scholarly journals Effect of Osmolality on the Hydraulic Permeability Coefficient of Red Cells

1968 ◽  
Vol 52 (6) ◽  
pp. 941-954 ◽  
Author(s):  
G. T. Rich ◽  
R. I. Sha'afi ◽  
A. Romualdez ◽  
A. K. Solomon
Keyword(s):  
Permeability Coefficient ◽  
Water Movement ◽  
Red Cells ◽  
Hydraulic Permeability ◽  
Outer Face ◽  
Bathing Medium ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Similar Decrease ◽  
Human Red Cells

The osmotic water permeability coefficient, Lp, for human and dog red cells has been measured as a function of medium osmolality, and found to depend on the osmolality of the bathing medium. In the case of human red cells Lp falls from 1.87 x 10-11 cm3/dyne sec at 199 mOSM to 0.76 x 10-11 cm3/dyne sec at 516 mOSM. A similar decrease was observed for dog red cells. Moreover, Lp was independent of the direction of water movement and the nature of the solute used to provide the osmotic pressure gradient; it depended only on the final osmolality of the medium. Furthermore, Lp was not affected by pH in the range of 6 to 8 nor by the presence of drugs such as valinomycin (1 x 10-6 M) and tetrodotoxin (3.2 x 10-6 M). The instantaneous nature of the response to changes in external osmolality suggests that the hydraulic conductivity of the membrane is controlled by a thin layer at the outer face of the membrane.

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.

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 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 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.

Water and nonelectrolyte permeability in brain synaptosomes isolated from normal and uremic rats

1986 ◽  
Vol 250 (2) ◽  
pp. R306-R312 ◽  
Author(s):  
A. S. Verkman ◽  
C. L. Fraser
Keyword(s):  
Light Scattering ◽  
Permeability Coefficient ◽  
Time Course ◽  
Scattered Light ◽  
Volume Ratio ◽  
High Energy ◽  
Urea Transport ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Water Efflux

Water and nonelectrolyte permeabilities of synaptosomes isolated from the brain of normal and uremic rats were measured by stopped-flow light scattering. Intensity of scattered light (550 nm) increased linearly with decreasing synaptosome size in the range of normal size to 30% of normal size. In response to a 250-mM inwardly directed gradient of an impermeant solute (mannitol or sucrose), there was a 100- to 500-ms time course of increased light scattering resulting from osmotic water efflux. In response to an inwardly directed urea gradient, light scattering first increased (water efflux) and then decreased (urea influx) over a 2- to 10-s time course. Based on an average synaptosome surface-to-volume ratio of 86,000 cm-1, determined by electron microscopy, the permeability coefficient for osmotic water transport (Pf) is 4.5 X 10(-3) cm/s and for urea transport (Purea) is 1.5 X 10(-6) cm/s (23 degrees C); temperature-dependent studies gave an activation energy for Pf of 18 (greater than 16 degrees C) and 3 kcal/mol (less than 16 degrees C) and for Purea of 9.8 kcal/mol (10-55 degrees C). Osmotic water and urea transport were not inhibited by 2 mM p-chloromercuribenzene sulfonate, 120 microM phloretin, and 10 microM phenylurea or by exposure to high-energy radiation (0-10 Mrad). Diffusional water permeability coefficient is approximately 4 X 10(-4) cm/s based on the time course of light scattering after mixture of synaptosomes in D2O buffer with isosmotic H2O buffer. Water and urea transport properties of synaptosomes isolated from uremic rats were not significantly different from those of normal rats.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Urea permeability of human red cells.

