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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In canine and porcine coronary arteries, experimental atherosclerosis (induced by endothelial denudation followed by a high-cholesterol diet) potentiates the vasoconstrictor effects of histamine, serotonin, and ergonovine. In isolated human atherosclerotic coronary arteries, only hypersensitivity to histamine has been demonstrated. This discrepancy could be due to several factors. First, the atherosclerotic lesions in human vessels are different from those observed in the animal, since experimental atherosclerosis often corresponds only to the early stage of the disease in humans. Second, the human atherosclerotic coronary arteries were isolated mainly from patients with cardiac failure, a condition that alters the responses of coronary smooth muscle to vasoactive amines. With regard to endothelium-dependent vasodilators, marked attenuations of the relaxations to substance P, bradykinin, and the Ca2+ ionophore A23187 have been described in isolated human atherosclerotic arteries. Acetylcholine elicits variable responses in these preparations and even if the arteries are devoid of atherosclerotic lesions, it often fails to relax them. In addition to this endothelial dysfunction, severely atherosclerotic human coronary vessels exhibit a slightly decreased responsiveness to nitroglycerin and SIN-1 but not to forskolin. Another abnormality of the smooth muscle is a marked attenuated beta-adrenergic relaxation. Thus, atherosclerosis of human coronary vessels induces not only marked alterations in endothelium-dependent responses but also modifies the sensitivity to several endothelium-independent vasodilators.
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PMID:Atherosclerosis and responses of human isolated coronary arteries to endothelium-dependent and -independent vasodilators. 248 97

The recent discovery of endothelium-derived relaxation factor (EDRF) has altered the traditional classification of vasodilators used in angina pectoris and heart failure. If a vasodilator induces release of EDRF from the epithelium it is classified as endothelium-dependent, if not it is independent. Sodium nitroprusside and SIN-1 (active metabolite of molsidomine) are the main independent vasodilators since the endothelium relaxation factor appears to be principally a nitric oxide radical in these synthetic vasodilators. In contrast, calcium-channel blockers and a good number of endogenous chemical mediators (acetylcholine, bradykinin, serotonin, etc.) are endothelium-dependent. Furthermore, simple increase in blood flow through the large vessels can result in endothelium-dependent vasodilation (flow rate-dependence) the extent of which depends on the drug examined. The fact that the pharmacologic response of a vasodilator can be altered under certain pathologic conditions (atherosclerosis, hypertension, diabetes, etc.) further increases the importance of the role of the vascular endothelium in the action of vasodilators since endothelial modulation may then be completely diverted to secretion of endothelium-derived contracting factors (EDCFS).
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PMID:[Vasodilator agents and the vascular endothelium]. 262 13

Drug interactions common to all angiotensin-converting enzyme (ACE) inhibitors include those with thiazide diuretics and other antihypertensive agents. Interactions involving specific ACE inhibitors include captopril-digoxin, resulting in decreased clearance of digoxin from plasma in patients with heart failure, and captopril-probenecid, causing a decrease in captopril clearance. Tissue kinins, such as bradykinin, are metabolised by ACE inhibitors. Interactions involving bradykinin include captopril-indomethacin, in which an attenuation of the antihypertensive effects of captopril is manifest. Interestingly, neither enalapril nor lisinopril appear to show this interaction with indomethacin. Kinin-based interactions may also be important in the genesis of ACE inhibitor-induced cough and skin rash. Renal dysfunction affects the pharmacokinetics and pharmacodynamics of all ACE inhibitors, necessitating dosage reduction. Hepatic impairment is of less clinical importance, causing a delay in the onset of action of enalapril with initial doses, but probably having little relevance to long-term therapy.
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PMID:Drug interactions with ACE inhibitors. 267 38

