Electrophysiological studies on lateral intercellular spaces ofNecturus gallbladder epithelium

1985 ◽  
Vol 403 (3) ◽  
pp. 301-307 ◽  
Author(s):  
O. Ikonomov ◽  
M. Simon ◽  
E. Fr�mter
Keyword(s):  
Gallbladder Epithelium ◽  
Intercellular Spaces ◽  
Lateral Intercellular Spaces ◽  
Electrophysiological Studies

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

1992 ◽  
Vol 99 (3) ◽  
pp. 297-316 ◽  
Author(s):  
L Reuss ◽  
B Simon ◽  
Z Xi
Keyword(s):  
Cell Membrane ◽  
Partial Substitution ◽  
Gallbladder Epithelium ◽  
Intercellular Spaces ◽  
Streaming Potentials ◽  
Necturus Gallbladder ◽  
Lateral Intercellular Spaces ◽  
Transepithelial Voltage ◽  
Concentration Changes ◽  
Time Courses

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 (Vms) change (reference, basolateral solution) was positive with sucrose addition and negative with sucrose removal. Bilateral Cl- removal (cyclamate replacement) had no effect on the polarity or magnitude of the Vms change elicited by addition of 100 mM sucrose. In contrast, bilateral Na+ removal (tetramethylammonium [TMA+] replacement) inverted the Vms change (from 2.7 +/- 0.3 to -3.2 +/- 0.2 mV). Replacement of Na+ and Cl- with TMA+ and cyclamate, respectively, abolished the change in Vms. 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 Vms 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 TBACl are similar. Hyperosmotic and hypoosmotic challenges yielded initial Vms 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 Vms 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.

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
Sign in / Sign up

Export Citation Format

Share Document