Single proximal tubules of the Necturus kidney. III. Dependence of H2O movement on NaCl concentration

1959 ◽  
Vol 197 (2) ◽  
pp. 313-318 ◽  
Author(s):  
Erich E. Windhager ◽  
Guillermo Whittembury ◽  
Donald E. Oken ◽  
Hans J. Schatzmann ◽  
A. K. Solomon
Keyword(s):  
Water Movement ◽  
Water Flux ◽  
Potential Gradient ◽  
Solute Flux ◽  
Experimental Conditions ◽  
Nacl Concentration ◽  
Proximal Tubular ◽  
Solute Movement ◽  
The Relationship ◽  
Net Water Flux

Stopped flow microperfusion technique ( Am. J. Physiol. 195: 563, 1958) was used to study water movement across the proximal tubular wall of Necturus kidney. In 23 experiments, net water movement was measured from perfusion solutions containing 50, 62.5, 75 and 100 mEq. NaCl/1. which were made isosmotic with Necturus plasma by addition of mannitol. Water movement was shown to depend upon luminal NaCl concentration. Studies of the relationship between net solute flux and water flux demonstrated a linear relationship: net water flux (mµl/sec.) = 9.4 x net solute flux + 0.003. Net water flux is statistically zero when net solute flux is zero. Under these experimental conditions no force is important for water movement other than that arising from solute movement. It is concluded that net movement of Na has taken place up an electrochemical potential gradient, indicating active transport of this ion. Furthermore, movement of water from the tubule is considered to be passive since net water flux may be accounted for quantitatively in terms of osmotically induced forces arising from net solute movement.

scholarly journals ION AND WATER FLUXES IN THE ILEUM OF RATS

1957 ◽  
Vol 41 (1) ◽  
pp. 143-168 ◽  
Author(s):  
Peter F. Curran ◽  
A. K. Solomon
Keyword(s):  
Water Movement ◽  
Water Flux ◽  
Electrical Potential ◽  
Linear Functions ◽  
Solute Flux ◽  
Electrical Potential Difference ◽  
Nacl Concentration ◽  
Rate Of Absorption

Studies have been carried out on the movement of salt and water across the small intestine of the rat. Segments of the ileum of anesthetized rats have been perfused in vivo with unbuffered NaCl solutions or isotonic solutions of NaCl and mannitol. Kinetic analysis of movements of Na24 and Cl36 has permitted determination of the efflux and influx of Na and Cl. Net water absorption has been measured using hemoglobin as a reference substance. Water was found to move freely in response to gradients of osmotic pressure. Net water flux from isotonic solutions with varying NaCl concentration was directly dependent on net solute flux. The amount of water absorbed was equivalent to the amount required to maintain the absorbed solute at isotonic concentration. These results have been interpreted as indicating that water movement is a passive process depending on gradients of water activity and on the rate of absorption of solute. The effluxes of Na and Cl are linear functions of concentration in the lumen, but both ions are actively transported by the ileum according to the criterion of Ussing (Acta Physiol. Scand., 1949, 19, 43). The electrical potential difference between the lumen and plasma has been interpreted as a diffusion potential slightly modified by the excess of active Cl flux over active Na flux. The physical properties of the epithelial membrane indicate that it is equivalent to a membrane having negatively charged uniform right circular pores of 36 Å radius occupying 0.001 per cent of the surface area.

Single proximal tubules of Necturus kidney IV. Dependence of H2O movement on osmotic gradients

1959 ◽  
Vol 197 (5) ◽  
pp. 1121-1127 ◽  
Author(s):  
Guillermo Whittembury ◽  
Donald E. Oken ◽  
Erich E. Windhager ◽  
A. K. Solomon
Keyword(s):  
Permeability Coefficient ◽  
Protein Concentration ◽  
Water Movement ◽  
Water Flux ◽  
Proximal Tubules ◽  
Na Transport ◽  
Perfusion Fluid ◽  
Water Permeability Coefficient ◽  
The Relationship ◽  
Net Water Flux

The relationship between net water flux and osmotic gradients across the Necturus kidney proximal tubule was studied with stopped flow microperfusion technique. To minimize water movement induced by Na transport, perfusion solutions contained 62.5 mm/l. NaCl; at this concentration no net water movement is observed with isosmolar solutions. Mannitol was added to prepare perfusion solutions with gradients ±70 mOs/l. relative to plasma. With these gradients, water movement was symmetrical in both directions across the membrane: tubular volume decreased 46% with hypoosmolar perfusion fluid, and increased 51% with hyperosmolar fluid. The membrane water permeability coefficient, Pf, is 0.15 x 10–8 ml/(cm2 sec. cm H2O). This coefficient permits calculation of net water movement ascribable to plasma protein osmotic pressure. The calculated value is approximately 1% of the fluid normally absorbed by the tubule. This conclusion was confirmed in separate experiments in which albumin was added to perfusion fluid to produce a protein concentration 67% higher than in plasma. Under these conditions, water was still absorbed from the tubule, indicating that proteins do not play a major role in water absorption.

