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Journal articles on the topic 'Solute permeability'
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1
Cordeiro, Margarida M., Armindo Salvador, and Maria João Moreno. "Calculation of Permeability Coefficients from Solute Equilibration Dynamics: An Assessment of Various Methods." Membranes 12, no. 3 (February 23, 2022): 254. http://dx.doi.org/10.3390/membranes12030254.
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Predicting the rate at which substances permeate membrane barriers in vivo is crucial for drug development. Permeability coefficients obtained from in vitro studies are valuable for this goal. These are normally determined by following the dynamics of solute equilibration between two membrane-separated compartments. However, the correct calculation of permeability coefficients from such data is not always straightforward. To address these problems, here we develop a kinetic model for solute permeation through lipid membrane barriers that includes the two membrane leaflets as compartments in a four-compartment model. Accounting for solute association with the membrane allows assessing various methods in a wide variety of conditions. The results showed that the often-used expression Papp = β × r/3 is inapplicable to very large or very small vesicles, to moderately or highly lipophilic solutes, or when the development of a significant pH gradient opposes the solute’s flux. We establish useful relationships that overcome these limitations and allow predicting permeability in compartmentalised in vitro or in vivo systems with specific properties. Finally, from the parameters for the interaction of the solute with the membrane barrier, we defined an intrinsic permeability coefficient that facilitates quantitative comparisons between solutes.
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Adamson, R. H., V. H. Huxley, and F. E. Curry. "Single capillary permeability to proteins having similar size but different charge." American Journal of Physiology-Heart and Circulatory Physiology 254, no. 2 (February 1, 1988): H304—H312. http://dx.doi.org/10.1152/ajpheart.1988.254.2.h304.
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We investigated the hypothesis that solute charge modulates transcapillary exchange in microvessels with continuous endothelium. Two globular proteins, alpha-lactalbumin and ribonuclease, having approximately the same size (mol wt 14,176 and 13,683, respectively) but different net charge (-10 and +4, respectively) were test solutes. Each solute was labeled with the fluorescent probe tetramethylrhodamine isothiocyanate. Labeling did not significantly change solute size, but increased negative charge on each solute by one valency unit. An in vivo fluorescent microscope technique [Huxley et. al., Am. J. Physiol. 252 (Heart Circ. Physiol. 21): H188-H197, 1987] was used to measure solute permeability coefficients (P) in single microvessels of frog mesentery at 14-16 degrees C. The mean P for alpha-lactalbumin, measured when capillary pressure was 10 cmH2O, was 2.1 X 10(-6) cm/s and the mean P for ribonuclease was 4.3 X 10(-6) cm/s. Our results conform to the hypothesis that the transcapillary pathways of frog mesenteric microvessels are negatively charged. With the use of a Donnan-type model for electrostatic partitioning, charge density in the pathway is estimated as 11.4 meq/l. Comparison of measured Ps with those for small solutes in frog mesenteric microvessels indicates that molecular size is a proportionally more significant determinant of solute permeability in continuous capillaries than is solute charge.
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Fu, Bingmei M., Roger H. Adamson, and Fitz-Roy E. Curry. "Determination of Microvessel Permeability and Tissue Diffusion Coefficient of Solutes by Laser Scanning Confocal Microscopy." Journal of Biomechanical Engineering 127, no. 2 (September 18, 2004): 270–78. http://dx.doi.org/10.1115/1.1865186.
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Interstitium contains a matrix of fibrous molecules that creates considerable resistance to water and solutes in series with the microvessel wall. On the basis of our preliminary studies (Adamson et al., 1994, Microcirculation 1(4), pp. 251–265; Fu et al., 1995 Am. J. Physiol. 269(38), pp. H2124–H2140), by using laser-scanning confocal microscopy and a theoretical model for interstitial transport, we determined both microvessel solute permeability (P) and solute tissue diffusion coefficient (Dt) of α-lactalbumin (Stokes radius 2.01nm) from the rate of tissue solute accumulation and the radial concentration gradient around individually perfused microvessel in frog mesentery. Pα‐lactalbumin is 1.7±0.7(SD)×10−6cm∕s(n=6). Dt∕Dfree for α-lactalbumin is 27%±5%(SD)(n=6). This value of Dt∕Dfree is comparable to that for small solute sodium fluorescein (Stokes radius 0.45nm), while Pα‐lactalbumin is only 3.4% of Psodiumfluorescein. Our results suggest that frog mesenteric tissue is much less selective to solutes than the microvessel wall.
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Fu, Bingmei M., and Shang Shen. "Structural mechanisms of acute VEGF effect on microvessel permeability." American Journal of Physiology-Heart and Circulatory Physiology 284, no. 6 (June 1, 2003): H2124—H2135. http://dx.doi.org/10.1152/ajpheart.00894.2002.
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To investigate the ultrastructural mechanisms of acute microvessel hyperpermeability by vascular endothelial growth factor (VEGF), we combined a mathematical model ( J Biomech Eng 116: 502–513, 1994) with experimental data of the effect of VEGF on microvessel hydraulic conductivity ( L p) and permeability of various-sized solutes. We examined the effect of VEGF on microvessel permeability to a small solute (sodium fluorescein, Stokes radius 0.45 nm), an intermediate solute (α-lactalbumin, Stokes radius 2.01 nm), and a large solute [albumin (BSA), Stokes radius 3.5 nm]. Exposure to 1 nM VEGF transiently increased apparent permeability to 2.3, 3.3, and 6.2 times their baseline values for sodium fluorescein, α-lactalbumin, and BSA, respectively, within 30 s, and all returned to control within 2 min. On the basis of L p (DO Bates and FE Curry. Am J Physiol Heart Circ Physiol 271: H2520–H2528, 1996) and permeability data, the prediction from the model suggested that the most likely structural changes in the interendothelial cleft induced by VEGF would be a ∼2.5-fold increase in its opening width and partial degradation of the surface glycocalyx.
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Niles, W. D., F. S. Cohen, and A. Finkelstein. "Hydrostatic pressures developed by osmotically swelling vesicles bound to planar membranes." Journal of General Physiology 93, no. 2 (February 1, 1989): 211–44. http://dx.doi.org/10.1085/jgp.93.2.211.
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When phospholipid vesicles bound to a planar membrane are osmotically swollen, they develop a hydrostatic pressure (delta P) and fuse with the membrane. We have calculated the steady-state delta P, from the equations of irreversible thermodynamics governing water and solute flows, for two general methods of osmotic swelling. In the first method, vesicles are swollen by adding a solute to the vesicle-containing compartment to make it hyperosmotic. delta P is determined by the vesicle membrane's permeabilities to solute and water. If the vesicle membrane is devoid of open channels, then delta P is zero. When the vesicle membrane contains open channels, then delta P peaks at a channel density unique to the solute permeability properties of both the channel and the membrane. The solute enters the vesicle through the channels but leaks out through the region of vesicle-planar membrane contact. delta P is largest for channels having high permeabilities to the solute and for solutes with low membrane permeabilities in the contact region. The model predicts the following order of solutes producing pressures of decreasing magnitude: KCl greater than urea greater than formamide greater than or equal to ethylene glycol. Differences between osmoticants quantitatively depend on the solute permeability of the channel and the density of channels in the vesicle membrane. The order of effectiveness is the same as that experimentally observed for solutes promoting fusion. Therefore, delta P drives fusion. When channels with small permeabilities are used, coupling between solute and water flows within the channel has a significant effect on delta P. In the second method, an impermeant solute bathing the vesicles is isosmotically replaced by a solute which permeates the channels in the vesicle membrane. delta P resulting from this method is much less sensitive to the permeabilities of the channel and membrane to the solute. delta P approaches the theoretical limit set by the concentration of the impermeant solute.
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Mullen, T. L., M. Muller, and J. T. Van Bruggen. "Role of solute drag in intestinal transport." Journal of General Physiology 85, no. 3 (March 1, 1985): 347–63. http://dx.doi.org/10.1085/jgp.85.3.347.
