Early stages of the natriuretic hormone story.

The paper reviews the early stages of the research on natriuretic hormone. The described experimental work was designed and accomplished in several internationally recognized laboratories where the author was invited to extend his projects. The cross-circulation experiments in animals with acutely increased extracellular fluid volume documented, that in the mechanism of natriuresis - besides a series of the physical natriuretic factors - there is still room for an active humoral natriuretic substance.

[What does the relation of digoxin-like immunoactivity and serum insulin levels in pregnant women signify?].

Background: Digoxin-like immunoactivity (DLIA) reflects the presence of endogenous substances which are close to cardiac glycosides. These substances via inhibition of Na(+)-K(+)-ATPase increase intracellular calcium stores (Ca2+i) and may modulate various Ca(2+)-dependent mechanisms. Although DLIA are known primarily as hypertension and natriuresis promoting factors, several recent works have suggested that DLIA relates also to diabetes mellitus.

Endogenous digoxin-like immunoactivity and diabetes mellitus: facts and hypotheses.

Substances with digoxin- and ouabain-like immunoactivity (DLIA) are specific inhibitors of Na(+)-K(+)-ATPase which increase the total amount of intracellular stored calcium (Ca2+i). In diabetic patients, DLIA levels have been reported to be increased. Although this increase is probably secondary to sodium retention and volume expansion (included in diabetic subjects by hyperinsulinemia and/or diabetic nephropathy), the question arises of whether it has pathophysiological consequences: namely, whether substances with DLIA, via their effect on Na(+)-K(+)-ATPase activity and Ca2+i stores, could in diabetic subjects facilitate development of hypertension and/or modulate insulin sensitivity or insulin secretion.

Head-up tilt and lower body suction: comparison of hormone responses in healthy men.

The purpose of this study was to compare, in the same subjects, hormonal responses to 30-min head-up tilt (HUT) and lower body suction (LBNP) of different intensity (24 degrees and 70 degrees, and 15 and 35 mm Hg, respectively). Basal pooled individual data from -10 min (n = 32) were within normal reference limits: norepinephrine (NE) averaged 318 +/- 23 pg/ml; epinephrine, 34.0 +/- 5.

[The clinical significance of natriuretic hormones].

Out of all until now discovered natriuretic factors it is still the atrial natriuretic factor (ANF) which is the most significant with its diuretic, natriuretic and vasodilatory effects. Its effect is antagonistic to sodium retention factors. The increase of its levels in arterial hypertension is more of secondary character, but according to some authors the functional deficit of ANF secretion can be applied also primarily in the development and maintenance of high blood pressure.

[Neurohumoral activity in liver cirrhosis].

The authors assessed in 40 patients with cirrhosis of the liver and in 33 controls the plasma renin activity (PRA), aldosterone (PA), the atrial natriuretic factor (ANF) and the digoxin like activity (DLA) in plasma under basal conditions. In patients with cirrhosis of the liver they found significantly lower levels of PRA, PA and DLA, as compared with the control group, the ANF levels were not significantly altered. In the group with cirrhosis the highest neuroendocrine activity was recorded, in particular of PRA and PA in decompensated cirrhotics receiving diuretic treatment.

[Personal experience with determination of endogenous, digoxin-like substances in patients with myocardial infarct and other cardiopathies].

A group of 65 patients with acute infarction of myocardium (IM) who were not treated with digitalis preparations were subdued to examination to the presence of digitalis-like substances in their urine by means of radioimmuno-analytic method with use of anti-digoxin antibodies. The control group was constituted of 69 healthy subjects. Patients afflicted with IM had significantly increased concentrations of DLS in serum in comparison with health subjects.

[Endogenous digoxin-like and ouabain-like substances].

Despite the fact that cardioglycosides have been used in the treatment of cardiac failure for more than 2000 years, endogenous digoxin and ouabain-like substances were identified from the chemical aspect only in 1990. They are steroids, their main site of origin being the adrenals. It is assumed that they play a part in the regulation of the body fluids and sodium in the organism and participate in the regulation of cardiac activity.

