The chloride concentration in the lateral intercellular spaces of MDCK cell monolayers

1995 ◽  
Vol 144 (1) ◽  
Author(s):  
P. Xia ◽  
B.-E. Persson ◽  
K.R. Spring
Keyword(s):  
Mdck Cell ◽  
Chloride Concentration ◽  
Intercellular Spaces ◽  
Cell Monolayers ◽  
Lateral Intercellular Spaces

pH, morphology, and diffusion in lateral intercellular spaces of epithelial cell monolayers

1994 ◽  
Vol 266 (1) ◽  
pp. C73-C80 ◽  
Author(s):  
P. J. Harris ◽  
J. Y. Chatton ◽  
P. H. Tran ◽  
P. M. Bungay ◽  
K. R. Spring
Keyword(s):  
Diffusion Coefficient ◽  
Mdck Cells ◽  
Transepithelial Transport ◽  
Osmotic Gradient ◽  
Intercellular Spaces ◽  
Cell Monolayers ◽  
Lateral Intercellular Spaces ◽  
Epithelial Cell Monolayers ◽  
And Diffusion ◽  
Measuring Ph

The lateral intercellular spaces (LIS) of reabsorptive epithelia are the site of the proposed local osmotic gradient responsible for transepithelial transport. We developed techniques for loading the LIS of living cultured renal cells (MDCK and LLC-PK1) with the fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF), visualizing LIS geometry, measuring pH, and determining the BCECF diffusion coefficient within the LIS. The LIS pH was remarkably constant and differed substantially from that of the superfusate in both the presence and absence of HCO3 or CO2. The LIS of MDCK cells had a pH of 7.66 +/- 0.04 in bicarbonate-free solutions of pH 7.0, 7.4, or 7.8. In bicarbonate-containing solutions, MDCK LIS pH was acidic to the superfusate by 0.3-0.4 units. In the absence of bicarbonate, the LIS of LLC-PK1 cells was markedly acidic (6.83 +/- 0.05), becoming alkaline by approximately 0.25 units in the presence of bicarbonate. Gradients in pH or dye concentration were not detected within the LIS. The diffusion coefficient of BCECF within the LIS was approximately equal to that seen in free solution.

scholarly journals Pseudo-streaming potentials in Necturus gallbladder epithelium. II. The mechanism is a junctional diffusion potential.

1992 ◽  
Vol 99 (3) ◽  
pp. 317-338 ◽  
Author(s):  
L Reuss ◽  
B Simon ◽  
C U Cotton
Keyword(s):  
Time Course ◽  
Bathing Solution ◽  
Intercellular Spaces ◽  
Similar Time ◽  
Streaming Potentials ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Transepithelial Voltage ◽  
Time Courses ◽  
Good Agreement

The mechanisms of apparent streaming potentials elicited across Necturus gallbladder epithelium by addition or removal of sucrose from the apical bathing solution were studied by assessing the time courses of: (a) the change in transepithelial voltage (Vms). (b) the change in osmolality at the cell surface (estimated with a tetrabutylammonium [TBA+]-selective microelectrode, using TBA+ as a tracer for sucrose), and (c) the change in cell impermeant solute concentration ([TMA+]i, measured with an intracellular double-barrel TMA(+)-selective microelectrode after loading the cells with TMA+ by transient permeabilization with nystatin). For both sucrose addition and removal, the time courses of Vms were the same as the time courses of the voltage signals produced by [TMA+]i, while the time courses of the voltage signals produced by [TBA+]o were much faster. These results suggest that the apparent streaming potentials are caused by changes of [NaCl] in the lateral intercellular spaces, whose time course reflects the changes in cell water volume (and osmolality) elicited by the alterations in apical solution osmolality. Changes in cell osmolality are slow relative to those of the apical solution osmolality, whereas lateral space osmolality follows cell osmolality rapidly, due to the large surface area of lateral membranes and the small volume of the spaces. Analysis of a simple mathematical model of the epithelium yields an apical membrane Lp in good agreement with previous measurements and suggests that elevations of the apical solution osmolality elicit rapid reductions in junctional ionic selectivity, also in good agreement with experimental determinations. Elevations in apical solution [NaCl] cause biphasic transepithelial voltage changes: a rapid negative Vms change of similar time course to that of a Na+/TBA+ bi-ionic potential and a slow positive Vms change of similar time course to that of the sucrose-induced apparent streaming potential. We conclude that the Vms changes elicited by addition of impermeant solute to the apical bathing solution are pseudo-streaming potentials, i.e., junctional diffusion potentials caused by salt concentration changes in the lateral intercellular spaces secondary to osmotic water flow from the cells to the apical bathing solution and from the lateral intercellular spaces to the cells. Our results do not support the notion of junctional solute-solvent coupling during transepithelial osmotic water flow.

