N-terminal pro atrial natriuretic peptide in human plasma.

N-Terminal pro ANP (atrial natriuretic peptide) in human plasma has been measured by radioimmunoassay after extraction on Sep-Pak cartridges. Immunoreactive N-terminal pro ANP circulates in human plasma at higher levels than alpha-hANP (approximately 20-fold higher in normal subjects) and was elevated in patients with essential hypertension, cardiac transplantation and patients with chronic renal failure. In chronic renal failure patients undergoing hemodialysis, C-terminal ANP (ANP 99-126), but not N-terminal ANP, declined significantly after dialysis.

Radioimmunoassay for plasma neuropeptide-Y in physiological and physiopathological states and response to sympathetic activation.

A radioimmunoassay has been developed for measuring plasma neuropeptide-Y immunoreactivity using extraction on Sep-Pak C18 cartridges. Neuropeptide-Y concentrations (mean +/- SEM) in plasma from 15 normotensive individuals were 223.6 +/- 14.

Plasma atrial natriuretic peptide, aldosterone, and plasma renin activity responses to gradual changes in dietary sodium intake.

The present study examines the responses of plasma atrial natriuretic peptide (ANP), aldosterone and plasma renin activity to small alterations in dietary sodium intake. Six normotensive subjects were equilibrated on a low sodium intake of 10 mmol/day for 4 days. Dietary sodium intake was then increased gradually by 50 mmol/day to a maximum of 350 mmol/day over a 7 day period.

Concentrations of N-terminal ProANP in human plasma: evidence for ProANP (1-98) as the circulating form.

Plasma levels of immunoreactive N-terminal ProANP have been measured in plasma from 19 healthy individuals, 15 patients with essential hypertension, 8 cardiac transplant recipients and 8 patients with chronic renal failure using two separate radioimmunoassays (RIAs), one directed against ProANP (1-30) and the other against ProANP (79-98). The mean concentrations of ProANP (1-30) and ProANP (79-98) were elevated in these groups of patients. There were positive correlations between levels of ProANP (1-30) and ProANP (79-98), with a correlation coefficient of 0.

Long term reduction in sodium balance: possible additional mechanism whereby nifedipine lowers blood pressure.

Objective: To assess the changes in sodium excretion and sodium balance after withdrawal of long term nifedipine.

Design: Single blind, placebo controlled study in patients receiving fixed sodium and potassium intakes.

Setting: Blood pressure unit of a teaching hospital in south London.

Capillary hypertension and abnormal pressure dynamics in patients with essential hypertension.

1. Pressure was measured within 28 capillaries of the nailfolds of nine patients with essential hypertension and in 33 capillaries of nine age- and sex-matched normotensive control subjects, using direct micropuncture, a dynamic servo-nulling system and computerized analysis. 2.

Symplastic spermatids (sys): a recessive insertional mutation in mice causing a defect in spermatogenesis.

A line of transgenic mice that carries an insertional mutation in a gene essential for spermatogenesis is described. Males homozygous for the transgenic insert are sterile, while female homozygotes and both male and female heterozygotes exhibit normal fertility. Developing spermatids in homozygous males form prominent abnormal multinucleated syncytia (symplasts) and do not complete maturation.

Lack of effect of dietary potassium on renal lithium clearance in man.

The effects of alterations in dietary potassium (40, 80 and 160 mmol day-1) on endocrine status and on renal lithium clearance were assessed in 10 healthy subjects on a fixed sodium intake; measurements were made on the fifth day of each dietary regimen. Plasma aldosterone concentration was found to increase with potassium intake, whereas plasma renin activity and the plasma concentration of atrial natriuretic peptide did not change significantly. Neither absolute lithium clearance nor fractional lithium excretion was affected measurably by changes in dietary potassium, suggesting that provided the potassium intake remains within the normal range it is unnecessary to control this factor during lithium clearance studies in man.

Abnormal arterial flow pattern in untreated essential hypertension: possible link with the development of atherosclerosis.

1. We compared the velocity waveforms in the superficial femoral artery measured by multichannel Doppler ultrasound in 45 subjects: 21 patients with untreated essential hypertension and 24 normal subjects of similar age and sex. 2.

Atrial natriuretic peptide--cyclic GMP coupling and urinary sodium excretion during acute volume expansion in man.

The present study examines hormonal and renal responses to acute volume expansion in normal man, with particular emphasis on the atrial natriuretic peptide (ANP)--cyclic GMP coupling. Two liters of isotonic saline were infused into eight normotensive male subjects over a 1-h period. Plasma and urinary measurements were made before, during, and up to 300 min after the start of the saline infusion.

Response to dynamic exercise in cardiac transplant recipients: implications for control of the sodium regulatory hormone atrial natriuretic peptide.

1. To study the importance of cardiac innervation in the regulation of atrial natriuretic peptide, plasma atrial natriuretic peptide levels were measured during symptom-limited, graded exercise on a cycle ergometer in seven male orthotopic cardiac transplant recipients. 2.

Kinetics of renal sodium excretion during changes in dietary sodium intake in man--an exponential process?

The kinetics of urinary sodium excretion was studied during sodium restriction and sodium supplementation in normal subjects. Eight were studied on a normal sodium intake (24 h urinary sodium: 133.3 + 9.