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This study presents experiments related to the role of solvent drag and solute drag in the transmembrane movement of nonelectrolytes in a perfused rat intestine preparation. Conditions were chosen to simulate the effects of luminal hyperosmolarity on the permeability of tracer solutes. Data are presented on net water flux, transepithelial potentials, and lumen-to-blood and blood-to-lumen tracer solute movements during control electrolyte perfusion and after making the perfusate hyperosmotic. The results indicate that both solvent drag and solute drag can play significant roles in the transepithelial movement of solute and solute permeabilities in the rat ileum preparation. It is suggested that the potential roles of solvent drag and solute drag should be accounted for or considered during the characterization of the mechanisms of biological membrane function.
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Varunkumar, M., and P. Muthu. "Fluid Flow and Solute Transfer in a Tube with Variable Wall Permeability." Zeitschrift für Naturforschung A 74, no. 12 (December 18, 2019): 1057–67. http://dx.doi.org/10.1515/zna-2019-0071.
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AbstractWe considered a steady flow of viscous incompressible fluid and solute transfer in an axisymmetric tube of uniform cross section with variable wall permeability, which is relevant to the study of movement of solute across the glomerular capillaries. The solutions for the nonlinear governing equations of the fluid flow and solute transfer are obtained by analytical/numerical methods. The combined effect of variable wall permeability and flow parameters on the hydrostatic pressure, osmotic pressure, velocity profiles, concentration profiles, and the total solute clearance are investigated and are presented in this paper. It is found that an increase in the variable permeability parameter increases the solute concentration at the wall.
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Antonenkov, Vasily D., and J. Kalervo Hiltunen. "Peroxisomal membrane permeability and solute transfer." Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 1763, no. 12 (December 2006): 1697–706. http://dx.doi.org/10.1016/j.bbamcr.2006.08.044.
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Zaheer, Muhammad, Hadayat Ullah, Saad Ahmed Mashwani, Ehsan ul Haq, Syed Husnain Ali Shah, and Fawaz Manzoor. "SOLUTE TRANSPORT MODELLING IN LOW-PERMEABILITY HOMOGENEOUS AND SATURATED SOIL MEDIA." Rudarsko-geološko-naftni zbornik 36, no. 2 (2021): 25–32. http://dx.doi.org/10.17794/rgn.2021.2.3.
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Fickian and non-Fickian behaviors were often detected for contaminant transport activity owed to the preferential flow and heterogeneity of soil media. Therefore, using diverse methods to measure such composite solute transport in soil media has become an important research topic for solute transport modeling in soil media. In this article, the continuous-time random walk (CTRW) model was applied to illustrate the relative concentration of transport in low-permeability homogeneous and saturated soil media. The solute transport development was also demonstrated with the convection-dispersion equation (CDE) and Two Region Model (TRM) for comparison. CXTFIT 2.1 software was used for CDE and TRM, and CTRW Matlab Toolbox v.3.1 for the CTRW simulation of the breakthrough curve. It was found that higher values of determination coefficient (R2) and lower values of root mean square error (RMSE) concerning the best fits of CDE, TRM, and CTRW. It was found that in the comparison of CDE, TRM, and CTRW, we tend to use CTRW to describe the transport behavior well because there are prevailing Fickian and non-Fickian transport. The CTRW gives better fitting results to the breakthrough curves (BTCs) when β has an increasing pattern towards 2.00. In this study, the variation of parameters in three methods was investigated and results showed that the CTRW modeling approach is more effective to determine non-reactive contaminants concentration in low-permeability soil media at small depths.
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Kevil, Christopher G., Tadayuki Oshima, Brett Alexander, Laura L. Coe, and J. Steven Alexander. "H2O2-mediated permeability: role of MAPK and occludin." American Journal of Physiology-Cell Physiology 279, no. 1 (July 1, 2000): C21—C30. http://dx.doi.org/10.1152/ajpcell.2000.279.1.c21.
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H2O2-mediated elevation in endothelial solute permeability is associated with pathological events such as ischemia-reperfusion and inflammation. To understand how H2O2mediates increased permeability, we investigated the effects of H2O2administration on vascular endothelial barrier properties and tight junction organization and function. We report that H2O2exposure caused an increase in endothelial solute permeability in a time-dependent manner through extracellularly regulated kinase 1 and 2 (ERK1/ERK2) signal pathways. H2O2exposure caused the tight junctional protein occludin to be rearranged from endothelial cell-cell junctions. Occludin rearrangement involved redistribution of occludin on the cell surface and dissociation of occludin from ZO-1. Occludin also was heavily phosphorylated on serine residues upon H2O2administration. H2O2mediates changes in ERK1/ERK2 phosphorylation, increases endothelial solute permeability, and alters occludin localization and phosphorylation were all blocked by PD-98059, a specific mitogen-activated protein (MAP) or ERK kinase 1 inhibitor. These data strongly suggest that H2O2-mediated increased endothelial solute permeability involves the loss of endothelial tight junction integrity through increased ERK1/ERK2 activation.
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VILHELMSSON, ODDUR, and KAREN J. MILLER. "Humectant Permeability Influences Growth and Compatible Solute Uptake by Staphylococcus aureus Subjected to Osmotic Stress." Journal of Food Protection 65, no. 6 (June 1, 2002): 1008–15. http://dx.doi.org/10.4315/0362-028x-65.6.1008.
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The effects of different humectants (sodium chloride, sucrose, and glycerol) on the growth of and compatible solute (glycine betaine, proline, and carnitine) uptake by the osmotolerant foodborne pathogen Staphylococcus aureus were investigated. While growth in the presence of the impermeant humectants sodium chloride and sucrose induced the accumulation of proline and glycine betaine by cells, growth in the presence of the permeant humectant glycerol did not. When compatible solutes were omitted from low-water-activity media, growth was very poor in the presence of impermeant humectants. In contrast, the addition of compatible solutes had essentially no effect on growth when cells were grown in low-water-activity media containing glycerol as the humectant. Carnitine was found to accumulate to high intracellular levels in osmotically stressed cells when proline and glycine betaine were absent, making it a potentially important compatible solute for this organism.
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Fu, B. M., R. H. Adamson, and F. E. Curry. "Test of a two-pathway model for small-solute exchange across the capillary wall." American Journal of Physiology-Heart and Circulatory Physiology 274, no. 6 (June 1, 1998): H2062—H2073. http://dx.doi.org/10.1152/ajpheart.1998.274.6.h2062.
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We previously proposed a two-pathway model for solute and water transport across vascular endothelium (Fu, B. M., R. Tsay, F. E. Curry, and S. Weinbaum. J. Biomech. Eng. 116: 502–513, 1994) that hypothesized the existence of a continuous slit 2 nm wide along tight junction strands within the interendothelial cleft in parallel with 20 × 150-nm breaks in tight junctions. We tested this model by measuring capillary permeability coefficients ( P) to a small solute (sodium fluorescein, radius 0.45 nm), assumed to permeate primarily the 2-nm small pore, and an intermediate-sized solute (FITC-α-lactalbumin, radius 2.01 nm) excluded from the small pore. Mean values of the paired diffusive permeability coefficients, P sodium fluorescein and P FITC-α-lactalbumin, were 34.4 and 2.9 × 10−6 cm/s, respectively, after corrections for solvent drag and free dye ( n = 26). These permeabilities were accounted for by transport through the large-break pathway without the additional capacity of the hypothetical 2-nm pathway. As a further test we examined the relative reductions of P sodium fluorescein and P FITC-α-lactalbuminproduced by elevated intracellular cAMP. Within 20 min after the introduction of rolipram and forskolin, P sodium fluorescein and P FITC-α-lactalbumindecreased to 0.67 and 0.64 times their respective baseline values. These similar responses to permeability decrease were evidence that the two solutes were carried by a common pathway. Combined results in both control and reduced permeability states did not support the hypothesis that a separate pathway across tight junctions is available for solutes with a radius as large as 0.75 nm. If such a pathway is present, then its size must be smaller than that of sodium fluorescein.
