Electroosmosis in Membranes: Effects of Unstirred Layers and Transport Numbers

Barry, Peter H.; Hope, AB

doi:10.1016/s0006-3495(69)86414-3

Cited by 102 publications

(69 citation statements)

References 7 publications

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“…(Barry & Hope, 1969a). This suggestion seems reasonable, because the size of the three changes was directly related to the time integral of the current (see Fig.…”

Section: I-90omentioning

confidence: 79%

Changes in axon light scattering that accompany the action potential: current‐dependent components

Cohen¹,

Keynes²,

Landowne

1972

The Journal of Physiology

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SUMMARY1. When light scattering was measured during hyperpolarizing and depolarizing voltage-clamp steps, relatively large scattering changes were found during the depolarizing steps. These large changes were found to depend on the time integral of the ionic current and not on the changes in conductance or potential.2. The current-dependent changes were examined at several scattering angles, and three distinct time courses were found. At 30-120, the main change occurred after the current when steps of 2-5 msec duration were used. This change was called I-90. At 15-30°, the change occurred with the same time course as the time integral of the current. This change was called I-25o. At 5-15o the scattering change occurred with a time course intermediate between that of I-90 and I-25o. This change was called I-10o.3. In all experiments, outward potassium and outward sodium currents led to similar light scattering changes indicating that specific effects of the cation carrying the current across the membrane were not involved.4. The size of I-900 was reduced by 29 % when an isethionate artificial sea water was substituted for the normal chloride artificial sea water. This reduction equalled the reduction predicted for a transport number effect at the membrane-solution interface. The time course of I-900 was similar to the predicted time course for a volume change in the periaxonal space, and such volume changes were tentatively identified as the origin of I-90.5. Because of difficulties in measuring the time course of I-25', it was not possible to distinguish between a water of hydration effect and a transport number effect as the cause of this change. Similarly, the origins 728 L. B. COHEN, R. D. KEYNES AND D. LANDOWNE of I-1O' were not identified. Only I-1IO was altered in size and time course when the external refractive index was increased with bovine albumin.6. When the scattering changes during the action potential were examined in light of the voltage-clamp experiments, we concluded that the forward-angle change was potential-dependent and that the long-lasting change at right angles probably represented a swelling of the periaxonal space resulting from the fact that chloride carried a significant fraction of the outward current during the action potential.

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“…(Barry & Hope, 1969a). This suggestion seems reasonable, because the size of the three changes was directly related to the time integral of the current (see Fig.…”

Section: I-90omentioning

confidence: 79%

Changes in axon light scattering that accompany the action potential: current‐dependent components

Cohen¹,

Keynes²,

Landowne

1972

The Journal of Physiology

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“…(51). Thus, the possi bility exists that the "sweeping-away" effect of osmotic water flow in the lateral intercellular spaces reduced the salt concentration and accordingly, the osmotic pressure gradient across the luminal interfaces (23,(32)(33)(34)(35)66 is the diffusional resistance (aII/Di') of the unstirred layer. Equation 11 indicates that Claii will be reduced in exponential relationship to both Jw and Rei.…”

Section: Resultsmentioning

confidence: 99%

“…Second, recent observations in our laboratory indicate that, in certain instances, osmotic flow-dependent changes in the concentration profiles of solutes at the interfaces between unstirred layers and membranes, rather than the solvent drag phenomenon, may account for changes in the fluxes of solutes across membranes during osmosis (31). Similarly, apparent electrokinetic phenomena in plant cells (32,33), gall bladder (34,35), and squid axon (36) may be referable, in part, to perturbations produced by volume flow in the ionic composition of unstirred layers at the membrane interfaces rather than to coupling of ionic and volume flows within membranes. On the basis of such observations, we are skeptical about analyses of water flux data which do not consider explicitly the effects of unstirred layers on transport processes.…”

