Distal tubular sodium reabsorption in the developing rat kidney

1981 ◽  
Vol 240 (6) ◽  
pp. F487-F491 ◽  
Author(s):  
A. Aperia ◽  
G. Elinder
Keyword(s):  
Rat Kidney ◽  
Age Groups ◽  
Distal Tubule ◽  
Sodium Reabsorption ◽  
Tubular Sodium Reabsorption ◽  
Saline Loading ◽  
Proximal Tubular ◽  
Old Rats ◽  
Developing Rat

The immature kidney has a blunted natriuretic response to saline loading. to localize the high fractional Na reabsorption in the developing nephron, we determined Na delivery to the early distal tubule (EDT) and the fraction of filtered Na remaining in the tubular fluid [(TF/P)Na/In] in the EDT and late distal tubule (LDT) in 24- and 40-day-old hydropenic (HP) and volume-expanded (VE) rats. During HP the (TF/P)Na/In ratio in EDT was significantly higher in the younger rats (12.6 +/- 2.0%) than in the older rats (4.2 +/- 0.6%), but because of a lower SNGFR in the younger rats th Na delivery to EDT was the same in both age groups. The (TF/P)Na/In ratio in LDT was not different in 24- and 40-day-old HP rats (1.1 +/- 0.4 and 1.7 +/- 0.3%, respectively). During VE th (TF/P)Na/In ratio in LDT was significantly lower in 24- (3.0 +/- 0.7%) than in 40-day-old rats (8.3 +/- 1.1%). The (TF/P)Na/In ratio in LDT correlated well with the urinary fractional Na excretion. It is concluded that the Na reabsorption capacity of the developing nephron is more efficient in the distal tubule than in the more proximal tubular segments.

Increased Proximal Tubular Sodium Reabsorption in Hypertensive Patients with Type 2 Diabetes

1989 ◽  
Vol 6 (7) ◽  
pp. 614-620 ◽  
Author(s):  
J.-C. Mbanya ◽  
T. H. Thomas ◽  
R. Taylor ◽  
K. G. M. M. Alberti ◽  
R. Wilkinson
Keyword(s):  
Type 2 Diabetes ◽  
Sodium Reabsorption ◽  
Hypertensive Patients ◽  
Tubular Sodium Reabsorption ◽  
Proximal Tubular

Mechanisms of angiotensin II natriuresis and antinatriuresis

1985 ◽  
Vol 249 (2) ◽  
pp. F299-F307 ◽  
Author(s):  
M. E. Olsen ◽  
J. E. Hall ◽  
J. P. Montani ◽  
A. C. Guyton ◽  
H. G. Langford ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Sodium Excretion ◽  
Distal Tubule ◽  
Urinary Sodium Excretion ◽  
Sodium Reabsorption ◽  
Ang Ii ◽  
Sodium Load ◽  
Proximal Tubular ◽  
Anesthetized Dogs

The aim of this study was to determine the role of changes in renal arterial pressure (RAP), renal hemodynamics, and tubular reabsorption in mediating the natriuretic and antinatriuretic actions of angiotensin II (ANG II). In seven anesthetized dogs, endogenous ANG II formation was blocked with captopril, and ANG II was infused intravenously at rates of 5-1,215 ng X kg-1 X min-1 while RAP was either servo-controlled at the preinfusion level or permitted to increase. When RAP was servo-controlled, ANG II infusion at all rates from 5-1,215 ng X kg-1 X min-1 decreased urinary sodium excretion (UNaV) and fractional sodium excretion (FENa) while increasing fractional reabsorption of lithium (FRLi) (an index of proximal tubular fractional sodium reabsorption) and causing no change in calculated distal tubule fractional sodium reabsorption (FRDNa). When RAP was permitted to increase, ANG II infusion rates up to 45 ng X kg-1. min-1 also decreased UNaV and FENa while increasing FRLi and causing no change in FRDNa. However, at 135 ng X kg-1 X min-1 and above, UNaV and FENa increased while FRLi and FRDNa decreased when RAP was allowed to rise, even though renal blood flow and filtration fraction were not substantially different from the values observed when RAP was servo-controlled. Filtered sodium load was slightly higher when RAP was permitted to increase during ANG II infusion compared with when RAP was servo-controlled, although the differences were not statistically significant. Thus, even very large doses of ANG II cause antinatriuresis when RAP is prevented from increasing.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of renal interstitial infusion of arachidonic acid on proximal sodium reabsorption

