Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
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Congestive heart failure is a syndrome common in the United States, especially in elderly patients. The most common etiology is coronary artery disease. A number of general factors contribute to the heart failure syndrome, including loss of muscle, decreased myocardial contractility, pressure or volume overload, or restricted filling. All of these factors may play a role in a given patient as, for example, with coronary artery disease. Although systolic dysfunction with a reduced ejection fraction is the most common heart failure syndrome, up to 40% of patients may have a relatively preserved ejection fraction with diastolic dysfunction. As the heart begins to fail, a number of compensatory mechanisms are activated. These include increased heart rate, the Frank-Starling mechanism, increased catecholamines, activation of the renin-angiotensin system, and release of atrial natriuretic peptides. Although these mechanisms are initially helpful to the cardiovascular system, they frequently overshoot, initiating a vicious cycle. For example, with a decrease in cardiac output, there is a reflex increase in systemic vascular resistance in order to maintain perfusion pressure. This increase in resistance, however, acts as a load on the left ventricle and further reduces cardiac output. The best evidence for the existence of this vicious cycle is the beneficial change in hemodynamics produced by vasodilator drugs and the ACE inhibitors. Thus, an understanding of pathophysiology allows for the selection of rational therapy. An unresolved problem in heart failure patients is how best to reduce the high incidence of sudden death, which is one of the major challenges for the future.
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PMID:Pathophysiology of congestive heart failure. 139 15

Plasma values of atrial natriuretic factor (ANF) were evaluated in 31 women with pregnancy-induced hypertension (PIH) and 31 normal pregnant women at the same age of gestation. In 27 women with PIH and 27 normal pregnant women forearm venous tone (FVT) was evaluated by Strain Gauge Plethysmography. Forearm vascular resistance (FVR) was measured as the ratio of mean blood pressure (MBP) to forearm blood flow. In addition Cardiac Index (CI) by means of transthoracic electrical bioimpedance and total peripheral vascular resistance (TPR) (with the Frank Equation) were also measured. In comparison with the normal pregnant women, the women with PIH had similar values of hematocrit (as an index of plasma volume) and significantly higher levels of FVR and TPR, while ANF plasma values did not differ significantly. Subdividing the women with PIH in relation to the presence of proteinuria (greater than or equal to 0.3 g/l), those with proteinuria, in addition to significantly higher levels of FVR and TPR, had significantly higher levels of FVT than normal pregnant women, while ANF plasma values were higher even though the difference was only near the level of significance. Hypertensive women with proteinuria also had higher values of FVT than hypertensive women without proteinuria. By means of multiple regression ANF did not show any significant correlations with hematocrit or sodium excretion. Hypertension with proteinuria seems to represent a more severe form of the disease in which, in addition to the probable influence of other factors such as the renin-angiotensin and prostaglandin systems, a greater increase in peripheral sympathetic tone than in hypertension alone appears to be present, causing a reduction in venous compliance in addition to the elevation in FVR and TPR, with increase in central blood volume and atrial stretch. This may explain the higher ANF plasma levels in these patients in comparison with normal pregnant women, even though the absence of a significant correlation of ANF with hematocrit and the fact that ANF increase was only near the level of significance may suggest a change in the relation between ANF secretion and atrial volume receptors in pregnancy either normal or complicated by hypertension. ANF does not seem to play an important role in water and sodium excretion in PIH probably because of the presence of very high plasma levels of hormones such as aldosterone, progesterone and oestriol which, together with renal prostaglandins, seem to be involved in diuresis and natriuresis in pregnancy.
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PMID:Plasma concentrations of atrial natriuretic factor and hemodynamics in pregnancy-induced hypertension. 183 84