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Kodešová, R., J. Kozák, J. Šimůnek, and O. Vacek. "Single and dual-permeability models of chlorotoluron transport in the soil profile." Plant, Soil and Environment 51, No, 7 (November 19, 2011): 310–15. http://dx.doi.org/10.17221/3591-pse.
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This study presents the transport of chlorotoluron in the soil profile under field conditions. The herbicide Syncuran was applied on a plot (4 m˛) using an application rate of 2.5 kg/ha of active ingredient. Soil samples were taken after 119 days to study the residual chlorotoluron distribution in the soil profile. The single and dual-permeability models in HYDRUS-1D (Šimůnek et al. 2003) were used to simulate water movement and herbicide transport in the soil profile. Soil hydraulic properties and their variability were previously studied by Kutílek et al. (1989). The solute transport parameters, such as the adsorption isotherm and the degradation rate, were determined in the laboratory. Since the solute transport in the field was probably affected by preferential flow, the chlorotoluron distribution in the soil profile calculated using the single-permeability model had a different character than observed chlorotoluron concentrations. The chlorotoluron distribution within depth calculated using the dual-permeability model was closer to the observed behavior of chlorotoluron. While the herbicide did not reach a depth of 8 cm for the single-porosity system, in the case of the dual-permeability model the solute moved to the depth of 60 cm. The dual-permeability model significantly improved correspondence between calculated and observed herbicide concentrations.
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Hempling, H. G. "Osmotic properties of cells: a computer laboratory." Advances in Physiology Education 261, no. 6 (December 1991): S17. http://dx.doi.org/10.1152/advances.1991.261.6.s17.
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A computer laboratory has been designed to teach the osmotic properties of cells. One program, CELL.BA, is for the teacher to enter values for the volume of cell water and osmotically inactive material, the concentration of impermeant solute in the cell, and the permeability of the plasma membrane to water and a nonelectrolyte. When the program is protected, students use it as a cell with unknown osmotic properties. They run experiments on the computer with different concentrations of impermeant or permeant solutes or combinations of the two. Changes in cell volume or solute concentration are collected as data and analyzed with the program, PERMEABILITY LAB.BA. This program provides a parameter list, and students try to fit the data that are graphed on the screen by choosing values for the unknown cell parameters and generating model curves. Programs are written for the Macintosh computer.
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Williams, J. C., and J. A. Schafer. "Cortical interstitium as a site for solute polarization during tubular absorption." American Journal of Physiology-Renal Physiology 254, no. 6 (June 1, 1988): F813—F823. http://dx.doi.org/10.1152/ajprenal.1988.254.6.f813.
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The possibility that significant concentration differences could exist between the interstitial fluid and capillary plasma was investigated by modeling the renal cortex as the following three compartments: tubular lumen, interstitium, and capillary lumen. A simple analysis of this system suggests that for the interstitium surrounding a proximal tubule, the concentration in the interstitium of a solute like glucose could be well over 1 mM greater than in the peritubular capillary if the solute permeability of the peritubular capillary were like that measured in other organs (i.e., less than 10 micron/s). The effect of varying capillary permeability on the interstitial concentrations of several solutes was examined using a modification of a model of the proximal tubule, and results were found to be similar to those obtained with the simpler analysis for glucose. This model was also used to see if placing an osmotic difference between the tubule lumen and capillary could cause significant solute polarization within the interstitium, as might occur in an experiment to measure the osmotic water permeability (Pf) of the proximal tubule in vivo. The results show that an apparent Pf calculated from the difference between the osmolalities of tubular perfusate and peritubular plasma is likely to underestimate the true Pf of the proximal tubule. Even for a high value of capillary permeability (10 micron/s, which allows relatively rapid diffusion between capillary and interstitium), the model predicts that the apparent Pf may underestimate the true value by half. Thus the analyses presented suggest that if the permeability of renal peritubular capillaries is similar to that measured in other organs the composition of the interstitium may be significantly different from capillary plasma, a situation that would have great impact on our view of the mechanism of volume absorption in the proximal tubule in vivo.
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Barrowcliffe, M. P., and J. G. Jones. "Solute permeability of the alveolar capillary barrier." Thorax 42, no. 1 (January 1, 1987): 1–10. http://dx.doi.org/10.1136/thx.42.1.1.
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Lopes, Gustavo H., Nelson Ibaseta, Pierrette Guichardon, and Pierre Haldenwang. "Effects of Solute Permeability on Permeation and Solute Rejection in Membrane Filtration." Chemical Engineering & Technology 41, no. 4 (February 20, 2018): 788–97. http://dx.doi.org/10.1002/ceat.201700203.
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Schaeffer, R. C., F. Gong, M. S. Bitrick, and T. L. Smith. "Thrombin and bradykinin initiate discrete endothelial solute permeability mechanisms." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 6 (June 1, 1993): H1798—H1809. http://dx.doi.org/10.1152/ajpheart.1993.264.6.h1798.
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This study documents the discrete solute permeability mechanisms associated with physiologically high concentrations of human alpha-thrombin and bradykinin stimulation of bovine pulmonary artery endothelial cell (BPAEC) monolayers using fluorescein isothiocyanate-hydroxyethyl starch macromolecules. Agonist-induced alterations of intracellular free calcium ([Ca2+]i) using fura-2 acetoxymethyl ester were also measured. BPAEC monolayers showed restricted diffusion consistent with a small-pore (approximately 150 A) radius under baseline conditions. Thrombin produced a major increase in monolayer permeability that was greatest for solute molecular radii (ae) > 100 A. This effect was associated with the exposure of the large (approximately 2,000 A) pores of the filter support by 50- to 1,050-microns2 open areas between approximately 0.5% of the adjacent endothelial cells. This heterogeneous endothelial barrier of parallel large- and small-pore transport pathways permitted solute convection with free diffusion across a few large pores to dominate the restricted diffusion of most apparently unperturbed endothelial junctions. Bradykinin produced a small, transient elevation in monolayer permeability to ae < 35 A, consistent with an increase in the number of small pores or a decrease in path length of this transport pathway. The bradykinin- and thrombin-induced peak elevations in [Ca2+]i were inversely associated with the degree of increased monolayer solute permeability, and enzymatically inhibited thrombin produced none of these effects. These data show that bradykinin and human alpha-thrombin represent two distinct classes of endothelial cell agonists that initiate discrete solute permeability mechanisms.
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Chinard, F. P. "Quantitative assessment of epithelial lining fluid in the lung." American Journal of Physiology-Lung Cellular and Molecular Physiology 263, no. 6 (December 1, 1992): L617—L618. http://dx.doi.org/10.1152/ajplung.1992.263.6.l617.
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Current techniques for the measurement lung epithelial fluid (ELF) volume depend on the dilution by a known volume of wash fluid (bronchoalveolar lavage) of a resident solute, such as urea, in the ELF or of a foreign solute introduced at known concentration in the lavage fluid. Knowledge of the ELF volume allows calculation of solute ELF concentrations. Urea concentration in ELF is assumed to be the same as in plasma. Although epithelial permeability to urea is low, entry of urea from tissues to lavage fluid occurs during the procedure and may lead to erroneous estimates of ELF volume as may loss of foreign solutes. Ideally, the extent of urea entry or of foreign solute loss should be estimated in each lavage. Other cautions are 1) equal osmolality of wash fluid and plasma, 2) minimizing residence time of wash fluid, 3) minimizing wash fluid-to-ELF volume ratio, and 4) adequate analytic procedures.
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BUCK, KRISTAN K. S., STEPHANIE R. DUNGAN, and RONALD J. PHILLIPS. "The effect of solute concentration on hindered gradient diffusion in polymeric gels." Journal of Fluid Mechanics 396 (October 10, 1999): 287–317. http://dx.doi.org/10.1017/s0022112099006035.
