scholarly journals Mucosal surface morphology of the toad urinary bladder. Scanning electron microscope study of the natriferic and hydro-osmotic response to vasopressin

1978 ◽  
Vol 77 (2) ◽  
pp. 598-610 ◽  
Author(s):  
JW Mills ◽  
LE Malick
Keyword(s):  
Urinary Bladder ◽  
Surface Morphology ◽  
Water Flux ◽  
Granular Cell ◽  
Mucosal Surface ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Scanning Electron Microscope Study ◽  
Osmotic Response ◽  
Scanning Electron

The mucosal cell surface of the toad urinary bladder was examined by scanning electron microscopy, and changes in the structure of the surface of the granular cell were correlated with specific physiological responses to vasopressin. Survey views of the mucosal surface demonstrated that there was no consistent repeating anatomical relationship between the granular cell and the mitochondria-rich cell that would support the concept of cooperativeness in the response to vasopressin. During base-line states of Na+-transport and water flux, the microvilli on the mucosal surface of the granular cell are arranged in a ridge-like network with occasional individual projections. When water flux is increased by exposing the tissue to vasopressin, in the presence of an osmotic gradient across the tissue the microvilli on the granular cell lose the ridge structure and appear, predominantly, as individual projection. Variability-of this appearance points out the necessity of examining large areas and many samples before the significance of any morphological change can be assessed. Blocking the simultaneously occurring natriferic response of the toad urinary bladder with 10(-2)M ouabain does not prevent these changes in the microvilli. When the hydro-osmotic response is blocked by eliminating the osmotic gradient, the granular cell shows no consistent change in mucosal surface morphology even when fixed at the height of the natriferic response. The mitochondria-rich and mucous cells did not show any change in morphology throughout these studies. We conclude that the changes in the mucosal surface morphology of the toad bladder seen after exposure to vasopressin are a result of the increased water flux that occurs when an osmotic gradient exists across the tissue, and are not related to the natriferic response or any specific alteration in the membrane properties.

Fluorescent markers to study membrane retrieval in antidiuretic hormone-treated toad urinary bladder

1986 ◽  
Vol 251 (2) ◽  
pp. C274-C284 ◽  
Author(s):  
H. W. Harris ◽  
J. B. Wade ◽  
J. S. Handler
Keyword(s):  
Electron Microscopy ◽  
Urinary Bladder ◽  
Horseradish Peroxidase ◽  
Antidiuretic Hormone ◽  
Apical Membrane ◽  
Granular Cell ◽  
Cell Uptake ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Apical Surface

Antidiuretic hormone (ADH) stimulation of toad urinary bladder causes fusion of intracellular vesicles called aggrephores with the apical plasma membrane of granular cells. Aggrephores contain intramembrane particle aggregates whose appearance in the apical membrane is believed to produce a large increase in its water permeability. ADH removal (ADH washout) is thought to cause the retrieval of aggrephores into granular cell cytoplasm. We studied granular cell uptake of dextran and horseradish peroxidase conjugated with fluorescein, rhodamine, or both during ADH washout. Granular cell uptake of fluorescent dextran was dependent on prior exposure to ADH, a linear function of dextran concentration, and increased by a transepithelial osmotic gradient. Immediately after removal of ADH, granular cell fluorescence was finely dispersed and located near the apical surface. Subsequently, it coalesced into larger bodies. This change was most apparent when a single bladder was subjected to two cycles of ADH stimulation and removal using a dextran containing a different fluorophore for each cycle. The ultrastructural correlate for these fluorescent patterns was identified using rhodamine-labeled horseradish peroxidase. Electron microscopy showed that after detachment from the apical membrane, label was initially in tubular-shaped vesicles near the apical surface. Later, these vesicles clustered near multivesicular bodies and transferred their label to these structures. These tubular vesicles closely resemble the morphology of aggrephores visualized by freeze-fracture electron microscopy. We conclude that these fluorescent compounds can be used as markers for the luminal contents of membrane retrieved during ADH washout and allow detailed study of its intracellular processing.

