NaCl Diffusion Research Articles

NaCl diffusion across an amphoteric ion exchange membrane

The diffusion of NaCl across an amphoteric ion exchange membrane has been studied by measuring the diffusion flux of NaCl and the self-diffusion fluxes of Na + and Cl − ions through this membrane. The NaCl fluxes through the amphoteric membrane are analysed on the basis of the Nernst-Planck equation and the TMS theory. The self-diffusion measurements make possible calculations of the individual difusion coefficients. The effects of the external pH on the physicochemical properties of the membrane are discussed. The measurement of the NaCl content in the membrane combined with the result of the membrane potential and with the result of the self diffusion measurements make it possible to obtain the theoretical values of the NaCl flux. These values are in satisfactory agreement with the experimental values.

Mechanism of water transport across the upper portion of the descending thin limb of long-looped nephron of hamsters

The mechanisms of water transport across the upper portion of the descending limb of long-looped nephron (LDLu) were examined by microperfusion of segments isolated from hamster kidneys. Because of cation permselectivity a streaming voltage was generated when a transmural osmotic gradient was imposed. When 100 mmol/l urea was added to the bath, the streaming voltage was -4.9 +/- 0.4 mV. Addition of 10(-4) mol/l parachloromercuribenzene sulfonate (PCMBS) decreased the voltage to -2.4 +/- 0.7 mV. This effect was associated with changes in osmotic water permeability (Pf, 10(-3) cm/s) from 243 +/- 42 to 47 +/- 15. PCMBS also decreased the transmural diffusional water permeability (Pdw, 10(-3) cm/s) from 9.4 +/- 0.6 to 7.2 +/- 0.6. The inhibitory effect of PCMBS was prevented by pretreatment with dithiothreitol. N-Butanol permeability was measured as an index of cellular resistance for diffusion. Large differences between Pf and Pdw can be explained both by cellular resistance to diffusion and by resistance through a water channel with a single file mechanism. The apparent activation energy for water transport, 13.3 x 10(3) joule/mol (3.16 kcal/mol), was low. These findings are compatible with the hypothesis that a water channel exists in this segment. PCMBS also inhibited the NaCl diffusion voltage, a parameter indicating cation permselectivity, in parallel with suppression of the streaming voltage, suggesting that the water channel is in part associated with cation permselectivity. The possibility that the PCMB-sensitive cation-permselective pathway exists in parallel cannot be ruled out.

Analysis of reabsorbate concentrations in the proximal tubules of dog kidneys during osmotic diuresis

To examine to what extent the reabsorbate concentrations, calculated as the flux ratios between solutes and water, represent the fluid composition in the lateral intercellular space (LIS) in the proximal tubules, reabsorption was stimulated by elevating PCO2 from 5 to 13 kPa before and during infusion of mannitol to a plasma concentration of 70 mM in volume-expanded dogs receiving ethacrynic acid. The reabsorbate concentration of NaHCO3 increased by 50 mM during mannitol infusion. The real concentration of NaHCO3 in LIS could not, however, be elevated by this amount, since the driving forces for fluid reabsorption then would have increased during osmotic diuresis due to diffusion of mannitol into LIS from plasma. A model analysis of diffusion in LIS showed that transcellular transport can only lead to trivial increases of LIS concentrations compared to plasma, whereas diffusion across tight junctions can increase LIS concentrations by several mM. NaCl diffusion and coupled transcellular water transport may therefore represent a significant contribution to total bicarbonate-dependent NaCl and water reabsorption in the proximal tubules.

