Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.15.1 (ACE)
18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. This study was undertaken to determine whether the AT1 receptor directly contributes to hypertension-induced cardiac hypertrophy and gene expressions. 2. Stroke-prone spontaneously hypertensive rats (SHRSP) were given orally an AT1, receptor antagonist (losartan, 30 mg kg-1 day-1), an angiotensin converting enzyme inhibitor (enalapril 10 mg kg-1 day-1), a dihydropyridine calcium channel antagonist (amlodipine, 5 mg kg-1 day-1), or vehicle (control), for 8 weeks (from 16 to 24 weeks of age). The effects of each drug were compared on ventricular weight and mRNA levels for myocardial phenotype- and fibrosis-related genes. 3. Left ventricular hypertrophy of SHRSP was accompanied by the increase in mRNA levels for two foetal phenotypes of contractile proteins (skeletal alpha-actin and beta-myosin heavy chain (beta-MHC)), atrial natriuretic polypeptide (ANP), transforming growth factor-beta-1 (TGF-beta 1) and collagen, and a decrease in mRNA levels for an adult phenotype of contractile protein (alpha-MHC). Thus, the left ventricle of SHRSP was characterized by myocardial transition from an adult to a foetal phenotype and interstitial fibrosis at the molecular level. 4. Although losartan, enalapril and amlodipine lowered blood pressure of SHRSP to a comparable degree throughout the treatment, losartan caused regression of left ventricular hypertrophy of SHRSP to a greater extent than amlodipine (P < 0.01). 5. Losartan significantly decreased mRNA levels for skeletal alpha-actin, ANP, TGF-beta 1 and collagen types I, III and IV and increased alpha-MHC mRNA in the left ventricle of SHRSP. Amlodipine did not alter left ventricular ANP, alpha-MHC and collagen types I and IV mRNA levels of SHRSP. 6. The effects of enalapril on left ventricular hypertrophy and gene expressions of SHRSP were similar to those of losartan, except for the lack of inhibition of collagen type I expression by enalapril. 7. Unlike the hypertrophied left ventricle, there was no significant difference between losartan and amlodipine in the effects on non-hypertrophied right ventricular gene expressions of SHRSP. 8. Our results show that hypertension causes not only left ventricular hypertrophy but also molecular transition of myocardium to a foetal phenotype and interstitial fibrosis-related molecular changes. These hypertension-induced left ventricular molecular changes may be at least in part mediated by the direct action of local angiotensin II via the AT1, receptor.
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PMID:Effects of an AT1 receptor antagonist, an ACE inhibitor and a calcium channel antagonist on cardiac gene expressions in hypertensive rats. 876 77

Angiotensin II exerts its action via at least two distinct receptor subtypes designated AT1 and AT2. AT1 receptors seem to be responsible for most of the known angiotensin II effects while the role of AT2 receptors is not yet clear. Adipocytes of adult rats express exclusively the AT1 subtype. Angiotensin II stimulates prostacyclin release in adult rat adipocytes and in mouse preadipocytes. In the latter prostacyclin release is completely blocked by an AT2 receptor antagonist. Adipocyte angiotensin II receptors seem to be regulated by age and fat mass. Blockade of these receptors by an AT1 antagonist seems to prevent adipose tissue hypertrophy. Moreover, adipose tissue contains all the main components of the renin-angiotensin system such as angiotensinogen, angiotensin converting enzyme, angiotensin II and angiotensin II receptors. Angiotensinogen expression in adipocytes is stimulated by a high fat diet concurrent with enlargement of fat mass, associated with insulin resistance. Angiotensin converting enzyme inhibitors improve insulin sensitivity. Taken together, there is evidence of interaction between insulin and angiotensin II in regulation of adipose tissue metabolism and cellularity. Clarification of these interactions could lead to significant progress in pharmacological treatment of obesity and its comorbidity.
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PMID:The role of angiotensin II and its receptors in regulation of adipose tissue metabolism and cellularity. 878 38

