scholarly journals Osmosis in Cortical Collecting Tubules

1974 ◽  
Vol 64 (2) ◽  
pp. 201-228 ◽  
Author(s):  
James A. Schafer ◽  
Clifford S. Patlak ◽  
Thomas E. Andreoli
Keyword(s):  
Steady State ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Osmotic Water Permeability ◽  
Osmotic Flow ◽  
Unstirred Layers ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
In Series ◽  
Collecting Tubules

This paper reports a theoretical analysis of osmotic transients and an experimental evaluation both of rapid time resolution of lumen to bath osmosis and of bidirectional steady-state osmosis in isolated rabbit cortical collecting tubules exposed to antidiuretic hormone (ADH). For the case of a membrane in series with unstirred layers, there may be considerable differences between initial and steady-state osmotic flows (i.e., the osmotic transient phenomenon), because the solute concentrations at the interfaces between membrane and unstirred layers may vary with time. A numerical solution of the equation of continuity provided a means for computing these time-dependent values, and, accordingly, the variation of osmotic flow with time for a given set of parameters including: Pf (cm s–1), the osmotic water permeability coefficient, the bulk phase solute concentrations, the unstirred layer thickness on either side of the membrane, and the fractional areas available for volume flow in the unstirred layers. The analyses provide a quantitative frame of reference for evaluating osmotic transients observed in epithelia in series with asymmetrical unstirred layers and indicate that, for such epithelia, Pf determinations from steady-state osmotic flows may result in gross underestimates of osmotic water permeability. In earlier studies, we suggested that the discrepancy between the ADH-dependent values of Pf and PDDw (cm s–1, diffusional water permeability coefficient) was the consequence of cellular constraints to diffusion. In the present experiments, no transients were detectable 20–30 s after initiating ADH-dependent lumen to bath osmosis; and steady-state ADH-dependent osmotic flows from bath to lumen and lumen to bath were linear and symmetrical. An evaluation of these data in terms of the analytical model indicates: First, cellular constraints to diffusion in cortical collecting tubules could be rationalized in terms of a 25-fold reduction in the area of the cell layer available for water transport, possibly due in part to transcellular shunting of osmotic flow; and second, such cellular constraints resulted in relatively small, approximately 15%, underestimates of Pf.

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.

Membrane organization and function of M1 and M23 isoforms of aquaporin-4 in epithelial cells

2004 ◽  
Vol 287 (3) ◽  
pp. F501-F511 ◽  
Author(s):  
Claudia Silberstein ◽  
Richard Bouley ◽  
Yan Huang ◽  
Pingke Fang ◽  
Nuria Pastor-Soler ◽  
...  
Keyword(s):  
Water Permeability ◽  
Single Channel ◽  
Phosphorylation Site ◽  
Freeze Fracture ◽  
Parietal Cells ◽  
Aquaporin 4 ◽  
Osmotic Water Permeability ◽  
Cellular Expression ◽  
Water Permeability Coefficient ◽  
Osmotic Water

Aquaporin-4 (AQP4) water channels exist as heterotetramers of M1 and M23 splice variants and appear to be present in orthogonal arrays of intramembraneous particles (OAPs) visualized by freeze-fracture microscopy. We report that AQP4 forms OAPs in rat gastric parietal cells but not in parietal cells from the mouse or kangaroo rat. Furthermore, the organization of principal cell OAPs in Brattleboro rat kidney is perturbed by vasopressin (arginine vasopressin). Membranes of LLC-PK1 cells expressing M23-AQP4 showed large, abundant OAPs, but none were detectable in cells expressing M1-AQP4. Measurements of osmotic swelling of transfected LLC-PK1 cells using videomicroscopy, gave osmotic water permeability coefficient ( Pf) values (in cm/s) of 0.018 (M1-AQP4), 0.019 (M23-AQP4), and 0.003 (control). Quantitative immunoblot and immunofluorescence showed an eightfold greater expression of M1- over M23-AQP4 in the cell lines, suggesting that single-channel pf (cm3/s) is much greater for the M23 variant. Somatic fusion of M1- and M23-AQP4 cells ( Pf = 0.028 cm/s) yielded OAPs that were fewer and smaller than in M23 cells alone, and M1-to-M23 expression ratios (∼1:4) normalized to AQP4 in M1 or M23 cells indicated a reduced single-channel pf for the M23 variant. Expression of an M23-AQP4-Ser111E mutant produced ∼1.5-fold greater single-channel pf and OAPs that were up to 2.5-fold larger than wild-type M23-AQP4 OAPs, suggesting that a putative PKA phosphorylation site Ser111 is involved in OAP formation. We conclude that the higher-order organization of AQP4 in OAPs increases single-channel osmotic water permeability by one order of magnitude and that differential cellular expression levels of the two isoforms could regulate this organization.