Osmometric behavior of Drosophila melanogaster embryos

The osmometric behavior of Drosophila melanogaster embryos in permeabilized eggs was studied in a microscope diffusion chamber designed to impose a rapid change in osmotic environment at various temperatures. A numerical model of NaCl diffusion in the chamber predicted that radial variations in concentration arising from the presence of a thin film of solution at the top of the chamber were negligible. On the basis of transient electrical conductance measurements in the chamber, characteristic time constants for the change in concentration averaged over the chamber depth occupied by the eggs were 0.99, 0.77, and 0.60 min at 0, 10, and 20 °C, respectively. The chamber response was sufficiently rapid that the characteristic response of the embryo was not masked. Equilibrium volumetric behavior of the embryos indicated that they behaved as nearly ideal osmometers over the range of 0.256 to 2.000 osm, and followed the relation FV eq = 0.123 C −1 + 0.541, where FV eq is equilibrium fractional volume and C is osmolality. Nonlinear regression of volumetric data during osmotic contraction yielded an average L p of 0.722 μm/(min · atm) at 20 °C and an apparent activation energy Δ E of 8.11 kcal/mol. The coefficients of variation in the L p estimates among individual embryos were 38, 18, and 47% at 0, 10, and 20 °C, respectively. With the use of probability rules and a model for volumetric behavior during freezing, it was determined that the observed variability in L p (assuming Δ E is fixed) considerably broadens the transition range of cooling rates over which the predicted probability of intracellular ice formation goes from 0 to 1. However, experimental observations (21) show the actual transition range is even wider, indicating that there exist other important sources of variability which determine the event of ice formation in D. melanogaster embryos.

Effects of Cl- transport inhibitors on Cl- permeability across hamster ascending thin limb

The highly conductive Cl- transport pathway exists in the ascending thin limb (ATL) of Henle's loop. To characterize the mechanism of the Cl- conductance across the ATL, we examined effects on Cl- permeability across hamster ATL of Cl- transport inhibitors, including 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB), diphenylamine carboxylate (DPC), and anthracene-9-carboxylic acid (9-AC), by the in vitro microperfusion technique. NPPB added to the bath caused reversible suppression of the relative permeability of Cl- to Na+ (PCl/PNa), as estimated from the NaCl diffusion voltage in a dose-dependent manner in a range from 3 x 10(-6) to 10(-3) M. The concentration of NPPB that inhibited PCl/PNa by 50% (ID50) was approximately 3 X 10(-5) M. When 3 X 10(-5) M NPPB was added to the bath, the lumen-to-bath flux coefficient for 36Cl (Kl----b,Cl- 10(-7) cm2/s) was decreased from 130.7 +/- 7.3 to 52.2 +/- 11.6 (n = 7, P less than 0.01). Application of NPPB in the lumen also caused reversible suppression of PCl/PNa, but this effect was less potent compared with the application of the drug via the bath. Whereas 10(-3) M 9-AC or 10(-3) M DPC decreased PCl/PNa by 6.5 +/- 1.2 and 10.2 +/- 2.6%, respectively, 3 X 10(-4) M NPPB decreased PCl/PNa by 69.7 +/- 3.8%. In maleimide-treated tubules, addition of 10(-3) M N-ethylmaleimide (NEM) increased PCl/PNa from 1.0 +/- 0.1 to 1.8 +/- 0.1 (n = 7, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Ca2+ on Cl- transport in thin ascending limb of Henle's loop.

Effects of ambient Ca2+ concentration on Cl- transport across the thin ascending limb of Henle's loop (TAL) were examined by the in vitro microperfusion technique. When Ca2+ concentration in the bathing fluid was decreased from 1.5 mM to nominally 0 mM at 37 degrees C, the relative permeability of Cl- to Na+ (PCl/PNa) estimated from the NaCl diffusion voltage changed from 2.44 +/- 0.20 to 1.27 +/- 0.16 (n = 7, P less than 0.01). When Ca2+ concentration of the luminal fluid was reduced, PCl/PNa was unchanged. When Ca2+ concentration in the bathing fluid was changed from 4.5 to nominally 0 mM, the lumen-to-bath flux coefficient for 36Cl (K36Cl(l----b)) was decreased, whereas the value for 22Na was unchanged, indicating that the reduction of Ca2+ concentration in the bathing fluid selectively inhibits Cl- transport without affecting Na+ transport. By contrast, at 23 degrees C, the elimination of Ca2+ from the bathing fluid caused only a small reduction of PCl/PNa. Although at 23 degrees C acidification of the bathing fluid caused only little or no decrease in Cl- permeability, the elimination of Ca2+ from the bathing fluid under acid pH markedly suppressed the (K36Cl(l----b)) (10(-7) cm2/s). The pH titration curves of relative Cl- permeability examined at three different Ca2+ concentrations at 37 degrees C revealed that the interaction between proton and Ca2+ was noncompetitive. Addition of quin 2-AM, which reduced intracellular Ca2+ concentration, to the bath caused an irreversible suppression of Cl- permeability, suggesting that the decrease in intracellular Ca2+ concentration also inhibits the Cl- transport across the TAL.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of anion transport inhibitors and ion substitution on Cl- transport in TAL of Henle's loop.

