Biomedical subjects

E B Pedersen

Publications and source records attributed to E B Pedersen.

At least 73 records · Page 4Linked to original sources

PubMed1997

Enriched immune-environment of blood-brain barrier deficient areas of normal adult rats.

The circumventricular organs (CVOs) in the brain are without a blood-brain barrier (BBB) and as such directly exposed to blood plasma constituents and blood-borne pathogens. In light of previous studies showing discrepancies regarding the immunocompetence of these organs, we initiated the present study to provide a comprehensive immunohistochemical analysis of the cellular expression of immune-associated antigens within the pineal gland, area postrema and the subfornical organ. In all CVOs, subpopulations of cells morphologically similar to complement receptor type 3 immunoreactive microglial/macrophage cells expressed major histocompatibility complex (MHC) class II antigen, leucocyte common antigen (LCA/CD45), as well as CD4 and ED1 antigen. Based on morphological criteria the MHC class II antigen expressing cells could be grouped into a major population of classical parenchymal and perivascular ramified microglial cells and a minor population presenting itself as scattered or small groups of rounded macrophage-like cells. CD4 and ED1 antigen were expressed by both cell types. CD45 was preferentially expressed by macrophage-like cells. MHC class I antigen was expressed by the vascular endothelium in both BBB-protected and BBB-deficient areas and was additionally present as a lattice-like network throughout the BBB-deficient parenchyma in all CVOs. The results suggest that the BBB-free areas of the brain besides being constantly surveyed by blood-borne macrophages, possess an intrinsic immune surveillance system based on resting and activated microglial cells, which may function as a non-endothelial, cellular barrier against blood-borne pathogens.

Animals↗

PubMed1997

Triple immunosuppression protects murine intracerebral, hippocampal xenografts in adult rat hosts: effects on cellular infiltration, major histocompatibility complex antigen induction and blood-brain barrier leakage.

Recently we reported protection of intracerebral mouse to rat hippocampal xenografts upon treatment with a combination of cyclosporin A, prednisolone and azathioprine. These findings are now supported in an extended analysis of graft-infiltrating cells. Host T-cell and macrophage infiltration and the immunocytochemical level of cellular expression of major histocompatibility complex class I and II antigens, measured by densitometric analysis, were compared between recipient rats receiving cyclosporin A alone or cyclosporin A in combination with prednisolone and azathioprine. The combination therapy resulted in a much improved survival of the xenografted hippocampal tissue with preservation of organotypic granule and pyramidal cell layers. Graft infiltration by T-cells and macrophages was significantly lower and the level of major histocompatibility complex class I and II antigen expression by the infiltrating cells markedly reduced. Lower expression of donor-type major histocompatibility complex class I antigen was also found in the xenografts in the trimedicated recipients, together with reduced blood brain barrier leakage and astrogliosis at the host-graft interface. The results demonstrate the benefits of using combined immunosuppressive strategies for protection of histoincompatible brain xenografts in the central nervous system.

Animals↗

PubMed1997

Effect of urodilatin infusion on renal haemodynamics, tubular function and vasoactive hormones.

1. The renal efficacy of urodilatin in humans has only been partly investigated. It is unknown whether intravenously infused urodilatin has an effect on sodium reabsorption in both the proximal and distal part of the nephron. 2. Twelve healthy subjects participated in this double-blind, placebo-controlled study in a cross-over design. They received, in a randomized order, a short term (60 min) infusion of urodilatin in three different doses (10, 20 and 40 ng min-1 kg-1 of body weight) and placebo. Renal haemodynamics were estimated by clearance technique with radioactive tracers, and proximal tubular handling of sodium was evaluated by lithium clearance. 3. The 20 ng min-1 kg-1 dose increased the urinary sodium excretion and urinary flow rate compared with the effects of placebo. It increased the glomerular filtration rate and decreased the effective renal plasma flow. In addition, the dose increased the lithium clearance compared with placebo, but did not significantly change the fractional excretion of lithium. On the other hand, it markedly decreased the distal fractional reabsorption of sodium. It also had a suppressive effect on renin secretion. The systemic arterial blood pressure was unchanged, but the dose increased the pulse rate and the haematocrit. The highest dose (40 ng min-1 kg-1) induced a wide variation in the natriuretic and diuretic responses, probably due to a blood-pressure-lowering effect. 4. We conclude, that the urodilatin dose of 20 ng min-1 kg-1 of body weight was most efficacious in this short-term infusion study, and that it had potent natriuretic and diuretic qualities, probably due to stimulation of the glomerular filtration rate and inhibition of sodium reabsorption in the distal part of the nephron.

