Note on lack of effect of ethylene on water permeability, electroosmotic efficiency, or transcellular water flow of the plasma membranes in Nitella

1977 ◽  
Vol 55 (5) ◽  
pp. 615-616 ◽  
Author(s):  
D. S. Fensom ◽  
S. M. Ross
Keyword(s):  
Water Flow ◽  
Water Permeability ◽  
Plasma Membranes ◽  
Pond Water ◽  
Monovalent Cation ◽  
Hydraulic Permeability ◽  
Water Flows ◽  
Cation Permeability ◽  
Transcellular Osmosis ◽  
Permeation Properties

Ethylene (4.0 mM) in artificial pond water had no significant effect on three permeation properties of the plasma membranes of Nitella 2 h after addition. Neither the hydraulic permeability measured by transcellular osmosis, the passive monovalent cation permeability measured by electroosmosis, nor the 'active' transcellular water flows were altered appreciably by ethylene in solution.

A transcellular water flux induced by light in Nitella

1973 ◽  
Vol 51 (5) ◽  
pp. 1045-1053 ◽  
Author(s):  
D. S. Fensom ◽  
S. L. Barclay ◽  
Sophie Law ◽  
R. G. Thompson
Keyword(s):  
Water Flow ◽  
Plasma Membranes ◽  
Water Flux ◽  
Pond Water ◽  
Basic Flow ◽  
Membrane Properties ◽  
Light Change ◽  
Hydraulic Permeability ◽  
Closed Chamber ◽  
Current Flows

When Nitella cells in artificial pond water (APW) are illuminated in an electroosmometer, water appears to move into the closed chamber of the instrument. This has been termed the "basic flow" of the instrument. A part of this basic flow is thermal expansion but an appreciable part is a water flow through the living cell. This transcellular water flow is increased by illumination of any part of the cell and is mostly removed by 10−3 mM N-dichlorophenyl-N′,N′-dimethylurea (DCMU). It is readily altered by conditioners which alter the membrane properties at one end of the cell compared with the other: carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) at 5 × 10−3 mM, dinitrophenol (DNP), 10−1 mM ouabain, and particularly pH. Asymmetrical changes in the hydraulic permeability of the membrane are indicated as the most probable cause of this water flow.An electric current flows between the two ends of the cell when the cell is differentially illuminated, particularly at the beginning or end of the light change. The current is thought to indicate the presence of some electrogenic pumps on the plasma membranes.

Cell osmotic water permeability of isolated rabbit proximal convoluted tubules

1983 ◽  
Vol 244 (5) ◽  
pp. F554-F563 ◽  
Author(s):  
P. Carpi-Medina ◽  
E. Gonzalez ◽  
G. Whittembury
Keyword(s):  
Water Flow ◽  
Water Permeability ◽  
Time Course ◽  
Basal Area ◽  
Osmotic Gradient ◽  
Osmotic Water Permeability ◽  
Osmotic Water ◽  
Transcellular Osmosis ◽  
Convoluted Tubules ◽  
Paracellular Water Flow

Cell osmotic water permeability, Pcos, of the peritubular aspect of the proximal convoluted tubule (PCT) was measured from the time course of cell volume changes subsequent to the sudden imposition of an osmotic gradient, delta Cio, across the cell membrane of PCT that had been dissected and mounted in a chamber. The possibilities of artifact were minimized. The bath was vigorously stirred, the solutions could be 95% changed within 0.1 s, and small osmotic gradients (10-20 mosM) were used. Thus, the osmotically induced water flow was a linear function of delta Cio and the effect of the 70-microns-thick unstirred layers was negligible. In addition, data were extrapolated to delta Cio = 0. Pcos for PCT was 41.6 (+/- 3.5) X 10(-4) cm3 X s-1 X osM-1 per cm2 of peritubular basal area. The standing gradient osmotic theory for transcellular osmosis is incompatible with this value. Published values for Pcos of PST are 25.1 X 10(-4), and for the transepithelial permeability Peos values are 64 X 10(-4) for PCT and 94 X 10(-4) for PST, in the same units. These results indicate that there is room for paracellular water flow in both nephron segments and that the magnitude of the transcellular and paracellular water flows may vary from one segment of the proximal tubule to another.