To identify the mechanism of Cl- transport across the thin ascending limb of Henle's loop (TAL), we examined effects of anion transport inhibitors and ionic substitution in the isolated segments of hamsters using the in vitro microperfusion technique. 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) at 10(-3) M changed the NaCl diffusion voltage (Vt) to the orientation that corresponds to the decrease in the Cl(-)-Na+ permeability ratio when it was added either to the bath or to the lumen. DIDS, added to the bath or to the lumen decreased the lumen-to-bath flux coefficient for 36Cl, KCl-(1----b) (X10(-7) cm2/s), from 74.5 +/- 2.1 to 17.9 +/- 3.6 and from 77.7 +/- 3.6 to 51.1 +/- 5.4, respectively, whereas it had little effect on the flux coefficient for 22Na, KNa+(1----b). Elimination of HCO3- slightly increased rather than decreased both NaCl diffusion potential and KCl-(1----b), indicating that Cl- transport is independent of HCO3- transport. Phloretin at 10(-3) M inhibited both diffusion potential and KCl-(1----b) to a similar extent as DIDS did. KNa+(1----b) was also changed little. The inhibitory effect of phloretin was rapid and reversible. Phloridzin was ineffective. Furosemide added to the bath at 10(-3) M decreased Vt and KCl-(1----b) from 29 +/- 0.9 to 5.3 +/- 0.7 mV and from 75.7 +/- 3.9 to 62.8 +/- 4.1 X 10(-7) cm2/s, respectively; but it was ineffective when added to the lumen. Elimination of Na+ caused only a small decrease in KCl-(1----b) from 119.2 +/- 6.9 to 107.3 +/- 8.5 X 10(-7) cm2/s. Elimination of K+ and addition of Ba2+ did not change KCl-(1----b). From these observations, we conclude that Cl- transport across the TAL is distinct from Na+ and is not coupled with Na+, K+, or HCO3-.

A numerical model for the formation of saline waters due to diffusion of dissolved NaCl in subsiding sedimentary basins with evaporites

Numerical modeling by a finite difference method incorporating the effects of vertical variations in pressure, temperature, salinity, and porosity shows that mass transport by diffusion may be a major brine-forming process in sedimentary basins containing halite beds. Vertical fluxes of dissolved NaCl are greatest when the subsidence rate is slow. At subsidence rates of 20 m m.y. −1 more than 250 m of salt can be dissolved over 150 m.y. At rapid subsidence rates, such as 500 m m.y. −1, pore waters are advected downward so rapidly that although a diffusion front develops above the evaporite, this front moves downward as the evaporite subsides, and diffusive fluxes at shallow depths are thus low. However, under such conditions, the pore water column becomes gravitationally unstable as a result of thermally-induced density inversions and the potential for convective overturn is enhanced with accompanying advective salt flux upward. Although dissolution and diffusion of NaCl are important processes in the burial history of evaporites, they are not adequate by themselves to produce the regional salinity versus depth profiles that are actually observed in some sedimentary basins. Diffusion-induced gradients progressively increase with depth whereas gradients actually observed in sedimentary basins tend to decrease with depth. The difference is presumably due to the activity of other mass transport mechanisms such as advection, convection and dispersion.

NaCl and Ca delivery at the bend of rat deep nephrons decreases during antidiuresis.