Adult↗

PubMed1997

Effects of prostacyclin on renal haemodynamics, renal tubular function and vasoactive hormones in healthy humans. A placebo-controlled dose-response study.

AIMS: To investigate the acute effects of prostacyclin (Flolan) on renal haemodynamics, renal tubular function, plasma concentration of angiotensin II (Ang II), aldosterone (Aldo), atrial natriuretic peptide (ANP), arginine vasopressin (AVP), mean arterial blood pressure (MBP), and heart rate (HR). METHODS: Thirteen healthy control subjects were investigated on two separate occasions in a placebo controlled, randomized, dose-response study of the effect of intravenous infusion of prostacyclin (PGI2, Flolan, 2, 4 and 8 ng kg(-1) min(-1)). Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by the use of constant infusion of [51Cr]-EDTA and [125I]-hippurane. Urinary output, urinary sodium excretion, fractional sodium excretion, fractional lithium excretion were measured and hormones were measured using radioimmunoassay. RESULTS: During prostacyclin (PGI2) infusion we observed a significant increase in RPF (PGI2: 4.8%; 6.1% and 5.2% vs Plac: -1.5%; -1.9% and -5.8% for 2, 4 and 8 ng kg(-1) min(-1) respectively; P < or = 0.05 for 4 and 8 ng kg(-1) min(-1)) in Ang II (PGI2: 20.0%; 42.9% and 88.9% vs Plac: 0.1%; 8.0% and 0.0%, P < or = 0.01 for 4 and 8 ng kg(-1) min(-1)) in ANP (PGI2: 13.6%; 12.7% and 37.5% vs Plac: -10.2%; -6.6% and -2.4%, P < or = 0.05 for 2 ng kg(-1) min(-1) and P < or = 0.01 for 4 and 8 ng kg(-1) min(-1)), and in HR (PGI2: 8.8%; 17.6% and 32.7% vs Plac: 0.8%; 4.1% and 3.5%, P < or = 0.05 for 2 and P < or = 0.01 for 4 and 8 ng kg(-1) min(-1)). A significant decrease was observed in MBP (MBP:PGI2: -1.7%; -1.9% and -5.6% vs Plac: -0.4%; -1.6% and +2.1%, P < or = 0.01 for 8 ng kg(-1) min(-1)). No significant changes were seen in the other effect variables. CONCLUSIONS: Infusion of prostacyclin in healthy control subjects increases renal plasma flow, angiotensin II, atrial natriuretic peptide, and heart rate and decreases mean blood pressure. Furthermore prostacyclin infusion does not change net sodium excretion in healthy controls.

Adult↗

PubMed1997

Renal functional reserve in pigs: renal haemodynamics, renal tubular function and salt and water homeostatic hormones during amino acid and dopamine stimulation.

The purpose of the study was to evaluate renal functional reserve [RFR is the difference between glomerular filtration rate (GFR) at rest and maximal GFR after stimulation] in a controlled study in normal pigs. Our basic hypothesis was that a decreased RFR may be used as an early indicator of renal deterioration, i.e. a test to disclose significant obstruction as opposed to simple dilatation in hydronephrosis. During various forms of stimulation (amino acids, captopril and dopamine), we measured changes in GFR, renal plasma flow (RPF), tubular reabsorption of sodium and water, net uptake from plasma to the kidney of three salt and water homeostatic hormones (angiotensin II, aldosterone and atrial natriuretic peptide) and of glucagon, which is thought to play a key role as mediator of the GFR increase during amino acid infusion. We found the largest GFR increase during combined infusion of amino acids and dopamine (+13%), but compared with a non-stimulated control group, the GFR increase was statistically non-significant. RPF increased by 57% during stimulation with amino acids plus dopamine (P < 0.001), while tubular reabsorption of sodium and water, and renal uptake of angiotensin II, aldosterone and atrial natriuretic peptide showed no significant differences between control and stimulation groups. The renal uptake of glucagon increased significantly during amino acid stimulation with no concomitant GFR increase. We conclude that in this experimental, non-obstructed model, RFR is a very insensitive measure, which cannot be used to discriminate between obstruction and simple dilatation in hydronephrosis. Further, our study does not support the hypothesis that glucagon is involved in GFR changes after amino acids.

