Mechanism of Fluid Transport by Epithelia

Spring, Kenneth R.

doi:10.1002/cphy.cp060405

Cited by 8 publications

(10 citation statements)

References 90 publications

(99 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In principle, water could flow across the cells and/or the paracellular pathway; i.e., the junctional complexes in series with the lateral intercellular spaces. The surface of junctional network per unit area of epithelium is very small relative to that of the cell membranes (Spring, 1991). However, the high ionic permeability of the junctions in this class of epithelia (Frrmter, 1972;Guggino, Windhager, Boulpaep, and Giebisch, 1982) suggests the possibility that their osmotic water permeability is also high, and hence junctional osmotic water flow cannot be ruled out a priori.…”

Section: Introductionmentioning

confidence: 99%

“…Tripathi and Boulpaep (1988) suggested that the lateral space is the site of origin of the streaming potential. If the changes of R, elicited by osmotic challenges reflect changes in lateral space width, as widely accepted (Fr6mter, 1972;Spring andHope, 1978, 1979;Stoddard and Reuss, 1988b), then the transepithelial voltage changes should increase as the spaces collapse because the fractional resistance of the junctions vis-a-vis the spaces would decrease.…”

Section: Paraceuular Origin Of Apparent Streaming Potentialsmentioning

confidence: 99%

“…The pathways and mechanisms of transepithelial water transport across so-called leaky epithelia have been the subject of considerable study (Sackin and Boulpaep,298 THE JOURNAL OF GENERAL PHYSIOLOGY • VOLUME 99 -1992 1975; Diamond, 1979;Hill, 1980;Weinstein, Stephenson, and Spring, 1981;BetTy, 1983;Reuss and Cotton, 1988;Whittembury and Carpi-Medina, 1988;Tripathi and Boulpaep, 1989;Verkman, 1989;Schafer, 1990;Spring, 1991;Whittembury and Reuss, 1991). It is generally accepted that spontaneous fluid absorption in this class of epithelia occurs by "osmotic coupling" of water transport to active salt transport.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Pseudo-streaming potentials in Necturus gallbladder epithelium. I. Paracellular origin of the transepithelial voltage changes.

Reuss

Simon

1992

The Journal of General Physiology

View full text Add to dashboard Cite

A B S T g A C T Apparent streaming potentials were elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution. In NaCl Ringer's solution, the transepithelial voltage (I'm,) change (reference, basolateral solution) was positive with sucrose addition and negative with sucrose removal. Bilateral CI-removal (cyclamate replacement) had no effect on the polarity or magnitude of the Vm, change elicited by addition of 100 mM sucrose. In contrast, bilateral Na + removal (tetramethylammonium [TMA +] replacement) inverted the Vm~ change (from 2.7 +-0.3 to -3.2 _+ 0.2 mV). Replacement of Na ÷ and C1-with TMA ÷ and cyclamate, respectively, abolished the change in V~,. Measurements of cell membrane voltages and relative resistances during osmotic challenges indicate that changes in cell membrane parameters do not explain the transepithelial voltage changes. The initial changes in Vm, were slower than expected from concomitant estimates of the time course of sucrose concentration (and hence osmolality) at the membrane surface. Paired recordings of the time courses of paracellular bi-ionic potentials (partial substitution of apical Na ÷ with tetrabutylammonium [TBA*]) revealed much faster time courses than those produced by sucrose addition, although the diffusion coefficients of sucrose and TBACI are similar. Hyperosmotic and hypoosmotic challenges yielded initial Vm, changes at the same rate; thereafter, the voltage increased with hypoosmotic solution and decreased with hyperosmotic solution. These late voltage changes appear to result from changes in width of the lateral intercellular spaces. The early time courses of the I'm, changes produced by osmotic challenge are inconsistent with the expectations for water-ion flux coupling in the junctions. We propose that they are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Paraceuular Origin Of Apparent Streaming Potentialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Pseudo-streaming potentials in Necturus gallbladder epithelium. I. Paracellular origin of the transepithelial voltage changes.