The effects of 1-desamino-8-D-arginine vasopressin (dDAVP) on superficial and juxtamedullary nephrons were investigated by micropuncture in diabetes insipidus (DI) Brattleboro rats chronically treated with the peptide. The rats, acutely deprived of endogenous calcitonin, parathyroid hormone (PTH), and glucagon [hormone-deprived (HD) rats], were examined either 4 days after cessation of dDAVP treatment (HDT, control diuretic rats) or when the treatment was continued until the micropuncture experiment, during which dDAVP was also given intravenously (HDT + dDAVP, experimental nondiuretic rats). In the presence of dDAVP, the reabsorption of Cl, Na, Mg, and Ca by the superficial loop of Henle was significantly increased, as previously observed in HD-untreated rats during acute infusion of dDAVP. The effects on the superficial distal tubule were also similar. The effects on K, however, were different both in the loop and in the distal tubule. At the bend of the juxtamedullary nephrons, the treatment alone (HDT rats) increased fractional delivery (FD%) of Na and Cl, whereas FD% of Mg, Ca, K, and P was unaltered. In HDT + dDAVP rats, FD% of H2O, Cl, Na, and Ca was significantly lower than in HDT rats, and FD% of K, Mg, and P did not differ significantly. In conclusion, in the presence of dDAVP, the FD% of H2O, Na, and Cl at the bend of the long-loop nephrons decreases, in accordance with our previous hypothesis that water removal along the rat descending limb increases outward NaCl diffusion along this segment.

The apparent reflexion coefficient of the leaky corneal endothelium to sodium chloride is about one in the rabbit.

1. Rabbit corneal thickness changes were measured after some of the NaCl in the bathing Ringer solution was substituted by a neutral sugar. 2. The response had three phases which could be closely modelled by three exponentials of different amplitudes and rate constants, originating from the time of the substitution. 3. The first, fastest, phase was interpreted as being driven by the pure osmotic pressure difference developed across the corneal endothelium by the difference between the removed NaCl and the added sugar in the bathing Ringer solution; the second was driven by the diffusion of NaCl out of the stroma; and the third, slowest, phase was driven by the diffusion of the added sugar into the stroma. 4. Consistent with the interpretation, only the third, slowest, phase had its rate constant dependent upon the nature of the substituting neutral sugar. 5. The amplitude of the pure osmotic phase was a linear function of the added sugar. Its amplitude was zero when an equal osmolarity of sugar was substituted for NaCl. 6. It was concluded that the reflexion coefficient of rabbit corneal endothelium to NaCl is the same as that to sucrose, raffinose and stachyose, i.e. about 1. 7. The calculated hydraulic conductivity of the endothelium plus stroma was about the same as that of stroma alone, and it was concluded that the hydraulic conductivity of corneal endothelium is large compared to corneal stroma. 8. It is proposed that most of the hydraulic flow in response to osmotic gradients passes through the cells, whereas salt diffuses through the paracellular route, resulting in an apparent reflexion coefficient of 1. 9. Thus, corneal endothelium is a 'leaky' (12 omega cm2) salt-permeable epithelium and, according to the present study, simultaneously a semi-permeable membrane. To resolve the terminology, we suggest the term 'bi-permeable' for such epithelia which have a high salt permeability but such a very high water permeability as to give apparent reflexion coefficients of 1.

Mass Transfer During Ripening of Cuartirolo Argentino Cheese

ABSTRACTThe mass transfer occurring during ripening of Cuartirolo Argentino cheese was mathematically modelled as an effective diffusion process. The model contained the final NaCl concentration profile resulting from the brining step as starting point and used the same effective diffusivity of NaCl as for brining. The equation developed allowed the calculation of the equilibrium salt concentration resulting from different brining times. Theoretical results were compared against experimental data showing very good agreement.

Effect of glutaraldehyde on renal tubular function. II. Selective inhibition of Cl- transport in the hamster thin ascending limb of Henle's loop.