1989 ◽  
Vol 257 (2) ◽  
pp. F237-F242 ◽  
Author(s):  
Y. Kinoshita ◽  
J. C. Romero ◽  
F. G. Knox
Keyword(s):  
Arachidonic Acid ◽  
Urinary Excretion ◽  
Proximal Tubules ◽  
Sodium Reabsorption ◽  
Renal Interstitium ◽  
Tubular Sodium Reabsorption ◽  
Proximal Tubular ◽  
The Individual ◽  
Stimulation Of ◽  
Interstitial Infusion

The effect of prostaglandins (PGs) on proximal sodium reabsorption has not been fully defined. The objective of the present study was to determine the response of proximal tubular sodium reabsorption to infusions of arachidonic acid and specific PGs into the renal interstitium in rats. Renal interstitial infusions of arachidonic acid as well as the individual PGs, I2, E2, and F2 alpha, were employed to elevate the concentration of these PGs in the kidney. Infusion of 10(-4) M arachidonic acid elicited a marked increase of urinary excretion of 6-keto-PGF1 alpha (a stable metabolite of PGI2) from 260.1 +/- 52.7 to 507.4 +/- 129.5 pg/min (P less than 0.05) and a smaller increase of PGE2 from 18.4 +/- 11.2 to 25.9 +/- 10.9 pg/min (P less than 0.05). When micropuncture samples were obtained from superficial late proximal tubules, infusion of arachidonic acid increased the fractional delivery of sodium (FDNa) from 47.8 +/- 5.9 to 58.3 +/- 4.6% (n = 6, P less than 0.01). In the presence of indomethacin, arachidonic acid failed to augment FDNa. Infusion of 10(-5) M PGI2 also increased FDNa from 51.4 +/- 3.4 to 64.0 +/- 4.4% (n = 10, P less than 0.01). PGF2 alpha did not change FDNa and PGE2 decreased it from 53.1 +/- 5.4 to 37.4 +/- 3.3% (n = 8, P less than 0.01). In summary, the present study demonstrates that renal interstitial infusion of arachidonic acid decreases sodium reabsorption by the superficial proximal tubules possibly through the stimulation of PGI2 production.

scholarly journals Prenatal programming of rat proximal tubule Na+/H+ exchanger by dexamethasone

2007 ◽  
Vol 292 (3) ◽  
pp. R1230-R1235 ◽  
Author(s):  
Amit Dagan ◽  
Jyothsna Gattineni ◽  
Vodi Cook ◽  
Michel Baum
Keyword(s):  
Proximal Tubule ◽  
Membrane Vesicles ◽  
Sodium Reabsorption ◽  
Prenatal Programming ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Proximal Tubular ◽  
Old Rats ◽  
Convoluted Tubules

Prenatal administration of dexamethasone causes hypertension in rats when they are studied as adults. Although an increase in tubular sodium reabsorption has been postulated to be a factor programming hypertension, this has never been directly demonstrated. The purpose of this study was to examine whether prenatal programming by dexamethasone affected postnatal proximal tubular transport. Pregnant Sprague-Dawley rats were injected with intraperitoneal dexamethasone (0.2 mg/kg) daily for 4 days between the 15th and 18th days of gestation. Prenatal dexamethasone resulted in an elevation in systolic blood pressure when the rats were studied at 7–8 wk of age compared with vehicle-treated controls: 131 ± 3 vs. 115 ± 3 mmHg ( P < 0.001). The rate of proximal convoluted tubule volume absorption, measured using in vitro microperfusion, was 0.61 + 0.07 nl·mm−1·min−1 in control rats and 0.93+ 0.07 nl·mm−1·min−1 in rats that received prenatal dexamethasone ( P < 0.05). Na+/H+ exchanger activity measured in perfused tubules in vitro using the pH-sensitive dye BCECF showed a similar 50% increase in activity in proximal convoluted tubules from rats treated with prenatal dexamethasone. Although there was no change in abundance of NHE3 mRNA, the predominant luminal proximal tubule Na+/H+ exchanger, there was an increase in NHE3 protein abundance on brush-border membrane vesicles in 7- to 8-wk-old rats receiving prenatal dexamethasone. In conclusion, prenatal administration of dexamethasone in rats increases proximal tubule transport when rats are studied at 7–8 wk old, in part by stimulating Na+/H+ exchanger activity. The increase in proximal tubule transport may be a factor mediating the hypertension by prenatal programming with dexamethasone.

scholarly journals EFFECT OF DIAZOXIDE ON PROXIMAL TUBULAR SODIUM REABSORPTION

1980 ◽  
Vol 14 (8) ◽  
pp. 989-989 ◽  
Author(s):  
W R Allen ◽  
B H Brouhard ◽  
R E Lynch
Keyword(s):  
Sodium Reabsorption ◽  
Tubular Sodium Reabsorption ◽  
Proximal Tubular
Sign in / Sign up

Export Citation Format

Share Document