Influence of Extracellular Volume Expansion on the Composition of Proximal Tubular Fluid in Man

1971 ◽  
Vol 40 (6) ◽  
pp. 479-486 ◽  
Author(s):  
J. P. Fillastre ◽  
R. Ardaillou ◽  
R. Isaac
Keyword(s):  
Sodium Chloride ◽  
Ethacrynic Acid ◽  
Extracellular Volume ◽  
Extracellular Fluid ◽  
Tubular Reabsorption ◽  
Sodium Reabsorption ◽  
Experimental Conditions ◽  
Bicarbonate Reabsorption ◽  
Proximal Tubular ◽  
Extracellular Volume Expansion

1. Distal blockade by simultaneous administration of ethacrynic acid and chlorothiazide was performed in healthy subjects whose extracellular fluid was expanded by iso-osmotic sodium chloride or bicarbonate. The results obtained were compared with those from non-expanded subjects (Ardaillou & Fillastre, 1969). 2. By this technique urine approximates in composition to proximal tubular fluid and may be used to provide information on its composition. As in other mammals, UNa/PNa and Uosm/Posm were close to 1, whatever the experimental conditions. UCl/PCl was always higher and UHCO3/PHCO3 always less than 1. 3. Extracellular fluid expansion with sodium chloride depresses water and sodium reabsorption as shown by the increase of tubular fluid and the diminution of UInul/PInul and TNa/GFR × PNa where TNa and GFR × PNa are respectively the amounts of sodium reabsorbed and filtered per min. It also decreases bicarbonate proximal Tm. The influence on bicarbonate reabsorption is more marked in alkali-loaded than in acid-loaded subjects. 4. Extracellular fluid expansion with iso-osmotic sodium bicarbonate also depresses water, sodium and bicarbonate reabsorption. These results suggest that chloride administration is not necessary to diminish bicarbonate reabsorption and that tubular reabsorption of bicarbonate depends in part on the state of effective extracellular volume.

Mechanism of natriuresis following intravascular and extracellular volume expansion

1969 ◽  
Vol 47 (2) ◽  
pp. 153-159 ◽  
Author(s):  
H. Sonnenberg ◽  
S. Solomon
Keyword(s):  
Blood Volume ◽  
Volume Expansion ◽  
Filtration Rate ◽  
Extracellular Volume ◽  
Extracellular Fluid ◽  
Sodium Reabsorption ◽  
Fluid Compartment ◽  
Proximal Tubular ◽  
Extracellular Volume Expansion ◽  
A Site

In clearance studies in rats, increases in filtration rate and electrolyte excretion were observed following both intravascular and extracellular fluid volume expansion. The inulin concentration ratio of proximal tubular fluid to plasma was decreased with extracellular expansion. Neither natriuresis nor fractional sodium reabsorption was related to the degree of intravascular expansion. Microperfusion studies demonstrated a decrease in proximal sodium reabsorption only when both intravascular and extravascular volumes were expanded; net sodium transport was not affected by a blood volume increase alone. From the data it is concluded that in the rat an increase in blood volume is followed by a rise of filtration rate and a fall of fractional reabsorption at a site distal to the proximal tubule, resulting in diuresis and natriuresis. If, in addition, the interstitial fluid compartment is expanded, a direct inhibition of the active transport component of proximal Na+ reabsorption occurs.

Volume expansion predominantly inhibits proximal reabsorption of NaCl rather than NaHCO3

1983 ◽  
Vol 245 (2) ◽  
pp. F272-F275 ◽  
Author(s):  
M. G. Cogan
Keyword(s):  
Sodium Chloride ◽  
Volume Expansion ◽  
Chloride Transport ◽  
Extracellular Volume ◽  
Sprague Dawley ◽  
Bicarbonate Reabsorption ◽  
Sprague Dawley Rats ◽  
Single Nephron ◽  
Extracellular Volume Expansion ◽  
Made In

