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Query: UMLS:C0035078 (renal failure)
 31,970 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In man, atrial natriuretic peptide (ANP) is released in pulsatile fashion into the right as well as left atrium in relation to atrial pressure and volume, i.e. wall tension. These responses are documented by a new radioenzymatic assay to measure ANP in human plasma relative to hemodynamic measurements during diagnostic cardiac catheterization, atrial pressure changes during various types of pacemaker stimulation, and changes in cardiopulmonary volumes during head-out water immersion or upper leg cuff occlusion. During the infusion of synthetic 1-28 alpha-human-ANP and attendant high normal plasma ANP concentrations, natriuresis and peripheral vasodilatation (using venous occlusion plethysmography) can be shown. The antipressor action of ANP, especially against angiotensin II (but less against noradrenaline), together with the antirenin and anti-aldosterone effects, suggest that the ANP system acts as a functional counterpart to the renin-angiotensin-aldosterone system. Accordingly, plasma ANP is elevated whenever renin is low (e.g. low-renin essential hypertension) and/or cardiopulmonary volume is elevated (e.g. cardiac or renal failure). In man, ANP probably plays a (patho-) physiological role, though its antipressor and natriuretic effects do not appear to be very potent.
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PMID:[Does atrial antipressor natriuretic peptide play a pathophysiological role?]. 296 81

The human heart secretes ANP, mainly or exclusively as the 1-28-amino-acid alpha-hANP. Secretion is increased when there is hypervolemia of the central circulation, either acute or chronic, the stimulus being, it is presumed, atrial stretch. The clearance rate of alpha-hANP has been documented in healthy volunteers but not in patients with clinical disorders. Injection or infusion of atrial peptides into normal humans has clear-cut hemodynamic, renal, and hormone effects. However, the doses used have been high and the results do not allow extrapolation to the realms of physiology. Patients with essential hypertension appear to have exaggerated renal responses to administered alpha-hANP, although the number of subjects studied is small and matching with normotensive controls was imperfect. By contrast, cardiac failure is characterized by impaired renal responses to atrial peptides. The place of atrial peptides in human physiology and pathophysiology is not clear and will require very low-dose infusion studies under exacting experimental conditions or the development of a specific inhibitor of circulating ANP. In theory, atrial peptides might find a place in therapeutics, most likely in cardiac failure or renal failure, but also essential hypertension if an orally active agonist can be developed.
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PMID:Human studies with atrial natriuretic factor. 296 67

An explosion of research over the last seven years has led to the discovery and characterization of a peptide, originating in the heart's atria, that possesses impressive vasorelaxant and natriuretic properties. Although the several atrial peptides that have been isolated by researchers working in different laboratories vary in length, all contain the same core sequence. Cardionatrin I, a 28-amino acid peptide, is the likely active circulating hormone. In the atrial peptide's action on vascular smooth muscle, it appears especially to counter the effects of angiotensin II. The peptide's effects on renal hemodynamics and sodium excretion include a marked increase in glomerular filtration rate. Atrial hormone also induces impressive natriuresis in experimental animals, for which an increase in glomerular filtration rate may be a necessary component. Atrial hormone has been found to reduce arterial blood pressure in both animals and humans. In experimental animals, the peptide appears to lower blood pressure by different mechanisms in high- and low-renin forms of hypertension, and to lower pressure to a greater degree and with lower doses in the former as compared with the latter. In patients with essential hypertension, primary aldosteronism, congestive heart failure, renal failure, and perhaps ascitic cirrhosis, plasma ANH levels tend to be higher than they are in normotensive individuals. Atrial hormone causes marked and sustained suppression of renal renin secretion and, thus, of plasma renin levels. In addition, atrial hormone blocks aldosterone secretion and opposes the vasoconstrictive effects of angiotensin II and the sodium-retaining action of aldosterone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Atrial natriuretic hormone: a regulator of blood pressure and volume homeostasis. 297 65