Estimation of the virtual water trade between two Spanish regions: Castilla-la Mancha and Murcia

2010 ◽  
Vol 10 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Ángel De Miguel ◽  
Eloy García ◽  
Irene De Buestamante
Keyword(s):  
Water Flow ◽  
Food Processing ◽  
Virtual Water ◽  
Water Transfer ◽  
Water Efficiency ◽  
International Context ◽  
Water Flows ◽  
Spanish Regions ◽  
La Mancha ◽  
Virtual Water Flow

Virtual water is defined as the water needed to produce a product. We can use virtual water flow calculations to estimate the water efficiency of a country, as well as its economic dependence on water resources. Former studies on this area have focused on quantifying the virtual water flows between countries, in an international context. In this study we reduce the action framework to regions within a country, determining the virtual water balance between two Spanish regions: Castilla-La Mancha and Murcia. In 2004, Castilla-La Mancha exported to Murcia 2,453,442 tons of commercial products, from which 1,191,628 tons were agricultural goods. In terms of virtual water, it means 1,365 hm3, including food-processing, and industrial products. It is necessary to add 350 hm3 to the result, because of the water transfer (Tajo-Segura transfer) between the rivers basins of these regions, so the final virtual water number, in 2004, was 1,715 hm3. The other way round, Murcia exported in 2004 2,069,000 tons of products, from which 490,351 tons were agricultural goods. That supposes 712 hm3 of virtual water. Virtual water flow is unbalanced and displaced towards Murcia with a difference of 1,003 hm3.

Water permeability of apical and basolateral cell membranes of rat inner medullary collecting duct

1990 ◽  
Vol 259 (6) ◽  
pp. F986-F999 ◽  
Author(s):  
B. Flamion ◽  
K. R. Spring
Keyword(s):  
Water Flow ◽  
Water Permeability ◽  
Cell Membranes ◽  
Apical Membrane ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Volume Regulatory Decrease ◽  
Water Permeation ◽  
Inner Medullary Collecting Duct ◽  
Medullary Collecting Duct

To quantify the pathways for water permeation through the kidney medulla, knowledge of the water permeability (Posmol) of individual cell membranes in inner medullary collecting duct (IMCD) is required. Therefore IMCD segments from the inner two thirds of inner medulla of Sprague-Dawley rats were perfused in vitro using a setup devised for rapid bath and luminal fluid exchanges (half time, t1/2, of 55 and 41 ms). Differential interference contrast microscopy, coupled to video recording, was used to measure volume and approximate surface areas of single cells. Volume and volume-to-surface area ratio of IMCD cells were strongly correlated with their position along the inner medullary axis. Transmembrane water flow (Jv) was measured in response to a variety of osmotic gradients (delta II) presented on either basolateral or luminal side of the cells. The linear relation between Jv and delta II yielded the cell membrane Posmol, which was then corrected for membrane infoldings. Basolateral membrane Posmol was 126 +/- 3 microns/s. Apical membrane Posmol rose from a basal value of 26 +/- 3 microns/s to 99 +/- 5 microns/s in presence of antidiuretic hormone (ADH). Because of amplification of basolateral membrane, the ADH-stimulated apical membrane remained rate-limiting for transcellular osmotic water flow, and the IMCD cell did not swell significantly. Calculated transcellular Posmol, expressed in terms of smooth luminal surface, was 64 microns/s without ADH and 207 microns/s with ADH. IMCD cells in anisosmotic media displayed almost complete volume regulatory decrease but only partial volume regulatory increase.

