Cadmium enhancement of proximal tubular sodium reabsorption

1962 ◽  
Vol 203 (6) ◽  
pp. 1005-1007 ◽  
Author(s):  
Arthur J. Vander
Keyword(s):  
Free Flow ◽  
Sodium Reabsorption ◽  
Untreated Animal ◽  
Sodium Gradient ◽  
Proximal Tubular ◽  
Renal Sodium Reabsorption ◽  
Stop Flow ◽  
Ureteral Occlusion ◽  
Distal Site ◽  
Rule Out

Stop-flow studies were performed to localize the site of cadmium action on renal sodium reabsorption. In the untreated dog undergoing mannitol diuresis, a maximal lumen:plasma sodium gradient was established across the proximal tubule during free flow with no further lowering of luminal concentration during ureteral occlusion, Naprox/NaFF = 1.02 ± .05. During occlusions after cadmium, sodium concentrations in proximally trapped fluid were reduced below free-flow values, Naprox/NaFF = 0.85 ± .08. This difference between treated and untreated animals was statistically significant ( P = < .001) and indicates that cadmium enhances proximal sodium reabsorption. Although distal sodium patterns were unaltered by cadmium, it was not possible to rule out a possible distal site since distal sodium reabsorption is already virtually complete during occlusion in the untreated animal. Cadmium, given intravenously as Cd115, was not excreted in the urine.

Graphical Placement of Transport Segments Along the Nephron From Urine Concentration Pattern Developed With Stop Flow Technique

1958 ◽  
Vol 195 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Walter S. Wilde ◽  
Richard L. Malvin
Keyword(s):  
Sodium Concentration ◽  
Urine Concentration ◽  
Free Flow ◽  
Sodium Reabsorption ◽  
Glucose Phosphate ◽  
Concentration Pattern ◽  
Glucose Reabsorption ◽  
Stop Flow ◽  
Ureteral Occlusion ◽  
Proper Length

The authors characterize transport within segments at points along the nephron by the concentration pattern developed along the renal tubule during stopped flow (brief ureteral occlusion during osmotic diuresis in dogs). The pattern is caught in serial urine samples on reinstatement of flow. They here develop a system of graphical construction which places active transport segments of proper length and position to account for the concentration patterns developed for the substances: Sodium, glucose, phosphate and para-aminohippurate (PAH). The system is based on mixing phenomena as nephrons of different length deliver their fluid content into mixed samples. Glucose reabsorption, phosphate reabsorption and PAH secretion occur in identical proximal segments, containing 45% of the total stop flow nephron volume. A far distal area for very effective active sodium reabsorption contains about 29% of the occluded nephron volume. The sodium concentration pattern does not delineate its own proximal segment but forms a plateau in that area. This results from the fact that proximal concentrations are not lowered during stop flow but remain the same as in new flow and free flow proximal fluid, no lower than the 30–60 mm concentration of free flow urine itself, considerably higher if distal removal of Na occurs during the new outflow.

Stop flow analysis of renal function in the monkey

1962 ◽  
Vol 202 (6) ◽  
pp. 1105-1108 ◽  
Author(s):  
Arthur J. Vander ◽  
Edward J. Cafruny
Keyword(s):  
Renal Function ◽  
Proximal Tubule ◽  
Flow Analysis ◽  
Macaque Monkey ◽  
Sodium Reabsorption ◽  
Glucose Reabsorption ◽  
Proximal Tubular ◽  
Potassium Secretion ◽  
Stop Flow ◽  
Ureteral Occlusion

Stop flow analysis has been used to study renal function in the macaque monkey. Mannitol diuresis produced excretion of 58–70% of filtered water and 22–34% of filtered sodium. An absence of water and sodium reabsorption from the proximal tubule during ureteral occlusion was observed in three of four experiments, suggesting that this portion of the monkey nephron cannot transport sodium as efficiently as the canine proximal tubule during osmotic diuresis or that it is less permeable to water. Creatinine secretion was observed and localized to the same portion of the proximal tubule which secretes PAH. Inorganic phosphate and glucose reabsorption also occurred in the proximal tubule. Sodium, chloride, and potassium stop flow patterns were identical to those reported for the dog. Chlorothiazide caused an inhibition of distal tubular sodium reabsorption and an enhancement of potassium secretion in the distal nephron. Proximal tubular activity of the drug could not be evaluated.