A two-barrier compartment model for volume flow across amphibian skin

2003 ◽  
Vol 285 (6) ◽  
pp. R1384-R1394 ◽  
Author(s):  
Peng Guo ◽  
Stanley D. Hillyard ◽  
Bingmei M. Fu
Keyword(s):  
Water Movement ◽  
Water Flux ◽  
Compartment Model ◽  
Molar Ratio ◽  
Solute Flux ◽  
Bathing Solution ◽  
Volume Flux ◽  
Amphibian Skin ◽  
Experimental Conditions ◽  
Tight Epithelia

The amphibian skin has long been used as a model tissue for the study of ion transport and osmotic water movement across tight epithelia. To understand the mechanism of water uptake across amphibian skin, we model the skin as a well-stirred compartment bounded by an apical barrier and a tissue barrier. The compartment represents the lateral intercellular space between cells in the stratum granulosum. The apical barrier represents the stratum corneum, the principal/mitochondria-rich cells, and the junctional area between cells. This barrier is hypothesized to have the ability to actively transport solutes through Na+-K+-ATPase. The actively transported solute flux is assumed to satisfy the Michaelis-Menten relationship. The tissue barrier represents a composite barrier comprising the stratum spinosum, the stratum germinativum, the basal lamina, and the dermis. Our model shows that 1) the predicted rehydration rates from apical bathing solutions are in good agreement with the experiment results in Hillyard and Larsen ( J Comp Physiol 171: 283-292, 2001); 2) under their experimental conditions, there is a substantial volume flux coupled to the active solute flux and this coupled volume flux is nearly constant when the osmolality of the apical bathing solution is >100 mosmol/kgH2O; 3) the molar ratio of the actively transported solute flux to the coupled water flux is about 1:160, which is the same as that reported in Nielsen ( J Membr Biol 159: 61-69, 1997).

Reflection coefficients and water permeability in rat proximal tubule

1989 ◽  
Vol 257 (4) ◽  
pp. F658-F668 ◽  
Author(s):  
R. Green ◽  
G. Giebisch
Keyword(s):  
Proximal Tubule ◽  
Water Permeability ◽  
Significant Contribution ◽  
Water Flux ◽  
Reflection Coefficients ◽  
Ionic Fluxes ◽  
Peritubular Capillaries ◽  
Solute Movement ◽  
Rat Proximal Tubule ◽  
Net Water Flux

Simultaneous microperfusion of proximal tubules and peritubular capillaries in kidneys of rats anesthetized with Inactin was used to measure reflection coefficients. All perfusates contained cyanide to inhibit active transport; the tubular perfusate was isotonic and the peritubular capillaries were perfused with solutions made hypertonic with NaCl, NaHCO3, L-glucose, or sodium ferrocyanide. Measurements of recollected fluid enabled a precise mean gradient and ionic fluxes to be calculated; net water flux was measured with inulin. Imposed gradients always partly dissipated. Reflection coefficients were 0.59 +/- 0.01 for NaCl, 0.87 +/- 0.04 for NaHCO3-, and 0.96 +/- 0.07 for ferrocyanide, assuming that L-glucose was 1. Water permeability of the proximal tubule was 1,030 microns/s. Ionic permeability of Cl- (21.6 +/- 1.3 X 10(-5) cm/s) was greater than that for Na+ (13.3 +/- 2.7 X 10(-5) cm/s); permeability for L-glucose was 5.4 +/- 1.3 X 10(-5), and for ferrocyanide ions 2.7 +/- 0.9 X 10(-5) cm/s. It is concluded that in rat proximal tubule both NaCl and NaHCO3 have reflection coefficients less than 1.0 and solute asymmetry across the epithelium is a significant driving force for fluid reabsorption. Furthermore the data suggest that there is a significant contribution of solvent drag to solute movement.

Ion and Water Transport in Isolated Intestine of the Marine Teleost, Cottus Scorpius

1965 ◽  
Vol 42 (1) ◽  
pp. 177-189
Author(s):  
C. R. HOUSE ◽  
K. GREEN
Keyword(s):  
Sodium Chloride ◽  
Sea Water ◽  
Water Movement ◽  
Water Flux ◽  
Chloride Ions ◽  
Osmotic Gradient ◽  
Respiration Rates ◽  
The Mean ◽  
Neutral Sodium ◽  
Net Water Flux

