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Biomedical subjects

W Rascher

Publications and source records attributed to W Rascher.

At least 217 records · Page 12Linked to original sources
PubMed1987

Influence of dopamine on atrial natriuretic peptide level in premature infants.

The role of dopamine (DA) in the activation and/or release of atrial natriuretic peptide (ANP) was investigated in 11 premature infants during the early postnatal period. Mean plasma concentration of ANP and free DA level before DA infusion was 252.6 +/- 210 fmol/ml, and 0.4 +/- 0.2 ng/ml, respectively. DA infusion in a dose of 2 micrograms/kg/min caused a rise in plasma free DA level to 59.7 +/- 21.5 ng/ml and a significant increase in GFR, diuresis, sodium excretion and fractional sodium excretion. The plasma concentration of ANP, however, remained unchanged (252.6 +/- 210.0 vs. 213 +/- 143.0 fmol/ml). Thus, our data failed to demonstrate a stimulatory effect of DA on ANP release in premature infants. The role of the high plasma concentration of ANP in preterm neonates immediately after birth has to be clarified.

Atrial Natriuretic Factor↗
PubMed1987

Atrial natriuretic peptide and extracellular volume contraction after birth.

Plasma concentrations of atrial natriuretic peptide (ANP) were measured in full-term newborns immediately after birth and on the 3rd, 5th, 7th and 10th day of life. The ANP concentrations were within the normal range in the first hours of life. Plasma concentrations of ANP had increased significantly on the 3rd and 5th day of life, while body weight decreased continuously. After the 5th day of life ANP concentration decreased continuously reaching its minimum on the 10th day whereas body weight increased. The mechanism behind ANP release shortly after birth is not known. The increase in ANP concentration in plasma may however induce changes in body fluid compartments shortly after birth which would result in physiological weight loss.

Age Factors↗
PubMed1987

Atrial natriuretic peptide and patent ductus arteriosus in preterm infants.

Preterm infants with symptomatic patent ductus arteriosus had considerably raised plasma concentrations of atrial natriuretic peptide. Surgical ligation of the patent ductus arteriosus was associated with an immediate fall in plasma atrial natriuretic peptide concentration. Thus left to right shunting and left atrial distension may cause atrial natriuretic peptide release in preterm infants with patent ductus arteriosus.

Atrial Natriuretic Factor↗
PubMed1987

Atrial natriuretic peptide in infants and children.

Atrial natriuretic peptide (ANP) was measured in the plasma of 192 normal infants and children aged 1 day to 18 years. Plasma ANP was high during postnatal adaptation, particularly in premature infants. In 96 infants and children aged 4 months to 18 years, plasma ANP was similar to values obtained in 7 healthy adult volunteers (23.9 +/- 11.9 vs. 25.7 +/- 4.6 fmol/ml). There was no significant relationship between ANP and age. ANP is elevated about twofold in full-term neonates being 3-4 days of age, and returned to normal thereafter. It is concluded that ANP is raised during the postnatal adaptation. This hormone is possibly involved in the postnatal volume contraction and may antagonize vasoconstrictor hormones that are elevated during the postnatal period.

Adolescent↗
PubMed1987

[New blood pressure lowering drugs in childhood].

The treatment by antihypertensive agents has recently been improved by the introduction of angiotensin converting-enzyme inhibitors, and of calcium antagonists, which have been applied successfully in children with acute and chronic hypertension. The converting enzyme inhibitor captopril is used increasingly for the treatment of severe forms of persistent hypertension in children. Side effects from this drug can largely be avoided by using low daily doses. The calcium-antagonist nifedipine can now be regarded as the drug of choice in the treatment of acute elevation of blood pressure in infants and children. For this indication it appears to be superior to other drugs because of its prompt and safe efficacy after sublingual administration.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

Hormonal regulation of water metabolism in children with nephrotic syndrome.

The roles of the antidiuretic hormone arginine-vasopressin (AVP), atrial natriuretic peptide (ANP), renin, aldosterone and catecholamines in the pathogenesis of impaired water excretion were studied in edematous children with nephrotic syndrome. Compared to non-proteinuric children with nephrotic syndrome in remission, edematous children during relapse had lower serum concentrations of sodium and chloride with lower plasma osmolality, but had higher hematocrit values (P less than 0.05, each). Plasma concentration of AVP was higher in edematous children (P less than 0.01). Compared to healthy, normal children, edematous nephrotic children had higher plasma concentrations of AVP, aldosterone, renin, noradrenaline, and adrenaline (P less than 0.01, each), but had similar levels of plasma ANP. Head out water immersion and infusion of 5 ml/kg 20% human serum albumin solution, both procedures known to increase central blood volume, resulted in a reduction of elevated hormone concentrations to near-normal levels and caused a rise in sodium and water excretion. Following albumin infusion, mean ANP rose fivefold, and plasma concentrations of this hormone correlated positively with urine flow (r = 0.64, N = 18, P less than 0.01) and with sodium excretion (r = 0.62, N = 18, P less than 0.01). It is concluded that AVP, renin, aldosterone and catecholamines are stimulated in edematous children with nephrotic syndrome by reduction in effective circulatory blood volume. Central blood volume expansion induced either by water immersion or by infusion of concentrated albumin solution is able to correct elevated hormone levels and to induce salt and water excretion. Plasma ANP appears to trigger the diuretic and natriuretic effects of central volume expansion.