Stop-flow analysis applied to the excretion of hemoglobin

1960 ◽  
Vol 199 (2) ◽  
pp. 292-294 ◽  
Author(s):  
C. L. Malmendier ◽  
J. P. DeKoster ◽  
F. Vander Veiken ◽  
H. Brauman ◽  
M. DeMyttenaere ◽  
...  
Keyword(s):  
Flow Analysis ◽  
Middle Part ◽  
The Other ◽  
Physiological Data ◽  
Sodium Reabsorption ◽  
Water Reabsorption ◽  
Tubular Lumen ◽  
Influence Of Water ◽  
Stop Flow ◽  
Ureteral Occlusion

The stop-flow analysis has been applied to the study of the excretion of hemoglobin, in order to compare the physiological data with the morphological views. The study of the ratio U/P hemoglobin/U/P creatinine suggests that this protein penetrates the tubular lumen by diffusion during the ureteral occlusion and progressed slowly under influence of water reabsorption. During this migration, hemoglobin undergoes the effects of a double reabsorption: one in the middle part of the proximal convoluted tubule, the other more distally situated in a zone not distinguishable from the site of sodium reabsorption.

Effect of ureteral stop flow on renal tissue creatinine, PAH, K, and P in dogs

1965 ◽  
Vol 209 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Gaspar Carrasquer ◽  
A. Louise Baldwin
Keyword(s):  
Renal Pelvis ◽  
Ureteral Obstruction ◽  
Tissue Concentration ◽  
Renal Tissue ◽  
Free Flow ◽  
Tubular Function ◽  
Sodium Reabsorption ◽  
Phosphorus And Potassium ◽  
And Control ◽  
Stop Flow

Experiments have been designed to study tubular function by analysis of renal tissue under conditions of oliguria and mannitol diuresis. A 50-min ureteral obstruction of one kidney was induced by forcing previously excreted urine into the renal pelvis. Without releasing the obstruction, the experimental and control kidneys were removed simultaneously. Relationships between tissue concentration and tubular function have been demonstrated. Substances that are reabsorbed in medulla accumulate in its interstitium during free flow, and this accumulation is reduced by ureteral obstruction. Persistent filtration during stop flow is manifested by accumulation of creatinine throughout the kidney, and is attributed to a distal leak induced by sodium reabsorption. Accumulation of PAH in cortex is enhanced by ureteral obstruction in mannitol diuresis, but the localized effect on PAH is obscured by high levels of persistent filtration in oliguria. The maintenance of phosphorus and potassium levels during stop flow is attributed to their high intracellular concentrations.

CLEARANCE- UND STOP-FLOW-UNTERSUCHUNGEN AN INTAKTEN UND DIABETES-INSIPIDUS-RATTEN IN WASSER- UND OSMOTISCHER DIURESE OHNE UND MIT ZUFUHR EXOGENEN VASOPRESSINS

1966 ◽  
Vol 52 (2) ◽  
pp. 239-254 ◽  
Author(s):  
Günther Vogel ◽  
Ingrid Stoeckert ◽  
Ruth Winkler
Keyword(s):  
Diabetes Insipidus ◽  
Electrolyte Concentration ◽  
Free Water ◽  
Free Flow ◽  
Water Diuresis ◽  
Osmotic Diuresis ◽  
Free Water Clearance ◽  
Stop Flow ◽  
Ureteral Occlusion ◽  
Concentration Patterns

