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.

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 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.

Determination of Water Permeability Coefficient and Its Activation Energy for Rabbit Spermatozoa

Cryobiology ◽  
1995 ◽  
Vol 32 (2) ◽  
pp. 175-181 ◽  
Author(s):  
M.R. Curry ◽  
B.J. Redding ◽  
P.F. Watson
Keyword(s):  
Activation Energy ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Water Permeability Coefficient ◽  
Rabbit Spermatozoa

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 Determination of Water Permeability Coefficient for Human Spermatozoa and its Activation Energy1

1993 ◽  
Vol 48 (1) ◽  
pp. 99-109 ◽  
Author(s):  
E. E. Noiles ◽  
P. Mazur ◽  
P. F. Watson ◽  
F. W. Kleinhans ◽  
J. K. Critser
Keyword(s):  
Water Permeability ◽  
Permeability Coefficient ◽  
Human Spermatozoa ◽  
Water Permeability Coefficient

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

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.

scholarly journals Permeability of Concrete and Correlation with Microstructure Parameters Determined by 1H NMR

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yurong Zhang ◽  
Shengxuan Xu ◽  
Zhaofeng Fang ◽  
Junzhi Zhang ◽  
Chaojun Mao
Keyword(s):  
Water Permeability ◽  
Permeability Coefficient ◽  
Pore Diameter ◽  
Gas Permeability ◽  
Steady State Flow ◽  
Test Device ◽  
Water Permeability Coefficient ◽  
Microstructure Parameters ◽  
The Relationship ◽  
Better Than

Water and gas permeability coefficients of concrete with different water-binder (w/b) ratios and admixtures were measured by a self-designed test device based on the steady-state flow method for liquid and the method of differential pressure in stability for gas, respectively. In addition, the micropore structure of concrete was determined by 1H nuclear magnetic resonance (NMR). Results indicated that there are good correlations between water and gas permeability of concrete with different w/b ratios, with correlation coefficient greater than 0.90. Better correlations between water permeability and segmental contributive porosity ranged from 10 to 100 nm and 100 to 1000 nm can be identified, but the gas permeability is more relevant to the segmental contributive porosity ranging from 100 to 1000 nm. Moreover, the correlation between water permeability and contributive porosity for each pore diameter is always better than that of gas permeability. The influence of admixtures on the relationship between permeability and pore size distribution of concrete is significant. Moreover, water permeability coefficient is one or two orders of magnitude lower than the gas permeability coefficient.

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