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

Inhibitors of the renin-angiotensin system lower blood pressure of spontaneously hypertensive rats, although plasma renin is not elevated. To test the hypothesis that the actions of angiotensin II within the kidney may contribute to the high blood pressure in spontaneously hypertensive rats, we infused valsartan, a subtype 1 angiotensin II receptor antagonist, via the suprarenal artery into the right kidney of conscious, freely moving, unilaterally nephrectomized (left) spontaneously hypertensive rats (12 to 14 weeks old). Valsartan (0.3 mg/kg per day for 48 hours) lowered blood pressure (change in blood pressure, -7 +/- 3, -19 +/- 4, and -26 +/- 4 mm Hg, n = 11, at 12, 24, and 48 hours) after intrarenal administration but had no significant effect on blood pressure after intravenous administration (change in blood pressure, 1 +/- 5, -3 +/- 4, and 10 +/- 5 mm Hg, n = 7, at 12, 24, and 48 hours). Infusion of vehicle (0.9% saline) intrarenally had no significant effect on blood pressure (change in blood pressure, 2 +/- 5, -1 +/- 6, and 0 +/- 7 mm Hg, n = 11, at 12, 24, and 48 hours). The maximum fall in blood pressure reached after intrarenal administration of this dose of valsartan was similar to the maximum fall induced after intravenous administration of higher doses (change in blood pressure, -14 +/- 5, -27 +/- 4, and -32 +/- 5 mm Hg, n = 7, at 12, 24, and 48 hours after 3 mg/kg per day i.v.). Thus, endogenous angiotensin II acting within the kidney appears to play an important role in the maintenance of high blood pressure in spontaneously hypertensive rats.
Hypertension 1993 Jun
PMID:Kidney is an important target for the antihypertensive action of an angiotensin II receptor antagonist in spontaneously hypertensive rats. 850 92

The molecular and cellular mechanisms by which hypertension enhances atherosclerosis are poorly understood. Angiotensin II (Ang II) has been implicated in the regulation of cellular lipoxygenases (LO), which are thought to play a role in atherogenesis by inducing oxidative modification of low density lipoprotein (LDL). We sought to test the hypothesis that Ang II would stimulate murine macrophage LO activity (which has both 12- and 15-LO activity). Competitive binding studies revealed the presence of Ang II AT1 receptors on mouse peritoneal macrophages (MPM) and J-774 cells, but not on the RAW cell line. Valsartan, a specific AT1 receptor antagonist inhibited Ang II binding, whereas PD 123319, an AT2 receptor antagonist did not. Incubation of MPM or J-774 cells with Ang II (10 pM to 1 microM) for 24 h led to a 2.5-3.5-fold increase in LO activity, measured as generated 13-HODE or 12(S)-HETE. This stimulation was inhibited by valsartan, but not by PD 123319. In contrast, Ang II did not stimulate LO activity in RAW macrophages. Semiquantitative reverse transcriptase-polymerase chain reaction showed a 2-3-fold increase in LO mRNA in MPM, but not in RAW cells after treatment with Ang II. Ang II also induced an increase in 12-LO protein. In addition, pretreatment of J-774 cells with Ang II increased in a dose-dependent manner the ability of the cells to modify LDL, resulting in greater chemotactic activity for monocytes, typical of minimally modified LDL. This stimulation was inhibited by AT1 receptor blockade. In summary, these data suggest that Ang II increases macrophage LO activity via AT1 receptor-mediated mechanisms and this further increases the ability of the cells to generate minimally oxidized LDL. These studies provide a link between hypertension and the associated increased atherosclerosis observed in hypertensive patients.
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PMID:Angiotensin II increases macrophage-mediated modification of low density lipoprotein via a lipoxygenase-dependent pathway. 926 Nov 83