The present study quantitated the effect of extracellular volume expansion on absolute proximal bicarbonate, chloride, and water reabsorption in 10 Sprague-Dawley rats. Paired free-flow micropuncture measurements were made in the plasma-replete euvolemic state and following 10% body wt isohydric, colloid-free volume expansion. Single nephron glomerular filtration rate and glomerular ultrafiltrate concentration of bicarbonate and chloride were similar in the two conditions. Volume expansion caused absolute proximal reabsorption of bicarbonate to fall by only 7% (from 987 +/- 39 to 920 +/- 53 pmol/min, P less than 0.05). This decrement in bicarbonate reabsorption was compatible with the known increase in bicarbonate permeability and backleak induced by expansion. In contrast, a marked 26% fall in absolute proximal chloride reabsorption occurred (from 1,601 +/- 147 to 1,180 +/- 149 peq/min, P less than 0.005), attributed to alteration in transcellular rather than passive sodium chloride transport. Thus, the decrease in absolute proximal volume reabsorption (from 19.7 +/- 1.0 to 16.7 +/- 1.2 nl/min, P less than 0.005) induced by volume expansion was predominantly a consequence of inhibition of sodium chloride rather than sodium bicarbonate reabsorption.

Influence of Hydrostatic and Oncotic Pressure on Sodium Reabsorption in the Unilateral Pyelonephritic Dog Kidney

1974 ◽  
Vol 47 (4) ◽  
pp. 367-376
Author(s):  
J. P. Wagnild ◽  
F. D. Gutmann ◽  
R. E. Rieselbach
Keyword(s):  
Sodium Chloride ◽  
Volume Expansion ◽  
Extracellular Fluid ◽  
Sodium Reabsorption ◽  
Oncotic Pressure ◽  
Peritubular Capillary ◽  
Physical Force ◽  
Dog Kidney ◽  
Capillary Fluid ◽  
Diseased Kidney

1. The diseased kidney in the dog with experimental unilateral reduction in nephron population, has been shown previously to undergo an exaggerated inhibition of sodium reabsorption after extracellular fluid (ECF) volume expansion induced by isotonic sodium chloride solution compared with the control kidney. The latter serves to maintain a non-azotaemic environment. 2. In the present studies, manoeuvres designed to alter predominantly either post-glomerular hydrostatic pressure (PGHP) or peritubular capillary oncotic pressure (COP) were performed to investigate further the mechanism of this exaggerated natriuresis. 3. Volume expansion with 5 g/dl albumin in 145 mmol/l sodium chloride (saline), thereby increasing PGHP without changing COP, produced exaggerated diseased kidney natriuresis, but of a smaller magnitude than when the same dogs were studied under a lesser degree of intravascular volume expansion with 145 mmol/l saline. Renal vasodilatation produced by systemically administered dopamine, which increases PGHP without ECF volume expansion, also produced exaggerated natriuresis by the diseased kidney. 4. A selective decrease in COP induced by expansion with saline in conjunction with trimethophan camsylate (Arfonad)-induced hypotension also produced exaggerated diseased kidney natriuresis, but to a lesser degree than saline expansion alone in the same dogs. 5. Thus experimental manoeuvres designed to reduce peritubular capillary fluid reabsorption by either predominantly increasing PGHP or decreasing COP produced exaggerated diseased kidney natriuresis. This exaggerated natriuretic response to manoeuvres which predominantly altered either physical force by itself did not approach the response elicited by expansion with saline. 6. The data suggest that alterations in Starling forces play an important role in mediating the exaggerated diseased kidney natriuresis after an acute saline load.

The functional response to furosemide in a case of de Toni-Debre-Fanconi disease

1986 ◽  
Vol 113 (4_Suppl) ◽  
pp. S452-S457
Author(s):  
DAVID SANTOS-ATHERTON ◽  
SILVESTRE FRENK
Keyword(s):  
Sodium Chloride ◽  
Metabolic Alkalosis ◽  
Fanconi Syndrome ◽  
Chronic Treatment ◽  
Amino Nitrogen ◽  
Tubular Reabsorption ◽  
Dietary Sodium ◽  
Hyperchloremic Acidosis ◽  
Proximal Tubular ◽  
Dietary Sodium Chloride