Blood pressure regulation in ANF-transgenic mice: role of angiotensin and vasopressin.

Transgenic mice overexpressing a transthyretin promoter-ANF structural fusion gene have a life-long reduction in arterial blood pressure compared to nontransgenic littermates. The present study was designed to test the hypothesis that the high plasma level of ANF in the transgenic mice inhibits the renin-angiotensin and/or vasopressin systems, thereby causing the hypotension. Mice were anaesthetized with Inactin and arterial pressure and heart rate were monitored before and during Saralasin infusion and vasopressin V1 receptor blockade.

The role of endogenous digitalis-like factor in blood pressure regulation in essential hypertension.

We examined plasma renin activity (PRA), plasma aldosterone (PA), atrial natriuretic factor (ANF) and endogenous digitalis-like factor (DLF) in 15 healthy subjects and 15 patients with essential hypertension (EH) to obtain basal values and values after extracellular fluid volume (ECFV) expansion caused by infusion of isotonic saline solution over a period of 2 hours (20 mg/kg). A significant increase in diuresis and natriuresis accompanied by a decrease in PRA and PA and an increase in ANF was observed in both groups. No significant differences were observed in ANF levels between normotensive subjects and hypertensive patients.

[The effect of water immersion on humoral and urinary parameters in healthy persons and in patients with liver cirrhosis].

The authors subjected 10 healthy subjects and 13 patients inflicted by liver cirrhosis in the stage of vascular decompensation (ascites and/or oedemas) to water immersion (WI). The group of healthy subjects responded during WI by a significant increase of diuresis and sodium diuresis at its maximum in the third hour, which was accompanied by a decrease of plasma aldosterone (PA) and a decrease of atrial natriuretic factor (ANF) and digoxin-like activity (DLA). The decrease of plasma vasopressin (PAVP) was not statistically significant.

Effect of a low salt diet on blood pressure and vasoactive hormones in the hereditary hypertriglyceridemic rat.

In hereditary HTG rats, basal systolic blood pressure using tail-cuff sphygmomanometry was significantly higher (122.1 +/- 2.1 mm Hg; n = 16) than that in NTG animals (107.

On the role of digoxin-like substances, ANP, and AVP in natriuresis induced by hypertonic saline infusion in dogs.

The increase of sodium concentration in cerebrospinal fluid or in plasma triggers the osmoregulatory mechanism, namely, the enhancement of renal free-water reabsorption and natriuresis. The increase of free-water reabsorption has been recognized for many years as a consequence of the osmotically released vasopressin (AVP). However, the control of renal sodium excretion in the mechanism of osmoregulation has not been clarified It has been suggested to be, at least in part, of hormonal nature, implying the decreased release of aldosterone and the increased release of atrial natriuretic peptide (ANP), digoxin-like substances (DLIS), and AVP.

Hydroosmotic activities of arginine-vasopressins modified either in positions 1, 2 and 4 or at N-terminal extensions.

Vasopressin and its synthetic analogs were studied for their effect on transepithelial water flux in frog urinary bladder. As compared with AVP, 1-deamino-8-D-arginine vasopressin (dDAVP) was about 40 times less effective in stimulating osmotic water flow. The vasopressin analogs obtained by modification in positions 1 and 2 were: [1-(1-mercapto-4-tert-butylcyclohexaneacetic acid)] AVP (I); [1-(1-mercapto-4-methylcyclohexaneacetic acid)]AVP (II); [1-(1-mercapto-4-methylcyclohexaneacetic acid)-2-O-methyltyrosine]AVP (III); and those modified in position 4 were: [1-(1-mercaptocyclohexaneacetic acid)-4-arginine] AVP (IV); [1-(2-mercaptopropionic acid)-4-arginine]AVP (V).

