Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Losartan is the first orally active angiotensin II receptor type 1 antagonist for a new class of cardiovascular therapeutic agent. Losartan is converted to an active metabolite (E3174) after oral administration in humans and rats. Both losartan and E3174 contribute to the net angiotensin II receptor blockade and produce anti-hypertensive effect. Losartan not only blocks the vasoconstrictive effect of angiotensin II but also inhibits its mitogenic effect; thus losartan is expected to protect against end-organ-damage-related hypertension and chronic heart failure. Unlike angiotensin-coverting-enzyme inhibitor, losartan does not elicit adverse effects of cough and angioneurotic edema by its blockade of angiotensin II receptor. It is also expected to reduce proteinuria in nephropathy. In addition to its blockade of angiotensin II receptor, losartan blocks thromboxane A2 receptor and facilitates excretion of uric acid, although therapeutic importance of these effects are under investigation. In summary, losartan, an angiotensin II type 1 receptor antagonist is a new class of antihypertensive agent and its therapeutic potentials are not merely reduction of blood pressure but total protection from end-organ damage resulting from activation of both the systemic and local renin-angiotensin system.
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PMID:[Pharmacological characteristics and clinical application of losartan, an orally active AT1 angiotensin II receptor antagonist]. 1052 59

Angiotensin II plays a significant role in cell growth and proliferation in model systems and in humans. In addition, angiotensin II appears to facilitate sympathetic activation and the release of endothelin-1, and also to promote apoptosis. The use of angiotensin-converting enzyme (ACE) inhibitors has provided beneficial effects on left ventricular hypertrophy (LVH) regression and on cardiac remodelling in the presence of heart failure. Data from experimental models as well as studies in humans suggest that the increase of bradykinin mediated by ACE inhibitors provides most of the beneficial effects of ACE inhibitors. The new class of angiotensin receptor blocker appears to provide cardioprotective effects that are similar to those of the ACE inhibitors. Most of the beneficial effects provided by these agents appear to be related to a more complete blockade of angiotensin II type 1 (AT1) receptor. However, costimulation of the angiotensin II type 2 (AT2) receptor appears to increase nitric oxide and thus to cause some bradykinin-like effects. Evidence for the role of angiotensin II in promoting LVH and cardiac failure as well as for abnormal regulations of the angiotensin signal transduction pathways in model systems and in humans are reviewed. Second, the mechanisms for the beneficial effects of angiotensin II modulation by ACE inhibitors versus angiotensin II antagonists studied in model systems are presented. Finally, results from pivotal phase II studies such as Evaluation of Losartan In The Elderly (ELITE), as well as an overview of the ongoing phase III trials involving the use of ARB in high risk patients are presented.
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PMID:Cardioprotective effect of angiotensin II receptor antagonists. 1057 47

The aim of this study was to examine the effects of both angiotensin II type I receptor antagonism using losartan (LOS) and beta-receptor blockade by metoprolol (MP) in isoproterenol-induced cardiac injury in the rat. Two weeks after isoproterenol (ISO) application, 90 ISO and 30 control (CTRL) rats were examined. ISO rats were treated for two weeks with either LOS, MP, or vehicle (n = 30 each group). Compared to CTRL, ISO induced left ventricular hypertrophy (LVH), fibrosis, and overexpression of extracellular matrix proteins. LOS significantly attenuated these changes. MP only reduced LVH, but exerted no effect on structural alterations. LV end-diastolic and mean right atrial pressures were significantly increased in the ISO group and normalized in the LOS and MP group. Mean aortic blood flow velocity was significantly decreased in the ISO group and unaltered in the LOS and MP group versus CTRL. Blood pressure was decreased in ISO and LOS rats. MP treatment had no effect on blood pressure, but significantly lowered heart rate. Isoproterenol induced mild heart failure. Losartan and metoprolol applications in ISO-treated rats were highly effective in attenuating hemodynamic alterations and LVH. Early application of losartan 24 hours after isoproterenol-induced cardiac injury revealed significant beneficial effects on myocardial structure.
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PMID:Effects of beta-receptor blockade and angiotensin II type I receptor antagonism in isoproterenol-induced heart failure in the rat. 1061 17

