possibly also other nonsteroidal anti-inflammatory drugs (NSAID) in patients receiving antihypertensive therapy can directly affect rheological properties of the blood due to the activation of red blood cell aggregation. Increased aggregation of red blood cells during antihypertensive therapy may be an important indicator of the worsening of organ perfusion.
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PMID:[The effect of aspirin on rheological properties of erythrocytes in essential hypertension]. 1215 52

Endothelin-1 (ET-1) is a pleiotropic hormone produced primarily by the endothelium. Synthesis of ET-1 is stimulated by the major signals of cardiovascular stress, such as vasoactive agents (angiotensin II, norepinephrine, vasopressin, and bradykinin), cytokines (e.g., tumor necrosis factor alpha and transforming growth factor beta), and other factors, including thrombin and mechanical stress. ET-1 induces vasoconstriction, is proinflammatory, promotes fibrosis, and has mitogenic potential, important factors in the regulation of vascular tone, arterial remodeling, and vascular injury. These effects are mediated via two receptor types, ETA and ETB. The role ET-1 plays in normal cardiovascular homeostasis and in mild essential hypertension in humans is unclear. However, certain groups of essential hypertensive patients may have ET-1-dependent hypertension, including blacks (subjects of African descent), salt-sensitive hypertensives, patients with low renin hypertension, and those with obesity and insulin resistance. ET-1 has also been implicated in severe hypertension, heart failure, atherosclerosis, and pulmonary hypertension. In all of these conditions, plasma immunoreactive ET levels are elevated and tissue ET-1 expression is increased. Accordingly, it is becoming increasingly apparent that ET-1 plays an important role in cardiovascular disease and in some forms of hypertension in humans. Data from clinical trials using combined ETA-ETB receptor blockers have already demonstrated significant blood-pressure-lowering effects. Thus, targeting the endothelin system may have important therapeutic potential in the treatment of hypertension, particularly by contributing to the prevention of target organ damage and the management of cardiovascular disease.
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PMID:Role of endothelin in human hypertension. 1283 65

Investigation into the role of endothelin-1 (ET-1) in renal function has revealed two major direct actions leading to the control of extracellular volume and blood pressure. These are the regulation of renal hemodynamics and glomerular filtration rate and the modulation of sodium and water excretion. In the rat remnant kidney model of chronic renal failure, ET-1 production is increased in blood vessels and renal tissues. These changes are related to an increase in preproET-1 expression and correlate with the rise in blood pressure, the development of cardiovascular hypertrophy, and the degree of renal insufficiency and injury. Selective ETA receptor blockade prevents the progression of hypertension and the vascular and renal damage, supporting a role for ET-1 in chronic renal failure progression. The increase in ET-1 production can be associated with other local mediators, including angiotensin II, transforming growth factor-beta1 and nitric oxide, the local production of which is also altered in chronic renal failure. In human patients with essential hypertension, atherosclerosis, and nephrosclerosis, plasma ET-1 levels are increased compared with patients with uncomplicated essential hypertension. Similarly, plasma ET-1 concentrations are markedly increased in patients with end-stage renal disease undergoing dialysis, and this correlates with blood pressure, suggesting that ET-1 may contribute to hypertension in these patients. The treatment of anemia in patients with renal failure with human recombinant erythropoietin increases blood pressure by accentuating the underlying endothelial dysfunction and the elevated vascular ET-1 production. Overall, these results support a role for ET-1 in hypertension and the end-organ damage associated with chronic renal failure. ETA receptor blockade may then represent a potential target for the management of hypertension and cardiovascular and renal protection.
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PMID:Endothelin-1 in chronic renal failure and hypertension. 1283 72

Endothelins (ETs) are potent vasoconstrictor peptides and are associated with several disease states like pulmonary hypertension, systemic hypertension and heart failure. Endothelin-1 (ET-1) is the first member of the family and it has the receptor subtypes known as ETA and ETB. The receptors ETA and ETB are attractive new therapeutic targets for diseases associated with elevated ET-1 levels. Several studies have thus led to the discovery of selective ETA receptor antagonists as well as non-selective ETA/ETB antagonists. The preclinical and clinical studies have clearly established that these antagonists are effective in the treatment of essential hypertension, pulmonary hypertension, heart failure and atherosclerosis. The advances in this area have resulted in the FDA approval of the orally active dual antagonist Bosentan for pulmonary hypertension in 2001. This review highlights the synthesis and structure-activity of the endothelin receptor antagonists and covers the literature in this area up to 2001.
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PMID:Endothelin receptor antagonists: an overview of their synthesis and structure-activity relationship. 1585 28


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