Angiotensin-converting enzyme (ACE) inhibitors are a new class of drugs, whose main indications are the treatment of hypertension and of heart failure. Data obtained with captopril, the first orally active ACE inhibitor, affords an understanding of the rationale of their therapeutic use based on the knowledge of their mechanisms of action, efficacy, contraindications and precautions, dosage and frequency of administration, side-effects, interactions and advantages. ACE inhibitors appear to exert their haemodynamic effect mainly by inhibiting the renin-angiotensin-aldosterone system, but also by modulating sympathetic nervous system activity and by increasing prostaglandin synthesis. Therefore they act both on vasoconstrictor and volume factors, since they cause vasodilation (the main effect) and mild natriuresis without affecting the heart rate and contractility and, probably, favourably influencing renal, coronary and cerebral circulation. So far it appears that ACE inhibitors can be usefully employed in the treatment of heart failure, in which they reduce both pre- and after-load, and mainly of hypertension. In the past captopril has been used to treat only severe and or resistant hypertension and some secondary forms, like renal parenchymal and renovascular hypertension, but now it seems that captopril is useful also to treat mild to moderate essential hypertension. Their efficacy in reducing blood pressure is similar to that of thiazide diuretics and of beta-blockers, the two drugs now considered of first choice and they exert their hypotensive action without the development of pseudotolerance or tolerance. ACE inhibitors seem, at the moment, contraindicated in pregnancy and in hyperkalaemic syndromes and must be used with caution in patients with collagen disease (mainly associated with renal failure), with severe bilateral renal artery stenosis (and with severe artery stenosis of a solitary kidney) and with severe sodium depletion. It is now established that captopril has a flat dose response curve and that it must be given (twice daily) at a dose not exceeding 150 mg/day. The same pharmacological approach must be used with future ACE inhibitors in order to establish the right posology and the frequency of administration. In this respect enalapril seems to be a promising ACE inhibitor with a prolonged action (at least 24 hours). The exact posology of ACE inhibitors might be crucial, since it has been shown that the side-effects of captopril (skin rashes, fever, taste disturbances, proteinuria and neutropenia) are dose dependent.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Angiotensin-converting enzyme inhibitors in hypertension: a review. 300 82

Circulating inhibitors of the Na+ pump have been proposed as participating in sodium excretion, extracellular and vascular volume regulation and as hypertensiogenic agents. The presence of digitalis-like compounds in human plasma has been investigated by measuring its ability to compete with tritiated ouabain for binding to the digitalis site of red blood cells. Their activities in plasma from either hypertensive or volume expanded patients were compared. High levels were found in plasma from 37 p. cent of the untreated patients with essential hypertension, 64 p. cent of patients with end-stage renal failure and 71 p cent of acromegalic patients in the hypersecreting phase. The patients of these two last classes have been selected as being normotensives and without family history of hypertension. An increased activity of the inhibitor should more likely be linked to the positive Na+ balance and the volemic expansion which characterise these last two diseases than to high blood pressure. The observations that the activity of the inhibitor is correlated with the plasma volume in acromegalic patients, it returns to normal values after hemodialysis in renal insufficiency or successful therapy of acromegaly and the decrease in its activity is proportional to the weight lost during dialysis in uremic patients, agree with this proposal.
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PMID:[Circulating inhibitor of sodium active transport in essential hypertension and volemic expansion]. 300 21

Endogenous digitalis-like factors have been implicated in the adaptations that accompany renal insufficiency and in the pathogenesis of hypertension. We recently described several fractions of normal human plasma that inhibit NaK-ATPase and exhibit apparent digoxin-like immunoreactivity. To determine if hypertension and/or renal insufficiency affect plasma levels of these factors, we examined four patient groups: normotensive controls; hypertensive subjects with normal renal function; hypertensives with moderate renal insufficiency; and chronic dialysis patients. Plasma levels of digoxin-like immunoreactivity and NaK-ATPase inhibitory activity were significantly increased in hypertensive patients with mild renal failure (7.6 +/- 1.1 ouabain equivalents, mean +/- SEM, N = 21 vs 4.1 +/- 1.1 in normotensive controls, N = 20, P less than 0.05). NaK-ATPase inhibitory activity tended to be higher in patients with primary hypertension and normal renal function (5.5 +/- 0.7 ouabain equivalents, P less than 0.07); in dialysis patients, it was not different from controls. There was no correlation between NaK-ATPase inhibitory activity and blood pressure in any group. There was a significant rise in plasma NaK-ATPase inhibitory activity during dialysis (+ 1.8 +/- 0.7 ouabain equivalents, N = 22, P less than 0.03). As we have found that NaK-ATPase inhibitory activity in the plasma of normal humans can be separated into three distinct fractions, EI1, EI2, and EI3, we analyzed the plasma of 10 dialysis patients further. The increase in NaK-ATPase inhibitory activity could be attributed to fractions EI1 and EI3. These results suggest that plasma NaK-ATPase inhibitors increase with chronic renal insufficiency, but not hypertension alone. Although hemodialysis may acutely raise plasma levels, long-term dialysis returns them to the normal range.
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PMID:Endogenous digitalis-like factors in hypertension and chronic renal insufficiency. 302 36

There is increasing evidence for endogenous, circulating compounds that interact with the digitalis receptor of [Na,K]ATPase and with antidigoxin antisera. Circulating levels of these digitalis-like compounds increase in response to fluid or salt loading and appear to play a role in diseases characterized by fluid and salt retention, e.g. renal failure, liver disease, acromegaly, experimental and human hypertension, and preeclampsia. Because of assay nonspecificity, many diverse substances are being measured. Of the few compounds currently identified as having "digitalis-like" activity, none appears to be the natural ligand of the digitalis receptor and none appears linked with hypertension. Nevertheless, research still suggests that digitalis-like factors may have a central role in essential hypertension and related disorders.
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PMID:Endogenous digitalis-like natriuretic factors. 303 37