Abstract The case of a 13-year-old boy with the advanced clinical picture of the idiopa thic DeToni-Debré-Fanconi syndrome is described, on whom acute studies of proximal tubular functions and of the effect of furosemide thereon were performed. Sodium bicarbonate loading corrected the hyperchloremic acidosis, but induced an increase of urinary bicarbonate loss of over 20 % of the filtered amount. Furosemide corrected bicarbonate reabsorption in spite of the presence of metabolic alkalosis. The urinary excretion of alpha-amino nitrogen, glucose, and phosphates decreased and tubular reabsorption of the two latter increased under furosemide. On a chronic treatment with furosemide and dietary sodium chloride restriction, correction of hyperchloremic acidosis, hypophosphatemia and rickets was achieved.

scholarly journals Demonstration of a hormonal inhibitor of proximal tubular reabsorption during expansion of extracellular volume with isotonic saline

1968 ◽  
Vol 47 (4) ◽  
pp. 761-773 ◽  
Author(s):  
Floyd C. Rector ◽  
Manuel Martinez-Maldonado ◽  
Neil A. Kurtzman ◽  
Jack C. Sellman ◽  
Fred Oerther ◽  
...  
Keyword(s):  
Extracellular Volume ◽  
Isotonic Saline ◽  
Tubular Reabsorption ◽  
Proximal Tubular ◽  
Proximal Tubular Reabsorption

Interactions between angiotensin and nitric oxide in the renal response to volume expansion

1995 ◽  
Vol 269 (3) ◽  
pp. R504-R510 ◽  
Author(s):  
M. T. Llinas ◽  
J. D. Gonzalez ◽  
F. J. Salazar
Keyword(s):  
Nitric Oxide ◽  
Sodium Excretion ◽  
Volume Expansion ◽  
Extracellular Volume ◽  
Sodium Reabsorption ◽  
Ang Ii ◽  
Synthesis Inhibition ◽  
Renal Response ◽  
Group 2 ◽  
Extracellular Volume Expansion

This study examined, in anesthetized dogs, the possible interactions between nitric oxide (NO) and angiotensin II (ANG II) in mediating the renal response to an extracellular volume expansion (ECVE). It was found that the intrarenal maintenance of ANG II levels (group 1) or the intrarenal NO synthesis inhibition (group 2) did not induce changes in renal hemodynamics but reduced (P < 0.05) the ECVE-induced increments in sodium excretion and fractional lithium excretion (FeLi). In the third group, ANG II synthesis was inhibited during NO synthesis blockade. It was found in this group that the NO synthesis inhibition reduced the ECVE-induced increment in sodium excretion (P < 0.05) but did not modify the ECVE-induced increment in FeLi. These results suggest that the increase of proximal sodium reabsorption induced by the No synthesis inhibition is mediated by endogenous ANG II levels. In the fourth group, it was observed that NO synthesis inhibition, during the intrarenal maintenance of ANG II levels, induced a decrease of renal blood flow (P < 0.05) and reduced the natriuretic response to ECVE to a lower level (P < 0.05) than that observed in groups 1 and 2. The results of this group suggest that endogenous NO modulates the vasoconstrictor and antinatriuretic effects of ANG II during an ECVE. In summary, the results of this study suggest that there is an important interaction between NO and ANG II in mediating the renal response to an ECVE.

Homeostatic efficiency of tubuloglomerular feedback in hydropenia, euvolemia, and acute volume expansion

1993 ◽  
Vol 264 (6) ◽  
pp. F930-F936 ◽  
Author(s):  
S. C. Thomson ◽  
R. C. Blantz
Keyword(s):  
Volume Expansion ◽  
Closed Loop ◽  
Polynomial Regression ◽  
Extracellular Volume ◽  
Tubuloglomerular Feedback ◽  
Maximum Value ◽  
Proximal Tubular ◽  
Extracellular Volume Expansion ◽  
Tubular Flow

We assessed the homeostatic efficiency of the tubuloglomerular feedback (TGF) system in Inactin-anesthetized Munich-Wistar rats by use of perturbation analysis in closed-loop micropuncture studies. Nephrons were studied in vivo under conditions of hydropenia (HYD, n = 17), euvolemia (EUV, n = 23), and acute isoncotic extracellular volume expansion (EXP, n = 15). Proximal tubular flow was perturbed in free-flowing nephrons with a microperfusion apparatus. Flow rate (VM) was measured upstream from the perturbation (VH) by a noninvasive optical technique. The dependence of VM on VH was estimated by polynomial regression. By using fractional compensation (C = -dVM/dVH), as an index of homeostatic efficiency, we constructed efficiency profiles (C vs. VH). At VH = 0, C tended toward higher values with decreasing volume status, although the effect did not achieve significance. The maximum value of C did not differ between groups. The efficiency profiles shifted leftward with each increment in volume (P < 0.03, HYD vs. EXP), suggesting that the TGF system adapts to acute increments in volume by shifting the efficiency profile in favor of a vasodilatory role.