OSMOTIC INHIBITION OF THE NATRIFERIC RESPONSE OF THE TOAD URINARY BLADDER TO VASOPRESSIN

1975 ◽  
Vol 67 (1) ◽  
pp. 119-125
Author(s):  
P. J. BENTLEY
Keyword(s):  
Urinary Bladder ◽  
Water Movement ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Electrical Potential Difference ◽  
Osmotic Gradient

SUMMARY The electrical potential difference and short-circuit current (scc, reflecting active transmural sodium transport) across the toad urinary bladder in vitro was unaffected by the presence of hypo-osmotic solutions bathing the mucosal (urinary) surface, providing that the transmural flow of water was small. Vasopressin increased the scc across the toad bladder (the natriferic response), but this stimulation was considerably reduced in the presence of a hypo-osmotic solution on the mucosal side, conditions under which water transfer across the membrane was also increased. This inhibition of the natriferic response did not depend on the direction of the water movement, for if the osmotic gradient was the opposite way to that which normally occurs, the response to vasopressin was still reduced. The natriferic response to cyclic AMP was also inhibited in the presence of an osmotic gradient. Aldosterone increased the scc and Na+ transport across the toad bladder but this response was not changed when an osmotic gradient was present. The physiological implications of these observations and the possible mechanisms involved are discussed.

Release of cyclic AMP by toad urinary bladder

1975 ◽  
Vol 228 (3) ◽  
pp. 954-958 ◽  
Author(s):  
S Urakabe ◽  
JS Handler ◽  
J Orloff
Keyword(s):  
Epithelial Cells ◽  
Urinary Bladder ◽  
Cyclic Amp ◽  
Cell Membrane ◽  
Water Permeability ◽  
Ringer Solution ◽  
Mucosal Surface ◽  
Toad Urinary Bladder ◽  
Solution Bathing

Cyclic AMP accumulates in the Ringer solution bathing the toad urinary bladder in vitro. At least 4 times more cyclic AMP is released into the solution bathing the serosal surface than into the solution bathing the mucosal surface. Most of the cyclic AMP originates in the epithelial cells rather than the stroma. Vasopressin increased the content of cyclic AMP in the epithelial cells and increases the amount of cyclic AMP in the Ringer solution. Since there is not an increase in medium cyclic AMP when cell cyclic AMP levels are increased by theophylline, it is suggested that theophylline may reduce the permeability of the cell membrane to cyclic AMP. Finally, it is demonstrated that 10 mM NaF increase the amount of cyclic AMP in the epithelial cells and in the solution bathing the bladder, but block the effect of vasopressin on water permeability, presumably at a step subsequent to the formation of cyclic AMP.

Water and nonelectrolyte permeabilities of apical membranes of toad urinary bladder granular cells

1992 ◽  
Vol 262 (5) ◽  
pp. C1109-C1118 ◽  
Author(s):  
E. B. Grossman ◽  
H. W. Harris ◽  
R. A. Star ◽  
M. L. Zeidel
Keyword(s):  
Urinary Bladder ◽  
Plasma Membranes ◽  
Magnetic Beads ◽  
Apical Membrane ◽  
Granular Cell ◽  
Structural Features ◽  
Toad Urinary Bladder ◽  
Apical Surface ◽  
General Applicability ◽  
Apical Membranes

Certain types of epithelial cells such as those lining the toad urinary bladder have been classified as "tight" because their apical membranes exhibit low permeabilities to water, ions, and small nonelectrolytes. However, the permeability properties and structural features of these specialized apical membranes remain unclear because these membranes have never been purified. To isolate toad bladder granular cell apical membranes, we derivatized the bladder apical surface with the membrane-impermeant bifunctional reagent N-hydroxysulfosuccinimydyl-S,S-biotin (NHS-SS-biotin). After cell disruption, these derivatized apical membranes were purified using streptavidin-coated magnetic beads in a magnetic field. With the use of lactoperoxidase-mediated radioiodination as a marker for apical membrane, this preparative procedure purified apical membrane 48- or 72-fold as compared with homogenate. Thin section electron microscopy revealed unilamellar vesicles with some nonvesiculated membranes, while fragments of organelles such as mitochondria were absent. Water and nonelectrolyte permeabilities of purified apical membrane vesicles were similar to those obtained in intact bladders in the absence of antidiuretic hormone stimulation. The results demonstrate that isolated apical vesicles do not contain water channels and confirm the applicability of Overton's rule to the apical membrane of the toad urinary bladder. The technique has general applicability to isolation of other plasma membranes, and the apical membranes obtained are suitable for structural analysis.

