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.

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.

Ultrastructural changes in isolated perfused proximal tubules during osmotic water flow

1987 ◽  
Vol 253 (6) ◽  
pp. F1091-F1104
Author(s):  
A. B. Maunsbach ◽  
S. Tripathi ◽  
E. L. Boulpaep
Keyword(s):  
Cell Volume ◽  
Water Flow ◽  
Streaming Potential ◽  
Volume Density ◽  
Proximal Tubules ◽  
Ultrastructural Changes ◽  
Organic Substrates ◽  
Osmotic Water ◽  
Cell Volumes ◽  
Osmotic Water Flow

Steady-state effects of osmotic gradients on extracellular spaces and cell volumes were studied by ultrastructural morphometry in isolated perfused Ambystoma proximal tubules. Solute clamping, high-resolution pressure and flow control of lumen and bath solutions were all ascertained before and during fixation. Isosmotic removal of organic substrates in the lumen reversibly abolished transport, as confirmed by transepithelial potential decrease from -4.7 +/- 0.5 to -0.5 +/- 0.2 mV (n = 8) but had no effect on ultrastructural parameters. The walls of the extracellular spaces are therefore not deformed by spontaneous solute-coupled water transport. A hyperosmolar lumen generated a streaming potential of -1.56 +/- 0.15 mV (n = 8), reduced cell volume to 65%, reduced lateral intercellular space (LIS) volume to 20%, and LIS volume density to 29% of control without significant effects on the volume of the basal extracellular labyrinth (BEL). A hyperosmolar bath generated a streaming potential of +1.96 +/- 0.30 mV (n = 7), reduced cell volume to 68%, and increased LIS volume density to 236% of control. BEL volume was 55% larger during lumen-to-bath flow than during bath-to-lumen flow. Because cell volume reduction is very similar for both directions of osmotic water flow, the oppositely directed volume changes in the extracellular spaces are secondary to transepithelial water flow. The greater change in volume of LIS compared with BEL indicates that the outermost parts of the LIS are more resistive to transepithelial water flow than the slitlike communications of the BEL with the peritubular space.

Vasopressin- and cAMP-induced changes in ultrastructure of isolated perfused inner medullary collecting ducts

1993 ◽  
Vol 265 (2) ◽  
pp. F225-F238 ◽  
Author(s):  
S. Nielsen ◽  
J. Muller ◽  
M. A. Knepper
Keyword(s):  
Water Permeability ◽  
Apical Membrane ◽  
Endocytic Pathway ◽  
Ultrastructural Changes ◽  
Osmotic Water Permeability ◽  
Intercellular Spaces ◽  
Osmotic Water ◽  
Collecting Ducts ◽  
Induced Changes ◽  
Camp Stimulation

Studies were performed to correlate arginine vasopressin (AVP)-induced changes in epithelial ultrastructure with changes in osmotic water permeability in isolated perfused rat terminal inner medullary collecting ducts (tIMCD). The tubules were perfused in three time periods, i.e., a 40-min basal period, a 40-min period with 0.1 nM AVP in the bath, and a 60-min withdrawal period. In each phase, the osmotic water permeability (Pf) was measured, and the perfused tubules were fixed for electron microscopy. AVP caused a four- to eightfold increase in Pf and induced several ultrastructural changes as follows: increased cell height of IMCD cells, expansion of the intercellular spaces, formation of large vacuoles, and increased coated pit density in the apical plasma membrane [from 0.6 +/- 0.2 (n = 6) to 2.9 +/- 0.3 (n = 7) pits/100 microns membrane length]. During AVP withdrawal, Pf decreased toward the basal value in association with partial reversal of the ultrastructural changes including a decrease in coated pit density to 1.0 +/- 0.2 (n = 4). Stimulation with 8-bromoadenosine 3',5'-cyclic monophosphate (8-bromo-cAMP) (0.1 mM) produced similar changes in Pf. Coated pit density increased to 2.1 +/- 0.4 (n = 4) after cAMP stimulation and after cAMP withdrawal decreased to 1.2 +/- 0.2 (n = 6). In contrast to stimulation with AVP, cAMP stimulation did not result in dilated intercellular spaces or formation of large vacuoles. The only ultrastructural feature that directly correlated with the water permeability was the density of coated pits in the apical membrane. Organelles involved in the endocytic pathway were studied with cationized ferritin or albumin-gold in the luminal perfusate. At the end of 40 min basal perfusion or AVP stimulation, luminal tracer was found almost exclusively in large multivesicular bodies (MVB). Tubules perfused with tracer during AVP withdrawal demonstrated rapid tracer accumulation in small vesicles and small MVB within 3-5 min, a time point corresponding to the rapid phase of Pf decrease. Later (30-60 min) the label was mainly confined to large MVB. Occasionally during AVP stimulation or withdrawal, small coated vesicles and smooth vesicles with coated extensions were noted to contain tracer. The data demonstrate AVP-mediated coated pit formation and cellular changes and show very rapid internalization of apical membrane after AVP withdrawal.