The heart is one of the major target organs that becomes secondarily involved with the unrelenting and progressive vascular disease of essential hypertension. As a result of this increasing afterload that is imposed upon the left ventricle, the ventricular chamber adapts structurally and functionally. Structural changes involve an increase in muscle mass that is achieved through left ventricular hypertrophy (in a manner similar to the arteriolar changes demonstrated by increased thickening). Unless antihypertensive therapy is interdicted in this disease process, left ventricular failure will ensue as the major cardiac hemodynamic consequence. Left ventricular hypertrophy is also associated with a risk that is independent of the pressure overload and hemodynamic risk. Although antihypertensive therapy will reduce from the hemodynamic alterations, only recently have epidemiological findings suggested that the independent risk of LVH may be reduced with pharmacological therapy. There are no data available to indicate just which agents may reduce the risk from LVH; but relatively recent studies seem to indicate that while all agents may reduce LVH with prolonged therapy only certain classes of agents will do so independent of their hemodynamic factors. Some of these agents, however, may impair cardiac function if arterial pressure is increased abruptly following therapeutic reduction of cardiac mass. Other agents may preserve normal function--or even may improve function. Among those classes of antihypertensive agents that reduce cardiac mass at least in part due to nonhemodynamic factors, are the angiotensin converting enzyme inhibitors, the calcium antagonists, and most adrenergic inhibitors. Evidence will be presented demonstrating the hemodynamic/structural dissociation of those pharmacological agents that reduce cardiac mass with short-term treatment in spontaneously hypertensive rats with left ventricular hypertrophy. Although centrally active adrenolytic, angiotensin converting enzyme (ACE) inhibitors, and calcium antagonists all reduce cardiac mass, their structural and cardiac functional effects differ greatly. Even within the ACE inhibitor group their effects vary--improving, impairing, or not changing the Frank-Starling relationships following reduction in left ventricular mass. We postulate great variability of cardiac intramyocytic penetrance of the pharmacological agents and their local intracellular effects on mitogenesis of the ventricular myocyte. The implications on cardiac function and therapy have vast potential. Therefore, current investigative areas involving new concepts of molecular biology of the cardiac myocyte may provide great promise to the quest of unraveling some of the newly postulated questions: What is the role of ionized intracellular calcium? Do the local renin-angiotensin systems in the cardiac and vascular myocyte participate in the development and regression of hypertrophy?(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Left ventricular hypertrophy: dissociation of structural and functional effects by therapy. 183 47

The circulatory compensatory mechanisms designed to cope quickly with physiological stress (e.g. sympathetic nervous system and the Frank-Starling mechanism) are less effective when there is chronic pathological stress, such as congestive heart failure (CHF). Other mechanisms come into play that operate over a longer time (e.g. activation of the renin-angiotensin-aldosterone system, myocardial hypertrophy and physiological deconditioning). Changes in blood vessels and skeletal muscle metabolism that result from inadequate delivery of oxygenated blood to working muscles belong to the group of mechanisms that develop slowly. When CHF therapy is successful, the abnormalities produced by this latter group of mechanisms will improve, but slowly. The concept that compensatory mechanisms have either short or long time constants for activation and reversal may explain why exercise tolerance improves much later than haemodynamics, which can be reversed acutely with vasodilator therapy.
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PMID:Time-constant adaptations in heart failure. 191 37

PMS is probably a group of entities which include various symptoms that occur during the 7 to 10 days before menstruation and disappear a few hours after the onset of menstruation. The definition of PMS lacks objective criteria. The most common symptoms are irritability, bloating, aggressiveness, mastodynia, and headaches. The prevalence of PMS is estimated at 30 to 40 per cent. PMS is more prevalent among women working outside the home, alcoholics, women of high parity, and women with toxemic tendency; it probably runs in families. The etiology of PMS is no less obscure to us than when it was first described by Frank in 1931. No single theory has been established to explain the entire diversity of PMS symptomatology. The multitude of possible etiologic factors includes psychosocial bases, progesterone deficiency, prolactin excess, thyroid hypofunction, renin angiotensin alternations, antidiuretic hormone excess, decreased colloidosmotic pressure, endorphin activity alternations, serotonin metabolism alternations, prostaglandin action, vitamin deficiency, and such unconventional theories as the ovarian infection or the "yeast overgrowth" theory. A partial resolution of this divergence of hypotheses comes from the biopsychosocial model developed by Keye and Trunnel. According to this model, a biologic, perhaps genetically determined, predisposition to PMS is realized when past and present life experiences, attitudes, beliefs, coping styles, and social forces interact to stress a woman. The diagnosis of PMS is based on establishing a relationship between the luteal phase of the cycle and the symptoms. The evaluation of PMS patients includes the use of a monthly diary to scale the symptoms, a physical examination, and biochemical studies to rule out other disorders. Management includes education, reassurance, and drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The premenstrual syndrome. 218 58