Reuss

Simon

1992

The Journal of General Physiology

View full text Add to dashboard Cite

show abstract

“…The water permeability values used here were originally model fits by Gin et al (2007), and the largest value used is probably 1–2 orders of magnitude too large, based on the range for typical epithelia (Spring, 2010). The exact membrane water permeabilities are difficult to measure in glandular acini (Hill et al, 2004), and we are not aware of any values for parotid glands in the literature.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, a common argument of those who accept the osmotic mechanism but reject the paracellular pathway is that the area of the tight junctions is too small to be permeable enough to admit a significant osmotic water flux (e.g. Spring (2010) offers a good discussion of this). In response to this, the main advocates of a paracellular water pathway tend to argue that a paracellular flux must be driven by non-osmotic mechanisms (Shachar-Hill and Hill, 2002).…”

Section: Introductionmentioning

confidence: 99%

Efficiency of Primary Saliva Secretion: An Analysis of Parameter Dependence in Dynamic Single-Cell and Acinus Models, with Application to Aquaporin Knockout Studies

2012

View full text Add to dashboard Cite

Secretion from the salivary glands is driven by osmosis following the establishment of osmotic gradients between the lumen, the cell and the interstitium by active ion transport. We consider a dynamic model of osmotically-driven primary saliva secretion, and use singular perturbation approaches and scaling assumptions to reduce the model. Our analysis shows that isosmotic secretion is the most efficient secretion regime, and that this holds for single isolated cells and for multiple cells assembled into an acinus. For typical parameter variations, we rule out any significant synergistic effect on total water secretion of an acinar arrangement of cells about a single shared lumen. Conditions for the attainment of isosmotic secretion are considered, and we derive an expression for how the concentration gradient between the interstitium and the lumen scales with water and chloride transport parameters. Aquaporin knockout studies are interpreted in the context of our analysis and further investigated using simulations of transport efficiency with different membrane water permeabilities. We conclude that recent claims that aquaporin knockout studies can be interpreted as evidence against a simple osmotic mechanism are not supported by our work. Many of the results that we obtain are independent of specific transporter details, and our analysis can be easily extended to apply to models that use other proposed ionic mechanisms of saliva secretion.

show abstract

Fluid Recirculation in Necturus Intestine and the Effect of Alanine

Hill

Shachar-Hill

1997

Journal of Membrane Biology

View full text Add to dashboard Cite

Fluid absorption by Necturus small intestine has been studied using radiolabeled dextrans as molecular probes of the paracellular pathway under voltage-clamped conditions. Fluxes of H3-dextrans of MW up to 20K were followed in both directions between mucosal (M) and serosal (S) baths by fractionating those that passed the epithelium as a function of molecular radius. Consideration of the unstirred layers in the baths and the surface geometry rules out any contribution made by solute polarization. The geometry of the paracellular system was measured by light microscopy, TEM and SEM, and values were used in conjunction with a program that calculates convective-diffusive coupling in the tight junctions, intercellular spaces and subepithelium in series. The results indicate that the net fluxes are due to the convection of fluid through two opposing paracellular fluid circuits with different size selectivity, resulting in net absorption at small radii. Alanine at 20 mM stimulates fluid and salt uptake by a factor of 2. Its effect on the two convective components is to increase the M to S flux and decrease the S to M. The selectivities are not significantly different from those before alanine treatment. The volume absorption predicted from the net probe fluxes is very close to that measured gravimetrically across the epithelium.

show abstract

Mechanism of Fluid Transport by Epithelia

Cited by 8 publications

References 90 publications

Pseudo-streaming potentials in Necturus gallbladder epithelium. I. Paracellular origin of the transepithelial voltage changes.

Pseudo-streaming potentials in Necturus gallbladder epithelium. I. Paracellular origin of the transepithelial voltage changes.

Efficiency of Primary Saliva Secretion: An Analysis of Parameter Dependence in Dynamic Single-Cell and Acinus Models, with Application to Aquaporin Knockout Studies

Fluid Recirculation in Necturus Intestine and the Effect of Alanine

Contact Info

Product

Resources

About