Essential hypertension is a major Public Health issue. Although the number of treated hypertensive patients has increased, only 25% of treated patients have their blood pressure levels under control. The benefit of treating hypertension has been proven, but cardiovascular morbidity and mortality rates remain high. The ideal antihypertensive drug should not only normalize blood pressure levels, but also reduce the associated cardiovascular morbidity and mortality rates. The role of angiotensin II in systemic hypertension and its complications has been recently redefined. The potent trophic effects of angiotensin II on blood vessels and on cardiac cells have been well demonstrated, especially the role of angiotensin II in left ventricular hypertrophy, vascular hypertrophy, endothelial dysfunction, and congestive heart failure. Of all ongoing mortality and morbidity trials in systemic hypertension, VALUE (Valsartan Antihypertensive Long-term Use Evaluation) is the only one comparing an angiotensin II antagonist (valsartan) with a third-generation calcium channel blocker (amlodipine). The main hypothesis of the VALUE trial is that, for an equivalent decrease in blood pressure, valsartan will be more effective than amlodipine in decreasing cardiac mortality and morbidity. VALUE is a prospective, multinational, multicentre, double-blind, randomized, active-controlled, 2-arm parallel group comparison with a response-dependent dose titration scheme. VALUE involves 14,400 patients in over 30 countries, who will be followed for 4 years or until 1450 patients experience a primary endpoint. The population to be included in VALUE consists of hypertensive men and women, aged 50 years or older, and at a relatively high risk of sustaining a cardiovascular event. The high risk profile is defined taking into account age, gender, and a list of cardiovascular risk factors and disease factors. Risk factors are cigarette smoking, hypercholesterolaemia, diabetes mellitus, uncomplicated left ventricular hypertrophy, proteinuria, and high serum creatinine. Disease factors include documented history of myocardial infarction, peripheral vascular disease, stroke or transient ischaemic attack, or the presence of left ventricular hypertrophy with strain on the ECG. A unique feature of VALUE is the assessment of the predictive power of this cardiovascular risk factor scale in a large population of treated hypertensive patients. The trial started on 10 September 1997.
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PMID:The Valsartan Antihypertensive Long-term Use Evaluation (VALUE) trial of cardiovascular events in hypertension. Rationale and design. 975 88

Angiotensin II receptor antagonists have become clinically available for the treatment of arterial hypertension. Presently, there is little information about their effects on BP, proteinuria, and renal function in patients with moderate or advanced renal failure. This study examines the effects of the angiotensin II antagonist Valsartan (80 mg/d) on proteinuria and glomerular permselectivity in patients with chronic renal failure during a 6-mo treatment, using a double-blind, randomized, placebo-controlled study (treatment group [V-group]: n = 5, age 57 +/- 7 yr, serum creatinine 365 +/- 122 micromol/L; placebo group [P-group]: n = 4, age 62 +/- 11 yr, serum creatinine 346 +/- 61 micromol/L). Study parameters included BP, 24-h proteinuria, GFR, and effective renal plasma flow (ERPF) as determined by inulin and para-aminohippurate clearance. Changes in glomerular permselectivity were assessed by measuring the fractional clearances of neutral dextrans by HPLC gel-permeation chromatography. Valsartan lowered the mean arterial pressure on average by 13 +/- 7 mmHg during the 6-mo treatment (P < 0.05). GFR and ERPF remained almost unchanged. However, after 6 mo of Valsartan treatment, proteinuria was reduced by 396 +/- 323 mg/24 h (26 +/- 18%) and albuminuria by 531 +/- 499 mg/24 h (41 +/- 21%) with regard to baseline values (P < 0.05). In the P-group, both proteinuria and albuminuria increased slightly with time (by 30 +/- 43% and 30 +/- 54%, respectively, NS). The fractional clearances of high molecular weight dextrans >66 A were significantly reduced after 6 mo of Valsartan treatment (P < 0.05), indicating a reduction of the glomerular shunt volume by 54 +/- 20% (P < 0.05) according to the model of Deen et al. (Am J Physiol 249: 347-389, 1985). The mean pore size radius of the glomerular membrane remained unchanged. This effect was independent of glomerular hemodynamic changes. Valsartan persistently lowered proteinuria in patients with chronic renal failure. Although GFR and ERPF remained nearly stable, this effect could be attributed to an improvement in glomerular permselectivity.
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PMID:Effects of the angiotensin II antagonist valsartan on blood pressure, proteinuria, and renal hemodynamics in patients with chronic renal failure and hypertension. 984 76