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The effect of solute concentration on hindered diffusion of sphere-like colloidal solutes in stiff polymer hydrogels is examined theoretically and experimentally. In the theoretical development, it is shown that the presence of the gel fibres enhances the effect of concentration on the thermodynamic driving force for gradient diffusion, while simultaneously reducing the effect of concentration on the hydrodynamic drag. The result is that gradient diffusion depends more strongly on solute concentration in gels than it does in pure solution, by an amount that depends on the partition coefficient and hydraulic permeability of the gel–solute system. Quantitative calculations are made to determine the concentration-dependent diffusivity correct to first order in solute concentration. In order to compare the theoretical predictions with experimental data, rates of diffusion have been measured for nonionic micelles and globular proteins in solution and agarose hydrogels at two gel concentrations. The measurements were performed by using holographic interferometry, through which one monitors changes in refractive index as gradient diffusion takes place within a transparent gel. If the solutes are modelled as spheres with short-range repulsive interactions, then the experimentally measured concentration dependence of the diffusivities of both the protein and micelles is in good agreement with the theoretical predictions.
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Khuzhayorov, Bakhtiyor, Azizbek Usmonov, N. M. A. Nik Long, and Bekzodjon Fayziev. "Anomalous Solute Transport in a Cylindrical Two-Zone Medium with Fractal Structure." Applied Sciences 10, no. 15 (August 3, 2020): 5349. http://dx.doi.org/10.3390/app10155349.
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In this paper, a problem of anomalous solute transport in a coaxial cylindrical two-zone porous medium with fractal structure is posed and numerically solved. The porous medium is studied in the form of cylinder with two parts: macropore—with high permeability characteristics in the central part and micropore—with low permeability around it. Anomalous solute transport is modeled by differential equations with a fractional derivative. The solute concentration and pressure fields are determined. Based on numerical results, the influence of the fractional derivatives order on the solute transport process is analysed. It was shown that with a decrease in the order of the derivatives in the diffusion term of the transport equation in the macropore leads to a “fast diffusion” in both zones. Characteristics of the solute transport in both zones mainly depend on the concentration distribution and other hydrodynamic parameters in the macropore.
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Clark, MR, and ME Rossi. "Permeability characteristics of deoxygenated sickle cells." Blood 76, no. 10 (November 15, 1990): 2139–45. http://dx.doi.org/10.1182/blood.v76.10.2139.2139.
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Abstract This study investigated the effect of acute deoxygenation on membrane permeability characteristics of sickle cells. Measured fluxes of Na+ and K+ in ouabain-inhibited cells, of chloride and sulfate exchange in 4,4′-diisothiocyanostilbene-2,2′-disulfonate (DIDS)-inhibited and untreated cells, and of erythritol, mannitol, and arabinose in cytochalasin B-inhibited cells indicated that a deoxygenation-induced permeability change occurred in sickle cells only for cations and chloride. Monovalent cation permeabilities increased five-fold, and chloride influx into DIDS treated cells was enhanced nearly threefold on sickle cell deoxygenation. In contrast, no detectable increase in permeability to the other solutes was found. To gain perspective on these findings, similar measurements were performed in normal cells treated with diamide, an agent shown by others to induce a coupled increase in membrane permeability and phospholipid translocation, reminiscent of deoxygenation-induced changes in sickle cells. Although the increase in cation permeability was no greater than that in sickled cells, treatment with 2 mmol/L diamide also produced a twofold increase in the first order rate constants for sulfate exchange and mannitol efflux, indicating a relatively nonselective permeability increase that permitted flux of larger solutes than in the case of deoxygenated sickle cells. These results suggest that the deoxygenation of sickle cells induces a permeability increase that is relatively insensitive to charge, but is restrictive with respect to solute size.
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Clark, MR, and ME Rossi. "Permeability characteristics of deoxygenated sickle cells." Blood 76, no. 10 (November 15, 1990): 2139–45. http://dx.doi.org/10.1182/blood.v76.10.2139.bloodjournal76102139.
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This study investigated the effect of acute deoxygenation on membrane permeability characteristics of sickle cells. Measured fluxes of Na+ and K+ in ouabain-inhibited cells, of chloride and sulfate exchange in 4,4′-diisothiocyanostilbene-2,2′-disulfonate (DIDS)-inhibited and untreated cells, and of erythritol, mannitol, and arabinose in cytochalasin B-inhibited cells indicated that a deoxygenation-induced permeability change occurred in sickle cells only for cations and chloride. Monovalent cation permeabilities increased five-fold, and chloride influx into DIDS treated cells was enhanced nearly threefold on sickle cell deoxygenation. In contrast, no detectable increase in permeability to the other solutes was found. To gain perspective on these findings, similar measurements were performed in normal cells treated with diamide, an agent shown by others to induce a coupled increase in membrane permeability and phospholipid translocation, reminiscent of deoxygenation-induced changes in sickle cells. Although the increase in cation permeability was no greater than that in sickled cells, treatment with 2 mmol/L diamide also produced a twofold increase in the first order rate constants for sulfate exchange and mannitol efflux, indicating a relatively nonselective permeability increase that permitted flux of larger solutes than in the case of deoxygenated sickle cells. These results suggest that the deoxygenation of sickle cells induces a permeability increase that is relatively insensitive to charge, but is restrictive with respect to solute size.
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Yan, Min, Chunhui Lu, Jie Yang, Yifan Xie, and Jian Luo. "Impact of Low- or High-Permeability Inclusion on Free Convection in a Porous Medium." Geofluids 2019 (November 26, 2019): 1–11. http://dx.doi.org/10.1155/2019/8609682.
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Density-driven free convection in porous media is highly affected by large-scale heterogeneity, typical of which are low- or high-permeability inclusions imbedded in homogeneous porous media. In this research, we applied the modified Elder problem to investigate the impact of low- or high-permeability inclusions on the migration of a dense, unstable salt plume. Sensitivity analyses were conducted in terms of the permeability contrast, the effective area (the area of the inclusion beneath the source zone), and the distance of the inclusion from the source zone, all of which were found to play a significant role in controlling the total mass flux released from the source into the media. Results show that (1) a high-permeability inclusion has stronger effects than low-permeability inclusion, due to significantly unbalanced solute distributions caused by accelerated solute transport, (2) the inclusion with a larger effective area has more potential to influence free convection, (3) free convection is more sensitive to the low-/high-permeability inclusion vertically closer to the source zone, and (4) free convection is more susceptible to the low-permeability inclusion horizontally closer to the source zone. For high-permeability inclusions, the inclusion horizontally closer to the source zone influences the transport process more significantly at the early stage, and conversely, the inclusion far from the source zone has a later impact. The results obtained could offer significant implications for understanding unstable density-driven flow and solute transport in porous media with structured heterogeneity.
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Curry, F. E., J. C. Rutledge, and J. F. Lenz. "Modulation of microvessel wall charge by plasma glycoprotein orosomucoid." American Journal of Physiology-Heart and Circulatory Physiology 257, no. 5 (November 1, 1989): H1354—H1359. http://dx.doi.org/10.1152/ajpheart.1989.257.5.h1354.
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Haraldsson and Rippe suggested that the circulating glycoprotein orosomucoid (alpha 1-acid glycoprotein) contributes to the net charge on microvessel walls (Acta Physiol. Scand. 129: 127-135, 1987). We tested their hypothesis in individually perfused microvessels of frog mesentery by measuring solute permeability coefficients of two globular proteins (alpha-lactalbumin and ribonuclease) having approximately the same size (Stokes radius, 2 nm) but different charge (-11 and +3, respectively). In vessels perfused with orosomucoid (0.1 and 1 mg/ml) in a Ringer-albumin perfusate, the solute permeability coefficient of alpha-lactalbumin decreased to one-half [0.47 +/- 0.25 (SD)] the value in the absence of orosomucoid, and the solute permeability coefficient of ribonuclease was close to six times as large as alpha-lactalbumin permeability. Both results may be accounted for if orosomucoid increases the net negative charge on microvessel walls in frog mesentery from 11.2 to 28 meq/l. A similar change in microvessel charge would be more than sufficient to account for the decrease in albumin clearance in the presence of orosomucoid reported by Haraldsson and Rippe in rat muscle microvessels.