Aldosterone↗

PubMed1997

Effect of felodipine on renal function and vasoactive hormones in infrarenal aortic surgery.

We have examined the possible renoprotective effect of felodipine 5 mg orally, given daily for 5 days before operation, in 29 patients undergoing elective infrarenal aortic surgery in a randomized, blinded and placebo-controlled study. Effective renal plasma flow (ERPF), glomerular filtration rate (GFR), urine output, fractional sodium clearance and plasma concentrations of angiotensin II, aldosterone, arginine vasopressin and atrial natriuretic peptide did not differ between the felodipine and placebo groups. ERPF and GFR were not reduced after operation in the placebo group. In the felodipine group, GFR was higher 24 h after operation compared with before operation. We conclude that increased GFR in the felodipine group, measured 24 h after operation, may indicate a beneficial effect of felodipine but in the present context this was not clinically important. Felodipine had no significant effect on vasoactive hormones.

Aged↗

PubMed1997

Effects of the calcium antagonist felodipine on renal haemodynamics, tubular sodium handling, and blood pressure in cyclosporin-treated dermatological patients.

BACKGROUND: Deterioration of renal function and rise in blood pressure are clinically important side-effects of cyclosporin (CsA) treatment. Calcium antagonists may have a renoprotective effect against CsA nephrotoxicity. PURPOSE: To investigate the effect of the dihydropyridine calcium-channel blocker felodipine on renal haemodynamics, tubular sodium handling, and blood pressure in CsA-treated patients with no primary renal disease, 18 patients with various CsA-treated dermatological diseases were allocated to receive either felodipine 5 mg (extended release tablets) once daily for 4 weeks followed by placebo for 4 weeks, or vice versa, in a prospective, randomized, double-blind study. The patients were investigated before treatment and at the end of each treatment period. RESULTS: After felodipine, both glomerular filtration rate (GFR) and renal plasma flow (RPF) were significantly higher compared to placebo (89.4 +/- 17.5 (mean +/- SD) vs 79.0 +/- 15.9 ml/min and 412.0 +/- 107.6 vs 326.1 +/- 78.0 ml/min respectively, P < 0.001 for both), and filtration fraction (FF) was lower (0.22 +/- 0.03 vs 0.25 +/- 0.03, P < 0.001). Both systolic and diastolic blood pressure were lower after felodipine compared to placebo (116 +/- 11/71 +/- 7 vs 133 +/- 18/83 +/- 10 mmHg, P < 0.001 for both). Furthermore, proximal output of sodium, i.e. fractional excretion of lithium, was higher after felodipine (26.9 +/- 7.3% vs 20.4 +/- 5.5%, P < 0.001) as well as total sodium excretion (0.33 +/- 0.19 vs 0.19 +/- 0.08 mmol/min, P < 0.001). CONCLUSIONS: It is concluded, that felodipine 5 mg once daily for 4 weeks increased GFR, RPF, and sodium excretion in cyclosporin-treated dermatological patients with no primary renal disease. Furthermore, felodipine lowers blood pressure in these patients. The effects of felodipine may be due to an antagonizing effect against CsA-induced nephrotoxicity.

Adolescent↗

PubMed1997

Impaired renal haemodynamic response to amino acid infusion in essential hypertension during angiotensin converting enzyme inhibitor treatment.

