Correlation between net water flux, osmotic concentration of the interstitial fluid, and osmotic water permeability of the isolated skin ofBufo bufo bufo (L.)

1975 ◽  
Vol 96 (2) ◽  
pp. 95-100 ◽  
Author(s):  
Christian U. Christensen
Keyword(s):  
Water Permeability ◽  
Interstitial Fluid ◽  
Water Flux ◽  
Bufo Bufo ◽  
Osmotic Water Permeability ◽  
Osmotic Concentration ◽  
Osmotic Water ◽  
Net Water Flux

Regulation of osmotic water permeability during differentiation of inner medullary collecting duct

1991 ◽  
Vol 260 (5) ◽  
pp. F710-F716 ◽  
Author(s):  
E. Siga ◽  
M. F. Horster
Keyword(s):  
Water Permeability ◽  
Epithelial Transport ◽  
Collecting Duct ◽  
Osmotic Water Permeability ◽  
Osmotic Concentration ◽  
Inner Medullary Collecting Duct ◽  
Osmotic Water ◽  
Nephron Segment ◽  
Medullary Collecting Duct

Urinary osmotic concentration capacity during renal ontogeny is subject to changes of medullary cytoarchitecture and of segmental epithelial transport characteristics. Osmotic equilibrium between interstitial and tubular fluid of the terminal nephron segment in response to vasopressin is an absolute essential of maximal urinary osmotic concentration. The regulation of osmotic water permeability (Pf) in this terminal epithelial segment during ontogenetic differentiation has not been documented. The inner medullary collecting duct (IMCD), the terminal 40% of total segmental length, was dissected at two stages of postnatal ontogenetic differentiation from immature (days 7-15) and from mature (days 33-37) rat kidneys and perfused in vitro. Pf (micron/s) was measured (bath hyperosmotic) in the absence and presence of arginine vasopressin (AVP, 230 pM). Basal Pf was 32.3 +/- 4.03 (n = 26) in the immature IMCD (IMCDi) and 111.5 +/- 20.6 (n = 15) in the mature segment (IMCDm). AVP increased Pf in IMCDi from 46.4 +/- 10.5 to 102 +/- 25.7 micron/s, whereas in IMCDm the AVP-dependent change of Pf was from 104.2 +/- 41.2 to 693 +/- 176 micron/s. AVP (2,300 pM) did not further increase Pf in IMCDi. Forskolin (50 microM) changed Pf in IMCDi from 34.9 +/- 6.3 to 104.1 +/- 16 micron/s; the corresponding change in IMCDm was from 150 +/- 32 to 985.8 +/- 133 micron/s. An analogue of adenosine 3',5'-cyclic monophosphate (cAMP; 10(-3) M) increased Pf in IMCDi from 35.5 +/- 11.4 to 138.5 +/- 32.6 and in IMCDm from 79.6 +/- 32.3 to 702.2 +/- 283 micron/s.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Osmotic water permeability of human red cells.

1981 ◽  
Vol 77 (5) ◽  
pp. 549-570 ◽  
Author(s):  
T C Terwilliger ◽  
A K Solomon
Keyword(s):  
Systematic Error ◽  
Water Permeability ◽  
Perturbation Technique ◽  
Mean Value ◽  
Red Cells ◽  
Osmotic Water Permeability ◽  
Osmotic Water ◽  
New Perturbation ◽  
The Relationship ◽  
Human Red Cells

The osmotic water permeability of human red cells has been reexamined with a stopped-flow device and a new perturbation technique. Small osmotic gradients are used to minimize the systematic error caused by nonlinearities in the relationship between cell volume and light scattering. Corrections are then made for residual systematic error. Our results show that the hydraulic conductivity, Lp, is essentially independent of the direction of water flow and of osmolality in the range 184-365 mosM. the mean value of Lp obtained obtained was 1.8 +/- 0.1 (SEM) X 10-11 cm3 dyne -1 s-1.

