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 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiotensin converting enzyme (ACE) inhibitors as well as angiotensin II receptor antagonists are able to prevent the vasoconstrictive effect of angiotensin II on the efferent renal vessels, which is believed to play an important role in renovascular hypertension. This effect is assumed to be essential for the demonstration of renovascular hypertension by captopril renography. In this study, renographic changes induced by captopril and the AT1 receptor antagonist valsartan were compared in patients with a high probability for renovascular hypertension. Twenty-five patients with 33 stenosed renal arteries (grade of stenosis >50%) and hypertension were studied. Captopril, valsartan and baseline renography were performed within 48 h using technetium-99m mercaptoacetyltriglycine. Blood pressure was monitored, plasma renin concentration before and after intervention was determined and urinary flow was estimated from the urinary output of the hydrated patients. Alterations in renographic curves after intervention were evaluated according to the Santa Fe consensus on ACE inhibitor renography. Captopril renography was positive, indicating renovascular hypertension, in 25 of the 33 stenosed vessels, whereas valsartan renography was positive in only ten. Blood pressure during captopril and valsartan renography was not different; reduction in blood pressure was the same after valsartan and captopril. Plasma renin concentration was comparable for valsartan and captopril studies, showing suppressed values after intervention in as many as 12 of the 25 patients. Urinary flow after valsartan was higher than after captopril (P<0.05). However, this difference could not explain the markedly higher sensitivity of captopril compared with valsartan in demonstrating renal artery stenosis. In 14 of the 25 patients, blood pressure response to revascularisation was monitored, showing a much better predictive value for captopril renography. It is concluded that captopril renography is much more sensitive than valsartan renography in detecting a clinically significant renal artery stenosis. Furthermore, our data suggest that other effects, such as that on the prostaglandin-bradykinin system, are of at least similar importance to ACE inhibition for the high diagnostic sensitivity of captopril renography regarding renovascular hypertension.
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PMID:ACE inhibition is superior to angiotensin receptor blockade for renography in renal artery stenosis. 1200 4

Posttransplant erythrocytosis (PTE) is defined as a persistently elevated hematocrit to a level greater than 51% after renal transplantation. It occurs in 10% to 15% of graft recipients and usually develops 8 to 24 months after engraftment. Spontaneous remission of established PTE is observed in one fourth of the patients within 2 years from onset, whereas in the remaining three fourths it persists for several years, only to remit after loss of renal function from rejection. Predisposing factors include male gender, retention of native kidneys, smoking, transplant renal artery stenosis, adequate erythropoiesis prior to transplantation, and rejection-free course with well-functioning renal graft. Just as in other forms of erythrocytosis, a substantial number (approximately 60%) of patients with PTE experience malaise, headache, plethora, lethargy, and dizziness. Thromboembolic events occur in 10% to 30% of the cases; 1% to 2% eventually die of associated complications. Posttransplant erythrocytosis results from the combined trophic effect of multiple and interrelated erythropoietic factors. Among them, endogenous erythropoietin appears to play the central role. Persistent erythropoietin secretion from the diseased and chronically ischemic native kidneys does not conform to the normal feedback regulation, thereby establishing a form of "tertiary hypererythropoietinemia." However, erythropoietin levels in most PTE patients still remain within the "normal range," indicating that erythrocytosis finally ensues by the contributory action of additional growth factors on erythroid progenitors, such as angiotensin II, androgens, and insulin-like growth factor 1 (IGF-1). Inactivation of the renin-angiotensin system (RAS) by an angiotensin-converting enzyme (ACE) inhibitor, or an angiotensin II type 1 AT1 receptor blocker represents the most effective, safe, and well-tolerated therapeutic modality.
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PMID:Posttransplant erythrocytosis. 1263 34