WATER FLOWS AROUND THE COMB PLATES OF THE CTENOPHORE PLEUROBRACHIA PLOTTED BY COMPUTER: A MODEL SYSTEM FOR STUDYING PROPULSION BY ANTIPLECTIC METACHRONISM

1993 ◽  
Vol 177 (1) ◽  
pp. 113-128 ◽  
Author(s):  
D. Barlow ◽  
M. A. Sleigh ◽  
R. J. White
Keyword(s):  
Computer Program ◽  
Water Flow ◽  
High Speed ◽  
Beat Frequency ◽  
Longitudinal Axis ◽  
Model System ◽  
The Other ◽  
Contour Maps ◽  
Water Flows ◽  
Pleurobrachia Pileus

Patterns of water flow around steadily beating comb plates of Pleurobrachia pileus were tracked using suspended plastic beads. The positions of the beads and the comb plates in the plane of the central longitudinal axis of the comb row were digitised from high-speed cine films covering several beat cycles. All of the data from each sequence were combined using a computer program which integrated them into a standard cycle, and the resulting data were plotted by a second computer program to produce charts for different stages in the beat cycle showing the flow velocity at a grid of points. On these charts, contour maps were drawn to indicate the speed and direction of the water flow. Water is drawn towards each comb row from ahead and from the sides and accelerates strongly backwards in a fairly narrow stream which joins those from the other seven comb rows at the rear of the animal. At a beat frequency of 10 Hz the comb plates move with a tip speed of up to 70 mm s-1 in their effective stroke; they have an estimated Reynolds number of 9 in this stroke. Changes in inter- plate volume between adjacent antiplectically coordinated plates are very important in propulsion, particularly near the end of the effective stroke when pairs of adjacent plates close together and cause the high-speed water from around the ciliary tips to be shed into the overlying stream as a series of jets at speeds of 50 mm s-1 or more. The antiplectic coordination of the comb plates makes a major contribution to the efficiency of propulsion.

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.

ADH-induced water permeability and particle aggregates: alteration by a synthetic estrogen

1991 ◽  
Vol 261 (1) ◽  
pp. F144-F152 ◽  
Author(s):  
G. Calamita ◽  
Y. Le Guevel ◽  
J. Bourguet
Keyword(s):  
Urinary Bladder ◽  
Water Flow ◽  
Water Permeability ◽  
Glucose Transporter ◽  
Apical Membrane ◽  
Selective Inhibition ◽  
Synthetic Estrogen ◽  
Permeability Changes ◽  
Particle Aggregates ◽  
Amphibian Urinary Bladder

In the amphibian urinary bladder, the increase in water permeability induced by antidiuretic hormone (ADH) is accompanied by the appearance of apical intramembrane particle (IMP) aggregates that are believed to contain specific channels for water. In a previous work, we have shown that 3,3'-diallyldiethylstilbestrol (DADES), a synthetic estrogen which is a blocker of the glucose transporter, also inhibits the hydrosmotic response to ADH in the bladder. Our aim in the present study was to analyze the alterations of the membrane fine structure further and to correlate them with the water permeability changes. The results point to a selective inhibition of the ADH-induced net water flow, probably due to an interference with one of the last steps of the response to the hormone. This inhibition is associated with an increase in the density of the apical IMP aggregates, which are thus probably not operational. The resting net water flow is not inhibited and, surprisingly, typical IMP aggregates are frequently observed in the apical membrane after DADES treatment. The compound also induces the appearance of unusual loose IMP clusters that can only be seen on the apical membrane of the granular cells and that share several ultrastructural similarities with the ADH-induced aggregates. These results suggest that 1) apical DADES treatment stimulates the insertion of IMP aggregates in the apical membrane of the urinary bladder and 2) DADES inhibits the ADH-induced water flow by interfering with the aggregates and thus probably by blocking the specific water channels.

Fluid Absorption in the Kidney Proximal Tubule

Physiology ◽  
1987 ◽  
Vol 2 (1) ◽  
pp. 22-26
Author(s):  
JA Schafer
Keyword(s):  
Proximal Tubule ◽  
Water Flow ◽  
Water Permeability ◽  
Interstitial Fluid ◽  
High Water ◽  
Fluid Absorption ◽  
Humoral Factors ◽  
Solute Absorption ◽  
Leaky Epithelium

Fluid absorption in the proximal tubule can be driven by a small osmotic difference between the luminal and interstitial fluids because this leaky epithelium has a high water permeability. The osmotic difference is produced by solute absorption, which tends to dilute the luminal fluid and concentrate the interstitial fluid. However, important questions remain unanswered regarding the pathway for water flow and the role of hemodynamic and humoral factors.

