Maintenance of Acidic Lateral Intercellular Spaces by Endogenous Fixed Buffers in MDCK Cell Epithelium

1998 ◽  
Vol 166 (1) ◽  
pp. 9-14 ◽  
Author(s):  
S.M. Dzekunov ◽  
K.R. Spring
Keyword(s):  
Mdck Cell ◽  
Intercellular Spaces ◽  
Lateral Intercellular Spaces

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.

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.

Size Variations in the Lateral Intercellular Spaces of the Endolymphatic Sac Induced by Dietary Factors

1990 ◽  
Vol 100 (3) ◽  
pp. 217???222 ◽  
Author(s):  
Phillip A. Wackym ◽  
Rinaldo F. Canalis ◽  
Ulla Friberg ◽  
Helge Rask-Andersen ◽  
Fred H. Linthicum
Keyword(s):  
Dietary Factors ◽  
Endolymphatic Sac ◽  
Intercellular Spaces ◽  
Lateral Intercellular Spaces

scholarly journals ULTRASTRUCTURAL STUDIES OF VASOPRESSIN EFFECT ON ISOLATED PERFUSED RENAL COLLECTING TUBULES OF THE RABBIT

1968 ◽  
Vol 36 (2) ◽  
pp. 355-367 ◽  
Author(s):  
Charles E. Ganote ◽  
Jared J. Grantham ◽  
Harold L. Moses ◽  
Maurice B. Burg ◽  
Jack Orloff
Keyword(s):  
Water Transport ◽  
Water Flow ◽  
Cell Membranes ◽  
Bulk Water ◽  
Ultrastructural Changes ◽  
Rabbit Kidney ◽  
Intercellular Spaces ◽  
Osmotic Water ◽  
Lateral Intercellular Spaces ◽  
Collecting Tubules

Isolated cortical collecting tubules from rabbit kidney were studied during perfusion with solutions made either isotonic or hypotonic to the external bathing medium. Examination of living tubules revealed a reversible increase in thickness of the cellular layer, prominence of lateral cell membranes, and formation of intracellular vacuoles during periods of vasopressin-induced osmotic water transport. Examination in the electron microscope revealed that vasopressin induced no changes in cell structure in collecting tubules in the absence of an osmotic difference and significant bulk water flow across the tubule wall. In contrast, tubules fixed during vasopressin-induced periods of high osmotic water transport showed prominent dilatation of lateral intercellular spaces, bulging of apical cell membranes into the tubular lumen, and formation of intracellular vacuoles. It is concluded that the ultrastructural changes are secondary to transepithelial bulk water flow and not to a direct effect of vasopressin on the cells, and that vasopressin induces osmotic flow by increasing water permeability of the luminal cell membrane. The lateral intercellular spaces may be part of the pathway for osmotically induced transepithelial bulk water flow.

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