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)

Left ventricular hypertrophy is a major risk factor associated with the appearance of adverse cardiovascular events. A distortion in myocardial structure, mediated by an abnormal accumulation of fibrillar collagen within the adventitia of intramyocardial coronary arteries and neighbouring interstitial spaces, alters the electrical and mechanical behaviour of the myocardium. The mechanisms responsible for the regulation of cardiac myocyte growth and collagen accumulation are therefore of considerable interest. Herein we review results of in vivo studies conducted in the authors' laboratory that addressed these issues in various experimental models. The findings indicate that in arterial hypertension myocardial hypertrophy is related to ventricular systolic pressure work. Myocardial fibrosis, on the other hand, is not related to haemodynamic workload, but rather the presence of mineralocorticoid excess relative to sodium intake and excretion. Accordingly, fibrosis can appear in both the hypertensive left and non-hypertensive right ventricles. Pharmacological probes, administered in variable doses, were used to further test and support this hypothesis. In both primary and secondary hyperaldosteronism, it was possible to prevent the pathological structural remodelling of the myocardium with an aldosterone receptor antagonist, while in unilateral renal ischaemia ACE inhibition was similarly cardioprotective. Other studies demonstrated that it was feasible to regress the fibrous tissue response and normalise diastolic stiffness. This concept of cardioreparation suggests that heart failure due to this type of structural remodelling may be reversible.
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PMID:Regulatory mechanisms of myocardial hypertrophy and fibrosis: results of in vivo studies. 130 Dec 54

The major risk factor associated with the appearance of adverse cardiovascular events and outcome attributable to cardiovascular disease is left ventricular hypertrophy (LVH). Why this should be so resides not in the increase in myocardial mass per se, but in the disruption of myocardial structure. An abnormal accumulation of fibrillar collagen within the adventitia of intramyocardial coronary arteries and neighboring interstitial spaces represents such a distortion in structure. Furthermore, this fibrosis disrupts the electrical and mechanical behavior of the hypertrophied myocardium. Mechanisms responsible for fibrillar collagen accumulation have been examined in intact animals and cultured cardiac fibroblasts. In vivo studies indicate that myocardial fibrosis is associated with the presence of chronic mineralocorticoid excess, relative to sodium intake and excretion, not hemodynamic workload. Accordingly, fibrosis can appear in both the hypertensive, hypertrophied and nonhypertensive, nonhypertrophied ventricles. In both primary and secondary hyperaldosteronism it was possible to prevent myocardial fibrosis with an aldosterone receptor antagonist, while in unilateral renal ischemia angiotensin converting enzyme (ACE) inhibition was similarly cardioprotective. A regression in fibrous tissue and normalization of diastolic stiffness has also been possible using ACE inhibition, bringing forward the concept of cardioreparation and the notion that heart failure due to fibrosis may be reversible. In vitro studies indicate that effector hormones of the renin-angiotensin-aldosterone system stimulate fibroblast collagen synthesis. Aldosterone, in pathophysiologic concentrations, and angiotensin II, in much larger concentrations, each enhance collagen synthesis without altering the mitogenic potential of these cells. Thus, elevations in circulating aldosterone and angiotensin II, relative to sodium intake, have the potential to not only alter sodium homeostasis and vascular tonicity, but also the structure of cardiovascular tissue. Thus, myocardial fibrosis represents a structural basis for pathologic hypertrophy and ultimately accounts for the appearance of adverse cardiovascular events and outcomes.
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PMID:Pathologic hypertrophy with fibrosis: the structural basis for myocardial failure. 136 63

The cardiac interstitium is composed of non-myocyte cells and a structural fibrillar protein network which plays a dominant role in governing the structure, architecture, and mechanical behaviour of the myocardium. Herein we review the fibrillar collagen network, its various components, and the functions they serve in the normal and structurally remodelled myocardium in arterial hypertension. The heterogeneity in myocardial structure, created by the altered behaviour of non-myocyte cells, particularly cardiac fibroblasts, which are responsible for collagen synthesis or degradation and thereby fibrous tissue accumulation, is a major determinant for the appearance of diastolic dysfunction and ultimately systolic myocardial failure. Regulatory mechanisms related to this fibrous tissue response are reviewed to draw attention to the hitherto neglected role of cardiac fibroblasts in mediating adverse structural remodelling of the myocardium and showing how this can be prevented through the use of pharmacological agents that interfere with the regulation of the myocardial collagen matrix. Several lines of evidence suggest that circulating and tissue renin-angiotensin-aldosterone systems (RAAS) are involved in the structural remodelling of the non-myocyte compartment. These include the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition and aldosterone receptor antagonism that were found to prevent myocardial fibrosis in the rat with renovascular hypertension. In the rat with genetic hypertension, established left ventricular hypertrophy and abnormal myocardial diastolic stiffness due to interstitial fibrosis, RAAS inhibition resulted in restoration of myocardial structure and function to normal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Myocardial collagen matrix remodelling in arterial hypertension. 139 56