Modulation of antidiuretic hormone-dependent capacitance and water flow in toad urinary bladder

1984 ◽  
Vol 246 (4) ◽  
pp. F501-F508
Author(s):  
L. G. Palmer ◽  
N. Speez
Keyword(s):  
Urinary Bladder ◽  
Antidiuretic Hormone ◽  
Water Flow ◽  
Water Permeability ◽  
Apical Membrane ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Apical Surface ◽  
Membrane Area ◽  
Close Relationship

To test the hypothesis that antidiuretic hormone- (ADH) dependent water permeability is associated with changes in apical membrane area, hormone-dependent water flow and capacitance changes were measured in the toad urinary bladder under a number of different conditions. Dose-response relationships for water flow (Jv) and capacitance increases (delta C) were similar from 1 to 20 mU/ml ADH. At higher concentrations, Jv reached a plateau, while delta C decreased. The decrease in delta C was prevented by elimination of the osmotic gradient across the tissue. Serosal hydrazine (10 mM) increased Jv sevenfold and delta C threefold in the presence of 1 mU/ml ADH. Mucosal NH4Cl, at constant mucosal pH, increased Jv by 50-100%, but did not significantly change delta C. In the absence of an osmotic gradient, mucosal NH+4 increased delta C by 50%. NH4Cl had no effect on hydroosmotic response to 8-bromo-adenosine 3',5'-cyclic monophosphate (cAMP). Mucosal CO2 (9%) decreased Jv by greater than 90%, and delta C by 60% with 20 mU/ml ADH. Mucosal CO2 also inhibited the hydroosmotic response to 8-bromo-cAMP. Removal of serosal Na diminished cAMP-dependent Jv and delta C. The results confirmed the close relationship between ADH-dependent water permeability and membrane capacitance. They indicate, however, that under some circumstances membrane may be retrieved from the apical surface without affecting water permeability.

Protein synthesis inhibitors attenuate water flow in vasopressin-stimulated toad urinary bladder

1988 ◽  
Vol 254 (1) ◽  
pp. F139-F144
Author(s):  
B. S. Hoch ◽  
M. B. Ast ◽  
M. J. Fusco ◽  
M. Jacoby ◽  
S. D. Levine
Keyword(s):  
Protein Synthesis ◽  
Protein Kinase ◽  
Urinary Bladder ◽  
Water Flow ◽  
Toad Urinary Bladder ◽  
Osmotic Gradient ◽  
Protein Synthesis Inhibitors ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein

Vasopressin stimulates the introduction of aggregated particles, which may represent pathways for water flow, into the luminal membrane of toad urinary bladder. It is not known whether water transport pathways are degraded on removal from membrane or whether they are recycled. We examined the effect of the protein synthesis inhibitors cycloheximide and puromycin using repeated 30-min cycles of vasopressin followed by washout of vasopressin, all in the presence of an osmotic gradient, a protocol that maximizes aggregate turnover. “High dose” cycloheximide (200 micrograms/ml) inhibited flow immediately. “Low dose” cycloheximide (1 microgram/ml) did not affect initial flow; however, flow was inhibited by the fourth restimulation. On further rechallenge, inhibition persisted but did not increase. In the absence of vasopressin, inhibition did not develop. Despite the inhibition of flow in vasopressin-treated tissues, the cAMP-dependent protein kinase ratio (-cAMP/+cAMP), an index of in vivo cAMP effect, was elevated in cycloheximide-treated tissues, suggesting modulation at a distal site in the stimulatory cascade. Cycloheximide inhibited flow when 10 microM forskolin or 0.2 mM 8-BrcAMP was substituted for vasopressin in the fourth period; however, MIX (4 mM)-stimulated flow was enhanced by 1 microgram/ml cycloheximide but inhibited by 200 micrograms/ml cycloheximide. [14C]urea permeability was not inhibited by cycloheximide. Puromycin (0.5 mM) also inhibited water flow by the fourth challenge with vasopressin. The data suggest that protein synthesis inhibitors attenuate flow at a site that is distal to cAMP-dependent protein kinase.(ABSTRACT TRUNCATED AT 250 WORDS)

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