Novel bUT-B2 urea transporter isoform is constitutively activated

2009 ◽  
Vol 297 (2) ◽  
pp. R323-R329 ◽  
Author(s):  
P. Tickle ◽  
A. Thistlethwaite ◽  
C. P. Smith ◽  
G. S. Stewart
Keyword(s):  
Protein Kinase ◽  
Transient Response ◽  
Mdck Cell ◽  
Kinase Activity ◽  
Intracellular Camp ◽  
Protein Kinase Activity ◽  
Urea Transport ◽  
Urea Transporter ◽  
Cell Monolayers ◽  
Human Orthologs

Our previous studies have detailed a novel facilitative UT-B urea transporter isoform, bUT-B2. Despite the existence of mouse and human orthologs, the functional characteristics of UT-B2 remain undefined. In this report, we produced a stable MDCK cell line that expressed bUT-B2 protein and investigated the transepithelial urea flux across cultured cell monolayers. We observed a large basal urea flux that was significantly reduced by known inhibitors of facilitative urea transporters; 1,3 dimethylurea ( P < 0.001, n = 17), thionicotinamide ( P < 0.05, n = 11), and phloretin ( P < 0.05, n = 9). Pre-exposure for 1 h to the antidiuretic hormone vasopressin had no effect on bUT-B2-mediated urea transport (NS, n = 3). Acute vasopressin exposure for up to 30 min also failed to elicit any transient response (NS, n = 9). Further investigation confirmed that bUT-B2 function was not affected by alteration of intracellular cAMP (NS, n = 4), intracellular calcium (NS, n = 3), or protein kinase activity (NS, n = 4). Finally, immunoblot data suggested a possible role for glycosylation in regulating bUT-B2 function. In conclusion, this study showed that bUT-B2-mediated transepithelial urea transport was constitutively activated and unaffected by known regulators of renal UT-A urea transporters.

Transport of iron chelators and chelates across MDCK cell monolayers: implications for iron excretion during chelation therapy

2010 ◽  
Vol 91 (3) ◽  
pp. 401-412 ◽  
Author(s):  
Xi-Ping Huang ◽  
Jake J. Thiessen ◽  
Michael Spino ◽  
Douglas M. Templeton
Keyword(s):  
Mdck Cell ◽  
Chelation Therapy ◽  
Iron Chelators ◽  
Cell Monolayers ◽  
Iron Excretion

scholarly journals Studies on the Electrical Potential Profile across Rabbit Ileum

1971 ◽  
Vol 57 (6) ◽  
pp. 639-663 ◽  
Author(s):  
Richard C. Rose ◽  
Stanley G. Schultz
Keyword(s):  
Amino Acids ◽  
Brush Border ◽  
Electrical Potential ◽  
Metabolic Inhibitors ◽  
Electrical Potential Difference ◽  
Intercellular Spaces ◽  
Cell Interior ◽  
Rabbit Ileum ◽  
Lateral Intercellular Spaces ◽  
Rapid Replacement

When isolated strips of mucosal rabbit ileum are bathed by physiological electrolyte solution the electrical potential difference (PD) across the brush border (ψmc) averages 36 mv, cell interior negative. Rapid replacement of Na in the mucosal solution with less permeant cations, Tris or choline, results in an immediate hyperpolarization of ψmc. Conversely, replacement of choline in the mucosal solution with Na results in an abrupt depolarization of ψmc. These findings indicate that Na contributes to the conductance across the brush border. The presence of actively transported sugars or amino acids in the mucosal solution brings about a marked depolarization of ψmc and a smaller increase in the transmural PD (Δψms). It appears that the Na influx that is coupled to the influxes of amino acids and sugars is electrogenic and responsible for the depolarization of ψmc. Under control conditions Δψms can be attributed to the depolarization of ψmc together with the presence of a low resistance transepithelial shunt, possibly the lateral intercellular spaces. However, quantitatively similar effects of amino acids on ψmc are also seen in tissues poisoned with metabolic inhibitors or ouabain. Under these conditions Δψmc is much smaller than under control conditions. Thus, the depolarization of ψmc might not account for the entire Δψms, observed in nonpoisoned tissue. An additional electromotive force which is directly coupled to metabolic processes might contribute to the normal Δψms.

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