OBJECTIVE: To determine whether hyperfiltration induced by amino acid infusion can be influenced by angiotensin converting enzyme (ACE) inhibition. DESIGN: We studied the acute effects of ramipril in 12 healthy control subjects and in 14 patients with essential hypertension. We studied also the effects of 2 months' treatment with ramipril inn 12 patients with essential hypertension and performed a time-control study without amino acids infusion with 12 control subjects. The glomerular filtration rate (GFR), renal plasma flow (RPF), fractional excretion of sodium (FENa) and fractional excretion of lithium (FELi) were determined during 6 clearance periods of 30 min each and amino acids infusion was administered during the last four periods. Plasma concentrations of angiotensin II, aldosterone, atrial natriuretic peptide (ANP), arginine vasopressin, insulin and glucagon were determined. RESULTS: Both the GFR and the RPF increased markedly in healthy subjects after amino acid infusion both with (GFR 7%, RPF 7%) and without ramipril (GFR 7%), RPF 8%), both P < 0.05. Ramipril administered acutely to essential hypertensives prevented the amino acid-induced increase in RPF [with ramipril 5% (NS), without ramipril 9% (P < 0.05)]. The GFR increased equally with (5%) and without (8%) ramipril (P < 0.20). ACE inhibition after 2 months' treatment of essential hypertension blunted the amino acid-induced increase both in GFR and in RPF [with ramipril GFR 5% and RPF 3% (NS), without ramipril GFR 12%, RPF 11% (P < 0.05)]. The FENa did not change in all four experiments. The FELi, insulin and glucagon increased to the same extent in the first three experiments. ANP increased (P < 0.05) in control subjects both with and without ramipril; angiotensin II and aldosterone decreased significantly in control subjects without ramipril. CONCLUSIONS: The renal haemodynamic response both after acute and after short-term ACE inhibition is attenuated in essential hypertension. Presumably, this treatment makes the arterioles at the glomeruli unresponsive to subsequent amino acid infusion. This inhibition of hyperfiltration might be an important mechanism for the renal protective effect of ACE inhibition in some renal diseases.

Adult↗

PubMed1997

Single dose imipramine reduces nocturnal urine output in patients with nocturnal enuresis and nocturnal polyuria.

PURPOSE: We investigated the effect of imipramine on nocturnal urine output in patients with nocturnal enuresis. MATERIALS AND METHODS: There were 15 monosymptomatic enuretic patients 15 to 37 years and 8 control subjects 25 to 32 years old. We measured nocturnal urine output, urine osmolality, creatinine clearance, osmolal clearance, free water clearance, excretion of solutes, fractional excretion of sodium, fractional excretion of potassium and plasma vasopressin with and without a single oral dose of imipramine (1 mg./kg. of body weight) taken at 8 p.m. RESULTS: Baseline studies showed significantly larger and less concentrated nocturnal urine among enuretics compared with controls. We observed a marked antidiuretic effect of imipramine in 6 enuretics with severe nocturnal polyuria. The imipramine induced decrease in urine output was accompanied by reduced osmolal clearance. Approximately a third of the observed decrease in solute excretion was attributed to lower excretion of sodium and potassium. The remaining two-thirds were most likely caused by an increased tubular reabsorption of urea, which may be secondary to a sympathomimetic effect of imipramine tubules, possibly because of altered adrenal medullary function with an increase in proximal tubular sodium and water reabsorption. The resultant lower tubular flow rate facilitates tubular reabsorption of urea in the distal part of the nephron. CONCLUSIONS: Imipramine has a vasopressin independent antidiuretic effect if nocturnal polyuria is present. The antidiuretic effect of imipramine can be attributed primarily to increased alpha-adrenergic stimulation in the proximal tubules with a secondary increased urea and water reabsorption more distally in the nephron.

Adolescent↗

PubMed1997

A new, fast and reliable radioimmunoassay of brain natriuretic peptide in human plasma. Reference values in healthy subjects and in patients with different diseases.