Changes of hormones regulating electrolyte metabolism after space flight and hypokinesia.

The changes of hormones in plasma involved in the body fluid regulation were studied in human subjects during and after space flights in relation to redistribution of body fluids in the state of weightlessness. Since hypokinesia was used as a model for simulation of some effects of the stay in microgravity the plasma hormone levels in rats exposed to hypokinesia were also investigated. Plasma aldosterone values showed great individual variations during the first inflight days, the increased levels were observed with prolongation of space flights.

Periventricular lesions block natriuresis to hypertonic but not isotonic NaCl loads.

The renal excretion of Na and water after an intravenous load of hypertonic or isotonic saline was studied in conscious sheep in which periventricular tissue in the region of the lamina terminalis had been ablated. Hypertonic saline (3.4-4.

Endogenous digitalis-like factor in patients with acute myocardial infarction.

The authors examined endogenous digitalis-like factor (DLF) concentrations in the serum and urine in 65 patients with acute myocardial infarction. Radioimmunoassay was used for the examination and patients' data were analyzed in detail in relation to sex, risk factors and acute myocardial infarction complications. The concentrations of digitalis-like factor found in the serum of men (0.

Failure to demonstrate natriuretic activity in the posterior pituitary after immunoneutralization of the vasopressin content.

The attempt to demonstrate the presence of a natriuretic substance in the posterior pituitary after immunoneutralization of the AVP content failed. Rats infused i.v.

Suppression of natriferic activity of the vasopressin molecule by modifications in positions 1, 2 and 4.

The capacity of five synthetic analogs of [8-arginine] vasopressin (AVP) to stimulate frog skin sodium transport (natriferic activity) was characterized electrophysiologically using the method of short-circuit current, and compared to that of synthetic AVP. The analogs used were [8-arginine] vasopressins modified in positions 1 and 2: [1-(1-mercapto-4-tert-butylcyclohexaneacetic acid)] AVP (I); [1-(1-mercapto-4-methylcyclohexaneacetic acid)] AVP (II); [1-(1-mercapto-4-methylcyclohexaneacetic acid)-2-O-methyltyrosine] AVP (III); and in position 4: [1-(1-mercaptocyclohexaneacetic acid)-4-arginine] AVP (IV); [1-(2-mercaptopropionic acid)-4-arginine] AVP (V). The addition of synthetic vasopressins I, II and V to the frog skin resulted in a weaker stimulation of the skin sodium transport, measured as the level of the short-circuit current (Isc), as compared to that induced by synthetic AVP.

Stimulation of the sodium transport across the frog skin by three N-terminally extended arginine-vasopressins.

The standard Ussing method was used to electrophysiologically characterize the effects of three analogs of arginine-vasopressin (AVP) on the frog skin, a model Na-transporting epithelium. The analogs tested were N-terminally extended Arg8-vasopressins: Ala-AVP, Ser-Ala-AVP and Thr-Ser-Ala-AVP; synthetic Arg8-AVP was used as the reference agent. The vasopressins were applied to the basolateral side of the frog skin in concentrations ranging between 10(-8) to 10(-5) mol.

[Present state and perspectives of endocrinology in Czechoslovakia].

The contemporary state of the sub-discipline of endocrinology within the framework of internal medicine is generally considered rather desolate, but so far actual data were lacking. Based on an analysis of data provided by regional specialists in the Czech Republic and by regional (district) specialists in internal medicine in Slovak republic it may be said that in the majority of health institutions the number of endocrinologists does not reach even the unsatisfactory standard (i. e.

Endogenous digoxin-like substance in the urine of newborns and children.

Endogenous digoxin-like substance (EDLS) in urine has been considered to be the representative of the natriuretic hormone, the endogenous inhibitor of the sodium pump (the sodium-potassium transporting enzyme Na, K-ATPase). Its site of production remains unknown, and so does its chemical nature. It has been suggested however that EDLS and the atrial natriuretic factor represent two distinct natriuretic system.