Aldosterone↗
PubMed1987

Effect of low-dose dopamine on kidney function and vasoactive hormones in pediatric patients with advanced renal failure.

Dopamine (DA) was infused in a dose of 2 micrograms/kg/min in 12 children and adolescents with chronic renal failure to test the vasodilatory reserve capacity of the kidney. Mean basal GFR and ERPF were 17.8 and 93.1 ml/min/1.73 m2, respectively. DA infusion had no significant influence on GFR but effective renal plasma flow (ERPF) increased by 14% (p less than 0.05). After DA, GFR did not correlate with ERPF. There was a significant increase in urinary sodium excretion (+22%). Sodium excretion correlated with osmotic clearance and urine flow rate with free water clearance. Plasma prolactin concentration was decreased (p less than 0.01), whereas noradrenaline, adrenaline and free dopamine increased significantly after DA. Plasma renin activity, aldosterone, arginine vasopressin and atrial natriuretic peptide levels remained unchanged. The data indicate that in pediatric patients with advanced renal failure DA fails to increase filtration capacity, whereas effective renal plasma flow and sodium excretion are stimulated. It is speculated that in this situation preglomerular and tubular renal functions regulated by dopamine receptors are better conserved than those affecting glomerular microcirculation.

Adolescent↗
PubMed1986

Diuretic and hormonal responses to head-out water immersion in nephrotic syndrome.

The diuretic and natriuretic response to water immersion, which is known to increase effective central blood volume, was studied in eight edematous children with nephrotic syndrome. The rise in central blood volume was indicated by a decrease in hematocrit from preimmersion median of 40.2% to 38.6% during water immersion (P less than 0.05, Friedman test). Similarly, serum protein concentration fell from 36.7 gm/L to 33.5 gm/L (P less than 0.05). Water immersion induced diuresis from a preimmersion median of 0.33 ml/min/1.73 m2 to 1.52 ml/min/1.73 m2 (P less than 0.05). Osmolar clearance rose, as did sodium and potassium excretion. Urine osmolality fell during water immersion (P less than 0.05). Serum sodium concentration and plasma osmolality did not change. Plasma arginine vasopressin values fell from 11.1 pg/ml to 3.0 pg/ml (P less than 0.05), as did renin activity (8.5 ng to 5.2 ng angiotensin l/ml/hr, P less than 0.01), aldosterone (18.0 ng/dl to 10.1 ng/dl), and norepinephrine (344 pg/ml to 213 pg/ml, P less than 0.05). Water immersion produces a potent natriuretic and diuretic response in children with nephrotic syndrome.

Adolescent↗
PubMed1986

Role of atrial natriuretic peptide in sodium homeostasis in premature infants.

To examine the possible involvement of atrial natriuretic peptide (ANP) in sodium homeostasis in premature infants, two groups of low birth weight infants with different dietary sodium regimens were studied. Sodium balance and plasma concentration of ANP were measured at weekly intervals for 5 weeks. At 1 week of age the study was started by dividing infants into two groups, group 1 with low and group 2 with increased sodium intake. Mean plasma concentrations of ANP were 47.7 +/- 7.6 and 51.4 +/- 9.5 fmol/ml, respectively. A steady decrease in plasma ANP concentration to 18.8 +/- 2.9 fmol/ml was observed in infants with sodium intake 1.5 mmol/kg/d (group 1), which was related to the decrease in serum sodium concentration in this group. In contrast, supplementation with NaCl 4.6 mmol/kg/d (group 2) was associated with a 30% increase in plasma ANP concentration, significantly different (P less than 0.025) from that in infants not given supplement, and was also higher than the values in full-term neonates. Our data suggest that altered sodium homeostasis induces regulatory changes in plasma ANP levels. ANP may provide a sensitive and important hormonal system for the control of sodium balance, even in premature neonates.

Atrial Natriuretic Factor↗
PubMed1986

Plasma arginine-vasopressin levels during infusion of synthetic atrial natriuretic peptide on different sodium intakes in man.