Data from several epidemiologic studies have suggested that the prevalence of hypertension in patients with diabetes mellitus is approximately 1.5-2.0 times greater than in an appropriately matched nondiabetic population. In patients with insulin-dependent diabetes mellitus (IDDM), hypertension is generally not present at the time of diagnosis. As renal insufficiency develops, blood pressure rises and may exacerbate the progression to end-stage renal failure. In non-insulin-dependent diabetes mellitus (NIDDM), many patients are hypertensive at the time of diagnosis. The incidence of hypertension in NIDDM is related to the degree of obesity, advanced age, and extensive atherosclerosis that is typically present, and it probably includes many patients with essential hypertension. Several other pathophysiologic mechanisms also contribute to the genesis and maintenance of hypertension in the patient with diabetes. Hyperglycemia and increases in total-body exchangeable sodium may lead to extracellular fluid accumulation and expansion of the plasma volume. In some patients, alterations in the function of the renin-angiotensin-aldosterone system and vascular sensitivity to vasoactive hormones may also play a role. It has recently been suggested that hyperinsulinemia and insulin resistance may also contribute to the maintenance of an elevated blood pressure because insulin is known to promote sodium retention and enhance sympathetic nervous system activity. The evidence for these hypotheses and their respective contributions to the etiology of hypertension in IDDM and NIDDM are discussed.
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PMID:Etiology and prevalence of hypertension in diabetic patients. 307 72

This article has reviewed the involvement of the kidney as a target organ of essential hypertension. Since Bright first made the association of renal disease and hypertension in 1836, the nature of this relationship has been debated. Although there is evidence implicating abnormalities of renal function in the pathogenesis of essential hypertension, hypertension frequently precedes histologic evidence of alterations in renal structure. Nephrosclerosis, or hardening of the kidney, is the term used to describe the histologic changes occurring in the kidney as the result of hypertension. It can be though of as an acceleration of the normal aging process of the renal vasculature. Glomerular and tubular changes have been traditionally thought to be ischemic in origin. Experimental evidence supports the notion that, as renal function is lost, intraglomerular hypertension develops and may be responsible for additional nephron loss in hypertension. This idea may have therapeutic implications for hypertensive patients with renal insufficiency in that agents that reduce both systemic and intraglomerular pressure may be preferable. Hemodynamically, early hypertension is often characterized by normal peripheral and renal vascular resistance and an increased cardiac output. In established hypertension, cardiac output is usually normal, and peripheral and renal vascular resistances are increased. Renal blood flow is reduced, glomerular filtration rate is maintained, and the filtration fraction rises. In the absence of an accelerated malignant phase, renal failure is uncommon in essential hypertension. Males and blacks are most sensitive to the vascular damage of essential hypertension. Essential hypertension remains an important cause of end-stage renal disease, especially in blacks. Atherosclerotic obstruction of the renal arteries may be a more common cause of renal failure in patients with essential hypertension than has been previously recognized. There are few sensitive markers of early renal involvement in essential hypertension. Several studies of sensitive markers are promising and may detect patients who are prone to renal injury and deserve more aggressive treatment. Malignant hypertension is characterized pathologically by vascular changes of proliferative endarteritis and fibrinoid necrosis. Fortunately, its frequency is decreasing because of early identification and effective treatment of essential hypertension. Effective treatment of severe and malignant hypertension clearly leads to stabilization (and occasionally improvement) of renal function.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Renal parenchymal involvement in essential hypertension. 330 6

To assess the relationship between renal plasma flow (ERPF) or glomerular filtration rate (GFR) and the levels of norepinephrine (NE) or epinephrine (E) in plasma or urine in the presence of progressive degrees of non-oliguric renal functional impairment, these variables were assessed simultaneously in 18 normal subjects, 72 with parenchymal kidney disease and 14 with essential hypertension. ERPF and GFR were lower (P less than 0.01 to 0.001) in the groups with renal disease (mean +/- SD, 340 +/- 230 and 68 +/- 43 ml/min/1.73 m2, respectively) or essential hypertension (434 +/- 101 and 97 +/- 25 ml/min/1.73 m2) than normal subjects (597 +/- 133 and 118 +/- 14 ml/min/1.73 m2). Plasma and urinary NE and E did not differ significantly among groups and were unrelated with ERPF or GFR (range 4 to 160 ml/min/1.73 m2), except for reduced (P less than 0.001) urinary NE and E excretion in the presence of a GFR less than 20 ml/min. Subgroups with renal disease and a normal (N = 39) or high blood pressure (N = 33) also were comparable in their plasma and urinary NE and E, while ERPF and GFR tended to be lower in hypertensive patients. It is concluded that a chronic reduction in excretory kidney function may have no relevant impact on circulating levels of NE and E per se, although their urinary excretion falls distinctly at the stage of advanced renal failure. These aspects deserve consideration when pathogenetic or diagnostic studies of catecholamines are performed in normotensive or hypertensive patients with impaired kidney function.
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PMID:Plasma and urinary catecholamines as related to renal function in man. 356 Jun 39


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