1983 ◽  
Vol 82 (1) ◽  
pp. 1-23 ◽  
Author(s):  
J Brahm
Keyword(s):  
Permeability Coefficient ◽  
Red Cells ◽  
Urea Transport ◽  
Hydrophobic Core ◽  
Flow Tube ◽  
Maximal Inhibition ◽  
Simple Diffusion ◽  
Urea Permeability ◽  
Exchange Flux ◽  
Human Red Cells

The rate of unidirectional [14C]urea efflux from human red cells was determined in the self-exchange and net efflux modes with the continuous flow tube method. Self-exchange flux was saturable and followed simple Michaelis-Menten kinetics. At 38 degrees C the maximal self-exchange flux was 1.3 X 10(-7) mol cm-2 s-1, and the urea concentration for half-maximal flux, K1/2, was 396 mM. At 25 degrees C the maximal self-exchange flux decreased to 8.2 X 10(-8) mol cm-2 s-1, and K1/2 to 334 mM. The concentration-dependent urea permeability coefficient was 3 X 10(-4) cm s-1 at 1 mM and 8 X 10(-5) cm s-1 at 800 mM (25 degrees C). The latter value is consonant with previous volumetric determinations of urea permeability. Urea transport was inhibited competitively by thiourea; the half-inhibition constant, Ki, was 17 mM at 38 degrees C and 13 mM at 25 degrees C. Treatment with 1 mM p-chloromercuribenzosulfonate inhibited urea permeability by 92%. Phloretin reduced urea permeability further (greater than 97%) to a "ground" permeability of approximately 10(-6) cm s-1 (25 degrees C). This residual permeability is probably due to urea permeating the hydrophobic core of the membrane by simple diffusion. The apparent activation energy, EA, of urea transport after maximal inhibition was 59 kJ mol-1, whereas in control cells EA was 34 kJ mol-1 at 1 M and 12 kJ mol-1 at 1 mM urea. In net efflux experiments with no extracellular urea, the permeability coefficient remained constantly high, independent of a variation of intracellular urea between 1 and 500 mM, which indicates that the urea transport system is asymmetric. It is concluded that urea permeability above the ground permeability is due to facilitate diffusion and not to diffusion through nonspecific leak pathways as suggested previously.

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.

Effect of thiourea on PCMBS inhibition of osmotic water transport in human red cells

1984 ◽  
Vol 778 (1) ◽  
pp. 185-190 ◽  
Author(s):  
Bernard Chasan ◽  
Michael F. Lukacovic ◽  
Michael R. Toon ◽  
A.K. Solomon
Keyword(s):  
Water Transport ◽  
Red Cells ◽  
Osmotic Water ◽  
Human Red Cells

In Vitro Assay of Platelet Adhesiveness with Washed and Tanned Human Red Cells

1968 ◽  
Vol 20 (03/04) ◽  
pp. 384-396 ◽  
Author(s):  
G Zbinden ◽  
S Tomlin
Keyword(s):  
Platelet Adhesion ◽  
Sodium Citrate ◽  
Blood Platelets ◽  
In Vitro Assay ◽  
Red Cells ◽  
Platelet Adhesiveness ◽  
Vitro Assay ◽  
In Vitro System ◽  
Human Red Cells

SummaryAn in vitro system is described in which adhesion of blood platelets to washed and tannic acid-treated red cells was assayed quantitatively by microscopic observation. ADP, epinephrine and TAME produced a reversible increase in platelet adhesiveness which was antagonized by AMP. With Evans blue, polyanetholsulfonate, phthalanilide NSC 38280, thrombin and heparin at concentrations above 1-4 u/ml the increase was irreversible. The ADP-induced increase in adhesiveness was inhibited by sodium citrate, EDTA, AMP, ATP and N-ethylmaleimide. EDTA, AMP and the SH-blocker N-ethylmaleimide also reduced spontaneous platelet adhesion to red cells. No significant effects were observed with adenosine, phenprocoumon, 5-HT, phthalanilide NSC 57155, various estrogens, progestogens and fatty acids, acetylsalicylic acid and similarly acting agents, hydroxylamine, glucose and KCN. The method may be useful for the screening of thrombogenic and antithrombotic properties of drugs.

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