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Anderson, Bradley D., and Prakash V. Raykar. "Solute Structure-Permeability Relationships in Human Stratum Corneum." Journal of Investigative Dermatology 93, no. 2 (August 1989): 280–86. http://dx.doi.org/10.1111/1523-1747.ep12277592.
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Tan, Huanshu, Anirudha Banerjee, Nan Shi, Xiaoyu Tang, Amr Abdel-Fattah, and Todd M. Squires. "A two-step strategy for delivering particles to targets hidden within microfabricated porous media." Science Advances 7, no. 33 (August 2021): eabh0638. http://dx.doi.org/10.1126/sciadv.abh0638.
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The delivery of small particles into porous environments remains highly challenging because of the low permeability to the fluids that carry these colloids. Even more challenging is that the specific location of targets in the porous environment usually is not known and cannot be determined from the outside. Here, we demonstrate a two-step strategy to deliver suspended colloids to targets that are “hidden” within closed porous media. The first step serves to automatically convert any hidden targets into soluto-inertial “beacons,” capable of sustaining long-lived solute outfluxes. The second step introduces the deliverable objects, which are designed to autonomously migrate against the solute fluxes emitted by the targets, thereby following chemical trails that lead to the target. Experimental and theoretical demonstrations of the strategy lay out the design elements required for the solute and the deliverable objects, suggesting routes to delivering colloidal objects to hidden targets in various environments and technologies.
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Iveson, G. P., S. J. Bird, and J. B. Lloyd. "Passive diffusion of non-electrolytes across the lysosome membrane." Biochemical Journal 261, no. 2 (July 15, 1989): 451–56. http://dx.doi.org/10.1042/bj2610451.
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An osmotic-protection method has been used to study the permeability of rat liver lysosomes to 43 organic non-electrolytes of formula weights ranging from 62 to 1000. A lysosome-rich centrifugal fraction of rat liver homogenate was resuspended in an unbuffered 0.25 M solution of test solute, pH 7.0, and incubated at 25 degrees C for 60 min. The free and total activities of 4-methylumbelliferyl N-acetyl-beta-D-glucosaminidase were measured after incubation for 0, 30 and 60 min. Three patterns of results were seen. In pattern A the percentage free activity remained low throughout the 60 min incubation, indicating little or no solute entry into the lysosomes. In pattern B, the percentage free activity was initially low, but rose substantially during the incubation, indicating solute entry. In pattern C there was not even initial osmotic protection, indicating very rapid solute entry. The rapidity of solute entry into the lysosomes showed no correlation with the formula weight, but a perfect inverse correlation with the hydrogen-bonding capacity of the solutes. The results, which can be used to predict the ability of further compounds to cross the lysosome membrane by unassisted diffusion, are discussed in the context of metabolite and drug release from lysosomes in vivo.
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MASON, G. R., A. M. PETERS, E. BAGDADES, M. J. MYERS, D. SNOOK, and J. M. B. HUGHES. "Evaluation of pulmonary alveolar epithelial integrity by the detection of restriction to diffusion of hydrophilic solutes of different molecular sizes." Clinical Science 100, no. 3 (January 25, 2001): 231–36. http://dx.doi.org/10.1042/cs1000231.
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The rate of transfer of a hydrophilic solute from the alveoli to pulmonary blood following inhalation as an aerosol depends on the molecular size of the solute and the permeability of the alveolar epithelium. The value of this measurement for assessing damage to the epithelium in lung disease is compromised by cigarette smoking, which accelerates clearance by unknown mechanisms. The rates of clearance of 99mTc-labelled diethylenetriaminepenta-acetic acid (DTPA) (molecular mass 492 Da) and 113mIn-labelled biotinylated DTPA (B-DTPA) (molecular mass 1215 Da) were monitored simultaneously by dynamic γ-radiation camera imaging following simultaneous inhalation, and compared between eight normal non-smoking subjects and nine habitual cigarette smokers. The clearance rates of DTPA were 0.95 (S.D. 0.39)%/min in non-smokers and 4.13 (1.06) %/min in smokers. These were about twice the clearance rates of B-DTPA, which in the corresponding groups were 0.41 (0.26) and 2.12 (0.72)%/min respectively. The ratio of the B-DTPA/DTPA clearance rates was, in all subjects, less than the ratio (0.74) of the cube roots of the molecular masses of the solutes, assumed to correspond to the ratio of their free diffusion coefficients in water, and was not significantly different between smokers and non-smokers. As alveolar permeability increased, the ratio of clearance rates in the entire population showed a significant trend to increase in a non-linear fashion towards the value corresponding to the ratio of the free diffusion coefficients. We conclude that the diffusion of at least the larger of these two solutes through the pulmonary alveolar epithelium is restricted (i.e. associated with a reflection coefficient greater than zero). Cigarette smoking, however, does not appear to cause a loss of this restriction, and may increase solute clearance by other mechanisms, such as reducing fluid volume within the alveolus, thereby raising the local radiotracer concentration, or increasing the number of pores available for solute exchange without affecting pore size. Conversely, if restriction was lost in lung disease, the ratio of the clearance rates of two solutes of dissimilar sizes could be used to detect disease in smokers as well as non-smokers.
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Rivers, R. L., J. A. McAteer, J. L. Clendenon, B. A. Connors, A. P. Evan, and J. C. Williams. "Apical membrane permeability of MDCK cells." American Journal of Physiology-Cell Physiology 271, no. 1 (July 1, 1996): C226—C234. http://dx.doi.org/10.1152/ajpcell.1996.271.1.c226.
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The osmotic water permeability (Pf) and permeability to nonelectrolytes were determined for the apical membrane of clonal strain Madin-Darby canine kidney (MDCK) C12 cells cultured as cysts with the apical membrane facing the surrounding medium. Pf and solute permeabilities were calculated from the rate of volume change of cysts by digitizing images at 1-s intervals after instantaneous osmotic challenge. Image measurement was fully automated with the use of a program that separated the image of the cyst from the background by using adaptive intensity thresholding and shape analysis. Pf, calculated by curve fitting to the volume loss data, averaged 2.4 +/- 0.1 micron/s and was increased by addition of amphotericin B. The energy of activation for Pf was high (16.3 kcal/mol), and forskolin (50 microM) had no effect on Pf. Two populations of MDCK cysts were studied: those with two to three cells and those that appeared to be composed of only one cell. The Pf of multicell cysts was the same as single cell cysts, suggesting that paracellular water flow is not significant. Solute permeability was measured using paired osmotic challenges (sucrose and test solute) on the same cyst. Urea permeability was not different from zero, whereas the permeabilities of acetamide and formamide were consistent with their relative oil-water partition coefficients. Our data are similar to values from studies on the permeability properties of vesicles of water-tight epithelial apical membrane. The combination of the unique model of MDCK apical-out cysts and fully automated data analysis enabled determination of apical membrane permeability in intact epithelial cells with high precision.
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Pallone, T. L., S. Nielsen, E. P. Silldorff, and S. Yang. "Diffusive transport of solute in the rat medullary microcirculation." American Journal of Physiology-Renal Physiology 269, no. 1 (July 1, 1995): F55—F63. http://dx.doi.org/10.1152/ajprenal.1995.269.1.f55.