A new, fast and reliable radioimmunoassay for measurement of brain natriuretic peptide (BNP) in human plasma has been developed and its application is reported in healthy subjects and in patients with congestive heart failure, chronic renal failure, liver cirrhosis and essential hypertension. The antibody was raised in rabbits, the tracer was made by the iodogen method and polyethylene glycol was used for separation of free and bound tracer. BNP was extracted from plasma using Sep-Pak C18 cartridges. The recovery of unlabelled BNP added to plasma was 77.5 +/- 6.2% (mean +/- SD). The detection limit in plasma was 0.55 pmol l-1. No cross-reactivity existed with the natriuretic peptides ANP, CNP or urodilatin. In 124 healthy subjects the mean BNP was 1.8 +/- 1.0 pmol l-1 (SD), range 0.6-5.5. BNP increased slightly with age, was higher in women than men and had no circadian rhythm. In eight patients with congestive heart failure the median BNP level was 30.5 pmol l-1, range 3.9-65.3. In 14 patients with chronic renal failure the median BNP level was 50.5 pmol l-1, range 10.9-219.8 before dialysis, and 38.0 pmol l-1, range 9.4-180.0 immediately following dialysis. In 25 patients with liver cirrhosis the median BNP value was 7.8 pmol l-1, range 1.2-43.1. There was no difference between patients with or without ascites. In 18 medically treated patients with essential hypertension the median BNP level was 5.0 pmol l-1, range 1.2-45.5 pmol l-1.

Adult↗

PubMed1997

A comparison of the effect of ramipril, felodipine and placebo on glomerular filtration rate, albuminuria, blood pressure and vasoactive hormones in chronic glomerulonephritis. A randomized, prospective, double-blind, placebo-controlled study over two years.

The effects of an ACE-inhibitor (ramipril), a calcium antagonist (felodipine) and placebo on glomerular filtration rate (GFR), urinary albumin/creatinine ratio, blood pressure (BP) and vasoactive hormones were investigated in a randomized, prospective, double-blind, placebo-controlled study of patients with chronic glomerulonephritis and hypertension, with measurements at entrance and after 12 and 24 months. In total, 33 patients were included: 21 completed the study with 7 patients in each group. GFR was measured as 51Cr-EDTA clearance and the vasoactive hormones with radioimmunoassays. The reduction in GFR was significantly more pronounced in the felodipine group (-7 ml/min) than in the ramipril group (0 ml/min) but the same as in the placebo group (-6 ml/min). The urinary albumin/creatinine ratio was significantly more reduced in the ramipril group (-74 mg/mmol) than in the placebo group (-11 mg/mmol), which did not deviate from the felodipine group (-10 mg/mmol). BP was significantly reduced by ramipril and felodipine, but not by placebo. Angiotensin II and aldosterone in plasma increased or tended to increase in the felodipine and placebo groups, but were unchanged in the ramipril group. Endothelin increased only in the placebo group, and vasopressin, atrial natriuretic peptide, and brain natriuretic peptide were not significantly changed in any of the groups. It is concluded that ramipril seems to be superior to felodipine in chronic glomerulonephritis owing to better preservation of GFR.

Adolescent↗

PubMed1997

Heart function in patients with chronic glomerulonephritis and mildly to moderately impaired renal function. An echocardiographic study.

UNLABELLED: Left ventricular hypertrophy and diastolic heart dysfunction have been reported in essential hypertension and in patients with chronic renal failure, treated with haemodialysis, but a close association with blood pressure (BP) level has not been uniformly documented. Thus, other factors could be involved in the pathogenesis of cardiac dysfunction. The aims of the present echocardiographic study were to investigate cardiac morphology and function in patients with chronic glomerulonephritis with mildly to moderately impaired renal function, and to study the relation between echocardiographic findings and glomerular filtration rate (GFR), BP and age. Twenty patients with chronic glomerulonephritis and 14 healthy controls, of the same age- and sex-distribution, were examined by 2D-, M-mode and pulsed-wave Doppler echocardiography. In patients, GFR was determined as plasma clearance of Cr-EDTA. The patients had significantly thicker left ventricular (LV) posterior walls in end diastole (8.7 vs 8.1 mm, p < 0.05), and a higher LV mass index (106.5 vs 93.8 g/m2, p < 0.05). Systolic functional indices, i.e. LV fractional shortening and LV ejection fraction, were statistically significantly lower in patients than in controls (p < 0.05). LV diastolic function in patients was characterized by a statistically significantly lower early peak flow velocity (E-Vmax) (0.66 compared with 0.8 m/s) and early to late peak flow velocity ratio (E/A ratio) (1.07 vs 1.41), as well as E/A ratio of time velocity indices (VTI-E/A) (1.45 vs 1.99) (p < 0.05). The right ventricular filling indices showed a tendency towards a lower E-Vmax in patients (0.55 compared with 0.62 m/s, p = 0.1). In patients, statistically significant negative correlations were found between age and mitral E/A ratio (r = -0.76, p < 0.0001), as well as LV VTI-E/A(r = -0.81, p < 0.0001). The same trend was seen for the tricuspid E/A ratio. No statistically significant correlations were found in patients between mitral or tricuspid E/A ratio and GFR, BP, LV mass or heart rate. IN CONCLUSION: in a group of patients with chronic glomerulonephritis and mildly to moderately impaired renal function, it was found by means of echocardiography that there was a higher LV mass index and decreased systolic function, when compared with healthy controls. In addition, the patients had diastolic dysfunction of primarily the left ventricle. The echocardiographic findings were not correlated to BP level or renal function. This suggests that factors other than GFR or BP per se might be involved in the pathogenesis of cardiac dysfunction, at an early stage.

