Endothelins.

The endothelins (ET) represent a novel family of at least three isopeptides (ET-1, ET-2, ET-3), each consisting of 21 amino acids and two disulfide bridges. ET has originally been isolated from the supernatant of porcine aortic endothelial cells and has been found to be the most potent and long lasting vasoconstrictor agent yet discovered. ET is synthesized as a preprohormone and cleaved by unusual proteolytic processing.

Proinflammatory cytokines in cardiac myxomas.

Serum levels of various cytokines were measured in three patients with cardiac myxomas presenting with and without constitutional symptoms, immunological features and elevated plasma levels of interleukin-6. Interleukin-6 but not other cytokines (interleukin-1, tumour necrosis factor-alpha, interferon-gamma) relate to immunological features of the patients. Circulating levels of atrial natriuretic peptide correspond to haemodynamic changes but not to the tumour-bearing state itself.

Expression of atrial natriuretic peptide in thymic macrophages after dexamethasone treatment of rats.

The rat thymus represents a site of synthesis of atrial natriuretic peptide (ANP); the immunosuppressor dexamethasone strikingly increases ANP-expression in this immune organ. The presented data suggest that this increase can be attributed to macrophages. By means of immunohistochemistry and Northern blot analysis these immune cells were found to express ANP-immunoreactivity as well as mRNA coding for ANP.

A highly sensitive and rapid radioimmunoassay for the determination of arginine8-vasopressin.

A highly sensitive radioimmunossay for arginine8-vasopressin (argipressin; INN) measurement was developed using Amberlite XAD 2 resin columns to extract arginine8-vasopressin from acidified human plasma. Arginine8-vasopressin was determined by a rapid radioimmunoassay method (2 x 20 h) using a specific antibody and 125I-labelled antigen. The bound fraction was separated by adsorption of the free fraction onto bovine serum albumin-coated charcoal; this resulted in low unspecific binding of less than 2%.

Endothelin-3 like immunoreactivity in plasma of patients with cirrhosis of the liver.

A highly specific and sensitive radioimmunoassay (RIA) has been established for determination of endothelin-3 like immunoreactivity in human plasma to investigate its possible role in hemodynamic alterations due to liver disease. Crossreactivity with other endothelin isoforms was always below 4 %, the lower detection limit following extraction on Sep-Pak C18 cartridges was 0.5 pg/ml.

Atrial natriuretic peptide concentration in dogs with congestive heart failure, chronic renal failure, and hyperadrenocorticism.

The function of atrial natriuretic peptide (ANP) is claimed to be control of salt and water homeostasis, and thus, the hormone may be involved in the pathogenesis of certain diseases with impaired volume regulation. We, therefore, studied plasma ANP concentration in dogs with chronic renal failure, congestive heart failure, and hyperadrenocorticism. Dogs with chronic renal failure had twofold higher plasma ANP concentration (16.

[Indocyanine green test in the dog].

The ICG test is recommended as a replacement for the nowadays rarely performed BSP test. ICG has less side effects, and it has a greater range of use. Extrahepatic influences are of little importance.

Immunoreactive N-terminal fragment of proatrial natriuretic peptide, ANP (1-98), in plasma of healthy dogs and dogs with impaired volume regulation: a comparison with the C-terminal ANP (99-126).

Atrial natriuretic peptide (ANP) is stored in atrial myocytes as a 126 amino acid precursor molecule (ANP 1-126) and is cleaved during its release into circulation into the biologically active C-terminal ANP (99-126) and the N-terminal counterpart, ANP (1-98). While interest has focused on ANP (99-126) under physiological and pathophysiological conditions, data for the cosecreted N-terminal sequence, ANP (1-98) are generally missing. Plasma levels of the N-terminal immunoreactive peptide (N-ANP [1-98]) were measured in normal dogs, and in dogs with impaired volume regulation (congestive heart failure; chronic renal failure or Cushing's syndrome and compared with those of C-ANP (99-126).

[Diagnostic possibilities of ANP blood measurements in dogs].

Atrial natriuretic peptide has been considered to be a major regulator in the body's water and salt homeostasis. Antagonizing those mechanisms leading to volume retention and overload (renin, angiotensin, aldosterone), ANP has been suggested to play a critical role in the pathology of certain diseases like renal failure, congestive heart failure or hypertension. In this regard, we measured ANP plasma concentration in normal healthy dogs and dogs with renal failure, congestive heart failure and Cushing syndrome.

Altered density of glomerular binding sites for atrial natriuretic factor in bile duct-ligated rats with ascites.

The renal response to atrial natriuretic factor is blunted in cirrhosis with ascites. This might be due to alterations of renal receptors for atrial natriuretic factor. Therefore density and affinity of glomerular atrial natriuretic factor binding sites of bile duct-ligated rats with ascites (n = 10) and of sham-operated controls (n = 10) were determined.

Origin and characterization of atrial natriuretic peptide in the rat parotid gland.

The heart atria represent the major site of synthesis for atrial natriuretic peptide (ANP) which exerts potent natriuretic, diuretic and vasoactive functions. Recently, ANP-immunoreactivity has been detected in extracardial organs involved in water and electrolyte homeostasis, such as the intestine and certain exocrine glands. The present study investigates ANP in the parotid gland.

Dexamethasone action on rat thymic atrial natriuretic peptide.

The rat thymus gland expresses the ANP gene and synthesizes the ANP-precursor, suggesting a role for this peptide within the immune system. This study provides further evidence for this notion, as expression of ANP mRNA in the thymus is altered in response to administration of the glucocorticoid dexamethasone to rats (1.5 mg/kg).