Losartan is an orally active angiotensin II antangonist that selectively blocks effects mediated by the stimulation of the AT1 subtype of the angiotensin II receptor. This agent, at doses of 50-150mg/day, is as effective at lowering blood pressure as chronic angiotensin converting enzyme (ACE) inhibitors. Losartan is generally well tolerated and has an incidence of adverse effects very similar, in double-blind controlled trials, to that of placebo. It does not cause coughing, the most common side-effect of the ACE inhibitors, most probably because angiotensin II antagonism has no impact on ACE, an enzyme known to process bradykinin and other cough-inducing peptides. Losartan is a promising antihypertensive agent with the potential to become a first-line option for the treatment of patients with high blood pressure.
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PMID:Angiotensin II antagonists: a new class of antihypertensive agent. 879 3

1. Chronic angiotensin converting enzyme (ACE) inhibition or AT1 antagonism during postnatal development in the rat has been shown to cause renal tubular and vascular damage, particularly in the outer medulla. 2. The effects of ACE inhibition were investigated at a stage of development before the renal outer medulla is fully established. 3. Sprague-Dawley rat pups were given daily i.p. injections of either enalapril or saline from days 3-10. At day 11, kidneys were perfusion-fixed for either electron microscopy or immunocytochemistry. Sections were incubated in proliferating cell nuclear antigen (PCNA) antisera and the avidin-biotin immunoperoxidase method was used to detect an immunoreactive product, indicative of proliferating cells. 4. Following enalapril treatment, the normal structural arrangement of the outer medulla was disrupted compared with controls. Cell proliferation (PCNA-positive cells) in the medullary rays was reduced in enalapril-treated kidneys compared with control kidneys. 5. Thus, angiotensin II appears to be essential for normal tubular and vascular growth in postnatal renal development in the rat.
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PMID:Angiotensin converting enzyme inhibition in the postnatal rat results in decreased cell proliferation in the renal outer medulla. 880 May 82

1. In the present study, New Zealand genetically hypertensive (GH) rats were treated with valsartan, a specific angiotensin II (AT1) receptor antagonist, to measure the effects on blood pressure (BP), cardiac hypertrophy and the structure of resistance arteries. Normotensive (N) rats were used as controls. 2. Valsartan (val) was given to GH rats at three different doses (10, 3 or 0.3 mg/kg per day, via osmotic mini-pumps implanted i.p.) from age 4-10 weeks. Untreated GH (mini-pump + vehicle) and N rats (mini-pump + vehicle) were used as controls. BP was measured weekly and at the end of the experiment, left ventricular (LV) mass was recorded and the structure of mesenteric resistance arteries (MRA) was determined using stereological methods. 3. BP fell in a dose-dependent fashion, being reduced to normotensive levels by 10 mg/kg; LV mass was significantly reduced (P < 0.0001) to below normotensive values in the GH group given 10 mg/kg val and significantly reduced (P < 0.001), although not normalized, in the other two treatment groups. 4. In MRA, the media/lumen (M/L) ratio was reduced by val according to dose level, to below normotensive values in GHval10, and to levels not different from normotensive values in the GHval3 and GHval0.3 groups. 5. The hypertrophy of smooth muscle cells in GH rats was reduced with val treatment at all doses. 6. Reversal of cardiac and vascular hypertrophy occurred even when BP was not reduced to normotensive levels, indicating an effect on vessel growth but without any retardation of body growth. 7. These results suggest that the vascular structural changes seen after val and angiotensin converting enzyme inhibitor treatment are probably due to the blocking of angiotensin rather than any bradykinin effect.
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PMID:Remodelling of resistance arteries in genetically hypertensive rats by treatment with valsartan, an angiotensin II receptor antagonist. 880 May 89