The renin-angiotensin-aldosterone system (RAAS) plays an important part in the pathogenesis of arterial hypertension and the complications it causes in organs (the heart, the circulatory system, the brain, the kidneys), heart failure and kidney diseases. Materials that block the most upstream point of the RAAS cascade (ACE inhibitors - ACEI, AT1,-receptor (AT1R) blockers, aldosterone receptor blockers) have greatly expanded our options in the treatment and primary and secondary prevention of cardiovascular and renal diseases. ACEI and AT1R blockers interrupt the normal feedback provided by the release of renin into the circulatory system from the kidneys. After they are applied the reactive increase in active circulating renin leads to increased creation of angiotensin I and angiotensin II and the subsequent return of aldosterone secretions to pre-treatment values ("escape" phenomenon). The possible negative effect of these intermediary products of an incomplete blockade of RAAS on organ complications lead to an effort to develop a material that could block the renin-angiotensin cascade at its first stage--i.e. a renin blocker. The first efforts with renin antibodies or peptide analogues of renin prosegments failed to satisify the basic requirements for long-term medication--effectiveness when used orally. In recent years the first non-peptidic, oral renin ihibitor providing sustained effects has been developed, aliskiren fumarate. Aliskiren reduces BP depending on the dose (50-300 mg/day) in monotherapy or in combination with hydrochlorothiazide. Aliskiren lowers plasma renin activity (PRA) and neutralises the activation of the RAAS triggered by hydrochlorothiazide. Ambulatory BP monitoring has shown that taking the medicine once a day has a 24-hour effect and its continued residence in the kidneys suggests renoprotective effects. The compound is in the third stage of clinical tests as a monotherapy or in combination for the treatment of hypertension. It has also been shown to have an influence on the regression of cardiac hypertrophy (Aliskiren in Left-Ventricular Hypertrophy trial - ALLAY), the treatment of heart failure (Aliskiren Observation of Heart Failure Treatment trial - ALOFT) and diabetic (Aliskiren in the Evaluation of Proteinuria in Diabetes trial - AVOID). In April 206, the FDA permitted the use of aliskiren in the USA for the treatment of high BP and it is currently undergoing testing in Europe. The renin inhibitor has minimal undesirable side effects, like AT1-receptor blockers. The slightly lower effectiveness ofaliskiren than AT1-receptor blockers in reducing BP is caused by the fact that it does not block bradykinins. It is recommended as a monotherapy for clinical use or in combination with other antihypertensive medicines for conditions with high levels of PRA including its rise after diuretics, ACEI and AT1-receptor blockers. Aliskiren could therefore be used primarily with young patients, Caucasians, persons with ACEI intolerance, and also in diseases where angiotensin II is involved in the pathogenesis and the secondary prevention of cardiovascular disease. It is also safe for persons with concurrent renal problems, because it is mainly removed by the liver without great interference with other materials. Like ACEI, the renin inhibitor has a vasodilatory effect which could potentially improve the elasticity of arteries. The medicine has the same limitations and contraindications as ACEI and AT1R blockers, such as pregnancy and bilateral renal artery stenosis. A definitive assessment of the benefit of this new class of medicines and its broad application in the treatment of cardiovascular and other diseases will require demonstration of its long-term effect on morbidity and mortality, as well as comparison with other RAAS blockers in long clinical studies, which represent research programmes lasting another 7 to 8 years.
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PMID:[Does the rennin inhibitor aliskiren offer promising novel opportunities in the treatment of cardiovascular diseases?]. 1757 67

Chronic ventricular pressure overload states, such as hypertension, and elevated levels of neurohormones (norepinephrine, angiotensin II, endothelin-1) initiate cardiac hypertrophy and dysfunction and share the property of being able to bind to Gq-coupled 7-transmembrane receptors. The goal of the current study was to determine the role of endogenous cardiac myocyte Gq signaling and its role in cardiac hypertrophy and dysfunction during high blood pressure (BP). We induced renal artery stenosis for 8 weeks in control mice and mice expressing a peptide inhibitor of Gq signaling (GqI) using a 2 kidney, 1 clip renal artery stenosis model. 8 weeks following chronic high BP, control mice had cardiac hypertrophy and depressed function. Inhibition of cardiomyocyte Gq signaling did not reverse cardiac hypertrophy but attenuated increases in a profile of cardiac profibrotic genes and genes associated with remodeling. Inhibition of Gq signaling also attenuated the loss of cardiac function. We determined that Gq signaling downstream of angiotensin II receptor stimulation negatively impacted beta-adrenergic receptor (AR) responses and inhibition of Gq signaling was sufficient to restore betaAR-mediated responses. Therefore, in this study we found that Gq signaling negatively impacts cardiac function during high BP. Specifically, we found that inhibition of AT1-Gq signaling augmented betaAR mediated effects in a renal artery stenosis model of hypertension. These observations may underlie additional, beneficial effects of angiotensinogen converting enzyme (ACE) inhibitors and angiotensin receptor antagonists observed during times of hemodynamic stress.
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PMID:Inhibition of angiotensin II Gq signaling augments beta-adrenergic receptor mediated effects in a renal artery stenosis model of high blood pressure. 1893 63

