Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. When pregnant ewes and their fetuses are exposed to the synthetic glucocorticoid dexamethasone for 2 days early in pregnancy (days 26-28; term 145-150 days), female offspring have increased blood pressure relative to a control group. In one series, this was shown to be due to increased cardiac output, concomitant with a reset mean arterial pressure/heart rate reflex. The first group of such animals had, by the age of 7 years, left ventricular hypertrophy and reduced cardiac functional capacity. 2. The elevation in blood pressure is not maintained by any change in the peripheral renin-angiotensin system (RAS). 3. There is, however, preliminary evidence that some aspects of local RAS (particularly in the kidney and brain) could have participated in the 'programming' event. The levels of mRNA for angiotensin II receptors (AT1, AT2) and angiotensinogen are increased in the kidney of such dexamethasone-treated fetuses in late gestation (130 days), some 100 days after steroid treatment. Similar increases in AT1 mRNA in the medulla oblongata of the fetal brain and large increases of mRNA for angiotensinogen occur in the hypothalamus. 4. These findings, together with evidence from the literature, suggest that both the kidney and parts of the brain are affected by events that also 'program' high blood pressure in the offspring of animals in which the intra-uterine environment has been perturbed at some stage.
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PMID:Organs/systems potentially involved in one model of programmed hypertension in sheep. 1170 4

Gene therapy for hypertension is needed for the next generation of antihypertensive drugs. Current drugs, although effective, have poor compliance, are expensive and short-lasting (hours or one day). Gene therapy offers a way to produce long-lasting antihypertensive effects (weeks, months or years). We are currently using two strategies: antisense oligodeoxynucleotides (AS-ODN), an dantisense DNA delivered in viral vectors, to inhibit genes associated with vasoconstrictive properties. It is not necessary to know all the genes involved in hypertension, since many years of experience with drugs show which genes need to be controlled. AS-ODNs are short, single-stranded DNA that can be injected in naked form or in liposomes. AS-ODNs, targeted to AT1 receptors (AT1R), angiotensinogen (AGT), angiotensin converting enzyme (ACE) and beta 1-adrenergic receptors effectively reduce hypertension in rat models (SHR, 2K-1C and cold-induced) hypertension. The effects can last up to one month when delivered with liposomes. No side effects or toxic effects have been detected and repeated injections can be given. For the vector, adeno-associated virus (AAV) is used with a construct to include a CMV promoter, antisense DNA to AGT or AT1R and a reporter gene. Results in SHR demonstrate reduction and slowing of hypertension development with a single dose administration. Left ventricular hypertrophy is also reduced by AAV-AS-AGT treatment. Double transgenic mice (human renin plus human AGT) with high angiotensin II (Ang II) causing high blood pressure, treated with AAV-AT1R-AS, show a normalisation of blood pressure for over 6 months with a single injection of vector. We conclude that ODNs will probably be developed first because they can be treated like drugs for the treatment of hypertension with long-term effects. Viral vector delivery needs more engineering to be certain of its safety but one day may be used for a very prolonged control of blood pressure.
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PMID:Gene therapy for hypertension: sense and antisense strategies. 1172 1

Left ventricular hypertrophy (LVH) commonly occurs in patients with end-stage renal disease (ESRD) and is an independent risk factor for cardiovascular events. Angiotensin II type 1 receptor (AT1-R) antagonists may be able to reverse LVH independent to the hypotensive effect in the ESRD setting. Thirty chronically hemodialyzed uremic patients with hypertension were randomly assigned to receive the AT1-R antagonist losartan (n = 10), the angiotensin-converting enzyme (ACD) inhibitor enalapril (n = 10), or calcium antagonist amlodipine (n = 10). Left ventricular mass (LVM) index was measured by echocardiography before and 6 months after treatment. The baseline demographic and clinical characteristics did not differ between the three groups. The mean baseline LVM index also did not differ in the three groups. After 6 months of treatment, losartan treatment significantly reduced the LVM index (-24.7 +/- 3.2%) than amlodipine (-10.5 +/- 5.2%) or enalapril (-11.2 +/- 4.1%) therapy. All three groups had a similar decrease in the mean blood pressure with treatment. The plasma angiotensin II concentration increased 5-fold with losartan treatment. In contrast, the plasma angiotension II concentration did not change with enalapril and only increased 2-fold with amlodipine. Thus, the present study indicates that losartan more effectively regresses LVH in patients with ESRD than do enalapril and amlodipine despite a comparable depressor effect between the three drugs.
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PMID:Angiotensin II type 1 receptor antagonist, losartan, causes regression of left ventricular hypertrophy in end-stage renal disease. 1186 45