1. The unidirectional sodium fluxes from mucosa to serosa and from serosa to mucosa have been studied in the isolated small intestine of Cottus scorpius, bathed in Ringer and sulphate Ringer, by use of the isotope 22Na. In addition the unidirectional chloride fluxes have been studied in Ringer and choline Ringer using the isotope 36Cl. 2. In Ringer the mean±S.E. values of these fluxes have been found to be: for sodium, 8.4 ± 0.6(serosa to mucosa) and 23.9 ± 0.7 (mucosa to serosa)µequiv. cm.-2 hr.-1 and for chloride, 10.5 ± 0.9(serosa to mucosa) and 21.9 ± 0.9(mucosa to serosa) µequiv. cm.-2 hr.-1 In sulphate Ringer the mean ± S.E. values for sodium were 4.5 ± 0.3 (serosa to mucosa) and 6.8 ± 0.6 (mucosa to serosa) µequiv. cm.-2 hr.-1and in choline Ringer the mean ± S.E. values for chloride were 5.1 ± 1.0 (serosa to mucosa) and 5.4 ± 0.9 (mucosa to serosa) µequiv. cm.-2 hr.-1. 3. The respiration rates of pieces of intestine placed in Ringer, sulphate Ringer, choline Ringer and artificial sea water have been measured in a Warburg apparatus. 4. The mean ± S.E. values of oxygen consumption in these media have been found to be 0.4 ± 0.2 (Ringer), 0.3 ± 0.2 (sulphate Ringer), 0.3 ± 0.2 (choline Ringer) and 0.1 ± 0.2 (artificial sea water) µl. O2/mg. dry weight.hr. 5. The electric potential differences between identical serosal and mucosal media bathing isolated intestines have been measured. 6. The mean ± S.E. values of the potential difference in Ringer, sulphate Ringer, choline Ringer and artificial sea water have been found to be +0.6 ±0.3, +2.2 ± 0.2, + 0.8 ± 0.3 and + 1.3 ± 0.2 mV., respectively (mucosal medium taken as reference). 7. The hydraulic conductivity of the isolated intestine has been found by measuring the change in net water flux arising from the creation of an osmotic gradient across this tissue. Net water flux was measured by the change in weight of normal filled sacs. The mean ± S.E. value for this parameter has been found to be O.22 ± 0.05 µl./cm.2 mosmolar. hr. (or 2.4 ± 0.6 cm. sec.-1 atm.-1). 8. It has been found that, when artificial sea water is placed in the lumen of the intestine bathed in Ringer, a net flow of water into the lumen occurs. This net water flux falls to zero at a time dependent on the luminal volume (to be diluted) and, thereafter, a net water flux (mucosa to serosa) is established. 9. The net water movement across isolated intestines bathed on both sides by identical media has been studied. 10. The mean ± S.E. values for net water flux (mucosa to serosa) have been found to be: in Ringer, 8.1 ± 0.8, in sulphate Ringer, 3.6 ± 0.5 and in choline Ringer, 6.7 ± 0.6 µl. cm -2hr.-1. 11. The results are interpreted as showing that the net transfer of sodium and chloride ions between identical Ringer solutions is achieved by some process whereby these ions are ‘pumped’ in the form of electrically neutral sodium chloride. 12. It is considered that there is some evidence for the existence of a frictional interaction between sodium chloride and water as they pass across the intestine.

scholarly journals The Effect of Low Ionic Strength Extracellular Solutions on the Resting Potential in Skeletal Muscle Fibers

1967 ◽  
Vol 50 (6) ◽  
pp. 1485-1497
Author(s):  
David Holtzman
Keyword(s):  
Ionic Strength ◽  
Resting Potential ◽  
Sartorius Muscle ◽  
Extracellular Solution ◽  
Experimental Conditions ◽  
Nacl Concentration ◽  
Tip Potential ◽  
Low Ionic Strength ◽  
Relationship Of ◽  
The Relationship

Intracellular measurements of the resting potential were made in fibers of the frog sartorius muscle in solutions of varying salt composition and concentration to determine the effects of low ionic strength extracellular solutions on the resting potential. Changes in the glass microelectrode tip potential in low ionic strength solutions were minimized by adding ThCl4 to the extracellular solution. These experimental conditions allowed measurement of the relationship of the resting potential to the concentration of the salt in the extracellular solution by replacing it with the nonionic substance, sucrose. Substitution of sucrose for the extracellular NaCl produced a stable depolarization which was logarithmically related to the NaCl concentration. Substitution of sucrose for choline Cl, instead of NaCl, produced the same degree of depolarization. When Na salts of anions less permeable than chloride (Br, I, NO3) were used, the resting potentials in 116 mM solutions were close to those with chloride (±3mv). The depolarizations produced in low ionic strength solutions of these salts were significantly less than those with chloride.