Baroreceptor reflex plays an important role in the pathophysiology of essential hypertension. Experiments in dogs could demonstrate that after complete denervation of sinoaortic and cardiopulmonar baroreceptors a long-lasting hypertension with labile blood pressure behavior occurred. The sympathetic tone was enhanced significantly when studied in denervated rats. In patients with essential hypertension no comparable conditions to the "neurogenic hypertension" of animals exist. Therefore, studies in patients after orthotopic heart transplantation are of interest because those patients develop severe hypertension even if cyclosporine is not administered. Preliminary results reported here support a participation of baroreceptors in hypertension of transplanted patients. A further reason of essential hypertension is found on baroreceptor resetting. Changed ion concentrations and/or wall thickness of the respective blood vessels could be the cause. The sympathetic system influences the renin-angiotensin-system and baroreflex activity by central and peripheral mechanisms. It, for example, attenuates Ang-II and the baroreflex via central actions. Converting-enzyme-inhibitors (CEI) act in part as peripheral vasodilators without affecting the heart rate significantly. This effect is possibly due to lacking Ang-II that is able to increase the sensitivity of baroreceptors. In the past it has been shown that the inhibition of tissue-converting enzyme is more responsible for the antihypertensive effects of CEI than that of plasma-converting enzyme. The cardioprotective effects of CEI are suggested to be an important advantage in the treatment of hypertension and heart failure. These cardioprotective actions are partly due to accumulated bradykinin, just as are the hypotensive effects of CEI. The interactions between CEI and the sympathetic system should be differentiated into pre- and postsynaptic actions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Influence of baroreceptors on hypertension, pharmacotherapy with conversion enzyme inhibitors]. 269 53

Ramipril is a potent orally active converting enzyme inhibitor. Its active metabolite ramiprilat is classified as a reversible, slow- and tight-binding inhibitor. Ramipril lowers blood pressure in various models of hypertension and improves states of acute cardiac failure mainly by suppression of angiotensin II formation. Actions on both vasoconstrictor and volume factors are involved because ramipril causes vasodilation and mild natriuresis but preserves potassium. Sustained inhibition of converting enzyme in target tissues such as vascular wall, kidney and heart may explain cardiovascular changes over the long term. Ancillary effects may possibly emerge from modulation of the sympathetic nervous system but the contribution of bradykinin potentiation remains unclear.
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PMID:Ramipril: review of pharmacology. 303 30

Mechanically and chemically sensitive receptors in the ventricle have been described histologically and electrophysiologically. Early experiments documented the hypotension and bradycardia that resulted from the intracoronary administration of one of the veratrum alkaloids (the Bezold-Jarisch reflex). Mechanical distension of the ventricles also results in a reflex decrease in heart rate and a reduction in peripheral resistance. Skeletal muscle and coronary vascular resistance appear to be most prominently affected by stimulation of ventricular receptors. Coronary ischemia has also been shown to evoke reflex effects which are attributable to stimulation of ventricular receptors. The resultant bradycardia can be especially ominous in acute myocardial infarction. Changes in myocardial inotropic state have been shown to alter ventricular receptor discharge in experimental animals. This stimulus may evoke reflex changes in peripheral hemodynamics. A variety of humoral substances can alter ventricular receptor discharge and evoke Bezold-Jarisch like responses. These include bradykinin and prostaglandins. PGI2, when given intracoronary in small doses or intravenously in larger doses will lower blood pressure while inhibiting the baroreflex induced tachycardia. It has also been shown in some experiments that PGI2 and arachidonic acid can evoke overt bradycardia and hypotension via a reflex mechanism. The role of prostaglandins in cardiovascular reflex control may be important in pathophysiologic states such as coronary ischemia and heart failure. Ventricular receptors can interact centrally with the arterial baroreceptors to attenuate the baroreflex control of both heart rate and peripheral resistance. Finally, the stimulation of ventricular receptors can alter a variety of humoral substances which are important regulators of cardiovascular and fluid volume homeostasis. These include vasopressin, renin and catecholamines. Those studies which have been done within the last 10 years or so, especially in unanesthetized animals, have demonstrated that the Bezold-Jarisch reflex is more important to cardiovascular control than previously thought. Future work will be necessary to determine the precise role ventricular receptors play in various pathological situations.
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PMID:Left ventricular receptors: physiological controllers or pathological curiosities? 354 77