Adult↗

PubMed1997

Nocturnal blood pressure and relation to vasoactive hormones and renal function in hypertension and chronic renal failure.

The purpose of this study was to assess the blood pressure profile and to measure vasoactive hormones in patients with essential hypertension (n=61), secondary hypertension (n=32) and chronic renal failure (n=32) matched with healthy control subjects (n=35), and to study the relationship between circadian changes in blood pressure and baseline levels of vasoactive hormones and renal function. Non-invasive, automatic blood pressure measurement was performed for 24 or 48 h. Venous plasma concentrations of renin, angiotensin II, aldosterone, arginine vasopressin, atrial natriuretic peptide and endothelin were measured. The mean 24-h blood pressure was higher in all groups of hypertensive patients than in control subjects. The nocturnal blood pressure fall was preserved in essential hypertension, in contrast to secondary hypertension in which it was attenuated. In the patients with chronic renal failure the 24-h mean blood pressure was the same as in the controls. Night-time blood pressure was higher among the chronic renal failure patients than in the control group, and the nightly blood pressure fall in both diastolic and systolic blood pressure was reduced. Plasma concentrations of renin activity, arginine vasopressin, atrial natriuretic peptide, aldosterone and endothelin were significantly increased in secondary hypertension and chronic renal failure, compared to essential hypertension and control subjects. Plasma angiotensin II was increased in chronic renal failure compared to essential hypertension and controls. Estimated creatinine clearance and nightly blood pressure dips were inversely correlated in essential and secondary hypertension, i.e. with a decreasing renal function both systolic and diastolic nightly blood pressure dips were gradually attenuated. In the whole group of patients the nightly systolic and diastolic blood pressure dips were negatively correlated to basal plasma renin activity, plasma aldosterone and atrial natriuretic peptide levels, i.e. the higher the basal plasma hormone level the lower the blood pressure dip. In conclusion, patients with essential hypertension have elevated but normally configured 24-h blood pressure profiles, and patients with different kinds of secondary hypertension have elevated 24-h blood pressure profiles and attenuated nightly systolic and diastolic blood pressure falls. The more the renal function is reduced and the more the plasma levels of renin and aldosterone are increased, the more the nocturnal fall in blood pressure is reduced. It is suggested that the attenuated or absent decrease in nocturnal blood pressure in secondary renal hypertension is caused by an abnormally increased secretion of vasoactive hormones and/or by so far unknown factors released from the diseased kidney.

Adolescent↗

PubMed1997

Anti-HIV active naphthyl analogues of HEPT and DABO.

5-Ethyl-6-(1-naphthylmethyl)uracil and 5-ethyl-6-(1-naphthylmethyl)-2-thiouracil were alkylated to give, respectively. N-1 and S2, ethoxymethyl and methylthiomethyl uracil derivatives. 5-Ethyl-6-(1-naphthylmethyl)-2-thiouracil was also S2 alkylated with methyl bromoacetate. The products showed activity against HIV-1, and the N-1 alkylated derivatives were indeed highly active.