Micropuncture study of renal tubular transfer of sodium chloride in the rat

1961 ◽  
Vol 200 (3) ◽  
pp. 581-590 ◽  
Author(s):  
Erich E. Windhager ◽  
Gerhard Giebisch
Keyword(s):  
Potential Gradient ◽  
Tubular Epithelium ◽  
Concentration Gradients ◽  
Osmotic Diuresis ◽  
Micropuncture Study ◽  
Proximal Tubular ◽  
Renal Tubular ◽  
The Relationship ◽  
Proximal Convolution ◽  
Proximal Tubular Epithelium

Micropuncture studies were made in the rat on the relationship between net water and net sodium movement across proximal tubular epithelium during strong osmotic diuresis induced by intravenous infusion of a 20% mannitol solution. Results obtained in the mannitol series were compared with data obtained in rats during infusion of 0.9% saline. Collected tubular fluid and appropriate plasma samples were analyzed for C14 inulin or creatinine, chloride and radiosodium. The latter was injected intravenously several hours prior to tubular puncture. Net water reabsorption across the proximal tubule was less than under nondiuretic conditions. The concentration of radiosodium and of chloride in proximal tubular fluid was found to be below that of plasma in osmotic diuresis. Much steeper gradients for these ions were found across distal tubular epithelium indicating that parts other than the proximal convolution participate in the establishment of the over-all concentration gradients. Since net sodium movement occurred against an electrochemical potential gradient during osmotic diuresis, this study provides evidence for active transport of sodium ions across the proximal tubular wall.

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.

scholarly journals The Relationship between Resistance Exercise Performance and Ventilatory Efficiency after Beetroot Juice Intake in Well-Trained Athletes

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1094
Author(s):  
Noemí Serra-Payá ◽  
Manuel Vicente Garnacho-Castaño ◽  
Sergio Sánchez-Nuño ◽  
Lluís Albesa-Albiol ◽  
Montserrat Girabent-Farrés ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Exercise Test ◽  
Exercise Performance ◽  
Beetroot Juice ◽  
Experimental Conditions ◽  
Double Blind ◽  
Ventilatory Efficiency ◽  
End Tidal ◽  
Oxygen Uptake Efficiency Slope ◽  
The Relationship

The assessment of ventilatory efficiency is critical to understanding the matching of ventilation (VE) and perfusion in the lungs during exercise. This study aimed to establish a causal physiological relationship between ventilatory efficiency and resistance exercise performance after beetroot juice (BJ) intake. Eleven well-trained males performed a resistance exercise test after drinking 140 mL of BJ (~12.8 mmol NO3−) or a placebo (PL). Ventilatory efficiency was assessed by the VE•VCO2−1 slope, the oxygen uptake efficiency slope and the partial pressure of end-tidal carbon dioxide (PetCO2). The two experimental conditions were controlled using a randomized, double-blind crossover design. The resistance exercise test involved repeating the same routine twice, which consisted of wall ball shots plus a full squat (FS) with a 3 min rest or without a rest between the two exercises. A higher weight lifted was detected in the FS exercise after BJ intake compared with the PL during the first routine (p = 0.004). BJ improved the VE•VCO2−1 slope and the PetCO2 during the FS exercise in the first routine and at rest (p < 0.05). BJ intake improved the VE•VCO2−1 slope and the PetCO2 coinciding with the resistance exercise performance. The ergogenic effect of BJ could be induced under aerobic conditions at rest.

scholarly journals STRUCTURE-FUNCTION RELATIONSHIPS IN THE ADIPOSE CELL

1970 ◽  
Vol 46 (2) ◽  
pp. 342-353 ◽  
Author(s):  
Samuel W. Cushman
Keyword(s):  
Electron Microscopy ◽  
Fatty Acids ◽  
Colloidal Gold ◽  
Intracellular Transport ◽  
Nonesterified Fatty Acid ◽  
Experimental Conditions ◽  
Nonesterified Fatty Acids ◽  
Adipose Cell ◽  
Cell Functions ◽  
The Relationship

Pinocytic activity in the adipose cell has been examined by measuring the uptake of colloidal gold. Pinocytic activity occurs in the isolated adipose cell under all experimental conditions; a portion of the vesicular elements of the cell can be identified by electron microscopy as pinocytic in origin. The isolated adipose cell appears to take up serum albumin by pinocytosis. Pinocytic activity in the isolated adipose cell is enhanced by epinephrine, but not by insulin. The relationship between pinocytosis and the metabolic activity of the adipose cell has been studied by measuring simultaneously the uptake of radioactive colloidal gold, the incorporation of 14C-counts from U-glucose-14C into CO2, total lipid, triglyceride glycerol and triglyceride fatty acids, and the release of nonesterified fatty acids in the absence of hormones and in the presence of insulin or epinephrine. Correlations between hormone-produced alterations in lipid metabolism and in pinocytic activity suggest that intracellular nonesterified fatty acid levels are a factor in the regulation of both the cell's pinocytic activity and its metabolism and that pinocytosis in the adipose cell functions in the extracellular-intracellular transport of nonesterified fatty acids.

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