Water and solute permeability of rat lung caveolae: high permeabilities explained by acyl chain unsaturation

2005 ◽  
Vol 289 (1) ◽  
pp. C33-C41 ◽  
Author(s):  
Warren G. Hill ◽  
Eyad Almasri ◽  
W. Giovanni Ruiz ◽  
Gerard Apodaca ◽  
Mark L. Zeidel
Keyword(s):  
Water Permeability ◽  
Acyl Chain ◽  
Water Flux ◽  
High Water ◽  
Fatty Acyl ◽  
Rat Lung ◽  
Membrane Structures ◽  
Solute Permeability ◽  
Outer Leaflet ◽  
Osmotic Water

Caveolae are invaginated membrane structures with high levels of cholesterol, sphingomyelin, and caveolin protein that are predicted to exist as liquid-ordered domains with low water permeability. We isolated a caveolae-enriched membrane fraction without detergents from rat lung and characterized its permeability properties to nonelectrolytes and protons. Membrane permeability to water was 2.85 ± 0.41 × 10−3 cm/s, a value 5–10 times higher than expected based on comparisons with other cholesterol and sphingolipid-enriched membranes. Permeabilities to urea, ammonia, and protons were measured and found to be moderately high for urea and ammonia at 8.85 ± 2.40 × 10−7and 6.84 ± 1.03 × 10−2 respectively and high for protons at 8.84 ± 3.06 × 10−2 cm/s. To examine whether caveolin or other integral membrane proteins were responsible for high permeabilities, liposomes designed to mimic the lipids of the inner and outer leaflets of the caveolar membrane were made. Osmotic water permeability to both liposome compositions were determined and a combined inner/outer leaflet water permeability was calculated and found to be close to that of native caveolae at 1.58 ± 1.1 × 10−3 cm/s. In caveolae, activation energy for water flux was high (19.4 kcal/mol) and water permeability was not inhibited by HgCl2; however, aquaporin 1 was detectable by immunoblotting. Immunostaining of rat lung with AQP1 and caveolin antisera revealed very low levels of colocalization. We conclude that aquaporin water channels do not contribute significantly to the observed water flux and that caveolae have relatively high water and solute permeabilities due to the high degree of unsaturation in their fatty acyl chains.

Cell osmotic water permeability of isolated rabbit proximal straight tubules

1982 ◽  
Vol 242 (4) ◽  
pp. F321-F330 ◽  
Author(s):  
E. Gonzalez ◽  
P. Carpi-Medina ◽  
G. Whittembury
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Osmotic Water Permeability ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Straight Tubules ◽  
Tubular Surface ◽  
Set Up

Proximal straight tubules were dissected and mounted in a chamber with their lumina occluded. The well-stirred bath could be 95% changed within 84 ms to set up osmotic gradients (delta Coi) across the peritubular cell aspect. Volume changes (less than or equal to 10 pl/mm) were estimated from continuous records of diameter changes (error less than 0.1 micrometers). delta Coi greater than or equal to 2-3 mosM could be discerned. delta Coi values from 10 to 44 mosM were used to evaluate Posc, the cell osmotic water permeability coefficient, and extrapolated to delta Coi = 0. Posc = 25.1 (+/- 2.3) X 10(-4) cm3.s-1.osM-1.cm2 tubular surface area-1. These values are lower than those reported for Pose, the transepithelial osmotic water permeability coefficient, and become lower if corrected for the real (infolded) peritubular cell surface area. Thus, for a given osmotic difference, transcellular water flow finds a higher resistance than paracellular water flow. Experiments were also performed with delta Coi greater than 100 mosM, but interpretation of these data is difficult because of the presence of volume regulatory phenomena and other undesirable effects.

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.

scholarly journals Role of PKC and AMPK in hypertonicity-stimulated water reabsorption in rat inner medullary collecting ducts

2019 ◽  
Vol 316 (2) ◽  
pp. F253-F262 ◽  
Author(s):  
Josephine K. Liwang ◽  
Joseph A. Ruiz ◽  
Lauren M. LaRocque ◽  
Fitra Rianto ◽  
Fuying Ma ◽  
...  
Keyword(s):  
Water Permeability ◽  
Collecting Duct ◽  
Adenosine Monophosphate ◽  
Osmotic Water Permeability ◽  
Water Reabsorption ◽  
Compound C ◽  
Ampk Phosphorylation ◽  
Osmotic Water ◽  
Medullary Collecting Duct