The mechanisms involved in the diuretic action of the recently discovered group of atrial natriuretic peptides (ANP) are not entirely clear. To determine whether the diuresis and the changes in blood pressure produced by alpha-human ANP (alpha-hANP) involved a concomitant modification of circulating arginine-vasopressin (arg-VP), we evaluated the effects of synthetic alpha-hANP on plasma alpha-hANP, arg-VP, electrolytes, protein, haematocrit, blood pressure and urinary sodium and water excretion in 10 normal subjects on daily sodium intakes of 16, 140 and 310 mmol, respectively. Plasma alpha-hANP levels before and during a 45-min alpha-hANP infusion (0.09 micrograms/kg per min) tended to be slightly, though not significantly, higher on 'normal' or high sodium intake than on low sodium intake. Alpha-human ANP produced a fall in diastolic blood pressure (P less than 0.001) and to a lesser extent mean blood pressure, and a rise in heart rate (P less than 0.001) at all levels of sodium intake. The induction of diuresis, natriuresis and plasma volume contraction caused by alpha-hANP was greater on a high sodium intake than on 'normal' or low sodium intakes (P less than 0.001). Plasma arg-VP concentrations were lower (P less than 0.05) on a high than on a low sodium intake, but were not altered by an alpha-hANP infusion. The data indicate that in healthy humans circulating arg-VP may tend to decrease in response to a high salt diet. However, marked changes in plasma alpha-hANP concentrations have, regardless of sodium intake, no relevant influence on circulating arg-VP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Determinants of plasma arginine-vasopressin in children.

Plasma concentration of arginine-vasopressin (AVP) was measured in 145 healthy subjects aged one day to 18 years of age. AVP decreased with age immediately after birth. Above one year of age values of children did not significantly differ from those in adults. AVP significantly correlated with plasma and urine osmolality after water deprivation during 16 h. Plasma AVP rose during exercise and fell after volume expansion. Nausea and vomiting are potent nonosmotic determinants of AVP release in children. Nonosmotic factors of AVP release should be controlled when sampling blood for measuring AVP in children for diagnostic and investigational purposes.

Adolescent↗
PubMed1986

Blood levels and renal effects of atrial natriuretic peptide in normal man.

Since mammalian atria were recently found to contain vasoactive and natriuretic peptides, we investigated the following in normal humans: plasma human atrial natriuretic peptide concentrations, effective renal plasma flow (ERPF), glomerular filtration rate (GFR), urinary water and electrolyte excretion, blood pressure (BP), and catecholamine, antidiuretic hormone (ADH), angiotensin II, and aldosterone levels before, during, and after intravenous administration of the newly synthetized alpha-human atrial natriuretic peptide (alpha hANP). In 10 subjects alpha hANP given as an initial bolus of 50 micrograms followed by a 45-min maintenance infusion at 6.25 micrograms/min increased plasma alpha hANP from 58 +/- 12 to 625 +/- 87 (mean +/- SEM) pg/ml; caused an acute fall in diastolic BP (-12%, P less than 0.001) and a hemoconcentration (hematocrit +7%, P less than 0.01) not fully explained by a negative body fluid balance; increased GFR (+15%, P less than 0.05) despite unchanged or decreased ERPF (filtration fraction +37%, P less than 0.001); augmented (P less than 0.05- less than 0.001) urinary chloride (+317%), sodium (+224%), calcium (+158%), magnesium (+110%), phosphate excretion (+88%), and free water clearance (from -0.76 to +2.23 ml/min, P less than 0.001) with only little change in potassium excretion; and increased plasma norepinephrine (P less than 0.001) while plasma and urinary epinephrine and dopamine, and plasma ADH, angiotensin II, and aldosterone levels were unchanged. The magnitude and pattern of electrolyte and water excretion during alpha hANP infusion could not be accounted for by increased GFR alone. Therefore, in normal man, endogenous alpha hANP seems to circulate in blood. alpha hANP can cause a BP reduction and hemoconcentration which occur, at least in part, independently of diuresis and are accompanied by sympathetic activation. An increase in GFR that occurs in the presence of unchanged or even decreased total renal blood flow is an important but not sole mechanism of natriuresis and diuresis induced by alpha hANP in man.

Atrial Natriuretic Factor↗
PubMed1986

Atrial natriuretic peptide and volume changes in children.

The effect of volume changes on the plasma concentration of atrial natriuretic peptide (ANP) was investigated. In children with chronic renal failure predialysis plasma ANP was higher as compared to normal children and decreased significantly during hemodialysis. The decrease in plasma ANP correlated with body weight reduction. On the other hand, increase in plasma volume by infusion of albumin in children with nephrotic syndrome caused significant rise in plasma ANP and an increased natriuresis. Our data demonstrate that an expanded extracellular fluid volume and/or plasma volume appears to be a major stimulus for the release in ANP in children.

Adolescent↗
PubMed1986

Blood pressure and hormonal responses to sublingual nifedipine in acute childhood hypertension.