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Outer medullary descending vasa recta (OMDVR) permeability to sodium (PNa) is much lower than to urea (Purea). Based on these findings, we hypothesized that sodium and urea diffuse across the OMDFR wall by separate routes. To further test this, we simultaneously perfused OMDVR with 22Na and 36Cl, [14C]urea, [3H]raffinose, or tritiated water. The permeability of OMDVR to 22Na and [3H]raffinose was found to increase markedly and reversibly with perfusion rate. PNa was highly correlated with the permeability to Cl (PCl) and to [3H]raffinose (Praf) (R = 0.90 and 0.95, respectively) but not with Purea (R = 0.23). Praf was also correlated with inulin permeability (PIn) (R = 0.93). The intercepts for the regressions of PNa with PCl and Praf and for Praf with PIn were zero. In contrast, OMDVR with low PNa retained very high diffusional water permeability (PD) and Purea, a finding consistent with separate routes for permeation of those tracers. We previously established that thiourea is a competitive inhibitor of OMDVR urea transport. In the presence of 100 mM thiourea, OMDVR PNa and Purea were correlated (R = 0.71) but retained an intercept much > 0. We conclude that Na, Cl, raffinose, and inulin are likely to traverse the OMDVR wall through a common pathway, whereas specific mechanisms exist to regulate the permeation by urea and water.
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Kumar, Pardeep, and Hari Mohan. "Double-Diffusive Magneto Convection in a Compressible Couple-Stress Fluid Through Porous Medium." Zeitschrift für Naturforschung A 66, no. 5 (May 1, 2011): 304–10. http://dx.doi.org/10.1515/zna-2011-0506.
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The double-diffusive convection in a compressible couple-stress fluid layer heated and soluted from below through porous medium is considered in the presence of a uniform vertical magnetic field. Following the linearized stability theory and normal mode analysis, the dispersion relation is obtained. For stationary convection, the compressibility, stable solute gradient, magnetic field, and couple-stress postpone the onset of convection whereas medium permeability hastens the onset of convection. Graphs have been plotted by giving numerical values to the parameters to depict the stability characteristics. The stable solute gradient and magnetic field introduce oscillatory modes in the system, which were non-existent in their absence. A condition for the system to be stable is obtained by using the Rayleigh-Ritz inequality. The sufficient conditions for the non-existence of overstability are also obtained.
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Dou, Laetitia, Francine Anfosso, Florence Sabatier, Valérie Moal, Griet Glorieux, Rita De Smet, Raymond Vanholder, et al. "P-cresol, a uremic retention solute, alters the endothelial barrier function in vitro." Thrombosis and Haemostasis 92, no. 07 (2004): 140–50. http://dx.doi.org/10.1160/th03-07-0491.
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SummaryPatients with chronic renal failure (CRF) exhibit endothelial dysfunction, which may involve uremic retention solutes that accumulate in blood and tissues. In this study, we investigated the in vitro effect of the uremic retention solute p-cresol on the barrier function of endothelial cells (HUVEC). P-cresol was tested at concentrations found in CRF patients, and since p-cresol is protein-bound, experiments were performed with and without physiological concentration of human albumin (4 g/dl).With albumin, we showed that p-cresol caused a strong increase in endothelial permeability after a 24-hour exposure. Concomitant with this increase in endothelial permeability, p-cresol induced a reorganization of the actin cytoskeleton and an alteration of adherens junctions. These molecular events were demonstrated by the decreased staining of cortical actin, associated with the formation of stress fibers across the cell, and by the decreased staining of junctional VE-cadherin. This decrease in junctional VE-cadherin staining was not associated with a reduction of membrane expression. Without albumin, the effects of p-cresol were more pronounced. The specific Rho kinase inhibitor, Y-27632, inhibited the effects of p-cresol, indicating that p-cresol mediates the increase in endothelial permeability in a Rho kinase-dependent way. In conclusion, these results show that p-cresol causes a severe dysfunction of endothelial barrier function in vitro and suggest this uremic retention solute may participate in the endothelium dysfunction observed in CRF patients.
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Kanaporis, G., P. R. Brink, and V. Valiunas. "Gap junction permeability: selectivity for anionic and cationic probes." American Journal of Physiology-Cell Physiology 300, no. 3 (March 2011): C600—C609. http://dx.doi.org/10.1152/ajpcell.00316.2010.
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Gap junction channels formed by different connexins exhibit specific permeability to a variety of larger solutes including second messengers, polypeptides, and small interfering RNAs. Here, we report the permeability of homotypic connexin26 (Cx26), Cx40, Cx43, and Cx45 gap junction channels stably expressed in HeLa cells to solutes with different size and net charge. Channel permeability was determined using simultaneous measurements of junctional conductance and the cell-cell flux of a fluorescent probe. All four connexins allowed passage of both cationic and anionic probes, but the transfer rates were connexin dependent. The negatively charged probes [Lucifer yellow (LY; median axial diameter 9.9 Å, charge −2), carboxyfluorescein (CF; 8.2 Å; −2), and Alexa Fluor350 (AF350, 5.4 Å; −1)] exhibited the following permeability order: Cx43 > Cx45 > Cx26 > Cx40. In contrast, for the positively charged species permeability, the orders were as follows: Cx26 ≈ Cx43 ≈ Cx40 ≈ Cx45 for N, N, N-trimethyl-2-[methyl-(7-nitro-2,1,3-benzoxadiol-4-yl) amino] ethanaminium (NBD-m-TMA; 5.5 Å, +1) and Cx26 ≥ Cx43 ≈ Cx40 > Cx45 for ethidium bromide (10.3 Å, +1). Comparison of probe permeability relative to K+ revealed that Cx43 and Cx45 exhibited similar permeability for NBD-m-TMA and AF350, indicating weak charge selectivity. However, lesser transfer of CF and LY through Cx45 relative to Cx43 channels suggests stronger size-dependent discrimination of solute. The permeability of NBD-m-TMA for Cx40 and Cx26 channels was approximately three times higher than to anionic AF350 despite the fact that both have similar minor diameters, suggesting charge selectivity. In conclusion, these results confirm that channels formed from individual connexins can discriminate for solutes based on size and charge, suggesting that channel selectivity may be a key factor in cell signaling.
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Kevil, Christopher G., Naotsuka Okayama, and J. Steven Alexander. "H2O2-mediated permeability II: importance of tyrosine phosphatase and kinase activity." American Journal of Physiology-Cell Physiology 281, no. 6 (December 1, 2001): C1940—C1947. http://dx.doi.org/10.1152/ajpcell.2001.281.6.c1940.
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We previously reported that exposure of endothelial cells to H2O2results in a loss of cell-cell apposition and increased endothelial solute permeability. The purpose of this study was to determine how tyrosine phosphorylation and tyrosine phosphatases contribute to oxidant-mediated disorganization of endothelial cell junctions. We found that H2O2caused a rapid decrease in total cellular phosphatase activity that facilitates a compensatory increase in cellular phosphotyrosine residues. H2O2exposure also results in increased endothelial monolayer permeability, which was attenuated by pp60, an inhibitor of src kinase. Inhibition of protein tyrosine phosphatase activity by phenylarsine oxide (PAO) demonstrated a similar permeability profile compared with H2O2, suggesting that tyrosine phosphatase activity is important in maintaining a normal endothelial solute barrier. Immunofluorescence shows that H2O2exposure caused a loss of pan-reactive cadherin and β-catenin from cell junctions that was not blocked by the src kinase inhibitor PP1. H2O2also caused β-catenin to dissociate from the endothelial cytoskeleton, which was not prevented by PP1. Finally, we determined that PP1 did not prevent cadherin internalization. These data suggest that oxidants like H2O2produce biological effects through protein phosphotyrosine modifications by decreasing total cellular phosphatase activity combined with increased src kinase activity, resulting in increased endothelial solute permeability.
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Wangensteen, O. D., L. A. Schneider, S. C. Fahrenkrug, G. M. Brottman, and R. C. Maynard. "Tracheal epithelial permeability to nonelectrolytes: species differences." Journal of Applied Physiology 75, no. 2 (August 1, 1993): 1009–18. http://dx.doi.org/10.1152/jappl.1993.75.2.1009.
