Effect of Urodilatin Infusion on Renal Haemodynamics, Tubular Function and Vasoactive Hormones

1997 ◽  
Vol 92 (4) ◽  
pp. 397-407 ◽  
Author(s):  
JAN Carstens ◽  
Kaare T. Jensen ◽  
Erling B. Pedersen
Keyword(s):  
Blood Pressure ◽  
Body Weight ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Distal Part ◽  
Renal Haemodynamics ◽  
Sodium Reabsorption ◽  
Lithium Clearance ◽  
Short Term

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 crossover 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.

Short-term analysis of the relationship between blood pressure and urinary sodium excretion in normotensive subjects

2000 ◽  
Vol 98 (4) ◽  
pp. 495-500 ◽  
Author(s):  
Leonardo CENTONZA ◽  
Giovanna CASTOLDI ◽  
Roberto CHIANCA ◽  
Giuseppe BUSCA ◽  
Raffaello GOLIN ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Sodium Excretion ◽  
Filtration Rate ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Short Term ◽  
Quiet Wakefulness ◽  
Normotensive Subjects

The aim of this study was to investigate whether, in the short term, physiological blood pressure changes are coupled with changes in urinary sodium excretion in normotensive subjects, maintained at fixed sodium intake and under controlled postural and behavioural conditions. Twelve normotensive subjects were recruited. For each subject, seven urine samples were collected at fixed time intervals during an overall 26 h period: late afternoon (16.00–20.00 hours), evening (20.00–24.00 hours), night (24.00–06.00 hours), quiet wakefulness (06.00–09.00 hours), morning (09.00–12.00 hours), post-prandial (12.00–15.00 hours) and afternoon (15.00–18.00 hours). Blood pressure was monitored by an ambulatory blood pressure device during the whole 26 h period. Each urine sample was used to measure urinary sodium excretion and glomerular filtration rate (creatinine clearance). Blood pressure, heart rate, urinary sodium excretion and glomerular filtration rate recorded in the daytime were higher than those measured during the night-time. A significant positive correlation between mean blood pressure and urinary sodium excretion was found during the night, over the whole 26 h period, and during two subperiods of the daytime: quiet wakefulness and the post-prandial period. The coefficient of the pressure–natriuresis curve was significantly decreased by postural changes. We conclude that, in normotensive subjects, blood pressure and urinary sodium excretion are coupled in the short term. The assumption of an upright posture can mask this relationship, presumably by activating neurohumoral factors.

Glomerular Filtration Rate and Segmental Tubular Function in the Early Phase after Transplantation/Uninephrectomy in Recipients and Their Living-Related Kidney Donors

1994 ◽  
Vol 87 (5) ◽  
pp. 519-523 ◽  
Author(s):  
Anne-Lise Kamper ◽  
Niels-Henrik Holstein-Rathlou ◽  
Svend Strandgaard ◽  
Paul Peter Leyssac ◽  
Ole Munck
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Sodium Reabsorption ◽  
Lithium Clearance ◽  
Kidney Donors ◽  
Fluid Reabsorption ◽  
Living Related ◽  
Reabsorption Rate ◽  
Sodium Clearance