ABSTRACT To clarify the significance of vasopressin on various parameters of renal function, clearance and »stop-flow« tests on intact rats and those with induced diabetes insipidus were carried out during water and osmotic (mannitol) diuresis. With regard to renal clearance, urinary concentration and renal output, water diuresis in the intact and diabetic insipidus rats was the same: low urine osmolarity, low electrolyte concentration, positive free water clearance and low rate of electrolyte excretion. The concentration patterns taken 3 minutes after ureteral occlusion showed for Na+ and Cl−: low free flow values and proximal maximum; osmolarity: low free flow values with a distal maximum below the plasma concentration; creatinine: distal maximum; urea: high free flow values with distal maximum. In the osmotic diuresis of intact animals, the electrolyte concentration was substantially higher; correspondingly, excretory output was much increased as compared to water diuresis, with negative free water clearance. The »stop-flow« patterns for Na+ and Cl− – starting with 70–100 mmol/l – showed a distal minimum, for osmolarity a distal maximum; and the same for creatinine and urea. The measured parameters obtained from diabetic insipidus animals in osmotic diuresis showed a marked approximation – up to equivalence – to that of intact and diabetic insipidus animals in water diuresis. When diabetes insipidus animals in osmotic diuresis were administered arginine-vasopressin as a continuous infusion, the results completely matched those of the measured parameters in the osmotic diuresis of intact animals. The importance of vasopressin on renal transports can thus be demonstrated not only by clearance and excretory tests, but also by the concentration patterns after ureteral occlusion.

Inhibition of distal tubular sodium reabsorption by angiotensin II

1963 ◽  
Vol 205 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Arthur J. Vander
Keyword(s):  
Angiotensin Ii ◽  
Sodium Excretion ◽  
Sodium Concentration ◽  
Relative Increase ◽  
Sodium Reabsorption ◽  
Left Renal Artery ◽  
Tubular Sodium Reabsorption ◽  
Proximal Tubular ◽  
The Right ◽  
Stop Flow

Angiotensin II or norepinephrine was infused directly into the left renal artery of anesthetized dogs undergoing mannitol diuresis, and the right and left kidneys were compared for GFR (Ccr or Cin), RPF (Cpah), sodium excretion, and distal stop-flow sodium and inulin patterns. Both angiotensin and norepinephrine caused similar reductions of GFR and RPF on the left, as compared with the right, but only angiotensin prevented normal lowering of left distal stop-flow sodium concentration, even when length of occlusion was 14 min. The minimum effective dose was 6–12 mµg/kg min, and maximal differences between left and right sodium minima occurred with 50 mµg/kg min. Distal inulin patterns were not altered by angiotensin, nor were "postocclusive" inulin patterns. Clearance data demonstrated that when GFR changes were taken into account angiotensin caused a relative increase in sodium excretion compared to control or norepinephrine-infused dogs. These stop-flow and clearance data support the hypothesis that angiotensin inhibits distal sodium reabsorption by a direct tubular effect. No attempt was made to evaluate possible effects of angiotensin on proximal tubular sodium reabsorption.

Single-nephron function and renal oxygen consumption during rapid volume expansion

1976 ◽  
Vol 231 (4) ◽  
pp. 1166-1172 ◽  
Author(s):  
SW Weinstein ◽  
J Szyjewicz
Keyword(s):  
Oxygen Consumption ◽  
Proximal Tubule ◽  
Volume Expansion ◽  
Ringer Solution ◽  
Sodium Reabsorption ◽  
Distal Nephron ◽  
Renal Oxygen Consumption ◽  
Single Nephron ◽  
Proximal Tubular ◽  
Renal Sodium Reabsorption

Isotonic volume expansion reduces net filtrate reabsorption in the proximal tubule while increasing it in Henle's loop. To determine the role oxidative metabolism plays in these processes, experiments were performed on rats initially hydropenic and then rapidly volume expanded with isotonic Ringer solution. Whole-kidney sodium reabsorption, oxygen consumption, and single-nephron function were measured simultaneously. During volume expansion, net renal sodium reabsorption increased concomitantly with a fall in oxygen consumption and a reduction in proximal tubular absolute filtrate reabsorption. The increase in quantity of nonreabsorbed filtrate delivered into the loop of Henle greatly exceeded the amount excreted in the urine. Thus, filtrate reabsorption by the distal nephron segments increased. These data provide evidence that acute volume expansion reduces oxygen-dependent active solute transport in the proximal tubule. The increase noted in distal nephron sodium reabsorption appears nonoxygen dependent, energized by anaerobic glycolysis or occurring passively.