Ventricular dysfunction due to an abnormality of the heart which is associated with typical hemodynamic, renal and hormonal reactions, characterizes the clinical syndrome heart failure. The traditional definition of heart failure as the inability to pump an amount of blood sufficient to cover the metabolic needs of the body in the presence of adequate venous return, emphasizes mainly the reduction in cardiac output but not the increase in intracardiac pressures. Pressure or volume overload, decreased contractility, loss of muscle mass or restricted filling represent the most important pathological processes leading to heart failure. The disturbance of systolic ventricular function due to pressure or volume overload or diminished contractility is characterized by a decrease in the ejection fraction, the disturbance in diastolic ventricular function associated with restricted filling is characterized by elevated chamber stiffness. Decreased contractility is most commonly responsible for the development of heart failure. Impairment of diastolic ventricular function can only be regarded as the dominant mechanism leading to heart failure in the presence of a small noncompliant ventricle. Impairment of diastolic ventricular function in an enlarged heart is always associated with an impairment of systolic ventricular function and is, then, relegated to a subordinate role. Common causes of heart failure are coronary artery disease, hypertension, cardiomyopathies, valvular heart diseases and congenital heart diseases, for the incidence of which coronary artery disease is most frequently responsible. Most of these diseases lead to heart failure not via a single, but rather several of the specified pathophysiological processes. Possible mechanisms for loss of contractility include structural changes as well as alterations in excitation-contraction coupling. Possible mechanisms responsible for impaired diastolic ventricular function encompass, in addition to altered calcium flux, structural changes such as fibrosis and hypertrophy and factors such as asynchrony and abnormal loading conditions. With increasing derangement of cardiac function, there is recruitment of the compensatory mechanisms: hypertrophy of the cardiac muscle, Frank-Starling mechanism, activation of the sympathetic nervous system, the renin-angiotensin-aldosterone system and the arginine-vasopressin system. The goal is maintenance of adequate blood pressure and cardiac output whereby blood flow is redistributed in favor of the heart and brain and away from the skin, musculature and visceral organs. Activation of the neurohumoral system can lead to excessive vasoconstriction as well as sodium and water retention resulting in an undesired elevation of preload and afterload which, in turn, leads to further worsening of the heart failure.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Pathophysiologic and diagnostic aspects of heart failure]. 219 15

Altered renal function with renal NaCl-retention can be observed early in the course of congestive heart failure. The afferent pathway of this altered regulation involves changes occurring in the high pressure system as a consequence of foreward failure such as an increase in baroreceptor reflex activity. Efferent pathways may include the renin-angiotensin-aldosterone system, the sympathetic nervous system, prostaglandins, dopamine, ANF, and AVP. At present, the relative importance of these systems in mediating renal NaCl-retention in heart failure is still unclear. Expansion of the extracellular fluid volume as a consequence of renal NaCl-retention may, at least acutely, compensate for compromised myocardial function via the Frank-Starling mechanism. As a consequence of volume expansion, chronically increased cardiac preload and possibly afterload may however even aggravate cardiac failure. Diuretics may therefore induce variable effects in patients with congestive heart failure. Acutely, they may ameliorate symptoms of congestion in spite of the possibility of a further decrease in cardiac index. Chronically, they may reduce cardiac pre- and afterload. Through a variety of mechanisms, they may therefore increase cardiac performance in spite of a fall in filling pressures.
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PMID:[The role of diuretics in the treatment of chronic heart failure]. 219 19