Hypertonicity increases water permeability, independently of vasopressin, in the inner medullary collecting duct (IMCD) by increasing aquaporin-2 (AQP2) membrane accumulation. We investigated whether protein kinase C (PKC) and adenosine monophosphate kinase (AMPK) are involved in hypertonicity-regulated water permeability. Increasing perfusate osmolality from 150 to 290 mosmol/kgH2O and bath osmolality from 290 to 430 mosmol/kgH2O significantly stimulated osmotic water permeability. The PKC inhibitors chelerythrine (10 µM) and rottlerin (50 µM) significantly reversed the increase in osmotic water permeability stimulated by hypertonicity in perfused rat terminal IMCDs. Chelerythrine significantly increased phosphorylation of AQP2 at S261 but not at S256. Previous studies show that AMPK is stimulated by osmotic stress. We tested AMPK phosphorylation under hypertonic conditions. Hypertonicity significantly increased AMPK phosphorylation in inner medullary tissues. Blockade of AMPK with Compound C decreased hypertonicity-stimulated water permeability but did not alter phosphorylation of AQP2 at S256 and S261. AICAR, an AMPK stimulator, caused a transient increase in osmotic water permeability and increased phosphorylation of AQP2 at S256. When inner medullary tissue was treated with the PKC activator phorbol dibutyrate (PDBu), the AMPK activator metformin, or both, AQP2 phosphorylation at S261 was decreased with PDBu or metformin alone, but there was no additive effect on phosphorylation with PDBu and metformin together. In conclusion, hypertonicity regulates water reabsorption by activating PKC. Hypertonicity-stimulated water reabsorption by PKC may be related to the decrease in endocytosis of AQP2. AMPK activation promotes water reabsorption, but the mechanism remains to be determined. PKC and AMPK do not appear to act synergistically to regulate water reabsorption.

scholarly journals Adrenomedullin Inhibits Osmotic Water Permeability in Rat Inner Medullary Collecting Ducts

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2533
Author(s):  
Fuying Ma ◽  
Guangping Chen ◽  
Eva L. Rodriguez ◽  
Janet D. Klein ◽  
Jeff M. Sands ◽  
...  
Keyword(s):  
Water Permeability ◽  
Collecting Duct ◽  
Osmotic Water Permeability ◽  
Water Reabsorption ◽  
Kinase C ◽  
Osmotic Water ◽  
Collecting Ducts ◽  
Medullary Collecting Duct ◽  
Camp Levels ◽  
Reduced Water

Adrenomedullin (ADM) is a vasodilator that causes natriuresis and diuresis. However, the direct effect of ADM on osmotic water permeability in the rat inner medullary collecting duct (IMCD) has not been tested. We investigated whether ADM and its ADM receptor components (CRLR, RAMP2, and 3) are expressed in rat inner medulla (IM) and whether ADM regulates osmotic water permeability in isolated perfused rat IMCDs. The mRNAs of ADM, CRLR, and RAMP2 and 3 were detected in rat IM. Abundant protein of CRLR and RAMP3 were also seen but RAMP2 protein level was extremely low. Adding ADM (100 nM) to the bath significantly decreased osmotic water permeability. ADM significantly decreased aquaporin-2 (AQP2) phosphorylation at Serine 256 (pS256) and increased it at Serine 261 (pS261). ADM significantly increased cAMP levels in IM. However, inhibition of cAMP by SQ22536 further decreased ADM-attenuated osmotic water permeability. Stimulation of cAMP by roflumilast increased ADM-attenuated osmotic water permeability. Previous studies show that ADM also stimulates phospholipase C (PLC) pathways including protein kinase C (PKC) and cGMP. We tested whether PLC pathways regulate ADM-attenuated osmotic water permeability. Blockade of either PLC by U73122 or PKC by rottlerin significantly augmented the ADM-attenuated osmotic water permeability and promoted pS256-AQP2 but did change pS261-AQP2. Inhibition of cGMP by L-NAME did not change AQP2 phosphorylation. In conclusion, ADM primarily binds to the CRLR-RAMP3 receptor to initiate signaling pathways in the IM. ADM reduced water reabsorption through a PLC-pathway involving PKC. ADM-attenuated water reabsorption may be related to decreased trafficking of AQP2 to the plasma membrane. cAMP is not involved in ADM-attenuated osmotic water permeability.

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