Over the past 4 years, six angiotensin II receptor antagonists (ARBs) were approved for treating essential hypertension. They differ with respect to dosing, metabolism, elimination, clinical efficacy, and investigational applications. Candesartan cilexetil is the only prodrug among the agents. Losartan is distinguished from other ARBs by cytochrome P450 (CYP) 3A4- and CYP2C9-mediated biotransformation to its active metabolite EXP-3174. No ARB requires dosage adjustment for renal impairment, but the initial dose of losartan should be reduced 50% in hepatically impaired patients. None of the drugs is significantly cleared by hemodialysis. Completion of continuing trials will elucidate the drugs' role in treating heart failure, cerebral stroke, and myocardial infarction.
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PMID:Pharmacologic, pharmacokinetic, and therapeutic differences among angiotensin II receptor antagonists. 1067 91

To evaluate effectiveness of nonpeptide angiotensin-2 subtype-1 receptor antagonist losartan in therapy of symptomatic congestive heart failure in patients with ischemic heart disease, 116 patients were examined at the age of 36-62 (mean age 50.6 +/- 4.22). They had angina pectoris of functional class II-III (according to CCS) and congestive heart failure of functional class II-III (according to NYHA). All the patients were randomized into two groups. 60 patients of group 1 received basic medication with nitrates, diuretic (on demand), digoxin and aspirin. 56 patients of group 2 received basic medication and losartan (cozaar, MSD, USA) in the dose 25 mg/day for 48 weeks. Echocardiographic monitoring of the treatment efficacy was made. The outcomes of the treatment evidence that losartan improves the patients' clinical status and heart failure functional class. For twelve weeks losartan reduced left ventricular and atrial dilation positively influencing the isometric inotropic indices. In 48 weeks losartan arrested progression of pathologic remodelling of the left ventricle and prevents depression of total myocardial contractility. Losartan's positive effect in restriction of negative evolution of cardiac failure manifests on the treatment week 3.
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PMID:[Losartan in therapy of chronic heart failure]. 1072 50

1. We investigated the role in sympathetic nerve regulation of endogenous angiotensin (Ang)II in the brain in heart failure by examining the effect of losartan on the resting mean arterial blood pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) and the reflex reduction in RSNA elicited by acute volume expansion in conscious rabbits. 2. Heart failure was induced with doxorubicin (1 mg/kg, i.v., twice weekly for 6 weeks). On the experimental day, MAP, HR and RSNA were recorded in conscious rabbits before and after losartan (10 microg; n = 6) or Ringer's (control; n = 5) injected in the fourth brain ventricle. Animals were then administered an acute volume load with the plasma expander Haemaccel (Hoechst Marion Roussel, Lane Cove, NSW, Australia; 2 mL/min, i.v., for 30 min). 3. Losartan did not significantly affect the resting basal levels of MAP, HR and RSNA. There was no significant difference between losartan- and Ringer's-treated animals. 4. Volume expansion in the control group elicited a significant reduction of 40% in RSNA. In the losartan-treated group, a similar reduction (42%) was observed. There was no significant difference between the treatments. The administration of losartan did not significantly affect MAP and HR during volume expansion compared with the control group. 5. We conclude that AngII in the brainstem does not play a major role in the maintenance of resting MAP, HR and RSNA or in the reflex reduction in RSNA elicited by volume expansion in the conscious rabbit with doxorubicin-induced heart failure.
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PMID:Blockade of central angiotensin II does not affect the reduction in renal sympathetic nerve activity following a volume load in heart failure rabbits. 1090 96

The aim of the study was to investigate the effect of angiotensin-converting enzyme inhibitor enalapril and non-peptide blocker of AT1 receptors losartan on endothelial function of the shoulder artery in patients with congestive cardiac insufficiency. The examination covered 96 patients (mean age 46.71 +/- 4.13) with stable effort angina (functional class II-III) and circulatory insufficiency (NYHA functional class II-III) having end-diastolic left-ventricular volume > 160 ml, left ventricular ejection fraction < 35%, sinus rhythm, cardiothoracal index > 0.55 units. Patients with fibrillar tachyarrhythmia, high grade blocks, pacemaker migration, artificial pacemaker, myocardial infarction were not included in the trial. The patients were randomized into 3 groups 32 patients each. In addition to basic therapy patients of group 1 received long-acting nitrates, digoxin, aspirin and furosemide; group 2--enalapril in daily dose 10 mg; group 3--losartan in daily dose 25 mg. A course of treatment lasted 12 weeks. Endothelial function was assessed by high resolution echography, dopplerography performed before and after temporary occlusion of the shoulder artery and sublingual nitroglycerin. In patients with cardiac insufficiency, accelerated blood flow in the shoulder artery after its temporary occlusion promoted realization of the vasoconstrictory reaction. This was verified as endothelial dysfunction. In the course of the treatment all the patients achieved insignificant increase of the shoulder artery initial diameter. After sublingual intake of nitroglycerin vasodilation was also insignificant. 12-week enalapril and losartan prevented vasoconstriction in the shoulder artery in response to quicker circulation following arterial occlusion. However, higher maximal flow speed did not correspond to the increment in the artery diameter after the occlusion in any group. The flow-induced vasodilation was more pronounced in the enalapril group. Losartan group had a trend to an increase in the inner diameter of the shoulder artery. It is shown that enalapril and losartan in congestive cardiac insufficiency improves endothelium-dependent vasodilation caused by nitroglycerin. Enalapril demonstrated stronger ability than losartan to reverse endothelial dysfunction in patients with cardiac insufficiency resultant from ischemic heart disease.
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PMID:[Prospects of endothelial dysfunction reversion in patients with congestive heart failure]. 1097 40