The LIFE study ("Losartan Intervention For Endpoint reduction in hypertension study") demonstrated a significant cardiovascular protection by an angiotensin AT1 receptor antagonist, losartan, in hypertensive patients with left ventricular hypertrophy. At similar blood pressure control, losartan, as compared to atenolol, reduced the relative risk of primary cardiovascular event (death, myocardial infarction, or stroke) by 13% (p = 0.021) in the whole cohort of 9.193 patients after a mean follow-up of 4.7 years. In a subgroup of 1.195 diabetic patients, the protection was even more marked with a reduction of the combined risk of 24% (p = 0.031) and a fall of the mortality of 39% (p = 0.002). In conclusion, losartan prevents cardiovascular morbidity and death more effectively than atenolol, and seems to confer benefits beyond reduction in blood pressure.
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PMID:[Clinical study of the month. The LIFE study: cardiovascular protection of hypertensive patients by losartan]. 1207 99

ACE-inhibitors and AT, receptor antagonists play an important role in the treatment of cardiovascular and renal diseases. The criteria of evidence-based medicine indicate that ACE-inhibitors (in appropriate combinations with other cardiovascular agents) continue to represent the treatment of first choice in chronic heart failure, post-myocardial infarction with compromised ventricular function, high cardiovascular risk, and diabetic (type 1) nephropathy. It is here that the AT1 antagonists should be used--in particular when ACE-inhibitors are not tolerated. The AT1 antagonists, Irbesartan and Losartan, are applied, at appropriately high doses, primarily in hypertensives with diabetic (type 2) nephropathy. With the current exception of chronic heart failure, no confirmed data are yet available on the value of combination treatment. The LIFE study has shown that an AT1 antagonist is superior to an established beta blocker in hypertensives with an increased risk (left-ventricular hypertrophy), in particular when diabetes mellitus is impending or already present.
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PMID:[ACE inhibitor or AT1 antagonist. Is there a differential therapy?]. 1213 23

Apoptosis, a morphological form of programmed cell death required for control of cell populations, participates in reduced tissue volume associated with ventricular scarring. Prevention of apoptosis of excessive, damaged, or nonfunctioning cardiac or of infiltrating inflammatory cells is usually beneficial for the resolution of cardiac fibrosis. Angiotensin(Ang) II, the most important peptide that mediates the effects of the renin-angiotensin system, may play an important role in hypertension, hypertrophy, and interstitial fibrosis. Furthermore, AngII induced apoptosis of human venous endothelial cells, myocyte, and vascular smooth muscular cells by caspase cascade activation, and the both blockade of AngII type(AT)1 and AT2 receptor prevents AngII induced apoptosis, whereas selective agonistic stimulation of the AT2 receptor alone induces apoptosis. When AT1 or AT2 receptors are stimulated in vivo, apoptosis is enhanced in myocytes, myofibroblasts, and media smooth muscular cells. In the case of AT1 receptor stimulation, this may occur in cardiac myocytes secondary to ventricular hypertrophy. On the other hand, AT2 receptor stimulation induced apoptosis myofibroblasts associated with reduced interstitial fibrosis. Caspase-3 participates in the pathways of apoptosis triggered by in vivo AT1 and AT2 receptor stimulations.
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PMID:[Effects of angiotensin II type 1 and type 2 receptor on apoptosis]. 1239 79

Mice with a genetic deletion of the atrial natriuretic peptide (ANP) receptor, guanylyl cyclase A (GC-A -/-), have chronic arterial hypertension and cardiac hypertrophy from the first day of life. To characterize the role of the angiotensin II and endothelin systems in the development of this cardiovascular phenotype, the effects of chronic treatment with either the angiotensin type I (AT1) receptor antagonist losartan or the endothelin A receptor antagonist BSF208075 were tested. Losartan almost completely reversed systemic arterial hypertension and left ventricular hypertrophy of GC-A -/- mice. This was accompanied by a marked regression of the left ventricular mRNA expression of cardiac hypertrophy markers such as ANP and brain natriuretic peptide and a significant reduction of left ventricular and pulmonary interstitial collagen accumulation. BSF208075 had no effect on any of these cardiovascular parameters. Intriguingly, GC-A -/- mice also showed a very marked right ventricular hypertrophy, which was not reversed by losartan or BSF208075 treatment. Analyses of components of the renin-angiotensin system (RAS) revealed an inhibition of renal and systemic RAS contrasting with increased local left ventricular angiotensin II levels in GC-A -/- mice. Collectively, the results suggest that RAS plays a more important role than the endothelin system in the pathogenesis of arterial hypertension as well as left ventricular hypertrophy and fibrosis in GC-A gene-disrupted mice.
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PMID:Left but not right cardiac hypertrophy in atrial natriuretic peptide receptor-deficient mice is prevented by angiotensin type 1 receptor antagonist losartan. 1240 81

