Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) interconverts cortisol and cortisone. Congenital deficiency of the renal isoform of the enzyme results in hypertension, hypokalemia and suppression of the renin-angiotensin-aldosterone system--the apparent mineralocorticoid excess syndrome (AME). In these patients cortisol acts as a potent mineralocorticoid. Suppression of plasma cortisol with dexamethasone results in natriuresis, potassium retention and reduction in blood pressure. Ingestion of excess liquorice or taking carbenoxolone produces an acquired form of AME. The active component of liquorice is glycyrrhetinic acid (GE) and carbenoxolone is the hemisuccinate derivative. Both GE and carbenoxolone are potent inhibitors of 11 beta-OHSD. In vitro studies have shown that 11 beta-OHSD is present in aldosterone-selective tissues and acts as an autocrine mechanism which prevents cortisol from gaining access to the non-specific mineralocorticoid receptor (MR). Congenital or acquired absence of this enzyme allows cortisol to bind to MR resulting in AME. 11 beta-OHSD also appears to be important in controlling cortisol access to glucocorticoid receptors. Variable placental 11 beta-OHSD may alter foetal exposure to maternal cortisol and affect growth as indicated by the correlation between foetal weight and placental 11 beta-OHSD. Thus the tissue-specific distribution, ontogeny and modulation of this enzyme allows it to dictate glucocorticoid effects in addition to its key role in ensuring the specificity of the MR.
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PMID:Congenital and acquired syndromes of apparent mineralocorticoid excess. 838 30

Secondary aldosteronism has deleterious effects in patients with congestive heart failure (CHF) and can contribute to congestion, ventricular arrhythmias, and sudden death. Mortality is higher in patients with elevated levels of plasma aldosterone. Aldosterone increases as CHF progresses as a result of activation of the renin-angiotensin-aldosterone system (RAAS). This is further amplified by the routine use of diuretics. Angiotensin-converting enzyme (ACE) inhibitors produce a profound and consistent inhibition of angiotensin II production, but they exert only a mild and transient antialdosterone effect. In a number of studies involving ACE inhibitors, plasma aldosterone levels at the end of the trial do not differ significantly from baseline. Spironolactone, a specific aldosterone receptor antagonist, may exert an independent and additive effect to that of ACE inhibitors. Apart from its renal effects, recent evidence suggests that spironolactone may exert direct cardiac and vascular effects inhibiting cardiac collagen hypertrophy and limiting vascular constriction. Combining an ACE inhibitor and spironolactone may achieve a more complete inhibition of the whole RAAS and may produce further clinical benefits. The efficacy and safety of such a combination has not been properly addressed. In the CONSENSUS trial, plasma potassium and creatinine levels were not necessarily adversely affected when enalapril was added to the regimens of patients receiving spironolactone, a condition existing in > 40% of the patients enrolled in this study. One prospective open study and other anecdotal reports suggest that combining spironolactone and ACE inhibitors resulted in clinical improvement without serious side effects in patients who could not tolerate further increases in the ACE inhibitor dose.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Angiotensin-converting enzyme inhibitor and spironolactone combination therapy. New objectives in congestive heart failure treatment. 842 3

The case is described of a 40-year-old female with severe hypertension and hypokalaemic metabolic alkalosis, due to prolonged liquorice ingestion. The pseudo-aldosterone-like effects of liquorice have always been attributed to glycyrrhizic acid, but its biochemical substrate has remained elusive. It is now known that glycyrrhetenic acid, the hydrolytic metabolite of glycerrhizic acid, is the active component of liquorice which causes inhibition of the peripheral metabolism of cortisol. Cortisol binds with the same affinity as aldosterone to the mineralocorticoid receptor resulting in a hypermineralocorticoid condition. Ingestion of liquorice may therefore result in retention of sodium and water, hypertension, hypokalaemia, alkalosis and suppression of the renin-aldosterone system. The literature on liquorice-induced hypertension is briefly reviewed with emphasis on the biochemical features of this mineralocorticoid excess syndrome.
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PMID:Liquorice-induced hypertension--a new understanding of an old disease: case report and brief review. 854 95