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We developed a new excised tracheal preparation to measure the epithelial permeability of large lipid-insoluble nonelectrolytes and macromolecules. Tracheae were suspended vertically in a Ringer solution bath, and a solution containing labeled test solutes was positioned in the center of the tracheal segment, away from damaged ends. Permeability coefficients, calculated from solute fluxes into the bath, were constant for > or = 2 h at 37 degrees C, and no histological changes were observed. Measurements after epithelial removal with detergent indicate that in the intact trachea the epithelium represents > 90% of the resistance to transport. For the rat trachea, permeability coefficients for sucrose, inulin, and Dextran 20 were 9.22, 2.20, and 0.214 x 10(-7) cm/s, respectively. Values for cat tracheae were similar, those for rabbit tracheae were lower, and those for guinea pig tracheae were markedly greater. With the assumption of transport by diffusion through thin rectangular slits between epithelial cells, the rat and guinea pig data fit a slit width of 7–8 nm, whereas the rabbit and cat data cannot be explained by a model with slits of a single size.
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Breborowicz, Andrzej, Malgorzata Pawlaczyk–Kuzlan, Krzysztof Pawlaczyk, Ewa Baum, Paul Tam, and George Wu. "Replacement of Glucose with N-Acetylglucosamine in Peritoneal Dialysis Fluid—Experimental Study in Rats." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 21, no. 3_suppl (December 2001): 365–67. http://dx.doi.org/10.1177/089686080102103s69.
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Background Glucose is still used as an osmotic solute in peritoneal dialysis fluids, despite evidence of its local (peritoneal) and systemic toxicities. However a constant search is underway for a new, more biocompatible osmotic solute for peritoneal dialysis fluids. Objective The present study evaluated N-acetylglucosamine (NAG) in a concentration of 220 mmol/ L as an alternative to glucose for the osmotic solute in peritoneal dialysis fluid, during chronic peritoneal dialysis in rats. Methods For 8 weeks, male Wistar rats were infused with glucose-based or NAG-based dialysis fluid. Intraperitoneal inflammation and peritoneal permeability and morphology were evaluated in all rats during the study. Results Repeated intraperitoneal infusion of the NAG-based dialysis fluid resulted in a weaker intra-abdominal inflammatory reaction as compared with the reaction in rats infused with glucose-based dialysis solution. At the end of the study, the concentration of hyaluronan in the peritoneal interstitium obtained from NAG-treated rats was higher than that found in the interstitium taken from animals exposed to dialysis fluid containing glucose. Also, peritoneal permeability to total protein was lower in NAG-treated rats. Conclusion As an alternative to glucose, NAG used for the osmotic solute in peritoneal dialysis solution decreases the intraperitoneal inflammatory reaction induced by the process of peritoneal dialysis and, indirectly (owing to the increased hyaluronan content in the peritoneal interstitium), diminishes peritoneal permeability to protein.
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Leypoldt, J. K., A. S. Chiu, R. P. Frigon, and L. W. Henderson. "Dialysate to blood transport of macromolecules during peritoneal dialysis." American Journal of Physiology-Heart and Circulatory Physiology 257, no. 6 (December 1, 1989): H1851—H1859. http://dx.doi.org/10.1152/ajpheart.1989.257.6.h1851.
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Asymmetrical transport of macromolecules between plasma and the peritoneal cavity results primarily from unidirectional lymphatic removal from the peritoneal cavity. Recent work suggests, however, that macromolecular transport across the peritoneal-plasma barrier via the capillary wall (i.e., the peritoneal membrane) may also be asymmetrical. We determined the diffusive and convective transport properties for creatinine, p-aminohippurate, and neutral dextran (13-40 A) across the peritoneal membrane in the dialysate to blood direction during peritoneal dialysis using isotonic and hypotonic solutions in awake New Zealand White rabbits. Values of the diffusive permeability-area product that were calculated during the isotonic exchange were similar to, yet somewhat smaller than, those previously determined in the blood to dialysate direction for all test solutes. Solute reflection coefficients that were calculated during the hypotonic exchange were variable, yet the resulting mean solute reflection coefficient values for all the test solutes were similar to those previously determined in the blood to dialysate direction. We conclude that asymmetrical peritoneal transport of macromolecules with radii less than 40 A is not due to asymmetrical transport across the peritoneal membrane.
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Krediet, Raymond T., Désirée Zemel, Alexander L. T. Imholz, and Dirk G. Struijk. "Impact of Surface Area and Permeability on Solute Clearances." Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis 14, no. 3_suppl (June 1994): 70–77. http://dx.doi.org/10.1177/089686089401403s14.
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Rashid, Md Harun-Or, Son Q. T. Pham, Luke J. Sweetman, Leighton J. Alcock, Anthony Wise, Long D. Nghiem, Gerry Triani, Marc in het Panhuis, and Stephen F. Ralph. "Synthesis, properties, water and solute permeability of MWNT buckypapers." Journal of Membrane Science 456 (April 2014): 175–84. http://dx.doi.org/10.1016/j.memsci.2014.01.026.
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Harte, Philip T., Leonard F. Konikow, and George Z. Hornberger. "Simulation of solute transport across low-permeability barrier walls." Journal of Contaminant Hydrology 85, no. 3-4 (May 2006): 247–70. http://dx.doi.org/10.1016/j.jconhyd.2006.02.012.
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Whitworth, T. M., and S. J. Fritz. "Electrolyte-induced solute permeability effects in compacted smectite membranes." Applied Geochemistry 9, no. 5 (September 1994): 533–46. http://dx.doi.org/10.1016/0883-2927(94)90015-9.
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Kumar, Pardeep. "Convection in Compressible Dusty Fluids." EQUATIONS 2 (July 1, 2022): 84–93. http://dx.doi.org/10.37394/232021.2022.2.14.
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The aim of the present research was to study the thermosolutal convection in compressible fluids with suspended particles in permeable media. Following the linearized stability theory, Boussinesq approximation and normal mode analysis, it is found that that stable solute gradient introduces oscillatory modes which were non-existent in its absence. For the case of stationary convection, it is found that medium permeability and suspended particles have destabilizing effects whereas the stable solute gradient has a stabilizing effect on the system. This problem was further extended to include uniform rotation. In this case for stationary convection, the suspended particles are found to have destabilizing effect whereas stable solute gradient, rotation and compressibility have stabilizing effect on the system. The medium permeability has a destabilizing effect in the absence of rotation but has both stabilizing and destabilizing effects in the presence of rotation.
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Van Itallie, Christina M., Alan S. Fanning, Arlene Bridges, and James M. Anderson. "ZO-1 Stabilizes the Tight Junction Solute Barrier through Coupling to the Perijunctional Cytoskeleton." Molecular Biology of the Cell 20, no. 17 (September 2009): 3930–40. http://dx.doi.org/10.1091/mbc.e09-04-0320.
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ZO-1 binds numerous transmembrane and cytoplasmic proteins and is required for assembly of both adherens and tight junctions, but its role in defining barrier properties of an established tight junction is unknown. We depleted ZO-1 in MDCK cells using siRNA methods and observed specific defects in the barrier for large solutes, even though flux through the small claudin pores was unaffected. This permeability increase was accompanied by morphological alterations and reorganization of apical actin and myosin. The permeability defect, and to a lesser extent morphological changes, could be rescued by reexpression of either full-length ZO-1 or an N-terminal construct containing the PDZ, SH3, and GUK domains. ZO-2 knockdown did not replicate either the permeability or morphological phenotypes seen in the ZO-1 knockdown, suggesting that ZO-1 and -2 are not functionally redundant for these functions. Wild-type and knockdown MDCK cells had differing physiological and morphological responses to pharmacologic interventions targeting myosin activity. Use of the ROCK inhibitor Y27632 or myosin inhibitor blebbistatin increased TER in wild-type cells, whereas ZO-1 knockdown monolayers were either unaffected or changed in the opposite direction; paracellular flux and myosin localization were also differentially affected. These studies are the first direct evidence that ZO-1 limits solute permeability in established tight junctions, perhaps by forming a stabilizing link between the barrier and perijunctional actomyosin.