OBJECTIVE: To compare the blood pressure reduction induced by valsartan, a new angiotensin II receptor antagonist, with that induced by enalapril, an angiotensin converting enzyme (ACE) inhibitor in essential hypertension. METHODS: In total 189 adult outpatients with uncomplicated essential hypertension participated in this double-blind study. Patients were allocated randomly in equal numbers to be administered 80 mg valsartan or 20 mg enalapril daily for 12 weeks. Patients whose blood pressure had not been controlled adequately despite 8 weeks of monotherapy were administered additional therapy with 12.5 mg hydroclorothiazide (HCTZ) daily thereafter. Patients were assessed aftger 4, 8 and 12 weeks of therapy. The primary efficacy variable was the change from baseline in mean sitting diastolic blood pressure (SDBP) after 8 weeks of therapy. Other variables analyzed included the change in sitting systolic blood pressure and percentage responses after 8 weeks of therapy. RESULTS: Valsartan and enalapril were both effective at lowering the blood pressure. Similar falls were induced in the two groups with a similar time course of blood pressure reduction. The mean decreases in SDBP after 8 weeks of therapy were 13.2 mmHg for valsartan and 12.0 mmHg for enalapril. There was no significant difference between the treatments [P = 0.475, 95% confidence interval of the estimated difference (SBP after therapy - SDBP before therapy) -3.5 to 1.6 mmHg]. After 8 weeks of therapy 60.6% had responded to valsartan and 52.6% to enalapril (P = 0.267). Both treatments were tolerated well. Three patients administered enalapril and one patient administered valsartan discontinued their treatment because it made them cough. CONCLUSION: The data show that 80 mg valsartan is as effective as 20 mg enalapril in the treatment of moderate hypertension and that it is tolerated well.
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PMID:Valsartan, a new angiotensin II antagonist; blood pressure reduction in essential hypertension compared with an angiotensin converting enzyme inhibitor, enalapril. 1023 13

The recent decrease of cardiovascular mortality in the USA is less pronounced than it has been in the preceding three decades. Elsewhere, cardiovascular mortality decreased and in some countries it increased. Cerebrovascular disease and ischemic heart disease were responsible for 21% of deaths recorded by the World Health Organization in 1990 and 1997, of which hypertension was estimated to be directly responsible for half of these deaths. Apart from blood pressure (BP) elevation, essential hypertension is frequently associated with factors that increase the risk of poor cardiovascular outcomes: insulin resistance/dyslipidemia, elevated angiotensin and norepinephrine, a tendency for hypercoagulability, platelet overactivity, tachycardia, vulnerability to arrhythmias, vascular hypertrophy, endothelial dysfunction, and left ventricular hypertrophy. Excess activation of the renin-angiotensin system, independent of BP elevation, contributes to these abnormalities. To achieve better results in the future, focus must be shifted from BP lowering to recognition of specific effects of drugs on these diverse pathophysiologic aspects of hypertension. The Valsartan Antihypertensive Long-term Use Evaluation (VALUE) trial, which is evaluating the effect of valsartan (Diovan((R))) vs. amlodipine, is a milestone in the effort to test whether newer compounds offer a better reduction of the cardiovascular consequences of hypertension, as well as good BP control. The hypothesis is that valsartan by antagonizing the negative effects of angiotensin on smooth muscle cell growth, endothelial function, sympathetic overactivity, and coagulation, may have for the same degree of BP lowering, better protective effects than the leading calcium antagonist amlodipine.
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PMID:Long-term potential of angiotensin receptor blockade for cardiovascular protection in hypertension: the VALUE trial. Valsartan Antihypertensive Long-term Use Evaluation. 1044 89

Valsartan is a specific angiotensin II receptor antagonist with high selectivity for the AT(1) receptor subtype. After oral administration of single or repeated once-daily doses, valsartan 40-80 mg inhibits the pressor response to angiotensin II for 24 hours. In patients with mild-to-moderate hypertension, efficacy of valsartan appears to be independent of age, sex, and race, and is at least equivalent to that of calcium antagonists, ACE inhibitors, or thiazide diuretics. Response rate to valsartan 160 mg o.d. is significantly greater than after receiving losartan 100 mg o.d. Valsartan has additive effects with other antihypertensive drugs and combination therapy is effective in severe hypertension and in hypertension with renal insufficiency, where renal function is well maintained. Valsartan has good tolerability with a side-effect profile indistinguishable from placebo and superior to that of comparable drugs. Valsartan does not cause cough or adverse metabolic effects; first dose hypotension and rebound hypertension on abrupt withdrawal have not been encountered. Valsartan has clear clinical advantage in the management of hypertension. Its impact on prognosis in patients with a high risk of cardiovascular morbidity and mortality is under evaluation.
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PMID:Clinical advantage of valsartan. 1044 90