Diffusion and Permeation of Water in the Frog Egg: The Effect of Tension and Tonicity

1974 ◽  
Vol 61 (3) ◽  
pp. 697-703
Author(s):  
KJELL HANSSON MILD ◽  
SØREN LØVTRUP
Keyword(s):  
Plasma Membrane ◽  
Water Permeability ◽  
Incubation Time ◽  
Permeability Coefficient ◽  
External Medium ◽  
Body Cavity ◽  
Vitelline Membrane ◽  
Unstirred Layers ◽  
Water Permeability Coefficient ◽  
Isotopic Water

1. The isotopic water permeability coefficient, P, of the plasma membrane of frog body cavity eggs has been determined as a function of the incubation time in media of different tonicity. 2. It was found that the permeability decreases with the incubation time in hypotonic solutions. The observed changes may be correlated with an increase of the tension in the vitelline membrane. 3. In the evaluation of the experimental results the diffusion of water in the external medium (‘unstirred layers’) is taken into account.

scholarly journals The Effect of Amphotericin B on the Water and Nonelectrolyte Permeability of Thin Lipid Membranes

1969 ◽  
Vol 53 (2) ◽  
pp. 133-156 ◽  
Author(s):  
Thomas E. Andreoli ◽  
Vincent W. Dennis ◽  
Ann M. Weigl
Keyword(s):  
Amphotericin B ◽  
Lipid Membranes ◽  
Permeability Coefficient ◽  
Circular Cylinders ◽  
Osmotic Water Permeability ◽  
Polyene Antibiotic ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Membrane Bound ◽  
Nonelectrolyte Permeability

This paper reports the effects of amphotericin B, a polyene antibiotic, on the water and nonelectrolyte permeability of optically black, thin lipid membranes formed from sheep red blood cell lipids dissolved in decane. The permeability coefficients for the diffusion of water and nonelectrolytes (PDDi) were estimated from unidirectional tracer fluxes when net water flow (Jw) was zero. Alternatively, an osmotic water permeability coefficient (Pf) was computed from Jw when the two aqueous phases contained unequal solute concentrations. In the absence of amphotericin B, when the membrane solutions contained equimolar amounts of cholesterol and phospholipid, Pf was 22.9 ± 4.6 µsec-1 and PDDHDH2O was 10.8 ± 2.4 µsec-1. Furthermore, PDDi was < 0.05 µsec-1 for urea, glycerol, ribose, arabinose, glucose, and sucrose, and σi, the reflection coefficient of each of these solutes was one. When amphotericin B (10-6 M) was present in the aqueous phases and the membrane solutions contained equimolar amounts of cholesterol and phospholipid, PDDHDH2O was 18.1 ± 2.4 µsec-1; Pf was 549 ± 143 µsec-1 when glucose, sucrose, and raffinose were the aqueous solutes. Concomitantly, PDDi varied inversely, and σi directly, with the effective hydrodynamic radii of the solutes tested. These polyene-dependent phenomena required the presence of cholesterol in the membrane solutions. These data were analyzed in terms of restricted diffusion and filtration through uniform right circular cylinders, and were compatible with the hypothesis that the interactions of amphotericin B with membrane-bound cholesterol result in the formation of pores whose equivalent radii are in the range 7 to 10.5 A.

scholarly journals An Analysis of Unstirred Layers in Series with "Tight" and "Porous" Lipid Bilayer Membranes

1971 ◽  
Vol 57 (4) ◽  
pp. 464-478 ◽  
Author(s):  
Thomas E. Andreoli ◽  
Susan L. Troutman
Keyword(s):  
Lipid Bilayer ◽  
Effective Thickness ◽  
Porous Membranes ◽  
Lipid Bilayer Membranes ◽  
Bilayer Membranes ◽  
Permeability Coefficients ◽  
Unstirred Layers ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
In Series