Twelve infants and children were treated with sublingual application of the calcium antagonist nifedipine. Blood pressure fell within 1 h following administration of nifedipine to age-related normal values. Whereas plasma renin activity, plasma concentrations of aldosterone and arginine vasopressin did not change within 1 h after drug application, plasma noradrenaline rose (p less than 0.05), probably in response to vasodilatation. Plasma concentration of nifedipine at 30 and 60 min after application correlated positively with the fall in mean arterial pressure. Nifedipine was well tolerated and appeared to be an effective and safe drug in the treatment of acute rises of blood pressure in infants and children.

Adolescent↗
PubMed1986

Vasopressin in hyponatremia: what stimuli?

In hypoosmolar hyponatremia, vasopressin is commonly observed to be less than maximally suppressed. This is attributed to the presence of nonosmolar vasopressin stimuli. However, the exact relationship of nonsuppressed antidiuretic hormone to specific circulatory parameters is controversial. Therefore, in the present study, we examined this question in 100 hypoosmolar hyponatremic patients in the Department of Medicine. Despite plasma hypoosmolality, vasopressin was found to be measurable in 92% of patients. Seventy patients suffered from edematous disorders (congestive heart failure, cirrhosis) or volume contraction per se; in these patients we observed unequivocal, though indirect, evidence of advanced circulatory alterations. These were associated with hyponatremia and nonsuppressed vasopressin. However, the latter could not be related directly to a specific circulatory parameter such as mean arterial blood pressure, creatinine clearance, plasma renin activity (PRA), norepinephrine, or aldosterone. However, patients with nondetectable vasopressin (n = 8) differed significantly from those with high vasopressin concentrations (n = 8: PADH greater than 9 pg/ml); in the latter, pulse rate (104 +/- 3 vs. 82 +/- 5 beats/min), plasma urea concentration (90 +/- 5 vs. 32 +/- 5 mg/dl), plasma urate concentration (7.2 +/- 0.8 vs. 3.6 +/- 0.8 mg/dl), and PRA (36 +/- 7 vs. 9.5 +/- 4.6 ng AI/ml/h) were all significantly higher than in the former. It is concluded that, in hyponatremia, the relationship between circulatory impairment and vasopressin is complex.

Creatinine↗
PubMed1986

Cardiovascular, endocrine and renal effects of atrial natriuretic peptide in essential hypertension.

Plasma concentrations of human atrial natriuretic peptide (hANP) and effects of synthetic alpha-hANP on blood pressure (BP), on endocrine and metabolic variables, and on renal function were investigated in 10 patients with essential hypertension. Alpha-human atrial natriuretic peptide was given intravenously as a 50-micrograms bolus followed by a 45-min infusion at 0.1 microgram/kg per min. The following effects were observed: (1) a marked rise in plasma alpha-hANP, (2) a progressive fall in BP (from 181/127 to 165/109 mmHg) and plasma volume, (3) a probably baroreflex-mediated sympathetic activation, evidenced by raised heart rate and plasma norepinephrine levels, (4) an increase in serum free fatty acids and circulating insulin (+45%), (5) an enhanced diuresis (+770%) and excretion of sodium (+665%), chloride (+524%), phosphate (+518%), other electrolytes, amino acids and free water clearance, (6) biphasic responses in the glomerular filtration rate (GFR) and p-aminohippurate (PAH) clearance, with initial increases (+40 and 30%, respectively) followed by a rapid return to (GFR), or even a fall below (PAH clearance) control values, and (7) a marked rise in the filtration fraction. Plasma antidiuretic hormone and urinary prostaglandin E2, F2 alpha and dopamine levels were not modified during alpha-hANP infusion, while plasma renin increased. Discontinuation of alpha-hANP was followed by rises in plasma aldosterone, the aldosterone:renin ratio and cortisol. Compared with previously studied normal subjects, in the hypertensive patients alpha-hANP caused a distinctly greater diuresis and electrolyte excretion but lowered BP only slightly more. In essential hypertension, as in normal man, alpha-hANP circulates in the blood and may exert a wide spectrum of cardiovascular, metabolic, endocrine and renal actions.

Adult↗
PubMed1986

[Atrial natriuretic peptide. New aspects in the regulation of blood volume and electrolyte homeostasis].

Atrial natriuretic peptide (ANP) is a newly discovered hormone released from cardiac atrial myocytes into the circulation. Secretion of the hormone is triggered by atrial distension and volume overload. ANP consist of 28 aminoacids. The hormone induces natriuresis, diuresis and increases glomerular filtration rate. Moreover, it dilates vascular smooth muscle and opposes the effects of several vasoactive hormones. Thus ANP plays an important role in the regulation of body fluids and electrolyte homeostasis.

Aldosterone↗