1. Over the last 40 years a range of therapeutic strategies has been introduced for the long term treatment of hypertension. 2. Although safe effective agents are available a significant number of patients are unable or unwilling to take these drugs as long term treatment. 3. Both insufficient efficacy and adverse effects justify the search for new antihypertensive strategies. 4. Recent developments include orally active angiotensin (AT1) receptor antagonists (ARA) which appear to offer the benefits of prevention of angiotensin II effects without the adverse effects of bradykinin potentiation, such as cough, which limit the usefulness of angiotensin converting enzyme (ACE) inhibitors. 5. Imidazoline receptor agonists offer the potential of centrally active antihypertensives without the adverse effects of sedation and dry mouth. Further clinical experience is necessary to confirm whether the clinical efficacy and good tolerability are confirmed with long term use. 6. Both ARA and imidazoline preferring substances offer the bonus of a desirable haemodynamic profile in patients with heart failure and may open new therapeutic avenues in the management of cardiac failure.
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PMID:New therapeutic agents for hypertension. 880 42

Changes in microcirculation play an important role in the pathogenesis and maintenance of hypertension. The changes can be due to an alteration in vessel diameter or in the number of small blood vessels. In this study, the effects of prolonged administration of different blockers of the renin angiotensin system on the microcirculation of the cutaneous maximus muscle of young spontaneously hypertensive rats were determined by using the dorsal microcirculatory chamber model. Animals were treated with the angiotensin-converting enzyme inhibitor (ACE inhibitor) benazeprilat (3 mg/kg/d) or the specific angiotensin II AT1 receptor antagonist valsartan (3 mg/kg/d) for 4 weeks. Blood pressure was significantly lowered by 22 to 33% and to a similar extent in both treatment groups, whereas blood pressure in the control group continued to rise. Microvascular diameters and density were measured before and during the drug treatment and compared with those in the control group. There was no significant effect of either of the drug treatments on vascular diameters when compared with the control group for any vessel type (arterioles or venules). In contrast, there was a significant decrease in small arteriolar and venular density and in large venular density after treatment with the ACE inhibitor, whereas the angiotensin II AT1 receptor antagonist had no significant effect. The data do not suggest a role for angiotensin II in the long-term control of striated muscle microvascular tone. However, angiotensin II may be involved in microvascular growth via a non-AT1 receptor-mediated mechanism, or other vasoactive peptides degraded by ACE may contribute to the effects of the ACE inhibitor.
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PMID:Effects of prolonged blockade of the renin angiotensin system on striated muscle microcirculation of spontaneously hypertensive rats. 881 12

The present study was designed to evaluate the effect of chronic treatment with losartan, an AT1 angiotensin II receptor antagonist, and enalaprilat, an angiotensin converting enzyme inhibitor, on the presynaptic modulation of [3H]-norepinephrine release from isolated atria of spontaneously hypertensive rats (SHR) and their respective control, the Wistar-Kyoto rats (WKY). The rats received either losartan (5 mg/kg/day) or enalaprilat (1 mg/kg/day) for 12 days by means of osmotic minipumps. The atria were isolated and incubated with [3H]-norepinephrine and the release of radioactivity was used as an index of norepinephrine release. The experimental protocol consisted of two electrical stimulations and the drugs were administered 20 min before the second stimulation. The modulatory action of angiotensin II (0.01 and 1 mumol/L), the alpha 2-adrenoceptor agonist, oxymetazoline (1 mumol/L), the alpha 2-adrenoceptor antagonist, idazoxan (1 mumol/L) and the beta 2-adrenoceptor agonist fenoterol (1 mumol/L) were tested. The results show that losartan or enalaprilat both similarly reduced the blood pressure in SHR. However, only the chronic losartan treatment, and not enalaprilat, abolished the facilitatory effect of exogenously administered angiotensin II on the release of radioactivity. The prejunctional alpha 2- and beta 2-adrenoceptor modulatory mechanisms were not altered by either chronic treatments. Similarly, the facilitatory effect of angiotensin II was blocked by acute administration of losartan but not by enalaprilat. Finally, the facilitatory action of bradykinin on the release of radioactivity was unchanged by chronic enalaprilat treatment. These results confirm the presence of facilitatory AT1 angiotensin II receptors on sympathetic nerve terminals of rat atria. These results also confirm that sympathetic nerve terminal blockade by losartan or the blockade of endogenous angiotensin II formation by enalaprilat are likely to participate in the antihypertensive action of AT1 angiotensin II receptor antagonists and angiotensin converting enzyme.
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PMID:Effects of chronic treatment with losartan and enalaprilat on [3H]-norepinephrine release from isolated atria of Wistar-Kyoto and spontaneously hypertensive rats. 883 8

