scholarly journals Insulin's acute effects on glomerular filtration rate correlate with insulin sensitivity whereas insulin's acute effects on proximal tubular sodium reabsorption correlate with salt sensitivity in normal subjects

1999 ◽  
Vol 14 (10) ◽  
pp. 2357-2363 ◽  
Author(s):  
Jan C. ter Maaten ◽  
Stephan J. L. Bakker ◽  
Erik H. Serné ◽  
Pieter M. ter Wee ◽  
Ab J. M. Donker ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Insulin Sensitivity ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Normal Subjects ◽  
Salt Sensitivity ◽  
Sodium Reabsorption ◽  
Acute Effects ◽  
Tubular Sodium Reabsorption ◽  
Proximal Tubular

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.

Mechanism of the Impaired Natriuretic Response to Frusemide during Sodium Depletion: A Micropuncture Study in Rats

1996 ◽  
Vol 91 (3) ◽  
pp. 299-305 ◽  
Author(s):  
D. G. Shirley ◽  
S. J. Walter ◽  
R. J. Unwin
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Distal Tubule ◽  
Inhibitory Effect ◽  
Sodium Reabsorption ◽  
Loop Of Henle ◽  
Sodium Depletion ◽  
Anaesthetized Rats ◽  
Proximal Tubular

1. The nephron sites involved in the blunted natriuretic response to frusemide during sodium depletion were investigated using micropuncture techniques in anaesthetized rats. 2. Glomerular filtration rate was lower, and fractional sodium reabsorption in the proximal convoluted tubule higher, in sodium-depleted than in sodium-replete rats. Consequently, sodium delivery to the loop of Henle was reduced (by approximately 35%) in the sodium-depleted animals. Intravenous frusemide (2.5 mg h−1 kg−1; urinary water and electrolyte losses replaced) had no effect on glomerular filtration rate or proximal tubular sodium reabsorption in either group. 3. The inhibitory effect of intravenous frusemide on fractional sodium reabsorption in the nephron segments constituting the loop of Henle (measured by free-flow micropuncture) was attenuated during sodium depletion. However, when loops of Henle were microperfused at identical rates with artificial late proximal tubular fluid, no difference in the responses of sodium-depleted and sodium-replete rats to intraluminal frusemide (10−5 mol/l) could be detected. 4. In sodium-replete animals, the increased load of sodium delivered from the loop of Henle during frusemide administration resulted in a lowering of fractional sodium reabsorption in the distal tubule. In contrast, in sodium-depleted rats given frusemide, fractional distal sodium reabsorption tended to increase, so that values in the two groups of frusemide-treated animals were markedly different (0.30 ±0.04 versus 0.51 ±0.03). 5. It is concluded that the blunted natriuretic response to frusemide during sodium depletion results from at least three factors: a reduced sodium delivery to the loop of Henle; a reduced inhibitory effect of frusemide on fractional sodium reabsorption in the loop of Henle, which may be a consequence of the reduced sodium load; and enhanced fractional reabsorption of sodium in the distal tubule, which partially buffers the diuretic-induced increase in sodium delivery from the loop.

scholarly journals Renal sodium and water handling in hypothyroid patients: the role of renal insufficiency.

1990 ◽  
Vol 1 (2) ◽  
pp. 205-210
Author(s):  
M Allon ◽  
A Harrow ◽  
C B Pasque ◽  
M Rodriguez
Keyword(s):  
Renal Failure ◽  
Glomerular Filtration Rate ◽  
Chronic Renal Failure ◽  
Renal Insufficiency ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Normal Subjects ◽  
Sodium Reabsorption ◽  
Water Handling ◽  
Hypothyroid Patients

The mechanism responsible for renal tubular abnormalities in sodium and water excretion in hypothyroid patients is poorly understood. To evaluate the possible contribution of the reduced glomerular filtration rate of hypothyroidism to these abnormalities, tubular function in hypothyroid patients was compared with that in patients with chronic renal failure and in normal subjects. The lithium clearance method and oral water loading were used to evaluate parameters of tubular sodium and water handling, respectively. The hypothyroid and the chronic renal failure patients were selected to have similar reductions in glomerular filtration rate. As compared to the normal subjects, the hypothyroid and chronic renal failure patients had a decrease in proximal sodium reabsorption and an increase in distal sodium reabsorption. The changes in tubular handling of sodium were not different in the hypothyroid and the chronic renal failure patients. Maximal urinary flow rate and free water clearances were similarly reduced in the hypothyroid patients and the chronic renal failure patients. For all subjects studied, proximal sodium reabsorption and maximal urinary volume were directly correlated with the glomerular filtration rate, and distal nephron sodium reabsorption was proportionate to delivery of sodium from the proximal tubule. The results suggest that the abnormalities in tubular sodium and water handling in hypothyroid patients are comparable to those present in other patients with a similar degree of renal insufficiency. Thus, the tubular abnormalities in hypothyroidism may be a consequence of the associated decrease in glomerular filtration rate.