The hallmark of myocardial hypertrophy associated with congestive failure is interstitial fibrosis. How does the fibrosis develop, and what can be done about it? Hormonal and hemodynamic factors are examined. Experimental studies with ACE inhibitors or aldosterone receptor antagonists suggest that the fibrosis may be prevented or reversed.
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PMID:Myocardial remodeling and pathologic hypertrophy. 201 Apr 81

Blockade of endogenous angiotensin II (ANG II) biosynthesis by intramuscular administration of the angiotensin converting enzyme inhibitor captopril (1 or 10 mg/kg b.w.t.) completely suppressed salt appetite induced by sodium depletion in the pigeon. The effect was selective since captopril did not reduce deoxycorticosterone (DOCA)-induced salt appetite nor water drinking to ANG II and eledoisin. Blockade of brain ANG II receptors by pulse intracerebroventricular (pICV) injection of the ANG II receptor antagonist [Sarcosine1, isoleucine8] ANG II produced a marked, although partial, inhibition of salt appetite. The inhibition was quantitatively similar to the effectiveness of the ANG II receptor blockade, as measured by the suppression of drinking to pICV ANG II. Blockade of brain aldosterone (ALDO) receptors by pICV injections of the mineralocorticoid receptor antagonist RU-28318 did not significantly suppress depletion-induced appetite at doses that markedly reduced DOCA-induced salt appetite. These findings suggest that the pigeon might be completely dependent on ANG II for the expression of depletion-induced salt appetite. This is in contrast with what has been found in the rat, in which blockade of both ANG II and ALDO are necessary to suppress the appetite.
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PMID:The apparent dependence of salt appetite in the pigeon on endogenous angiotensin II. 296 Sep 95

The cardiac interstitium is composed of nonmyocyte cells and a structural protein network which plays a dominant role in governing the structure, architecture, and mechanical behavior of the myocardium. The heterogeneity in myocardial structure, created by the altered behavior of nonmyocyte cells, particularly cardiac fibroblasts which are responsible for myocardial collagen metabolism and fibrous tissue accumulation, may largely explain the appearance of diastolic and/or systolic myocardial failure. Regulatory mechanisms that are related to the fibrous tissue response in various cardiovascular diseases, e.g., hypertensive heart disease, dilated cardiomyopathy or post myocardial infarction, are of primary clinical interest. A better understanding of the hitherto neglected role of cardiac fibroblasts in mediating an adverse structural remodeling of the myocardium will lead to specific pharmacologic agents that interfere with the fibrous tissue response. Several lines of evidence based on in vivo and in vitro studies suggest that circulating and tissue renin-angiotensin-aldosterone systems (RAAS) are involved in the structural remodeling of the nonmyocyte compartment, including the cardioprotective effects of angiotensin converting enzyme (ACE) inhibition or aldosterone receptor antagonism that was found to prevent myocardial fibrosis in the rat with renovascular or genetic hypertension. In cultured adult cardiac fibroblasts, an angiotensin (Ang)II- or aldosterone-mediated dose-dependent increase in collagen synthesis could be completely abolished by the use of AngII type 1 or mineralocorticoid receptor antagonists, respectively. Likewise, the AngII-mediated decrease in the activity of matrix metalloproteinase 1, the key enzyme for interstitial collagen degradation, could be antagonized by AngII receptor blockade.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pharmacological modulation of cardiac fibroblast function. 777 64

In view of the hypothetical possibility that the vascular renin-angiotensin system (RAS) might include aldosterone biosynthesis and action in the vasculature, we have undertaken a study to identify aldosterone released into the perfusion circuit from the rat mesenteric artery, and to investigate the effects of an angiotensin converting enzyme inhibition (ACEI) on aldosterone production from the vasculature. After 30 min equilibration, 240 mL of perfusate was collected and subjected to reverse-phase HPLC and subsequent mass spectrometry. Mass spectra corresponding to authentic corticosterone and aldosterone were obtained from the samples of mesenteric artery perfusate. Production of aldosterone in the mesenteric artery was not changed by adrenalectomy, although it was reduced in the arterial perfusate from rats pretreated with ACEI. By RT-PCR the expression of CYP 11B2 and mineralocorticoid receptor genes were demonstrated in both vascular endothelial and smooth muscle cells. These studies constitute indirect evidence supporting our hypothesis that locally produced aldosterone in the vascular tissue acts on vascular tone and remodeling via a paracrine or autocrine manner.
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PMID:Aldosterone biosynthesis and action in vascular cells. 779 96