In order to further characterize Cl- transport of the thin ascending limb of Henle's loop (TAL), we observed the effects of glutaraldehyde on Na+ and Cl- transport in hamster TAL perfused in vitro. We found that 0.1 mol/l glutaraldehyde added either to the lumen or to the bath caused a rapid irreversible reversal of the NaCl diffusion potential. This was mainly accounted for by an inhibition of Cl- permeability (10(-7) cm2 s-1) from 93.51 +/- 8.39 to 14.89 +/- 3.91 (P less than 0.01, n = 9). By contrast, Na+ permeability changed little from 34.18 +/- 3.27 to 26.56 +/- 2.74 (P less than 0.01, n = 6). Glutaraldehyde treatment abolished the halogen-permselectivity of the TAL as determined by the voltage deflection seen upon ionic substitution. Permeabilities for Cl-, Br-, I-, and SCN- relative to Na+ were changed from 3.16 +/- 0.20, 3.22 +/- 0.19, 2.97 +/- 0.26 and 4.36 +/- 0.36 to 0.38 +/- 0.07, 0.35 +/- 0.06, 0.36 +/- 0.07 and 0.58 +/- 0.05, respectively. The effect of glutaraldehyde on the NaCl diffusion potential was dose-dependent in the range from 10(-5) to 10(-1) M. The effect was reversible at concentrations lower than 10(-3) M. Glutaraldehyde did not affect the NaCl diffusion potential of the long-loop descending limb. These observations constitute additional evidence that the mechanism of Cl- transport across the TAL is different from that of Na+ transport. Glutaraldehyde might inhibit Cl- transport in the TAL by cross-linking amino acid residues of the proteins essential for halogen transport across this segment.

Diffusion of ionic micelles in salt solutions: Sodium dodecyl sulfate + sodium chloride + water

A conductance technique has been used to measure ternary diffusion in aqueous sodium dodecyl sulfate (NaDS) + sodium chloride solutions at 25°C. The data show that diffusion of NaDS drives cocurrent flow of NaCl and that diffusion of NaCl drives countertransport of NaDS. Both coupled flows are large, the same order of magnitude as the driving flows. The strong interaction between solute flows is primarily due to electrostatics. If diffusion of NaDS in aqueous NaCl solutions is treated as a simple binary process, simultaneous flow of NaCl leads to apparent diffusion coefficients for NaDS that are significantly higher than true values. Equations are derived to predict multicomponent transport coefficients for solutions of micellar electrolytes with added salt.

Diffusion of heterovalent ions in ionic crystals

Diffusion of divalent and trivalent cations is investigated in NaCl and KCl under conditions of heterodiffusion at infinite dilution. This purpose is achieved by letting radiotracers of very strong specific activity diffuse in the intrinsic range of highly pure single crystals. The importance of the experimental procedures in yielding reliable results is emphasized. Thus, Co ++, although supposedly characterized by an anomalous diffusion in NaCl and KCl, gives very good diffusion profiles with the carrier-free isotope Co-58. Also Fe +++, whose diffusion was considered impossible, gives good diffusion profiles with certain experimental precautions. Analysis of the data gives, for the diffusion of Co ++, the migration enthalpy of 0.76 eV in NaCl and 0.66 eV in KCl and the migration entropy of −2.84 k in NaCl and −1.45 k in KCl. These results are in good agreement with the values for the full set of divalent cations.

魚肉内における塩類の移動速度 ＩＩ 魚肉内および表皮を通した食塩の移動速度

Penetration and extraction (desalting) of various salts in tuna flesh had been studied under various conditions in our previous paper. In this study, tranfer rates of NaCl have been measured for flesh of river chum (pre-spawning river chum salmon) and ocean chum (pre-spawning chum salmon caught in the North Pacific Ocean), in comparison to tuna flesh and the penetration rates into both salmon flesh through skin have also been evaluated. Observed concentration distributions and amounts of penetrated salt in flesh were explained by FICK's law of diffusion. And for both direction of diffusion, parallel to or perpendicalar to fiber, there were no differences in mechanism and in diffusivities. As flesh, especially in river chum, swelled and shrank in contact with certain concentration of salt solution, the amount of salt per unit volume of swollen flesh in equilibrium were used as surface concentration in the above calculation. And this treatment was certified experimentally in short time penetration. The rates of penetration into both flesh through skin were also expressed by diffusion in composite media and by diffusion accompanied surface resistance. The diffusivity of NaCl in the skin of river chum was larger than the other one, but its over-all resistance through skin was also larger caused by its larger thickness of skin.