1. Glomerular filtration rate and sequential tubular function were investigated in 18 adult renal transplant recipients and in their matched, adult living-related kidney donors before and 5 days after transplantation/uninephrectomy. At day 54, 13 donors and 11 recipients were re-investigated. Sixteen of these constituted eight matched pairs. This reduction in the study population was caused by the application of two withdrawal criteria. 2. In the recipients glomerular filtration rate was unchanged at day 5 and had increased to 61 ml/min at day 54 (P < 0.05). In the donors glomerular filtration rate had increased to 59 ml/min by day 5 (P < 0.01) and was unchanged at day 54. 3. In the recipients lithium clearance was unchanged at day 5 and had increased to 23 ml/min at day 54 (P < 0.01). In the donors the lithium clearance had increased by day 5 (P < 0.01). 4. In the recipients the absolute proximal fluid reabsorption rate was about 36 ml/min throughout the study period. In the donors the absolute proximal fluid reabsorption rate had increased to 42 ml/min by day 5 (P < 0.05) and increased further to 44 ml/min by day 54 (P < 0.01). 5. In the recipients sodium clearance increased from 0.54 ml/min to 2.10 ml/min at day 54 (P < 0.01). In the donors it increased from 0.64 ml/min to 0.99 ml/min at day 54 (P < 0.05). 6. Donor-recipient comparison showed that at day 54 there was no significant difference with regard to glomerular filtration rate, lithium clearance, absolute and fractional proximal fluid reabsorption rate and absolute distal sodium reabsorption rate. The sodium clearance was higher and the fractional distal sodium reabsorption rate was lower in the recipients. 7. In conclusion, the difference in function between donors and recipients at day 5 can probably be explained by the damaging effect of many inevitable factors on the graft. Fifty-four days after transplantation the function of the graft could not be distinguished from that of the remaining kidney. This suggests that the ideal homograft possesses a normal potential for compensatory hypertrophy once the effects of the initial post-operative ischaemia and toxic factors have subsided.

Lithium clearance and renal tubular sodium handling during acute and long-term nifedipine treatment in essential hypertension

1988 ◽  
Vol 75 (6) ◽  
pp. 609-613 ◽  
Author(s):  
Niels Eske Bruun ◽  
Hans Ibsen ◽  
Peter Skøtt ◽  
Dorthe Toftdahl ◽  
Jørn Giese ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Sodium Reabsorption ◽  
Lithium Clearance ◽  
Tubular Sodium Reabsorption ◽  
Potassium Clearance ◽  
Renal Tubular ◽  
Sodium Clearance

1. In two separate studies the lithium clearance method was used to evaluate the influence of acute and long-term nifedipine treatment on renal tubular sodium reabsorption. 2. In the acute study, after a 4 week placebo period two doses of 20 mg of nifedipine decreased supine blood pressure from 155/101 (20.6/13.5) ± 11/4 (1.5/0.5) to 139/88 (18.5/11.7) ± 16/9 (2.1/1.2) mmHg (kPa) (means ± sd; P < 0.01). Lithium clearance, glomerular filtration rate and sodium clearance did not change. Therefore the calculated values of absolute proximal and absolute distal sodium reabsorption rates were also unchanged, as were potassium clearance, urine flow and body weight. 3. In the long-term study, lithium clearance, glomerular filtration rate, sodium clearance, potassium clearance, urine flow and body fluid volumes were measured after a 4 weeks placebo period and after 6 and 12 weeks of nifedipine treatment. As compared with placebo, mean supine blood pressure decreased significantly. The glomerular filtration rate did not change but lithium clearance fell by 30%. Consequently, the absolute and the fractional proximal sodium reabsorption increased significantly. The fractional distal sodium reabsorption did not change. Sodium clearance, fractional sodium excretion, potassium clearance, plasma volume and extracellular fluid volume were also unchanged. 4. In conclusion, we found no changes of renal tubular sodium reabsorption during acute nifedipine treatment, whereas long-term nifedipine treatment caused a redistribution of tubular sodium reabsorption without a change in overall sodium excretion or body fluid compartments.

Amiloride-sensitive lithium reabsorption during doxazosin-induced blood pressure reduction in rats

1991 ◽  
Vol 81 (6) ◽  
pp. 809-814 ◽  
Author(s):  
Jørgen Søberg Petersen ◽  
Michael Shalmi ◽  
Martin Bak ◽  
Niels Lomholt ◽  
Sten Christensen
Keyword(s):  
Blood Pressure ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Mean Arterial Blood Pressure ◽  
Sodium Excretion ◽  
Filtration Rate ◽  
Excretion Rate ◽  
Urine Flow ◽  
Lithium Clearance ◽  
Arterial Blood