Angiotensin converting enzyme (ACE) inhibitor therapy in conjunction with loop diuretics and, possibly, digoxin, is associated with a relatively high incidence of recurrent heart failure and death. Even high doses of ACE inhibitors may not completely suppress the renin-angiotensin-aldosterone system; aldosterone "escape' may occur through non-angiotensin II dependent mechanisms involving corticotropin, atrial natriuretic peptide, serum potassium, and deficient high-density lipoprotein cholesterol concentrations. Addition of spironolactone (an aldosterone receptor blocker) to an ACE inhibitor regimen causes marked diuresis and symptomatic improvement. The Randomized Aldactone Evaluation Study (RALES) was organized to explore the role of combination therapy with spironolactone in patients with heart failure. Patients with New York Heart Association Functional Class II-IV heart failure and left ventricular ejection fractions < or = 40% who were on regimens comprising an ACE inhibitor, loop diuretic, and, possibly, digoxin were randomized to receive placebo or spironolactone in doses of 12.5, 25, 50, or 75 mg per day. Eve at the lowest dose of spironolactone, a significant decrease in plasma N-terminal pro-atrial natriuretic peptide occurred, with concomitant increase in concentrations of plasma renin and urinary aldosterone. As prophylaxis for heart failure, a daily dose of 25 mg of spironolactone and monitoring of serum potassium concentrations are recommended; symptomatic therapy in refractory or severe heart failure may require doses as high as 100 mg b.i.d. The RALES Mortality Trial will follow up 1400 similar patients for 3 years to determine the effect of the addition of spironolactone on combined mortality and hospitalization for heart failure.
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PMID:ACE inhibitor co-therapy in patients with heart failure: rationale for the Randomized Aldactone Evaluation Study (RALES). 868 55

Angiotensin converting enzyme (ACE) inhibition undoubtedly has become the cornerstone of heart failure treatment. Useful in each stage, it should possibly be considered first-line treatment in many patients with mild heart failure in whom fluid retention is not clearly present. Careful consideration of the optimal dose for the individual is important. Until further data are available concerning the efficacy and tolerability of high and low doses, the clinician should consider the target doses used in large controlled heart failure trials. Even under optimal dosing conditions, it is likely that ACE inhibition may not suffice in completely modulating the extensive neurohormonal stimulation extant in heart failure. In part this may result from a breakthrough of the ACE inhibitor effect as well as from activation of hormones and peptides that may not be affected by ACE inhibition. Also, a substantial proportion of patients may not tolerate sufficient ACE inhibition. Alternative or additional therapy aimed at modulating neurohormonal activation concerns interference with other parts of the renin angiotensin system, such as angiotensin II receptor and aldosterone receptor antagonism. Sympathetic activity and catecholamine levels may decrease with dopaminergic D2 agonists and, possibly, beta-blockade; in the latter, this may be confined to patients with pre-existing sympathetic over-activation. Increasing circulating levels of atrial natriuretic peptide via neutral endopeptidase inhibition may offer an alternative way to increase diuresis and natriuresis without neuroendocrine stimulation. Novel possibilities that have not yet been tested sufficiently in patients with heart failure include endothelin receptor antagonism, arginine vasopressin antagonism, and renin inhibition. Finally, digitalis glycosides may be considered neurohormonal modulators in addition to being positive inotropes. Heart failure is a complex condition that involves many organs and systems besides the heart. Polypharmacy tailored to the individual is mandatory. It is thus necessary to investigate approaches to the modulation of neurohormonal activation beyond ACE inhibition.
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PMID:Neurohormonal modulation in heart failure: ACE inhibition and beyond. 868 65