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Nair, Remya, Evgenia Protasova, Skule Strand, and Torleiv Bilstad. "Implementation of Spiegler–Kedem and Steric Hindrance Pore Models for Analyzing Nanofiltration Membrane Performance for Smart Water Production." Membranes 8, no. 3 (September 6, 2018): 78. http://dx.doi.org/10.3390/membranes8030078.
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A predictive model correlating the parameters in the mass transfer-based model Spiegler–Kedem to the pure water permeability is presented in this research, which helps to select porous polyamide membranes for enhanced oil recovery (EOR) applications. Using the experimentally obtained values of flux and rejection, the reflection coefficient σ and solute permeability Ps have been estimated as the mass transfer-based model parameters for individual ions in seawater. The reflection coefficient and solute permeability determined were correlated with the pure water permeability of a membrane, which is related to the structural parameters of a membrane. The novelty of this research is the development of a model that consolidates the various complex mechanisms in the mass transfer of ions through the membrane to an empirical correlation for a given feed concentration and membrane type. These correlations were later used to predict ion rejections of any polyamide membrane with a known pure water permeability and flux with seawater as a feed that aids in the selection of suitable nanofiltration (NF) for smart water production.
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Huxley, V. H., F. E. Curry, M. R. Powers, and B. Thipakorn. "Differential action of plasma and albumin on transcapillary exchange of anionic solute." American Journal of Physiology-Heart and Circulatory Physiology 264, no. 5 (May 1, 1993): H1428—H1437. http://dx.doi.org/10.1152/ajpheart.1993.264.5.h1428.
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We tested two hypotheses to account for the reduction in coupling of anionic solute to water flow (solvent drag) in microvessels during perfusion with plasma compared with albumin. Solvent drag is determined by both hydraulic conductivity (Lp) and solute reflection coefficient (sigma). Accordingly, decreased solvent drag during plasma perfusion must be the result of an increase in sigma (hypothesis 1) or reduction of Lp (hypothesis 2) or some combination of both mechanisms. These hypotheses were assessed by measuring Lp, sigma, and diffusive solute permeability (Psd) to the anionic protein alpha-lactalbumin in frog mesenteric exchange microvessels during plasma or albumin perfusion. The solute permeability coefficient to alpha-lactalbumin (Ps alpha-lactalbumin) was lower during exposure to plasma than bovine serum albumin (BSA) [(Ps alpha-lactalbumin)plasma/(Ps alpha-lactalbumin)BSA = 0.31 +/- 0.11 (means +/- SE, n = 9)]. Solute reflection coefficient to alpha-lactalbumin (sigma alpha-lactalbumin) was 0.69 +/- 0.02 in plasma and 0.34 +/- 0.03 in BSA (n = 7). Lp was not significantly influenced by perfusate protein composition (Lp plasma/Lp BSA = 1.02 +/- 0.11; n = 20). These data lead to the conclusion that the actions of plasma are to confer charge selectivity for anionic solute and, to a lesser extent, modify the porous pathways of the microvessel wall. Taken together, these results indicate that porous pathways contribute significantly to macromolecular flux in plasma-perfused vessels.
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Kukučka, Miroslav, and Nikoleta Kukučka Stojanović. "Intrinsic Dependence of Groundwater Cation Hydraulic and Concentration Features on Negatively Charged Thin Composite Nanofiltration Membrane Rejection and Permeation Behavior." Membranes 12, no. 1 (January 10, 2022): 79. http://dx.doi.org/10.3390/membranes12010079.
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Commercial nanofiltration membranes of different molecular weight cut-offs were tested on a pilot plant for the exploration of permeation nature of Ca, Mg, Mn, Fe, Na and ammonium ions. Correlation of transmembrane pressure and rejection quotient versus volumetric flux efficiency on nanofiltration membrane rejection and permeability behavior toward hydrated divalent and monovalent ions separation from the natural groundwater was observed. Membrane ion rejection affinity (MIRA) dimension was established as normalized TMP with regard to permeate solute moiety representing pressure value necessary for solute rejection change of 1%. Ion rejection coefficient (IRC) was introduced to evaluate the membrane rejection capability, and to indicate the prevailed nanofiltration partitioning mechanism near the membrane surface. Positive values of the IRC indicated satisfactory rejection efficiency of the membrane process and its negative values ensigned very low rejection affinity and high permeability of the membranes for the individual solutes. The TMP quotient and the efficiency of rejection for individual cations showed upward and downward trends along with flux utilization increase. Nanofiltration process was observed as an equilibrium. The higher the Gibbs free energy was, cation rejection was more exothermic and valuably enlarged. Low Gibbs free energy values circumferentially closer to endothermic zone indicated expressed ions permeation.
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Okuno, Yota, Tomoki Nishimura, Yoshihiro Sasaki, and Kazunari Akiyoshi. "Thermoresponsive Carbohydrate-b-Polypeptoid Polymer Vesicles with Selective Solute Permeability and Permeable Factors for Solutes." Biomacromolecules 22, no. 7 (June 24, 2021): 3099–106. http://dx.doi.org/10.1021/acs.biomac.1c00530.
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Weinbaum, S. "Interfacial Transport in Large and Small Blood Vessels." Applied Mechanics Reviews 43, no. 5S (May 1, 1990): S109—S118. http://dx.doi.org/10.1115/1.3120789.
Full textAbstract:
In this paper we shall review some recent mathematical models which have led to new conceptual views of the ultrastructural pathways by which water, solutes and large molecules cross the endothelial interface between tissue and blood. In particular, we shall show how a sequence of models for the endothelium and underlying tissue in large arteries have finally led to the experimental discovery of the large pore via which LDL and other large molecules enter the artery wall and how a new three-dimensional model for the interendothelial cleft in capillaries might reconcile the several long standing paradoxes relating to the measured filtration and solute permeability coefficients in the transcapillary exchange of water and hydrophilic solutes in the microcirculation.
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Ronco, C., A. Brendolan, C. Crepaldi, M. C. Bettini, M. Scabardi, F. Cappellari, L. Tasinazzo, L. Fortunato, and G. La Greca. "Technical and Clinical Evaluation of a New Asymmetric Polysulfone Membrane (Biosulfane®)." International Journal of Artificial Organs 16, no. 8 (August 1993): 573–84. http://dx.doi.org/10.1177/039139889301600803.
Full textAbstract:
First generation asymmetric polysulfone membranes had high hydraulic permeability (kf=40 ml/h/mmHg/sqm) but a low diffusive permeability due to the hydrophobic nature and wall thickness of 75–100 microns. We have tested a new polysulfone membrane with a wall thickness of 40 microns in a series of in vitro and in vivo dialysis session experiments. The new “Biosulfane®” membrane presented a Kf of 45.8 with constant performance up to 240 mins. The koA was 760 and the clearance value at 350 ml/min of Qb in hemodiafiltration was 255 ml/min for urea, 210 for creatinine, 225 for phosphate, 76 for inulin. In high flux dialysis the clearances were similar except for inulin which was 32% lower due to the lower convection amount. Beta-2 microglobulin clearance was 22 ml/min in high flux dialysis and 37 in hemodiafiltration. Solute sieving coefficients were close to 1 for the majority of the studied solutes in a wide range of molecular weights and slight variations were observed for charged solutes due to Donnan's effect. The sieving for Inulin was 0.96 while that for Beta-2 microglobulin was not measurable due to a large molecule adsorption on the inner structure of the fibres. The good performances of this membrane are probably due to reduced wall thickness and a consequent improvement in diffusive permeability to small size solutes.