Selective permeability barrier to urea in shark rectal gland

2005 ◽  
Vol 289 (1) ◽  
pp. F83-F89 ◽  
Author(s):  
Joshua D. Zeidel ◽  
John C. Mathai ◽  
John D. Campbell ◽  
Wily G. Ruiz ◽  
Gerard L. Apodaca ◽  
...  
Keyword(s):  
Activation Energy ◽  
Epithelial Cells ◽  
Water Flow ◽  
Water Permeability ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Water Flux ◽  
Rectal Gland ◽  
Basolateral Membranes ◽  
Urea Permeability

Elasmobranchs such as the dogfish shark Squalus acanthius achieve osmotic homeostasis by maintaining urea concentrations in the 300- to 400-mM range, thus offsetting to some degree ambient marine osmolalities of 900–1,000 mosmol/kgH2O. These creatures also maintain salt balance without losing urea by secreting a NaCl-rich (500 mM) and urea-poor (18 mM) fluid from the rectal gland that is isotonic with the plasma. The composition of the rectal gland fluid suggests that its epithelial cells are permeable to water and not to urea. Because previous work showed that lipid bilayers that permit water flux do not block flux of urea, we reasoned that the plasma membranes of rectal gland epithelial cells must either have aquaporin water channels or must have some selective barrier to urea flux. We therefore isolated apical and basolateral membranes from shark rectal glands and determined their permeabilities to water and urea. Apical membrane fractions were markedly enriched for Na-K-2Cl cotransporter, whereas basolateral membrane fractions were enriched for Na-K-ATPase. Basolateral membrane osmotic water permeability (Pf) averaged 4.3 ± 1.3 × 10−3 cm/s, whereas urea permeability averaged 4.2 ± 0.8 × 10−7 cm/s. The activation energy for water flow averaged 16.4 kcal/mol. Apical membrane Pf averaged 7.5 ± 1.6 × 10−4 cm/s, and urea permeability averaged 2.2 ± 0.4 × 10−7 cm/s, with an average activation energy for water flow of 18.6 kcal/mol. The relatively low water permeabilities and high activation energies argue strongly against water flux via aquaporins. Comparison of membrane water and urea permeabilities with those of artificial liposomes and other isolated biological membranes indicates that the basolateral membrane urea permeability is fivefold lower than would be anticipated for its water permeability. These results indicate that the rectal gland maintains a selective barrier to urea in its basolateral membranes.

The primary productivity and physiology of Ceratophyllum demersum. I. Gross macro primary productivity

1969 ◽  
Vol 20 (2) ◽  
pp. 115 ◽  
Author(s):  
JL Carr
Keyword(s):  
Water Flow ◽  
Primary Productivity ◽  
Red Light ◽  
Day Length ◽  
Ceratophyllum Demersum ◽  
Water Flows ◽  
Wet Weight ◽  
Number Of Leaves ◽  
Optimum Production ◽  
Laboratory Stream

An artificial laboratory stream was used to study production in Ceratophyllum demersum under various conditions of light intensity, light quality, day length, and water flow. An incandescent illumination of 1500 f.c. over a 12 hr day length gave optimum production. Moderate amounts of red light gave the greatest increase in wet weight but full red light was inhibitory. Blue light, rather than white light, controlled internode length, but small amounts of red light did not cause any inhibition of this internode lengthening. Production appeared to increase with water flows (current) up to 0.54 cm/sec, but this could have been due to temperature effects. Bud formation was arrested in the slowest water flow tested, viz. 0.46 cm/sec. This suggests that vegetative propagation is retarded by slow water flows. Neither length nor the number of leaves per node showed any response to current or temperature.

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