Diffusion of Small Solutes in the Lateral Intercellular Spaces of MDCK Cell Epithelium Grown on Permeable Supports

Diffusion of Small Solutes in the Lateral Intercellular Spaces of MDCK Cell Epithelium Grown on... The diffusion coefficients of four solutes ranging in molecular weight from 238 to 10,000 in the lateral intercellular spaces (LIS) of cultured kidney cells (MDCK) grown on permeable supports were determined from the spread of fluorescence produced after the release of caged compounds by a pulse from a UV laser. Two types of experiments were performed: measurement of the rate of change of fluorescence after releasing a caged fluorophore, and measurement of the change in fluorescence of a relatively static fluorescent dye produced by the diffusion of an uncaged ligand for the dye. Fluorescence intensity was determined by photon-counting the outputs of a multichannel photomultiplier tube. Diffusion coefficients were determined in free solution as well as in the LIS of MDCK cells grown on permeable supports and the hindrance factor, θ, determined from the ratio of the free solution diffusivity to that in the LIS. The hindrance factors for 3000-MW dextran, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS, MW 524) and N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES, MW 238) were not significantly different from 1. The diffusion of 10,000-MW dextran was substantially reduced in the LIS with a θ of 5.6 ± 0.3. Enzymatic digestion by neuraminidase of the sialic acid residues of the glycosylation groups in the LIS increased the diffusivity of the 10,000-MW dextran 1.8-fold indicating hindrance by the glycocalyx. We conclude that small solutes, such as Na+ and Cl−, would not be significantly restricted in their diffusion in the LIS and that solute concentration gradients could not develop along the LIS under physiologic conditions. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Diffusion of Small Solutes in the Lateral Intercellular Spaces of MDCK Cell Epithelium Grown on Permeable Supports

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 2000 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002320001050
Publisher site
See Article on Publisher Site

Abstract

The diffusion coefficients of four solutes ranging in molecular weight from 238 to 10,000 in the lateral intercellular spaces (LIS) of cultured kidney cells (MDCK) grown on permeable supports were determined from the spread of fluorescence produced after the release of caged compounds by a pulse from a UV laser. Two types of experiments were performed: measurement of the rate of change of fluorescence after releasing a caged fluorophore, and measurement of the change in fluorescence of a relatively static fluorescent dye produced by the diffusion of an uncaged ligand for the dye. Fluorescence intensity was determined by photon-counting the outputs of a multichannel photomultiplier tube. Diffusion coefficients were determined in free solution as well as in the LIS of MDCK cells grown on permeable supports and the hindrance factor, θ, determined from the ratio of the free solution diffusivity to that in the LIS. The hindrance factors for 3000-MW dextran, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS, MW 524) and N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES, MW 238) were not significantly different from 1. The diffusion of 10,000-MW dextran was substantially reduced in the LIS with a θ of 5.6 ± 0.3. Enzymatic digestion by neuraminidase of the sialic acid residues of the glycosylation groups in the LIS increased the diffusivity of the 10,000-MW dextran 1.8-fold indicating hindrance by the glycocalyx. We conclude that small solutes, such as Na+ and Cl−, would not be significantly restricted in their diffusion in the LIS and that solute concentration gradients could not develop along the LIS under physiologic conditions.

Journal

The Journal of Membrane BiologySpringer Journals

Published: May 1, 2000

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