Angiotensin II (Ang II), the biologically active component of renin-angiotensin system (RAS), acts through two receptor subtypes, the AT1 and the AT2 receptor. All classic physiological effects of Ang II, such as vasoconstriction, aldosterone and vasopressin release, sodium and water retention and sympathetic facilitation, are mediated by the AT1 receptor. Ang II, via its AT1 receptor, is also involved in cell proliferation, left ventricular hypertrophy, nephrosclerosis, vascular media hypertrophy, endothelial dysfunction, neointima formation and processes leading to athero-thrombosis. Recent investigations have established a role for the AT2 receptor in cardiovascular, brain and renal function as well as in the modulation of various biological processes involved in development, cell differentiation, tissue repair and apoptosis. This review summarizes new insights in the regulation, signalling and (patho-) physiological functions of AT1 and AT2 receptors. An extensive review on angiotensin receptors has been published recently (de Gasparo M et al., Pharmacol Rev 2000; 52: 415-72).
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PMID:Angiotensin AT1/AT2 receptors: regulation, signalling and function. 1279 27

Arterial Hypertension (AH) is characterized by reduced nitric oxide (NO) biosynthesis, activation of the Renin-Angiotensin-Aldosteron-System (RAAS), vasoconstriction, and microvascular rarefaction. The latter contributes to target organ damage, especially in left ventricular hypertrophy, and may partially be due to impaired angiogenesis. Angiogenesis, the formation of new microvessels and microvascular networks from existing ones, is a highly regulated process that arises in response to hypoxia and other stimuli and that relieves tissue ischemia. In AH, angiogenesis seems impaired. However, blood pressure alone does not affect angiogenesis, and microvascular rarefaction is present in normotensive persons with a family history for AH. Normal or increased NO in several processes and diseases enables or enhances angiogenesis (e.g. in portal hypertension) and reduced NO biosynthesis (for example, in a rat model of AH, in other disease models in vivo, and in endothelial NO Synthase knock out mice) impairs angiogenesis. Angiogenic growth factors such as Vascular Endothelial Growth Factor (VEGF) and Fibroblast Growth Factor (FGF) induce NO and require NO to elicit an effect. Effector molecules and corresponding receptors of the RAAS either induce (Bradykinin, Angiotensin II) or perhaps inhibit angiogenesis. The pattern of Bradykinin- and Angiotensin II-receptor expression and the capacity to normalize NO biosynthesis may determine whether ACE-inhibitors, Angiotensin II-receptor antagonists and other substances affect angiogenesis. Reconstitution of a normally vascularized tissue by reversal of impaired angiogenesis with drugs such as ACE inhibitors and AT1 receptor antagonists may contribute to successful treatment of hypertension-associated target organ damage, e.g. left ventricular hypertrophy.
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PMID:Hypertension and angiogenesis. 1287 Dec 5

1. Left ventricular hypertrophy (LVH) is an independent cardiovascular risk factor. Angiotensin AT1 receptor antagonism has been considered as a specific approach to block the renin-angiotensin system and been demonstrated to be able to prevent or regress LVH by interfering with the remodelling process of the heart. 2. Angiotensin AT1 receptor blockade induces a marked increase in angiotensin (Ang) II, which may stimulate the AT2 receptors. Gene expression of AT1 and AT2 receptors increases in a time-dependent manner in cardiac remodelling following myocardial infarction. 3. Considerable efforts have been made to clarify the role of AT2 receptors in cardiac hypertrophy and remodelling since the mid-1990s, resulting in controversial reports: the AT2 receptor mediates actions either opposite to or in coordination with those of the AT1 receptor. Moreover, there are many reports of no significant effects mediated by AT2 receptors. 4. Based on the studies reviewed in the present article, we assume that the predominant effect of AngII in cardiac hypertrophy and cardiac remodelling is growth promoting and that this effect is mediated mainly via AT1 receptors. The AT2 receptors may affect the hypertrophic process by interacting with other cardiac membrane proteins, enzymes and autacoids. Before coming to a conclusion as to whether AT2 receptor stimulation or antagonism is beneficial to the heart, more studies should be performed in different LVH models, especially long-term treatment protocols in vivo.
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PMID:Role of angiotensin AT1 and AT2 receptors in cardiac hypertrophy and cardiac remodelling. 1467 29


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