Anti-HIV Agents↗

PubMed1997

Development of a urodilatin-specific antibody and radioimmunoassay for urodilatin in human urine.

Urodilatin (URO) (95-126) is a renal-derived natriuretic peptide that is isolated only from human urine. This study describes the development of a URO-specific antibody and a RIA for URO in urine. At present, there is no commonly available URO-specific antibody. We produced a URO-specific antibody without cross-reactivity with atrial natriuretic peptide (ANP) analogs by immunization of rabbits with the URO (95-126) peptide and subsequent purification of the resulting URO antiserum with affinity chromatography with CNBr-activated Sepharose 4B. The urine samples were ethanol-extracted before assay. The CVs were 6.7% (intraassay) and 14.1% (interassay). This study reports the circadian urinary excretion of URO in 24 healthy subjects with seven sampling periods per 24 h.

Adult↗

PubMed1997

The effect of the full bladder on vasopressin secretion in healthy young adults.

Interactions between the central nervous system, bladder and kidneys have been investigated for many years in animal studies and have shown that bladder distension, in animals, leads to decreased urine production. The objectives of the current study were to determine the effect of a full bladder on urinary output, vasopressin secretion and urine osmolality in humans. The study involved healthy volunteers. They were studied for a period of 48 hours. This period included two 24-hour studies, one involving regular and frequent voidings (to produce a minimal bladder filling) and the other voiding postponement (to produce maximal bladder distension). In contrast to enuresis studies a circadian rhythm of vasopressin secretion was observed in the males involved in this study, whereas no significant rhythm of vasopressin secretion could be detected in the female subjects. However, this study was unable to confirm that, in humans, a full bladder causes a decrease in urine production, an increase in vasopressin secretion or an increase in urine osmolality.

Adult↗

PubMed1997

Desmopressin tablet treatment: factors influencing gastrointestinal absorption.

The effect of food ingestion on the gastrointestinal absorption and antidiuretic action of oral desmopressin (Minirin, DDAVP) was assessed in 16 healthy volunteers, aged 20-35 years. The gastrointestinal absorption of desmopressin was reduced and delayed if administered with or 90 minutes after a meal, but this did not influence the antidiuretic action of the drug, at least for the first 3 hours following desmopressin administration.

Absorption↗

PubMed1997

Abnormal distal tubular sodium reabsorption during dopamine infusion in patients with essential hypertension evaluated by the lithium clearance methods.

The effects of low-dose dopamine infusion on renal hemodynamics, tubular function estimated by the lithium clearance technique and plasma levels of angiotensin II (Ang II), aldosterone (Aldo), atrial natriuretic peptide (ANP) and arginine vasopressin (AVP) were studied in 11 patients with essential hypertension (HT) and in 10 healthy control subjects (CS). Antihypertensive treatment was terminated at least 2 weeks prior to examination. Dopamine (2 micrograms/kg/min) was infused for two hours. Before dopamine infusion all measured parameters, but blood pressure, did not deviate significantly between the two groups, including 24 h urinary sodium excretion prior to investigation (HT: 166.9 mmol/24 h vs. CS: 183.4 mmol/24 h, medians). Dopamine infusion resulted in an exaggerated natriuresis in the HT group when compared with the CS group; sodium excretion: (HT: from 260 to 759 mumol/min vs. CS: from 255 to 432 mumol/min, p < 0.01) and fractional sodium excretion: (HT: from 1.6 to 4.2% vs. CS: from 1.6 to 2.4%, p < 0.01 median values). Distal fractional sodium reabsorption was significantly lower in the HT patients (HT: from 94.0 to 88.5% vs. CS: from 94.0 to 91.6%, p < 0.01). ANP decreased significantly only in the HT group (HT: from 4.8 to 3.5 pmol/l vs. CS: from 3.2 to 3.4 pmol/l, p < 0.01). Renal hemodynamics, blood pressure, urinary output, Ang II, Aldo, and AVP were changed to the same degree or unchanged in both groups. It is concluded that the exaggerated natriuretic response seen in patients with essential hypertension during low-dose dopamine infusion probably is due to a enhanced dopamine sensitivity mainly in the distal parts of the nephron.

Adult↗