Two independent pharmacologic methods of specifically interfering with the renin-angiotensin-aldosterone system have been brought to the marketplace: angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs). These agents have the potential not only to be very widely used for a broad variety of clinical indications but also to compete against each other as treatments for hypertension, heart failure, renal impairment, and other conditions. Many short-term comparative studies of these two classes of drugs have now been completed. Most have focused on surrogate endpoints, such as blood pressure, renal function, or cough. These studies have generally concluded that ARBs are better tolerated but that the two drug classes otherwise have similar efficacy. The largest clinical trial comparing ARBs and ACE inhibitors thus far completed, Evaluation of Losartan in the Elderly (ELITE 2), failed to confirm the results of a smaller study; it did not demonstrate a significant improvement in outcomes (death or hospitalization for heart failure) with an ARB used alone, despite better tolerability. Many longer-term outcome studies with survival endpoints are under way, but most will compare the combination against an ACE inhibitor alone. These studies will define the optimal use of these agents in medicine for decades to come.
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PMID:Therapeutic trials comparing angiotensin converting enzyme inhibitors and angiotensin II receptor blockers. 1098 Nov 76

Angiotensin II (angiotensin) and transforming growth factor (TGF)-beta(1) play an important role in cardiac fibrosis. We examined Smad proteins in 8-wk post-myocardial infarction (MI) rat hearts. AT(1) blockade (losartan) attenuated the activation of TGF-beta(1) in target tissues. Losartan administration (8 wk, 15 mg. kg(-1). day(-1)) normalized total Smad 2 overexpression in infarct scar and remnant heart tissue and normalized Smad 4 in infarct scar. Phosphorylated Smad 2 (P-Smad 2) staining decreased in cytosol from failing heart vs. the control, which was normalized by losartan, suggesting augmented P-Smad 2 movement into nuclei in untreated failing hearts. Using adult primary rat fibroblasts treated with angiotensin (10(-6) M), we noted rapid translocation (15 min) of P-Smad 2 into the nuclei from the cytosol. Nuclear P-Smad 2 protein level increased with angiotensin treatment, which was blocked by losartan. We conclude that angiotensin may influence total Smad 2 and 4 expression in post-MI heart failure and that angiotensin treatment is associated with rapid P-Smad 2 nuclear translocation in isolated fibroblasts. This study suggests that cross talk between angiotensin and Smad signaling is associated with fibrotic events in post-MI hearts.
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PMID:Interaction between angiotensin II and Smad proteins in fibroblasts in failing heart and in vitro. 1108 60

The management of diabetic hypertension requires meticulous selection of agents in the antihypertension armamentorium. There may be several associated factors to be considered while treating a hypertensive diabetic. These include hyperglycemia, dyslipidemia, proteinuria, left ventricular hypertrophy and heart failure to name a few. Losartan is the first of a new class of agents in the list of antihypertensive drugs. By its selective angiotension II receptor (subtype AT1) blocking action it is postulated to bring about a more complete inhibition of the renin-angiotensin system. Thus, it might produce all the benefits of angiotensin converting enzyme (ACE) inhibitor therapy with the freedom from cough so commonly seen with the use of ACE inhibitors. This review attempts to analyze the possible benefits of losartan therapy in diabetes.
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PMID:Role of losartan therapy in the management of diabetic hypertension. 1127 47


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