scholarly journals THE EFFECT OF SMOOTH MUSCLE ON THE INTERCELLULAR SPACES IN TOAD URINARY BLADDER

1970 ◽  
Vol 46 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Donald R. DiBona ◽  
Mortimer M. Civan
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Water Flow ◽  
Toad Urinary Bladder ◽  
Reliable Index ◽  
Intercellular Spaces ◽  
Phase Microscopy ◽  
Osmotic Water ◽  
Smooth Muscle Relaxant ◽  
Osmotic Water Flow

Phase microscopy of toad urinary bladder has demonstrated that vasopressin can cause an enlargement of the epithelial intercellular spaces under conditions of no net transfer of water or sodium. The suggestion that this phenomenon is linked to the hormone's action as a smooth muscle relaxant has been tested and verified with the use of other agents effecting smooth muscle: atropine and adenine compounds (relaxants), K+ and acetylcholine (contractants). Furthermore, it was possible to reduce the size and number of intercellular spaces, relative to a control, while increasing the rate of osmotic water flow. A method for quantifying these results has been developed and shows that they are, indeed, significant. It is concluded, therefore, that the configuration of intercellular spaces is not a reliable index of water flow across this epithelium and that such a morphologic-physiologic relationship is tenuous in any epithelium supported by a submucosa rich in smooth muscle.

scholarly journals Tissue Sources and Blood Flow Limitations of Osmotic Water Transport Across the Peritoneum

1999 ◽  
Vol 10 (2) ◽  
pp. 347-353
Author(s):  
HAILU DEMISSACHEW ◽  
JOANNE LOFTHOUSE ◽  
MICHAEL F. FLESSNER
Keyword(s):  
Blood Flow ◽  
Water Transport ◽  
Water Flow ◽  
Water Flux ◽  
Hypertonic Solution ◽  
Water Fluxes ◽  
Volume Changes ◽  
Doppler Flowmetry ◽  
Chamber Volume ◽  
Osmotic Water

Abstract. Despite the daily use of hypertonic solutions to remove fluid from patients throughout the world who are undergoing peritoneal dialysis, the tissue sources of this water flow are unknown. To study this phenomenon in specific tissues, small plastic chambers were affixed to parietal and visceral surfaces of the peritoneum and were filled with either an isotonic or hypertonic solution. The volume changes over 60 to 90 min were determined and divided by the chamber area to yield the volume flux. The hypertonic solution produced a positive flux into the chamber of 0.6 to 1.1 μl/min per cm2 in all tissues tested. In contrast, the isotonic solution resulted in a net loss or an insignificant change in the chamber volume. Additional experiments tested the influence of blood flow on the hypertonic water flux during periods of control, reduced (50 to 80%), or postmortem (no) blood flow, as determined by laser Doppler flowmetry. With the exception of the liver, small but insignificant changes in the flux into the chamber were observed during the period of reduced flow; all water fluxes were markedly depressed during the postmortem period. It is concluded that both parietal and visceral tissues are sources of osmotically induced water flow into the cavity. Except for the liver, marked blood flow reductions have small but insignificant effects on osmotic water transport.

Activation energy for water transport in toad bladder

1983 ◽  
Vol 244 (1) ◽  
pp. C44-C49 ◽  
Author(s):  
P. Eggena
Keyword(s):  
Membrane Permeability ◽  
Water Flow ◽  
Room Temperature ◽  
Water Movement ◽  
Bladder Wall ◽  
Close Correlation ◽  
Bulk Water ◽  
Bulk Solution ◽  
Osmotic Water ◽  
Osmotic Water Flow

Activation energies (Ea) for water movement across vasopressin-(ADH) sensitive epithelia have been reported to be about 10 kcal/mol (1, 12). The present study shows that measurements of Ea for osmotic water flow across toad bladders are unreliable, because a temperature change induces marked alterations in membrane permeability to water within a 2.5-min interval. Thus bladders equilibrated with ADH either at room temperature or at 33 degrees C and then suddenly subjected to a lower temperature were found to exhibit a marked increase in membrane permeability to water. This observation suggests that there is a rapid turn-over of water permeability sites and that sudden exposure to cold inhibits the removal more than the induction of sites by ADH. To stabilize ADH-induced water channels for Ea measurements, bladders were exposed to ADH at room temperature, fixed with glutaraldehyde, and subjected to osmotic gradients at different temperatures. The Ea values for osmotic water flow across these ADH-permeabilized, glutaraldehyde-fixed bladders were 5.1 (4-12 degrees C), 4.3 (12-21 degrees C), 3.6 (21-36 degrees C), and 3.6 kcal/mol (30-38 degrees C). Ea values for shear viscosity of water in these temperature ranges were calculated to be 4.7, 4.2, 4.1, and 3.6 kcal/mol, respectively. The close correlation between Ea values for bulk water viscosity and osmotic water flow across the bladder wall suggests that an equivalent number of hydrogen bonds must be broken to achieve an increase in water flow through ADH-induced channels and an increase in fluidity of water in bulk solution.