Acceptance of the notion that physiologically specific interruption of the renin-angiotensin-aldosterone system (RAAS) is of considerable therapeutic benefit in the treatment of hypertension and congestive heart failure has generated great interest in the search for novel pharmacological inhibitors. The RAAS is expressed at the whole body, organ/tissue and cellular level through the action of the octapeptide angiotensin II (Ang II), the primary effector molecule of the RAAS. The availability of selective, potent, orally active and long-acting nonpeptide Ang II type 1 (AT1) receptor antagonists provided the opportunity to obtain the benefits of selectively blocking the RAAS at the level of the AT1 receptor that mediates most, if not all, of the important actions of Ang II, and avoid the nonspecificity of the Ang I converting enzyme (ACE) inhibitors. Losartan was the first, but by no means remained the only nonpeptide AT1 receptor antagonist. Numerous other "sartans" have emerged in the past several years and successfully completed clinical development. With the exception of Eprosartan, all others, i.e. Candesartan, Irbesartan, Saprisartan, Tasosartan, Telmisartan, Valsartan and Zolasartan, are based on modifications of Losartan's prototypic chemical structure. AT1 receptor antagonists represent the newest addition to the arsenal of cardiovascular therapeutics. The predominant role of the AT1 receptor in mediating the pathophysiological role of Ang II underlies the effectiveness of this novel class of agents to lower arterial blood pressure, reduce pre- and afterload, inhibit sympathetic nervous system activity and prevent cardiovascular hypertrophy and cardiac failure induced by inappropriate control of the RAAS.
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PMID:Angiotensin II receptor antagonists: an emerging new class of cardiovascular therapeutics. 1048 32

The aim of this study was to explore the regulation of angiotensin receptors after chronic infusion with angiotensin II (Ang II) and to clarify the relative roles of the angiotensin type 1 (AT(1)) and type 2 (AT(2)) receptors in the mediation of Ang II-induced mesenteric vascular hypertrophy. In male Sprague-Dawley rats, Ang II infusion at a dose of 58.3 ng/min by subcutaneous osmotic minipumps for 14 days led to increased mesenteric weight and wall:lumen ratio of the vessels and proliferation of smooth muscle cells. These vascular changes were attenuated by either valsartan, an AT(1) receptor antagonist, at a dose of 30 mg. kg(-1). d(-1) by gavage, or PD123319, an AT(2) receptor antagonist, at a dose of 830 ng/min by intraperitoneally implanted osmotic minipumps. Ang II infusion was associated with hypertension, which was prevented by valsartan, but not PD123319. (125)I-Sar(1), Ile(8) Ang II binding to mesenteric vasculature was increased after Ang II infusion. Valsartan treatment was associated with reduced Ang II binding to both receptor subtypes, whereas PD123319 was associated with reduced Ang II binding to only the AT(2) receptor subtype. These findings suggest that the trophic and proliferative effects of Ang II on the mesenteric vasculature are mediated by both AT(1) and AT(2) receptors.
Hypertension 1999 Sep
PMID:Role of angiotensin receptor subtypes in mesenteric vascular proliferation and hypertrophy. 1048 86

Valsartan (Diovan) is an antihypertensive drug belonging to the family of angiotensin II receptor antagonists. At a dose of 40 mg/d, its antihypertensive effect is inconsistent. At 80 mg/d its effect on blood pressure, its adverse effects, and its contraindications (mainly pregnancy and renal artery stenosis) are similar to those of angiotensin-converting enzyme (ACE) inhibitors, except that coughing is rarer with valsartan than with ACE inhibitors. Valsartan has no demonstrated advantage over losartan, another angiotensin II antagonist. Valsartan has not been shown to prevent complications of arterial hypertension, and its use is, therefore, less well validated than that of diuretics and beta-blockers.
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PMID:Valsartan. Just a second-line antihypertensive drug. 1058 70


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