Section: Introductionmentioning

confidence: 92%

Cellular constraints to diffusion

Schafer¹,

Andreoli²

1972

J. Clin. Invest.

100

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A B S T R A C T These experiments were intended to evaluate the effects of antidiuretic hormone (ADH) on dissipative water transport in cortical collecting tubules isolated from rabbit kidney. In the absence of ADH, the osmotic (Pf, cm sec-') and diffusional (PDW cm sec') water permeability coefficients were, respectively, 6±6 and 4.7±1.3 (SD). When ADH was added to the bathing solutions, Pf and PDw rose to, respectively, 186±38 and 14.2±1.6 (SD). In the absence of ADH, the tubular cells were flat and the lateral intercellular spaces were closed when the perfusing and bathing solutions were, respectively, hypotonic and isotonic; in the presence of ADH, the cells swelled and the intercellular spaces dilated. These data suggest that ADH increased the water permeability of the luminal membranes of the tubules.It was possible that the ADH-dependent Pf/PD, ratio was referable to the resistance of the epithelial cell layer (exclusive of luminal membranes) to water diffusion (RDW, sec cm-1). RDI was referable to cellular constraints to diffusion; for these solutes, the latter were 12-25 times greater than in water. Accordingly, it is possible that the ADHdependent Pf/PDW ratio was also due to cellular constraints to diffusion. INTRODUCTIONCertain biological tissues, such as the skin and urinary bladder of amphibians and the collecting tubule of the mammalian kidney, have a primary role in the regulation of water homeostasis. The purpose of this paper is to examine the mode of dissipative water transport across isolated collecting tubule segments from mammalian kidney, and the way in which antidiuretic hormone (ADH)' modifies these transport processes.Ussing and his coworkers (1, 2) first proposed that water traversed aqueous channels in anuran skin, and that ADH increased the size of such pores. The rate of osmotic water flow across anuran skin was considerably greater than might be expected for a diffusion process (1), i.e., the osmotic water permeability coefficient (Pf, cm sec-1) was greater than the diffusional water permeability coefficient (PDW, cm sec') ; and, ADH increased the Pf/PDW ratio. Koefoed-Johnsen and Ussing rationalized the difference between Pt and

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“…However, the interpretation of the results of such experiments is complicated by the fact that electrodiffusion of ions (mainly Na+ toward the cathode and Cl-toward the anode) across a membrane of selective permeability, such as the tracheal epithelium, inevitably creates an osmotic gradient in the unstirred layers adjacent to the membrane. This osmotic gradient in turn results from the transport number effect, a phenomenon which was demonstrated by Barry & Hope (1969). Thus, an osmotic Jv would occur, which would tend to obscure the purely electrically induced Jv and might invalidate this approach.…”

Section: Discussionmentioning

confidence: 99%

“…Yet this view is not universally accepted (Hill, 1975a) and other mechanisms, such as electrokinetic coupling between water and ions migrating across cells down the membrane potential (Hill, 1975b), or a fluid pump (Eldrup, Frederiksen, Mollgard & Rostgaard, 1982) have been suggested. However it was reported that, in leaky epithelia, the putative electrokinetic Jv, induced by an external electrical gradient, resulted mainly from an osmotic force built up in unstirred layers adjacent to the epithelial cells by the transport number effect, rather than from a direct coupling between water and ionic current (Barry & Hope, 1969;Wedner & Diamond, 1969).…”

Section: Introductionmentioning

confidence: 99%

Current‐induced volume flow across bovine tracheal epithelium: evidence for sodium‐water coupling.

Durand¹,

Durand-Arczynska²,

Vulliemin³

1984

The Journal of Physiology

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SUMMARY1. The passage of a constant current from lumen to serosa (Il-), in the range 0'5-2-0 mA, across ouabain-treated bovine tracheal epithelium, induced a stable volume flow (Jv) toward the serosa, proportional to the current. No consistent Jv occurred when current was applied from serosa to lumen.2. When the standard K+ (6 mM) in the bathing solution was omitted or replaced by choline, Jv was in the same direction as, and proportional to, the current, both with s_ and with li-S. The electro-osmotic permeability f was in the range of 10-15 ,1 h-1 cm-2 mA-1, i.e. 3-4 x 10-6 cm s-1 mA1.3. The fluxes of Na+, Cl-and mannitol were measured in current-clamp (1 mA, passed from serosa to lumen or lumen to serosa) or voltage-clamp (-20, 0 and + 20 mV) conditions, with and without K+. Net transepithelial Na+ fluxes toward the cathode were either smaller than (with I.-,) or equal to (with II,) the net fluxes of Cl-toward the anode.4. The total transepithelial conductance (St) increased with the applied electrical gradient, both with IS-, and with I-rS the change in Gt being larger with II-, than with I-,. This increase of Gt was less pronounced when K+ was omitted. 5. The analyses of partial ionic conductances (GNa and GCI) and of the flux ratios indicate the existence of non-conductive diffusion for Cl-and also for Na+.6. The direction ofthe electrical gradient influenced the permeability ratio PNa/IPCI With I.-1, PNa/PCi was consistently lower than 0 7, i.e. the mobility ratio of Na+ and Cl-in solution. With II, PNa/PCl was closer to 0-7. The highest Cl-selectivity of the epithelium was observed with IS-, in the presence of K+, i.e. under conditions which failed to induce any conspicuous J, 7. The passage of current at 1 mA induced a net flux of mannitol toward the cathode, i.e. in the same direction as Na+ net flux and J4 However, this mannitol flux was significant only in the absence of K+.8. These results indicate that Jv was predominantly coupled to the migration of Na+ along the electrical gradient, through a paracellular pathway. 20

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Electroosmosis in Membranes: Effects of Unstirred Layers and Transport Numbers

Cited by 102 publications

References 7 publications

Changes in axon light scattering that accompany the action potential: current‐dependent components

Changes in axon light scattering that accompany the action potential: current‐dependent components

Cellular constraints to diffusion

Current‐induced volume flow across bovine tracheal epithelium: evidence for sodium‐water coupling.

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