Sodium and Water Excretion in Nephrotic Patients: Effects of Changes in Renal Haemodynamics

1990 ◽  
Vol 79 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Michael Allon ◽  
Charles B. Pasque ◽  
Mariano Rodriguez
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Flow ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Urine Volume ◽  
Sodium Reabsorption ◽  
Plasma Volume Expansion ◽  
Water Excretion ◽  
Significant Change

1. Eight nephrotic patients were studied in order to evaluate the effects of acute changes in renal plasma flow and glomerular filtration rate on renal solute and water handling, in the absence of plasma volume expansion. 2. The subjects were studied first after the administration of captopril, a manoeuvre that increased renal plasma flow without a significant change in glomerular filtration rate, and a second time after receiving combined therapy with captopril and ibuprofen, a manoeuvre that decreased glomerular filtration rate without a significant change in renal plasma flow. 3. After captopril therapy, despite the increase in renal plasma flow, there was no significant change in proximal sodium reabsorption (as estimated from fractional lithium reabsorption), urine volume or urine osmolality. 4. The decrease in glomerular filtration rate observed after the administration of captopril plus ibuprofen was associated with decreases in fractional excretion of sodium and urine volume, and an increase in urine osmolality. The changes in these parameters of tubular function were proportionate to the changes in glomerular filtration rate. Fractional proximal sodium reabsorption increased substantially. 5. These observations suggest that, in the absence of plasma volume expansion, an increase in renal plasma flow does not increase sodium or water excretion by the nephrotic kidney. Moreover, during acute decreases in glomerular filtration rate, glomerulotubular balance appears to be disrupted, resulting in disproportionately high rates of proximal tubule sodium reabsorption.

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.

Feedback mediation of SNGFR autoregulation in hydropenic and DOCA- and salt-loaded rats

1979 ◽  
Vol 237 (1) ◽  
pp. F63-F74 ◽  
Author(s):  
L. C. Moore ◽  
J. Schnermann ◽  
S. Yarimizu
Keyword(s):  
Glomerular Filtration Rate ◽  
Arterial Pressure ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Tubuloglomerular Feedback ◽  
Single Nephron ◽  
Proximal Tubular

Tubuloglomerular feedback (TGF) mediation of autoregulation was investigated by measuring the response of single nephron glomerular filtration rate (SNGFR) to changes in arterial pressure (AP) following acute or chronic TGF inhibition. In hydropenic rats with intact TGF, distal SNGFR was 25.0 +/- 1.2 (SE) and 23.9 +/- 1.4 nl/min at AP of 111 and 135 mmHg, respectively. In the same 20 nephrons during proximal tubular microinfusion of furosemide, distal SNGFR was 23.6 +/- 1.4 (n = 16) and 29.7 +/- 1.4 nl/min (n = 20) (P less than 0.001, n = 16) at 112 and 133 mmHg. When determined proximally, SNGFR was 25.6 +/- 1.0 and 29.5 +/- 0.9 nl/min (P less than 0.001, n = 31) at 112 and 157 mmHg; kidney GFR increased similarly. These data and the predictions of a GFR model were then used to estimate autoregulatory efficiency. This analysis indicated that partial autoregulation occurred during TGF inhibition. Therefore, TGF is an essential, but probably not the only, mechanism mediating SNGFR autoregulation.

MAXIMUM TUBULAR REABSORPTION CAPACITY OF GLUCOSE IN DIABETES MELLITUS

1965 ◽  
Vol 50 (1) ◽  
pp. 79-94 ◽  
Author(s):  
A. Vitelli ◽  
C. Cattaneo ◽  
P. F. Martini
Keyword(s):  
Diabetes Mellitus ◽  
Renal Function ◽  
Glomerular Filtration Rate ◽  
Vascular Disease ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Normal Subjects ◽  
Tubular Reabsorption ◽  
Functional Changes ◽  
Two Factors

ABSTRACT The glomerular filtration rate (GFR) and maximum tubular reabsorption of glucose (TmG) were measured in 24 cases of diabetes mellitus. The patients, who were of different ages, varied with regard to the severity and duration of the disease and 11 patients showed clinical and functional evidence of vascular disease. The GFR and TmG were diminished in almost 50 per cent of cases, and the diminution of the two factors was closely correlated. The incidence of these renal functional changes was almost the same in the group of diabetics with vascular disease as in the group without complications. The GFR and TmG were not correlated with the age of the patients or with the severity of diabetes, though these factors were to some extent correlated with the duration of the disease. No relationship was observed between the incidence of impairment of the renal function and sex. The examinations carried out in this series of cases as well as in a number of normal subjects suggest various considerations with regard to the value of the various techniques which have been proposed for the measurement of the TmG.

scholarly journals Insulin Sensitivity Measured With Euglycemic Clamp Is Independently Associated With Glomerular Filtration Rate in a Community-Based Cohort

Diabetes Care ◽  
2008 ◽  
Vol 31 (8) ◽  
pp. 1550-1555 ◽  
Author(s):  
E. Nerpin ◽  
U. Riserus ◽  
E. Ingelsson ◽  
J. Sundstrom ◽  
M. Jobs ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Insulin Sensitivity ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Community Based ◽  
Euglycemic Clamp
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