The present experiments were designed to evaluate the effective thickness of the unstirred layers in series with native and porous (i.e., in the presence of amphotericin B) lipid bilayer membranes and, concomitantly, the respective contributions of membranes and unstirred layers to the observed resistances to the diffusion of water and nonelectrolytes between aqueous phases. The method depended on measuring the tracer permeability coefficients for the diffusion of water and nonelectrolytes (PDDi, cm sec-1) when the aqueous phase viscosity (η) was increased with solutes having a unity reflection coefficient, such as sucrose or dextran. The effective thickness of the unstirred layers (αt, cm) and the true, or membrane, permeability coefficients for diffusion of water and nonelectrolytes (Pmmi, cm sec-1) were computed from, respectively, the slope and intercept of the linear regression of 1/PDDi on η. In both the native and porous membranes, αt was approximately 110 x 10-4 cm. The ratio of Pf, the osmotic water permeability coefficient (cm sec-1) to PmmH2O was 1.22 in the native membranes and 3.75 in the porous membranes. For the latter, the effective pore radius, computed from Poiseuille's law, was approximately 5.6 A. A comparison of Pmmi and PDDi, indicated that the porous membranes accounted for 16, 25, and 66% of the total resistance to the diffusion of, respectively, H2O, urea, and glycerol, while the remainder was referable to the unstirred layers.

scholarly journals The water permeability of toad urinary bladder. I. Permeability of barriers in series with the luminal membrane.

1984 ◽  
Vol 83 (4) ◽  
pp. 529-541 ◽  
Author(s):  
S D Levine ◽  
M Jacoby ◽  
A Finkelstein
Keyword(s):  
Urinary Bladder ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Plasma Membranes ◽  
Toad Urinary Bladder ◽  
Luminal Membrane ◽  
Water Permeability Coefficient ◽  
In Series ◽  
Aqueous Layer ◽  
Lipophilic Component

Antidiuretic hormone (ADH) induces a large increase in the water permeability of the luminal membrane of toad urinary bladder. Measured values of the diffusional water permeability coefficient, Pd(w), are spuriously low, however, because of barriers within the tissue, in series with the luminal membrane, that impede diffusion. We have now determined the water permeability coefficient of these series barriers in fully stretched bladders and find it to be approximately 6.3 X 10(-4) cm/s. This is equivalent to an unstirred aqueous layer of approximately 400 microns. On the other hand, the permeability coefficient of the bladder to a lipophilic molecule, hexanol, is approximately 9.0 X 10(-4) cm/s. This is equivalent to an unstirred aqueous layer of only 100 microns. The much smaller hindrance to hexanol diffusion than to water diffusion by the series barriers implies a lipophilic component to the barriers. We suggest that membrane-enclosed organelles may be so tightly packed within the cytoplasm of granular epithelial cells that they offer a substantial impediment to diffusion of water through the cell. Alternatively, the lipophilic component of the barrier could be the plasma membranes of the basal cells, which cover most of the basement membrane and thereby may restrict water transport to the narrow spaces between basal and granular cells.

scholarly journals Water Permeability of Thin Lipid Membranes

1967 ◽  
Vol 50 (6) ◽  
pp. 1765-1784 ◽  
Author(s):  
Albert Cass ◽  
Alan Finkelstein
Keyword(s):  
Water Permeability ◽  
Electrical Resistance ◽  
Lipid Membranes ◽  
Permeability Coefficient ◽  
Plasma Membranes ◽  
Brain Lipids ◽  
Osmotic Permeability ◽  
Unstirred Layers ◽  
Water Permeability Coefficient

The osmotic permeability coefficient, Pf, and the tagged water permeability coefficient, Pd, were determined for thin (<100 A) lipid membranes formed from ox brain lipids plus DL-α-tocopherol; their value of approximately 1 x 10-3 cm/sec is within the range reported for plasma membranes. It was established that Pf = Pd. Other reports that Pf > Pd can be attributed to the presence of unstirred layers in the experimental determination of Pd. Thus, there is no evidence for the existence of aqueous pores in these thin phospholipid membranes. The adsorption onto the membrane of a protein that lowers its electrical resistance by a factor of 103 was found not to affect its water permeability; however, glucose and sucrose were found to interact with the membrane to modify Pf. Possible mechanisms of water transport across these films are discussed, together with the implications of data obtained on these structures for plasma membranes.

scholarly journals Impact of Biochar on Soil Water Permeability Coefficient During 2 Year Field Experiment

2020 ◽  
Vol 609 ◽  
pp. 012108
Author(s):  
Maciej Gliniak ◽  
Jakub Sikora ◽  
Urszula Sadowska ◽  
Agnieszka Klimek-Kopyra ◽  
Agnieszka Latawiec ◽  
...  
Keyword(s):  
Field Experiment ◽  
Soil Water ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Water Permeability Coefficient
Sign in / Sign up

Export Citation Format

Share Document