Although the etiology of congestive heart failure is complex, a disturbance of myocardial function due to ischemic heart disease or various forms of cardiomyopathy is by far the leading causative factor. In the early stages of failure various cardiac compensating mechanisms, such as hypertrophy, an increase in contractility and the Frank-Starling mechanism, prevent a major reduction in function. With ongoing failure, myocardial muscle function further deteriorates because of a disturbance in myocardial energy utilization, abnormalities in sympathetic neurotransmitter metabolism, a reduction in beta-receptor density, and, more importantly, a derangement of intracellular calcium transport. The subsequent reduction in cardiac output leads to activation of peripheral neurohumoral mechanisms, including sympathetic stimulation, an increase in circulating norepinephrine, stimulation of the renin-angiotensin-aldosterone system (RAAS), and increased arginine vasopressin production, which result in arterial and venous vasoconstriction, redistribution of tissue blood flow, and an increase in circulating blood volume. The adjustments, however, lead to a vicious circle, where heart function is further depressed by the increase in afterload, whereas the changes in the venous bed and the increase in circulating volume ultimately result in congestion. At this point, digitalis and diuretics alone are no longer sufficiently effective and vasodilators are indicated, possibly combined, in the later stages of failure, with positive inotropic drugs. The angiotensin converting-enzyme inhibiting agents seem particularly useful in this context, presumably because of their complex mode of action, interfering with the neurohumoral systems and peripheral vasculature at multiple sites. Particularly with these agents, a remarkable improvement in clinical condition and exercise capacity has been observed. Even so, the long-term prognosis in patients with severe congestive heart failure is still extremely poor with one-year mortality rates in New York Heart Association class III and IV patients ranging from 34% to 48%. In this article, the pathophysiology of congestive heart failure and the potential of drug therapy are further discussed.
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PMID:Congestive heart failure--pathophysiology and medical treatment. 242 92

Increasing and compelling evidence continues to amass that favors the existence of local tissue renin-angiotensin systems. All renin-angiotensin system components have been demonstrated in kidney, brain, arteries, adrenals, and other organs. Favoring its clinical importance are direct demonstration of its components in tissues; dissociation between hemodynamic and structural effects of renin-angiotensin system inhibition; evidence for local modulating roles with other humoral, autocrine/paracrine, and growth factors; and the effects of renin-angiotensin system inhibitors in patients who are anephric or have low plasma renin activity. Evidence will be presented demonstrating the hemodynamic/structural dissociation of pharmacologic agents that reduce cardiac mass in spontaneously hypertensive rats with left ventricular hypertrophy. Although centrally active adrenolytic agents, angiotensin-converting enzyme inhibitors, and calcium antagonists all reduce cardiac mass, their structural and cardiac functional effects differ greatly. Even within the angiotensin-converting enzyme inhibitor group their effects vary: improving, impairing, or not changing the Frank-Starling relationships. It is postulated that there is great variability of cardiac intramyocytic penetration of the pharmacologic agents and of their local intracellular effects on mitogenesis. The implications for cardiac function and therapy are vast.
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PMID:Clinical and physiologic significance of local tissue renin-angiotensin systems. 269 Jun 10

The hemodynamic situation in congestive heart failure (CHF) is greatly influenced by compensatory mechanisms within the heart itself as well as released from the central nervous system and from the kidneys. These measures are intended to maintain the cardiac output at a level as beneficial as possible and to distribute the blood flow to regions with the largest metabolic demands. Thus the hemodynamic consequences of CHF are reflected in the central circulation as well as in the periphery. Within the heart the Frank-Starling mechanism, adrenergic stimulation causing increase of heart rate and contractility, and during the chronic course also myocardial hypertrophy are operating. The central nervous and peripheral adaptive measures include increased sympathetic outflow bringing about an increased vasomotor tone with augmentation of pre- and afterload, and activation of the renin-angiotensin-aldosterone system, where angiotensin II further augments vasoconstriction directly and through central nervous stimulation. This vasoconstriction may be counteracted by humoral factors with vasodilatory properties, such as dopamine, bradykinin, acetylcholine and the metabolic products adenosine and lactic acid. The exact role of these and the possible importance of the antidiuretic hormone, arginine vasopressin, the prostaglandin system and the recently discovered atriopeptin remains to be established. As the compensatory mechanisms may maintain a fairly satisfactory hemodynamic situation at rest, investigations should be performed not only at rest but also during exercise to get an over-all impression of the cardiac functional state.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Endocrinology of cardiac failure. Pathophysiologic aspects--hemodynamics. 294 44


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