Hypertension is one of the most important cardiovascular risk factors. Without therapy hypertension leads to stroke, coronary heart disease with angina pectoris and myocardial infarction, kidney failure and/or peripheral vascular disease. The association between blood pressure and these cardiovascular complications can be demonstrated over the entire blood pressure range. The risk of stroke, myocardial infarction, renal failure or peripheral vascular disease increases with increasing blood pressure. Additional cardiovascular risk factors such as hyperlipidemia, smoking and diabetes involve a further increase in risk. Today hypertension can be effectively treated. To that end, diuretics, betablockers, ACE-inhibitors or calcium antagonists can be used. Alpha receptor antagonists and angiotensin AT1 receptor antagonists are also of value. The antihypertensive effectiveness of these drugs is comparable but may vary in individual patients. During antihypertensive therapy, a reduction in cerebrovascular and cardiac complications has been demonstrated for alpha methyldopa, diuretics and betablockers. In these studies, fatal and non-fatal strokes were reduced by 42%, while the reduction in cardiac events was less pronounced (14%). The reasons for this greater efficacy of antihypertensive therapy in the cerebral circulation are not clear. Other risk factors may be particularly important in the pathogenesis of coronary artery disease (e.g. genetic factors, hyperlipidemia and others) or hypertensive vascular changes in the coronary circulation may not be as reversible as they are in the cerebral circulation. The well documented correlation between stroke, myocardial infarction and hypertension, as well as the proven efficacy of antihypertensive therapy in preventing cardiovascular events, underscores the importance of effective and sustained blood pressure control in these patients.
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PMID:[Heart, brain and hypertension]. 884 9

Responses to angiotensin I and antiogensin I-(3-10), the precursors for angiotensin II and IV, were investigated in the mesenteric vascular bed of the cat. Under constant-flow conditions, injections of precursors and the active peptides into the mesenteric arterial perfusion circuit caused dose-related increases in receptor antagonist that were attenuated by the angiotensin AT1 receptor antagonist DuP532 (2-propyl-4-pentafluorethyl-1-[2'-(2H-tetrazol-5-YL)-1,1'-bi phenyl-4-YL methyl]1H-imidazole-5-carboxylic acid), but not by the angiotensin AT2 receptor antagonist PD123,319 ((S)1-[[4-(dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl )-4,5,6,7- tetrahydro-1H-imadazo[4,5-c]pyridine-6-carboxylic acid, ditriflouroacetate]). Responses to angiotensin I and II were similar as were responses to angiotensin I-(3-10) and angiotensin IV, and these responses were not altered by the presence of a time-delay coil in the perfusion circuit. Responses to angiotensin I and angiotensin I-(3-10) were decreased by the angiotensin converting enzyme inhibitor enalaprilat in a dose of the angiotensin converting enzyme inhibitor that had no effect on responses to angiotensin II and IV and that enhanced vasodilator responses to bradykinin. The putative angiotensin AT2 receptor agonist, p-aminophenylalanine6-angiotensin II, produced dose-related increases in mesenteric arterial perfusion pressure that were reduced by DUP532, suggesting that they are mediated by angiotensin AT1 receptors. These results suggest that angiotensin I and angiotensin I-(3-10) are rapidly and efficiently converted by an angiotensin converting enzyme-dependent pathway into active peptides that induce vasoconstriction by activating angiotensin AT1 receptors in the mesenteric vascular bed of the cat.
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PMID:Analysis of responses to angiotensin I and angiotensin I-(3-10) in the mesenteric vascular bed of the cat. 887 48


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