1. The effects of acute systemic α1-anoceptor blockade by doxazosin on glomerular filtration rate, urine flow, sodium clearance and lithium clearance were investigated in acutely prepared conscious rats. 2. Clearance experiments were performed during water diuresis (20 mmol/l NaCl and 110 mmol/l glucose, 3 ml/h). After a control period, animals were randomized to one of the following treatments: time-control (n = 9), doxazosin (50 μg primer; 30 μg h−1 kg−1) (n = 10), amiloride (1 mg primer; 2.4 mg h−1 kg−1) (n = 10) and doxazosin plus amiloride (n = 9). 3. Doxazosin reduced the mean arterial blood pressure from 125 to 108 mmHg; this was associated with transient reductions in glomerular filtration rate, urine flow and lithium clearance. After the transient anti-diuresis, the sodium excretion rate remained reduced in doxazosin-infused animals. Amiloride increased the sodium excretion rate without having effects on other variables. When doxazosin was given together with amiloride, the reduction in lithium clearance observed during the transient reduction in glomerular filtration rate and urine flow, was partly abolished. Thus the fractional lithium excretion was transiently increased in rats given doxazosin plus amiloride (from 29 to 40%), whereas in rats given doxazosin alone a non-significant reduction was observed (from 28 to 25%). The dissociation between lithium clearance and fractional lithium excretion in the two doxazosin-infused groups was only significant during the transient reduction in glomerular filtration rate and urine flow. 4. The results provide evidence for an amiloride-sensitive lithium reabsorption during acute systemic α1-adrenoceptor blockade. It is suggested that activation of baroreflexes during the acute reduction in mean arterial blood pressure is responsible for stimulation of distal lithium reabsorption by an unknown mechanism.

Changes in glomerular filtration rate, lithium clearance and plasma protein clearances in the early phase after unilateral nephrectomy in living healthy renal transplant donors

1988 ◽  
Vol 75 (6) ◽  
pp. 655-659 ◽  
Author(s):  
S. Strandgaard ◽  
A. Kamper ◽  
P. Skaarup ◽  
N. H. Holstein-Rathlou ◽  
P. P. Leyssac ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Protein ◽  
Immunoglobulin G ◽  
Filtration Rate ◽  
Early Response ◽  
Unilateral Nephrectomy ◽  
Lithium Clearance ◽  
Β2 Microglobulin ◽  
Observation Period

1. Glomerular and tubular function was studied before and 2 months after unilateral nephrectomy in 14 healthy kidney donors by measurement of the clearances of 51Cr-labelled ethylenediaminetetra-acetate, lithium, β2-microglobulin, albumin and immunoglobulin G. 2. The glomerular filtration rate (GFR) of the kidney that remained in the donor rose from 45 ± 10 (mean ± sd) to 59 ± 10 ml/min (P < 0.01) 5 days after contralateral nephrectomy and remained at this level through the observation period. 3. The lithium clearance (CLi) of the remaining kidney rose from 11.6 ± 3.7 to 20.5 ± 8.2 ml/min (P < 0.01) and remained significantly elevated throughout the observation period. 4. Absolute proximal fluid reabsorption rate (APR), which was estimated as GFR minus CLi, was unchanged 5 days after contralateral nephrectomy, but then rose gradually to reach significantly elevated levels after 4 weeks. 5. Fractional proximal reabsorption (FPR; APR/GFR) fell from 0.75 ± 0.06 to 0.66 ± 0.11 (P < 0.01) but subsequently rose to levels not significantly decreased from normal. 6. Twenty-four hour fractional clearances of β2-microglobulin, albumin and immunoglobulin G rose markedly on the day of nephrectomy, peaked at 2–3 days and subsequently fell to moderately elevated levels. 7. Both the CLj and the plasma protein clearance studies demonstrate that the early response of the remaining kidney to contralateral nephrectomy in man is an increase in GFR, an unchanged APR and a fall in FPR. The proximal tubules thus initially handle the increased filtrate load by passing it on to more distal nephron segments. Within 2–4 weeks, an adaptive increase is seen in proximal reabsorption of both protein and fluid, resulting in an almost complete normalization of glomerulotubular balance.

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