Atrial natriuretic peptide precursor material in rat testis.

Atrial natriuretic peptide (ANP) has recently been suggested to play a role in the regulation of male reproduction. Specifically, it has been shown to affect steroidogenesis in Leydig cells. The data presented here demonstrate that the rat testis also contains immunoreactive, ANP-like material (IR-ANP).

[Atrial natriuretic peptide. II. Pathophysiology and possible clinical significance. Review].

The heart atrium, as well as under certain pathophysiological conditions the ventricle, synthesize and release ANP. Exerting natriuretic, diuretic and vasorelaxant effects, this peptide plays an important role in the body's blood volume and blood pressure homeostasis. Whereas the pharmacological actions of ANP have been quite convincingly demonstrated, its physiological and pathophysiological role is less well defined.

Atrial natriuretic peptide in peripheral organs other than the heart.

The heart atria represent the major site of synthesis of atrial natriuretic peptide (ANP) in mammals including man, and its function as a regulator of water and salt homeostasis has been repeatedly suggested. However, more recently ANP has been located in organs not intimately related to cardiovascular physiology, e.g.

[Atrial natriuretic peptide. I: Biochemistry, general pharmacology and physiology. A review].

The recent discovery of the atrial natriuretic peptide (ANP) system and its possible physiological role in mammalians is discussed. The atrium is the major site of synthesis for ANP, where it is stored in specific secretory granules of atrial myocytes as a 126 amino acid precursor molecule (ANP 1-126). Upon adequate stimuli, such as atrial distension, the biologically active ANP (99-126) is released into the circulation.

A possible linkage of atrial natriuretic peptide to the immune system.

Recent work has suggested the existence of atrial natriuretic peptide (ANP)-like material in lymphoid follicles of the guinea pig intestine. To follow the hypothesis of an association of ANP with the immune system, we now report that the rat thymus, a primary lymphoid organ, is a site of ANP synthesis. This is based on the following experimental evidence: firstly, the material detected corresponds chromatographically with the precursor of ANP.

Atrial natriuretic peptide is synthesized in the human thymus.

Various neuropeptides have recently been isolated from the thymus, suggesting an interaction between the neuroendocrine and immune systems. We report here that the human thymus synthesizes a further peptide hormone, namely atrial natriuretic peptide (ANP). This is documented by the following findings.

Dehydration increases the density of C receptors for ANF on rat glomerular membranes.

The present study determined the presence of two types of binding sites for atrial natriuretic factor (ANF), the B and C receptor, on rat glomerular membranes. The effect of short-term salt loading and dehydration on these two receptor populations was investigated consecutively. Salt-loaded rats did not show significant changes in plasma ANF concentrations or in the number of ANF binding sites.

Different behaviour of the N-terminal and C-terminal fragment of proatrial natriuretic factor in plasma of healthy subjects as well as of patients with cirrhosis.

N-terminal (atrial natriuretic factor (ANF) 1-98) and C-terminal (ANF 99-126) fragments of proatrial natriuretic factor (NTA and CTA, respectively) were determined in plasma of healthy subjects adopting different postures and in patients with cirrhosis. Seven healthy subjects were investigated while seated and 30 min after assuming a horizontal position. NTA plasma concentrations increased in subjects in the horizontal position (from 734 +/- 250 (SE) fmol/ml to 902 +/- 227 fmol/ml; p less than 0.

Degradation and clearance of atrial natriuretic factors (ANF).

Atrial natriuretic factor, the first well defined natriuretic hormone is synthesized in the human heart as 151 aminoacid (AA) preprohormone and stored as 126 AA prohormone in atrial granules. Upon appropriate stimulation, the prohormone is cleaved into a 98 AA N-terminal fragment and a 28 AA C-terminal fragment, the biological active ANF(99-126), both circulating in plasma. Circulating ANF(99-126) is cleared by various organs, such as lung, liver and intestine, kidney and upper and lower limbs.

The rat thymus--a site of atrial natriuretic peptide synthesis.

The atrium of the heart has been demonstrated to represent the major site of synthesis of atrial natriuretic peptide (ANP), a potent natriuretic, diuretic and vasoactive hormone. Our recent studies revealed ANP-like material outside the heart, namely, in lymphoid follicles of the intestine and in the thymus, and now we report data demonstrating the thymus as a site of synthesis for ANP. The experimental evidence is as follows: firstly, the immunoreactive material detected corresponds chromatographically with the precursor of ANP.

Atrial natriuretic peptide in lymphoid organs of various species.

1. Evidence for the occurrence of atrial natriuretic peptide (ANP) in various lymphoid organs of different species (rat, mouse, pig, chicken) is provided. 2.

Immunoreactive atrial natriuretic peptide in the guinea pig spleen.

The presence of immunoreactive ANP precursor-like material in the guinea pig spleen is suggested. This is based on the following experimental evidence: An acidic extract of guinea pig spleen analysed by Sephadex G-50 gelfiltration contained 4.6 pmol/g wet tissue immunoreactive atrial natriuretic peptide (IR-ANP), coeluting with the 15 kDa synthetic ANP (2-126).

Water immersion increases the concentration of the immunoreactive N-terminal fragment of proatrial natriuretic factor in human plasma.

Atrial natriuretic factor (ANF) N-terminal (ANF 1-98) and C-terminal (ANF 99-126) fragments were determined by radioimmunoassay in human plasma. Mean basal plasma ANF N-terminal concentrations in 9 healthy subjects were 461 +/- 58 fmol/ml, significantly (p less than 0.0001) higher than ANF C-terminal concentrations (4.