Coupling of NaHCO3 and NaCl reabsorption in dog kidneys during changes in plasma PCO2

1979 ◽  
Vol 236 (3) ◽  
pp. F232-F239 ◽  
Author(s):  
O. Mathisen ◽  
T. Monclair ◽  
M. Raeder ◽  
F. Kiil
Keyword(s):  
Tubular Reabsorption ◽  
Bicarbonate Concentration ◽  
Molar Ratios ◽  
Bicarbonate Reabsorption ◽  
Wide Range ◽  
Proximal Tubular ◽  
Anesthetized Dogs ◽  
The Relationship ◽  
Proximal Tubular Reabsorption ◽  
Glomerulotubular Balance

To study the relationship between proximal tubular reabsorption of bicarbonate, sodium, and chloride, the effects of changes in plasma PCO2 were examined in anesthetized dogs. Distal tubular reabsorption was inhibited by ethacrynic acid; plasma bicarbonate concentration was kept constant at 33.4 +/- 0.3 mM; glomerular filtration rate (GFR) was varied over a wide range to examine glomerulotubular balance (constant fractional reabsorption). Hypercapnia (PCO2, 112.0 +/- 2.5 mmHg) increased bicarbonate reabsorption by about 30%, and hypocapnia (PCO2, 19.8 +/- 0.6 mmHg) decreased reabsorption of bicarbonate by more than 50% and altered reabsorption of sodium, chloride, and bicarbonate in the molar ratios 2.7:1.6:1, respectively. During hypercapnia the range of glomerulotubular balance was extended to a GFR 125% of control. During hypocapnia glomerulotubular balance was present only at GFR below 50% of control; reabsorption of bicarbonate sodium, and chloride was constant at GFR exceeding 50% of control. During metabolic acidosis hypercapnia had no significant effect on reabsorption of bicarbonate, sodium, and chloride. These observations support the hypothesis that bicarbonate reabsorption is the main driving force for osmotic reabsorption of water and NaCl in the proximal tubules.

Functional and morphologic patterns of renal maturation in the developing guinea pig

1981 ◽  
Vol 241 (6) ◽  
pp. F618-F624 ◽  
Author(s):  
C. Merlet-Benichou ◽  
M. Pegorier ◽  
M. Muffat-Joly ◽  
C. Augeron
Keyword(s):  
Filtration Rate ◽  
Tubular Reabsorption ◽  
Proximal Tubules ◽  
Sodium Reabsorption ◽  
Morphologic Change ◽  
Concomitant Increase ◽  
Renal Handling ◽  
Salt Loading ◽  
Glomerular Volume ◽  
Proximal Tubular

Clearance experiments were carried out in fetal, young, and adult pigs undergoing salt loading. Kidney sections were histologically examined and the proximal tubular length, glomerular volume, and number of glomeruli were estimated. Between days 48 and 55 of gestation, the significant increase in glomerular filtration rate was proportionately higher than the concentration increase in water, total solutes, and sodium reabsorption. During this period, neither the proximal tubular length nor the glomerular volume of the juxtamedullary nephrons changed significantly. The main morphologic change took place in the superficial cortex, where new glomeruli attached to very short tubules differentiated. From day 55 to birth, the increase in water, total solutes, and sodium filtered loads was proportionately smaller than the concomitant increase in tubular reabsorption. During this phase, the major morphologic change was the significant lengthening of the proximal tubules of the juxtamedullary and superficial nephrons. These findings suggest that for water, sodium, and total solutes the maturation of superficial nephrons is accompanied by a phase of functional glomerular preponderance. Despite the differentiation of the superficial nephrons, renal handling of normally filtered glucose did not change significantly. Functional glomerulotubular coupling for water, sodium, and total solutes took place soon after birth.

Sign in / Sign up

Export Citation Format

Share Document