ACE inhibitors have been shown to be effective in reducing the morbidity and mortality of patients with left ventricular systolic dysfunction, but their application to clinical practice in this situation is still limited. In part, the failure to prescribe an ACE inhibitor to a patient with left ventricular systolic dysfunction is due to perceptions regarding their side effects, such as cough and renal dysfunction. Relatively few patients with left ventricular systolic dysfunction and a serum creatinine > or = 2 mg/dl receive an ACE inhibitor in clinical practice. In this situation one should consider an agent such as fosinopril, which is metabolized by the liver as well as secreted by the kidney. In patients with moderate renal dysfunction, fosinopril has been well tolerated without an increase in serum creatinine. In patients who develop cough due to an ACE inhibitor, consideration should be given to an angiotensin II type 1 receptor blocking agent, such as losartan. The relative safety and efficacy of an ACE inhibitor compared with an angiotensin II type 1 receptor blocking agent is being explored in a prospective randomized trial (Evaluation of Losartan In The Elderly [ELITE]), as well as the safety and pharmacological effectiveness of adding an angiotensin II receptor antagonist to an ACE inhibitor (Randomized Angiotensin receptor antagonists-ACE-inhibitor Study [RAAS]). There may also be a role for the combination of an aldosterone receptor antagonists and an ACE inhibitor in patients with left ventricular systolic dysfunction. Once an ACE inhibitor is administered to a patient with left ventricular systolic dysfunction it should be continued indefinitely. ACE inhibitors may be of value not only in preventing the progression of heart failure but also in reversing endothelial dysfunction and preventing the development of atherosclerosis and its consequences, such as myocardial infarction.
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PMID:ACE inhibitors in heart failure: prospects and limitations. 921 Oct 22

Spironolactone, a competitive aldosterone receptor antagonist (ARA), has traditionally been the treatment of first choice in idiopathic hyperaldosteronism (IHA) and for preoperative management of aldosterone producing adenoma (APA). Spironolactone is partially absorbed, is extensively metabolized mainly by the liver and its therapeutic properties are attributable to active metabolite canrenone. At therapeutic doses of 25 to 400 mg per day, spironolactone effectively controls blood pressure and hypokalemia in the majority of cases. Endocrine side effect are often associated and mainly consist of gynecomastia, decreased libido and impotence in man and menstrual irregularities in women. Canrenone and the K+ salt of canrenoate are also in clinical use: they avoid the formation of intermediate products with anti-androgenic and progestational actions, resulting in a decreased incidence of side effects. Furthermore, a relatively new selective ARA compound (eplerenone) with reduced affinity for androgen and progesterone receptors, is currently undergoing clinical trials. In essential hypertension aldosterone can contribute to hypertension and increases the incidence of myocardial hypertrophy and cardiovascular events. On the other hand, inhibition of Renin-Angiotensin-Aldosterone System (RAAS) is associated with a decrease in blood pressure, with a regression of left ventricular hypertrophy and a reduction of target organ damage. Thus, ARA have been proposed as complementary treatment associated to ACE inhibitors and angiotensin receptor antagonists. Aldosterone is also known to play an important role in pathophysiolgy of congestive heart failure (CHF). In vitro and in vivo evidences suggest that aldosterone promotes myocardial fibrosis. This effect reflects direct, extra-epithelial actions of aldosterone via cardiac MR which are counteracted by ARAs in animal models. The RAAS is chronically activated in CHF. Non potassium-sparing diuretics further stimulate the RAAS and cause hypokalemia. Thus, use of ARAs in CHF was first proposed to correct potassium and magnesium depletion. At present ARAs are indicated in the management of primary hyperaldosteronism, in oedematous conditions in patients with CHF, in cirrhosis of the liver accompanied by oedema and ascites, in essential hypertension and in hypokalemic states. Its indication as adjunctive therapy of heart failure is currently under investigation. In fact, it is well known that even high doses of ACE inhibitors may not completely suppress the RAAS; aldosterone 'escape' may occur through non angiotensin II dependent mechanisms. Addition of spironolactone to an ACE inhibitor causes marked diuresis and symptomatic improvement. During the last few years, the RALES study (Randomized Aldactone Evaluation Study) was organized to explore the efficacy of combination therapy with spironolactone and ACE inhibitor in patients with CHF, class III or IV NYHA. The study was stopped 18 months early because the results were so statistically and clinically significant that it would be unethical to continue the trial. It is reported a 30 percent decrease in mortality and hospitalisation for cardiac causes in spironolactone-treated group vs placebo group.
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PMID:Aldosterone antagonists in hypertension and heart failure. 1079 May 93

Morbidity and mortality of heartfailure are decreasing because of improved medical treatment. The recompensation balance can however be very fragile, which is illustrated by three patients. A woman aged 73 and a man aged 62, both known with heart failure, became seriously ill after diarrhoea; examination revealed uraemia, hyperpotassaemia and raised digitalis levels. A man aged 72, also with heart failure and diarrhoea, developed sensory disorders in both feet. He, also, was found to suffer from renal insufficiency. All patients used an angiotensin converting enzyme inhibitor or an angiotensin-II-antagonist and an aldosterone receptor blocker as well. During the (innocent) intercurrent disease by which their intravascular volume diminished they developed a severe renal insufficiency which needed clinical, intensive treatment. After haemodialysis, all three recovered well. Renal function plays an essential role in the fragile treatment balance that exists in recompensated cardiac patients. The medication that is beneficial for the cardiac functioning may at the same time compromise the renal perfusion. Good monitoring and good instructions about what to do in case of intercurrent diseases are of vital importance in these patients.
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PMID:[Acute renal insufficiency due to vomiting or diarrhea: the Achilles heel of medical support for heart failure]. 1102 Aug 33


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