Cardiac receptors include both mechanically and chemically sensitive receptors located in atria and in ventricles. Atrial receptors innervated by myelinated vagal afferent fibers reflexly regulate heart rate and intravascular volume. On the other hand, stimulation of ventricular receptors can cause either reflex bradycardia and hypotension or, alternatively, excitation of the cardiovascular system. The former response is mediated by vagal afferents, whereas the latter is mediated by sympathetic (spinal) afferents. Under normal circumstances, cardiac receptors sense changes in wall motion or diastolic pressure and perhaps provide a fine tuning of the cardiovascular system. However, under certain pathological conditions such as coronary ischemia, which cause release of substances such as bradykinin and prostaglandins, there is an exaggerated response of the ventricular receptors. Because these receptors cause a reflex depression of the cardiovascular system and, in particular, induce renal vasodilation, they may protect the heart and kidney by lessening myocardial oxygen requirements and by increasing renal blood flow. In the situation of heart failure both atrial and ventricular receptors are reset and therefore provide for an exaggerated neurohumoral discharge. Finally, patients with aortic stenosis may demonstrate a paradoxical vasodilation and syncope during exercise when there likely is excessive stimulation of left ventricular receptors by the high transmural pressure.
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PMID:Cardiac receptors: their function in health and disease. 638 3

The Gaboon viper has acquired an impressive reputation which is at least partly unfounded. This handsome animal with such striking features is undoubtedly docile which accounts for the very low incidence of bite amongst humans. There are only six detailed clinical reports on the effect of bite and these are summarized in the review. The viper does indeed produce prodigious amounts of venom, but the toxicity, weight for weight, is rather low compared to other poisonous snakes. Venom extractions have been carried out on four snakes over a 13-year-period and the effects of this venom have been studied in a variety of experimental animals. Systemic envenomation is characterized by immediate abrupt hypotension, subsequent cardiac damage and dyspnoea. The individual venom components responsible for these effects have not been isolated but it seems likely that the two enzymes which have been studied extensively (phospholipase A2 and the thrombin-like enzyme, gabonase) do not contribute significantly to lethality. We propose three principal activities which give rise to the major signs of systemic envenomation. Haemorrhagin; causing widespread damage to microvasculature which leads to the pulmonary oedema and hence dyspnoea, and locally causes blistering. Cardiotoxin; a long-acting material causing cardiac muscle damage, arrhythmia and ultimately cardiac failure. Peripheral vasodilator; a short acting effect, operating either locally via bradykinin formation and/or unknown peptides or centrally on the vasomotor centre.
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PMID:The Gaboon viper (Bitis gabonica): its biology, venom components and toxinology. 639 43

Captopril is a specific inhibitor of kininase II which is responsible for the conversion of angiotensin I into the active angiotensin II and also for the inactivation of bradykinin. In different types of experimental and clinical hypertension, Captopril has a pronounced blood pressure-reducing action particularly when it is given together with a diuretic. Serious side-effects have hitherto restricted the use of Captopril to patients who do not respond or do not respond satisfactorily to routine antihypertensives. Since it has been shown that a considerable improvement in disturbed hemodynamics in hypertension and in certain forms of heart failure can be achieved with quite low doses of the preparation (2 x 2 mg daily) the use of Captopril may be indicated in greater amounts in moderate and severe hypertension.
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PMID:[Captopril - profile of a new antihypertensive (author's transl)]. 679 55

Chronic heart failure is associated with neurohumoral activation and alterations of the peripheral circulation and skeletal muscle. Several mechanisms are involved in the impaired peripheral perfusion, including increased sympathetic tone and increased vascular stiffness. Recently, data suggest an important role of the endothelium for perfusion of skeletal muscle in heart failure. Endothelium-dependent dilation of resistance vessels is blunted in patients with severe chronic heart failure and may be involved in the impaired reactive hyperemia in these patients. In conductance vessels, flow-dependent dilation and the nitroglycerin-induced dilator response is attenuated in congestive heart failure as compared to normal subjects, indicating both endothelial dysfunction and a defect of smooth muscle relaxation. Recent data suggest that angiotensin-converting enzyme (ACE) inhibitors can improve endothelial function of resistance vessels, reduce serum level of the soluble endothelial (vascular cell) adhesion molecule (VCAM-1) and, in addition, improve peripheral vascular function by reducing or limiting the influence of cyclo-oxygenase-dependent vasoconstricting factor(s). It is conceivable that these beneficial effects of chronic ACE inhibition are due, in part, to blockade of bradykinin degradation by the ACE and the increased endothelial synthesis of prostaglandins and/or the release of nitric oxide by enhanced tissue levels of bradykinin.
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PMID:Effect of chronic angiotensin-converting enzyme inhibition on endothelial function in patients with chronic heart failure. 748 81


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