Endogenous 17 beta-estradiol (E2) and low parenteral doses of exogenous E2 are vasodilators. High dose estrogens, especially ethinylestradiol (EE) and mestranol, stimulate the synthesis of hepatic proteins including coagulation factors, sex hormone binding globulin, and angiotensinogen (Aogen). In the steady state, high plasma levels of Aogen produce only a very small increase of angiotensin II (AII) and plasma renin activity, because AII inhibits the secretion of renin and lowers plasma renin concentration. However, the increase in AII is sufficient for a slight reduction in renal blood flow and a slight increase in exchangeable sodium and blood pressure; in susceptible women, blood pressure may rise considerably. Effects of estrogens on the brain may also be involved in blood pressure changes. Endogenous progesterone is a mineralocorticoid receptor antagonist. Endogenous or exogenous progesterone leads to sodium loss and a compensatory increase in renin secretion, plasma renin activity, AII, and plasma aldosterone, e.g. in the second half of the menstrual cycle. Synthetic progestogens are commonly devoid of the mineralocorticoid receptor antagonistic effect of progesterone, and some are weak estrogen receptor agonists. Combined use of EE and synthetic progestogens may therefore enhance estrogen effects on body sodium and blood pressure. A new progestogen (Drospirenone) with an antimineralocorticoid effect like that of progesterone is described that slightly lowers body weight and blood pressure in a contraceptive formulation together with EE. An almost ideal oral contraceptive would be progestogen like Drospirenone together with a low dose natural estrogen that does not stimulate Aogen synthesis. Since most oral formulations for postmenopausal estrogen replacement also stimulate hepatic protein synthesis (including Aogen) to some extent, the transdermal route of E2 application for contraceptive purposes should also be investigated, since it has reduced potential for undesirable side effects.
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PMID:Effects of estrogens and progestogens on the renin-aldosterone system and blood pressure. 873 94

Pseudohypoaldosteronism was first described in 1958 by Cheek and Perry, who reported an infant with severe salt wasting in the absence of any renal or adrenal defect. Since then several reports have described patients affected by symptoms consistent with resistance to mineralocorticoid action. The clinical picture is characterized by salt wasting and failure to thrive and is resistant to the administration of exogenous mineralocorticoids. Biological features are invariably high plasma and urinary aldosterone levels and elevated plasma renin activity associated with hyponatremia, hyperkalemia, and metabolic acidosis. The discovery of abnormal binding of aldosterone to the mineralocorticoid receptor (MR) in lymphocytes from affected patients, by analogy to findings in other syndromes of steroid hormone resistance, led to the hypothesis that the disease reflected a molecular defect in MR, which has prompted a series of molecular studies to characterize the defect. In this paper we review mechanisms of mineralocorticoid action, discuss the clinical features of mineralocorticoid resistance, overview the molecular characterization of the MR, and close with some pathophysiological hypotheses and questions.
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PMID:Mineralocorticoid resistance. 873 98

In uninephrectomized rats on 1% NaCl solution to drink, aldosterone (0.75 micrograms/h subcutaneously for 8 weeks) raises blood pressure and causes marked interstitial and perivascular cardiac fibrosis, effects not seen in animals on a low salt intake. In extending these initial findings, we have shown that cardiac fibrosis (i) is not reversed by correction of mineralocorticoid-induced hypokalemia; (ii) appears not to involve the plasma or tissue renin-angiotensin systems, as fibrosis is largely unaffected by concurrent administration of Losartan or Perindopril; (iii) is independent of cardiac hypertrophy, in that it is equally seen in right and left ventricles, and in rats rendered hypertensive without cardiac hypertrophy by the administration of 9 alpha-fluorocortisol; (iv) is independent of elevated blood pressure, in that it is found in normotensive animals infused peripherally with aldosterone and intracerebroventricularly with the mineralocorticoid receptor (MR) antagonist RU28318; (v) is via classical MR, in that it is blocked by concurrent administration of the MR antagonist potassium canrenoate; and (vi) may or may not be a direct cardiac effect, inasmuch as data for in vivo effects on collagen formation by cardiac fibroblasts are conflicting. Although there is a high probability that the action of aldosterone to cause cardiac fibrosis in this experimental model is an effect via non-epithelial MR, the locus of aldosterone action remains to be established, as do the molecular mechanisms linking MR occupancy by aldosterone and collagen deposition. In addition, and in particular, the mechanisms underlying the crucial contribution of high salt intake in this model of mineralocorticoid excess await exploration.
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PMID:Mineralocorticoids, salt, hypertension: effects on the heart. 873 7