scholarly journals PATHS OF TRANSTUBULAR WATER FLOW IN ISOLATED RENAL COLLECTING TUBULES

1969 ◽  
Vol 41 (2) ◽  
pp. 562-576 ◽  
Author(s):  
Jared J. Grantham ◽  
Charles E. Ganote ◽  
Maurice B. Burg ◽  
Jack Orloff
Keyword(s):  
Water Flow ◽  
Direct Evidence ◽  
Extracellular Fluid ◽  
Isotonic Solution ◽  
Intercellular Spaces ◽  
Osmotic Swelling ◽  
Induced Flow ◽  
Collecting Tubules ◽  
Intercellular Channel ◽  
Hydrostatic Pressure Difference

The cells of perfused rabbit collecting tubules swell and the intercellular spaces widen during osmotic flow of water from lumen to bath induced by antidiuretic hormone (ADH). Ouabain had no influence on these changes. In the absence of net water flow intercellular width was unaffected when tubules were swollen in hypotonic external media. Therefore, during ADH-induced flow widening of intercellular spaces is not a consequence of osmotic swelling of a closed intercellular compartment containing trapped solutes, but rather is due to flow of solution through the channel. Direct evidence of intercellular flow was obtained. Nonperfused tubules swollen in hypotonic media were reimmersed in isotonic solution with resultant entry of water into intercellular spaces. The widened spaces gradually collapsed completely. Spaces enlarged in this manner could be emptied more rapidly by increasing the transtubular hydrostatic pressure difference. In electron micrographs a path of exit of sufficient width to accommodate the observed rate of fluid flow was seen at the base of the intercellular channel. It is concluded that the intercellular spaces communicate with the external extracellular fluid and that water, having entered the cells across the luminal plasma membrane in response in ADH, leaves the cells by osmosis across both the lateral and basilar surface membranes.

Effects of prostacyclin on short-circuit current and water flow in the toad urinary bladder

1983 ◽  
Vol 244 (3) ◽  
pp. F270-F277
Author(s):  
T. Pohlman ◽  
J. Yates ◽  
P. Needleman ◽  
S. Klahr
Keyword(s):  
Urinary Bladder ◽  
Water Transport ◽  
Water Flow ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Camp Production ◽  
Acid Product ◽  
Osmotic Water ◽  
Osmotic Water Flow

The effects of prostaglandins of the E series on sodium and water transport have been studied extensively. PGE2 has been shown to inhibit the increase in osmotic water flow produced by vasopressin and to stimulate short-circuit current (SCC) in the toad bladder. On the other hand, the effects of prostacyclin (PGI2), an arachidonic acid product, on sodium and water transport have not been extensively evaluated. The present studies describe the effects of PGI2 on basal and vasopressin-stimulated osmotic water flow and on SCC in the urinary bladder of the toad. Studies were performed in the absence or presence of indomethacin. PGI2 in the absence of indomethacin had no effect on basal or vasopressin-stimulated osmotic water flow. When indomethacin was present, thereby eliminating intrinsic prostaglandin biosynthesis, PGI2 inhibited basal but not vasopressin-stimulated osmotic water flow. PGI2 increased SCC in the presence or absence of indomethacin. 6-keto PGF1 alpha, the stable metabolite of PGI2, had no effect on SCC. PGI2 stimulated cAMP production in isolated toad bladder epithelial cells. 2',5'-Dideoxyadenosine, an inhibitor of cAMP production, blocked the increase in SCC produced by PGI2, suggesting that the effects of this compound on SCC are mediated via cAMP.

The correlation of ethanol-induced depression of glucose and water transport with morphological changes in the hamster jejunum in vivo

1978 ◽  
Vol 56 (1) ◽  
pp. 123-131 ◽  
Author(s):  
J. E. Fox ◽  
T. F. McElligott ◽  
I. T. Beck
Keyword(s):  
Epithelial Cells ◽  
Light Microscopy ◽  
Glucose Transport ◽  
Water Transport ◽  
Structural Changes ◽  
Morphological Changes ◽  
Glucose Absorption ◽  
Intercellular Spaces ◽  
Lateral Intercellular Spaces

Glucose and water transport is depressed in the hamster jejunum in vivo by ethanol (4.8%) which also produced fluid-filled blebs at the tips of the villi. The epithelial cells over the blebs appeared stretched and cuboidal, the lateral intercellular spaces (LIS) were no longer recognizable, and the lacteals were closed. Forty-five minutes after discontinuation of the ethanol, water transport returned to normal while glucose transport remained depressed. At this time the villus structure had returned to normal. The blebs had disappeared, the LIS were again recognizable, and their appearance and number were similar to those in the control animals. Thus, the depression of water transport correlated with the obvious structural changes caused by ethanol; however, the depression of glucose absorption is associated with some effect of ethanol not evident by routine light microscopy.

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