Renal sodium reabsorption during saline loading and distal blockade in newborn dogs

1975 ◽  
Vol 228 (5) ◽  
pp. 1403-1408 ◽  
Author(s):  
LI Kleinman
Keyword(s):  
Proximal Tubule ◽  
Filtration Rate ◽  
Ethacrynic Acid ◽  
Sodium Reabsorption ◽  
Excellent Correlation ◽  
Saline Loading ◽  
Sodium Load ◽  
Proximal Tubular ◽  
Renal Sodium Reabsorption ◽  
Glomerulotubular Balance

The ability of the proximal tubule to respond to saline expansion and varying filtered sodium loads was studied in 27 neonatal dogs aged 1-23 days. Sodium reabsorption beyond the proximal tubule was blocked with ethacrynic acid and chlorothiazide. When puppies received an intravenous load of 0.9% saline for 1.5 h, fractional sodium reabsorption averaged 0.985. After the addition of distal blockade to the saline infusion fractional Na reabsorption fell to 0.512. During distal blockade alone fractional Na reabsorption was 0.701, and after 1.5 h of saline expansion added to distal blockade fractional Na reabsorption fell to 0.493. Thus, there was a significant decrease in proximal tubular fractional Na reabsorption after saline expansion in neonatal dogs, and the high fractional Na reabsorption and low Na excretion during saline loading without distal blockade must be due to a large distal Na reabsorption. When filtered sodium load was varied by raising and lowering the glomerular filtration rate during distal blockade, there was excellent correlation between amount of filtered and reabsorbed sodium (r = 0.92). Thus, glomerulotubular balance exists in newborn dogs when there is no saline expansion.

Insulin Effect on Renal Sodium Reabsorption in Adolescent Offspring of Essential Hypertensive Parents

Hypertension ◽  
1995 ◽  
Vol 26 (6) ◽  
pp. 1089-1092 ◽  
Author(s):  
B. Grunfeld ◽  
M. Gimenez ◽  
M. Balzaretti ◽  
L. Rabinovich ◽  
M. Romo ◽  
...  
Keyword(s):  
Sodium Reabsorption ◽  
Insulin Effect ◽  
Adolescent Offspring ◽  
Renal Sodium Reabsorption

Renal blood flow, early distal sodium, and plasma renin concentrations during osmotic diuresis

2000 ◽  
Vol 279 (4) ◽  
pp. R1268-R1276 ◽  
Author(s):  
Paul P. Leyssac ◽  
Niels-Henrik Holstein-Rathlou ◽  
Ole Skøtt
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Sodium Excretion ◽  
Plasma Renin ◽  
Urine Flow ◽  
Sodium Reabsorption ◽  
Osmotic Diuresis ◽  
Nacl Concentration ◽  
Proximal Tubular ◽  
Distal Tubules

Inconsistencies in previous reports regarding changes in early distal NaCl concentration (EDNaCl) and renin secretion during osmotic diuresis motivated our reinvestigation. After intravenous infusion of 10% mannitol, EDNaCl fell from 42.6 to 34.2 mM. Proximal tubular pressure increased by 12.6 mmHg. Urine flow increased 10-fold, and sodium excretion increased by 177%. Plasma renin concentration (PRC) increased by 58%. Renal blood flow and glomerular filtration rate decreased, however end-proximal flow remained unchanged. After a similar volume of hypotonic glucose (152 mM), EDNaClincreased by 3.6 mM, ( P < 0.01) without changes in renal hemodynamics, urine flow, sodium excretion rate, or PRC. Infusion of 300 μmol NaCl in a smaller volume caused EDNaCl to increase by 6.4 mM without significant changes in PRC. Urine flow and sodium excretion increased significantly. There was a significant inverse relationship between superficial nephron EDNaCl and PRC. We conclude that EDNa decreases during osmotic diuresis, suggesting that the increase in PRC was mediated by the macula densa. The results suggest that the natriuresis during osmotic diuresis is a result of impaired sodium reabsorption in distal tubules and collecting ducts.

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