Ca2+ regulation of tight-junction permeability and structure in Necturus gallbladder.

To explore the role of Ca2+ in tight-junction permeability, the Necturus gallbladder was exposed to varying Ca2+ concentrations and to the Ca2+ ionophore A23187 added to the mucosal side (1.9 X 10(-6) to 6.8 X 10(-5) M). Electrophysiological parameters measured in an Ussing-type chamber were correlated with tight-junction morphology revealed by freeze-fracture electron microscopy. In Ca2+-free bathing media, transepithelial resistance decreases and tight-junctional ultrastructure is fragmented. In 1.8 mM Ca2+ media, A23187 induces an initial drop in transepithelial resistance, followed by an increase in transepithelial resistance to a value 20% above base line. At peak response to A23187, NaCl diffusion potentials decrease. Freeze-fracture replicas reveal that the number of junctional strands increase pari passu with junctional depth. Both physiological and morphological changes were partially reversible. The initial decrease in transepithelial resistance coincided with a persistent hyperpolarization of the mucosal cell membrane potential difference and a decrease in the mucosal-to-serosal cell membrane resistance ratio. Thus A23187 alters both the transcellular and paracellular pathway, resulting in opposing effects on transepithelial resistance.

Unstirred layer effects in osmotic water flow across gallbladder epithelium

The standard one-dimensional model of the unstirred layer is applied in a re-examination of the experimental results of Wright, Smulders and Tormey (Wright, E.M., Smulders, A.P., Tormey, J. McD., 1972, J. Membrane Biol. 7:198) who reported large transients in the osmotic flux of water from the serosal to the mucosal side of rabbit gallbladder epithelium. They initiated osmosis by the addition of sucrose to the mucosal bathing solution (initially, approximately 300 nOsm NaCl) and observed that the initial flux was more than ten times its eventual steady-state value; they interpreted this as a consequence of the piling-up of NaCl in the unstirred tissue layer on the serosal side of the epithelium. The present analysis (both steady-state and unsteady) shows that if measured values of layer thickness delta are used, together with reasonable values of the reduced diffusivity of NaCl in the tissue and of the fraction of tissue available for water flow, then one would predict a discrepancy of only about 10%, not tenfold, between the initial and final values of the flux. Thus the standard model is inconsistent with the observations. Furthermore, Wright et al's results cannot be used to infer that the osmotic permeability of epithelial cell membranes is much larger than steady-state measurements on whole epithelia would indicate. Mucosal-to-serosal flow is also analyzed, and in this case a considerably greater osmotic permeability is predicted; this result is consistent with the observed changes in structure of the lateral intercellular spaces when the direction of flow is reversed.

Diffusion and sorption of simple ions in cellulose acetate—semipermeability

The diffusion and sorption properties of NaCl, NaI, KCl and KI have been studied in cellulose acetate (CA) membrane. Sorption is not reversible. Residual solute remains which can only be removed by ion exchange. Thus H +, K + and Na + membranes were prepared. The sorption of K was almost twice that of Na in which connection the biological difference between K and Na is of interest. Both K and Na sorption decrease with decreasing pH. The diffusion of NaCl was much less in the CA than in cellulose and decreased with decreasing concentration. At the higher concentrations the diffusion concentration gradient data implies a single barrier across the membrane as with cellulose but this becomes multibarrier at lower concentration. The observations are understandable according to electrokinetic theory. Salt retention properties in reverse osmosis are thus explained including the decreasing of the semipermeability with increasing solute concentrations. The much greater effectiveness of cellulose acetate vs cellulose is evident in terms of the reduced absorption and diffusion in the more compact less swollen molecular chain network of lower average dielectric constant.

LITERATURE ABSTRACTS

LITERATURE ABSTRACTS

Surface segregation and diffusion in calcium-doped NaCl

An attempt has been made to detect near-surface diffusion in calcium-doped NaCl caused by non-equilibrium segregation of the calcium impurity to the surface during the formation of the surface double layer. The effect is observable above 400°C, but below this temperature appears to be inhibited by bulk precipitation.