To understand the role of glucocorticoid and mineralocorticoid signalling during development and in whole animal physiology, we have disrupted the mouse glucocorticoid and mineralocorticoid receptor gene by gene targeting. Most of the mice with a disrupted glucocorticoid receptor gene die within the first hours after birth due to severe lung atelectasis. Perinatal induction of gluconeogenic enzymes in the liver is impaired. Regulation of the glucocorticoid synthesis via the hypothalamic-pituitary-adrenal axis is perturbed, leading to increased plasma levels of corticosterone and adrenocorticotrophic hormone. Activation of the hypothalamic-pituitary-adrenal axis results in extensive hypertrophy and hyperplasia of the cortical zones of the adrenal and induction of genes involved in steroid biosynthesis. The adrenal medulla is disorganized and severely reduced in size; no cells capable of adrenaline synthesis can be detected. Mineralocorticoid receptor deficient mice die mainly at day 9/10 after birth. Weightloss precedes death of homozygous mutant mice and is correlated with an increase in the haematocrit. As a consequence of this mutation, plasma levels of renin and aldosterone are high elevated.
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PMID:Molecular genetic analysis of glucocorticoid and mineralocorticoid signaling in development and physiological processes. 873 8

Defective aldosterone receptor binding is present in pseudohypoaldosteronism, and sporadic as well as familial cases have been reported. In familial pseudohypoaldosteronism, autosomal dominant as well as autosomal recessive inheritance has been described. The autosomal dominant form is characterized by a relative mild course of the disease and asymptomatic carriers of the defect in these families, whereas the autosomal recessive form is characterized by severe salt-losing symptoms; not uncommonly these families are consanguineous. To date no genetic mutation has been identified in the aldosterone receptor gene of affected patients. Studies to evaluate the biochemical defect and to characterize the inheritance pattern are of major interest for clinical as well as research purposes. Thus we studied the response of the renin-angiotensin-aldosterone system to sodium depletion using a single dose of furosemide. In 5 patients from five nonconsanguineous families and in all available family members the renin and aldosterone levels as well as serum sodium was measured before and after an oral dose of furosemide. The aldosterone receptor binding of peripheral mononuclear leukocytes was determined at the beginning of the study. In three families asymptomatic carriers of the defect could be identified in the baseline state by elevated levels of basal aldosterone and high renin concentration. The levels of renin and aldosterone did not differ between the symptomatic and asymptomatic individuals in these families. Interestingly the aldosterone receptor binding in the asymptomatic carriers of these families was normal. In the other two families, however, the basal hormonal data were normal in all relatives suggesting at first sporadic cases. During sodium depletion with furosemide, renin as well as aldosterone levels rose significantly in 1 parent and a sibling, respectively. In contrast to the first three families the aldosterone receptor binding in these family members was low. We propose to reclassify these family members as asymptomatic carriers and the patients as familial cases. Whether these cases are genetically identical to the 'classical autosomal dominant cases' remains to be seen. It seems that the pathogenesis of pseudohypoaldosteronism is even more heterogeneous than previously thought and factors other than aldosterone receptor binding are crucial and need further identification.
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PMID:Pseudohypoaldosteronism: family studies to identify asymptomatic carriers by stimulation of the renin-aldosterone system. 889 67


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