The role of renin-angiotensin-aldosterone system (RAAS) in regulating the volume and composition of extracellular fluid, blood pressure (BP) as well as onset and progression of cardiovascular and renal diseases has been studied for more than 150 years. The compounds that block the vital stages of the RAAS cascade, such as ACE-inhibitors (ACEI), AT1-receptor blockers (ARB) and aldosterone receptor antagonists, importantly extended our treatment options. However, the positive therapeutic effects of these compounds also have certain negative consequences. Administration of ACEIs and ARBs interrupts physiological feedback for renal renin release and leads to reactive elevation of circulating active renin and greater production of angiotensin I and angiotensin II with subsequent return of aldosterone secretion to the pre-treatment levels ('escape' phenomenon). These possible adverse effects of the intermediary products of incomplete RAAS blockade leading to organ complications have facilitated the efforts to develop compounds blocking the initial stages of renin-angiotensin cascade--i.e. direct renin blockers. After several years of unsuccessful attempts, the recent years have seen development of the first non-peptide, orally long-term effective renin inhibitor, aliskiren fumarate. In monotherapy or in combination with other antihypertensives (hydrochlorothiazide, ARB, ACEI), aliskiren reduces BP in a dose-dependent manner (75-600 mg/den). Aliskiren reduces plasma renin activity (PRA) and neutralises hydrochlorothiazide-induced RAAS activation. Once daily administration of the drug leads to longer than 24-hour activity and its prolonged blocking effects on the kidneys are the basis for its renoprotectivity. In addition to the significant antihypertensive effect, clinical studies also showed a range of organoprotective properties in patients with left ventricle hypertrophy (ALLAY study), heart failure (ALOFT study) and diabetic nephropathy (AVOID study). Similar to other AT1-blockers, aliskiren has a minimum of adverse side effects. Aliskiren for hypertension therapy was launched in clinical practice in USA in 2007 (Tekturna and combination formulation TekturnaHCl, respectively) and shortly after that in European Union as Rasilez. In the Czech Republic, aliskiren (Rasilez) was released for clinical use by diabetologists and nephrologists in patients with hypertension and concomitant diabetes, nephropathy and proteinuria in doses of 150-300 mg per day on 1. 8. 2009. It is recommended as monotherapy or in combination with other antihypertensives to treat conditions with elevated PRA, including PRA elevation following diuretic, ACEI or ARB administration. Aliskiren might be used in patients who do not tolerate ACEIs as well as in patients in whom angiotensin II participates in the pathogenesis of their diseases. Reno-protective properties leading to a reduction in proteinuria and delaying renal failure progression were observed in patients with diabetic as well as non-diabetic nephropathy. The drug is the subject to similar precautions and contraindications as ACEIs and ARBs, i.e. pregnancy and bilateral renal artery stenosis. To make meaningful conclusions about the so far positive contribution of this new treatment class and its broad applicability for the therapy of hypertension and other cardiovascular diseases, it will be imperative to assess its long-term effects on morbidity and mortality as well as to compare these agents with other RAAS blockers in long-term clinical studies; this represents a research effort for another 7-8 years.
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PMID:[Direct renin inhibitor aliskiren in the treatment of cardiovascular and renal diseases]. 2032 82

Hypertension is a disease classified as primary or secondary, manifested not only by elevation of blood pressure but also involved in structural and functional changes of target organs. Renal artery stenosis is a leading factor of secondary hypertension, and its progress is associated with overactivation of the renin-angiotensin-aldosterone system (RAAS). Aliskiren is a renin inhibiting drug that suppresses RAAS and culminates in decreased renin release, plasma angiotensin II concentration, and inhibition of aldosterone secretion. In this sense, the aim of the present study was to analyze the structural and ultrastructural morphophysiology of the adrenal glomerular zone, after treatment with aliskiren in Wistar rats with 2K1C hypertension. Parameters as structure and ultrastructure of the adrenal glomerular zone, cellular apoptosis, nuclear cell proliferation, and AT1 receptor expression were analyzed by immunostaining and electron microscopy. Our results showed that the hypertensive animals treated with aliskiren presented a reestablishment of AT1 receptor expression and decrease in apoptosis and autophagy. In addition, treatment with aliskiren improves the cell aspects in the adrenal glomerular zone, evidenced by ultrastructural analysis through preserved nuclei and well-developed mitochondria. Therefore, our evidence suggests that aliskiren has a beneficial effect on the adrenal glomerular zone remodeling in animals with renovascular hypertension.
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PMID:Aliskiren Reduces the Adrenal Zona Glomerulosa Apoptosis and Autophagy in Wistar Rats with 2K1C Hypertension. 3314 9