A comparison of the acute effects of cicletanine and bendrofluazide on urinary electrolytes and plasma potassium in essential hypertension.

The acute effects on urinary electrolyte excretion and plasma potassium were compared of the anti-hypertensive dihydrofuropyridine cicletanine with the thiazide bendrofluazide in 6 patients with uncomplicated essential hypertension. Cicletanine 50 mg or 100 mg and bendrofluazide 5 mg caused no acute decrease in blood pressure compared to placebo for 24 h after treatment. In the 24 h after a single dose of cicletanine 50 mg there was no increase in urinary sodium, potassium or volume compared to placebo.

Potassium channel stimulation in normal subjects and in patients with essential hypertension: an acute study with cromakalim (BRL 34915).

We studied the acute effects of the potassium channel opener cromakalim on blood pressure, the renin-angiotensin-aldosterone system and renal function in eight patients with essential hypertension and five normal subjects. In the hypertensive patients, blood pressure decreased significantly from 2 to 6 h after treatment with cromakalim 1.5 mg compared with placebo, but was unchanged in the normotensives.

Atrial natriuretic peptides and tubular sodium handling during normal daily life in men.

The relationship between segmental renal tubular sodium handling (using the renal clearance of ingested lithium as a marker of proximal tubular sodium handling) and circulating plasma levels of atrial natriuretic factor (ANF) was studied in a sample of 295 untreated men drawn from a male population at work under their usual living conditions. Plasma ANF was positively and significantly related to sodium excretion at the distal nephron, indicating that this hormone interacts with a distal renal tubular site to influence the control of sodium excretion in man.

Is renal lithium clearance altered in essential hypertension?

In order to assess whether enhanced fractional sodium reabsorption in the proximal tubule might contribute to the development of essential hypertension, we examined the relationship between arterial blood pressure and lithium clearance (CLi; used as an estimate of end-proximal fluid delivery) or fractional lithium excretion [FELi; measured using the clearances of creatinine and 51Cr ethylenediamine tetraacetic acid (EDTA) as estimates of glomerular filtration rate] in normal young males (n = 32) and in patients with essential hypertension (n = 44). In neither group was there evidence of a negative correlation between blood pressure and CLi or FELi. Mean values for CLi and FELi in a subgroup of hypertensive patients (n = 20) were almost identical to those in 20 normotensives matched for age, sex and race.

Double-blind study of three sodium intakes and long-term effects of sodium restriction in essential hypertension.

20 patients with mild hypertension (average supine blood pressure without treatment, 164/101 mm Hg) reduced their salt intake to 50 mmol (3 g) per day for a month. They then entered a 3 month double-blind randomised crossover study of three levels of sodium intake: 200, 100, and 50 mmol per day. Blood pressure was significantly reduced on the middle and lowest sodium intakes.

Immunoreactive N-terminal pro-atrial natriuretic peptide in human plasma: plasma levels and comparisons with alpha-human atrial natriuretic peptide in normal subjects, patients with essential hypertension, cardiac transplant and chronic renal failure.

1. Plasma levels of immunoreactive N-terminal pro-atrial natriuretic peptide (N-terminal ANP) have been measured in 25 normal subjects, 29 patients with essential hypertension, six cardiac transplant recipients, seven patients with dialysis-independent chronic renal failure and 11 patients with haemodialysis-dependent chronic renal failure. Plasma was extracted on Sep-Pak cartridges and N-terminal ANP immunoreactivity was measured using an antibody directed against pro-ANP (1-30).

Nifedipine and systemic hypertension.

Nifedipine reduces blood pressure predominantly by reducing systemic vascular resistance due to a direct vasodilating action on the arterioles. This peripheral vasodilation appears greater the more severe the hypertension. Studies have demonstrated an additive effect of beta blockers and converting-enzyme inhibitors in patients not controlled with nifedipine alone.

Prolonged decrease in blood pressure after atrial natriuretic peptide infusion in essential hypertension: a new anti-pressor mechanism?

1. To study the anti-hypertensive effects of atrial natriuretic peptide (ANP), eight patients with mild to moderate essential hypertension, on no treatment, were infused with alpha-human ANP (102-126) (37 pmol min-1 kg-1) or placebo for 60 min and observed for a further 4 h on the fifth day of low and high sodium diets in a randomized, cross-over study. 2.

Hormonal responses to gradual changes in dietary sodium intake in humans.

The effects of gradual (50 mmol/day) increases in dietary sodium intake from 10 to 350 mmol/day on plasma atrial natriuretic peptide (ANP), aldosterone, and plasma renin activity (PRA) were studied in six normal subjects. With the increases in sodium intake there was a progressive increase in urinary sodium from 12.2 +/- 4.

Nifedipine and hypertension: roles of vasodilation and sodium balance.

Nifedipine reduces blood pressure predominantly by reducing systemic vascular resistance due to a direct vasodilating action on the arterioles. This peripheral vasodilation appears greater the more severe the hypertension. Nifedipine also causes a long-term loss of sodium, which may be an additive mechanism for the blood pressure fall.

Synthesis and characterization of a bovine hexokinase 1 cDNA probe by mixed oligonucleotide primed amplification of cDNA using high complexity primer mixtures.

Hexokinase (EC 2.7.1.