scholarly journals Evidence that ADH-stimulated intramembrane particle aggregates are transferred from cytoplasmic to luminal membranes in toad bladder epithelial cells.

1980 ◽  
Vol 85 (1) ◽  
pp. 83-95 ◽  
Author(s):  
J Muller ◽  
W A Kachadorian ◽  
V A DiScala
Keyword(s):  
Urinary Bladder ◽  
Freeze Fracture ◽  
Toad Urinary Bladder ◽  
Granular Cells ◽  
Thin Sections ◽  
Intramembrane Particle ◽  
Luminal Membrane ◽  
Particle Aggregates ◽  
Cytoplasmic Structures ◽  
Induced Changes

In freeze-fracture (FF) preparations of ADH-stimulated toad urinary bladder, characteristic intramembrane particle (IMP) aggregates are seen on the protoplasmic (P) face of the luminal membrane of granular cells while complementary parallel grooves are found on the exoplasmic (E) face. These IMP aggregates specifically correlate with ADH-induced changes in water permeability. Tubular cytoplasmic structures whose membranes contain IMP aggregates which look identical to the IMP aggregates in the luminal membrane have also been described in granular cells from unstimulated and ADH-stimulated bladders. The diameter of these cytoplasmic structures (0.11 +/- 0.004 micrometers) corresponds to that of tubular invaginations of the luminal membrane seen in thin sections of ADH-treated bladders (0.13 +/- 0.005 micrometers). Continuity between the membranes of these cytoplasmic structures (which are not granules) and the luminal membrane has been directly observed in favorable cross-fractures. In FF preparations of the luminal membrane, these apparent fusion events are seen as round, ice-filled invaginations (0.13 +/- 0.01 micrometer Diam), of which about half have the characteristic ADH-associated aggregates near the point of membrane fusion. They are less numerous than, but linearly related to, the number of aggregates counted in the same preparations (n = 78, r = 0.71, P less than 0.01). These observations suggest that the IMP aggregates seen in luminal membrane after ADH stimulation are transferred preformed by fusion of cytoplasmic with luminal membrane.

scholarly journals Role of osmotic forces in exocytosis: studies of ADH-induced fusion in toad urinary bladder.

1981 ◽  
Vol 91 (2) ◽  
pp. 584-588 ◽  
Author(s):  
W A Kachadorian ◽  
J Muller ◽  
A Finkelstein
Keyword(s):  
Plasma Membrane ◽  
Urinary Bladder ◽  
Antidiuretic Hormone ◽  
Basic Mechanism ◽  
Toad Urinary Bladder ◽  
Bathing Medium ◽  
Intramembrane Particle ◽  
Luminal Membrane ◽  
Particle Aggregates

Antidiuretic hormone (ADH) treatment of toad urinary bladder activates an exocytotic-like process by which intramembrane particle aggregates are transferred from membranes of elongated cytoplasmic tubules to the luminal-facing plasma membrane. We find that the number of these ADH-induced fusion events, and the number of aggregates appearing in the luminal membrane, are reduced when the luminal bathing medium is made hyperosmotic. As an apparent consequence of the inhibition of their fusion with the luminal membrane, the elongated cytoplasmic tubules become enormously swollen into large, rounded vesicles. These results are consistent with the view that osmotic forces are essential to the basic mechanism of exocytosis.

Freeze-fracture electron microscopy: relationship of membrane structural features to transport physiology

1977 ◽  
Vol 232 (2) ◽  
pp. F77-F83 ◽  
Author(s):  
J. B. Wade ◽  
W. A. Kachadorian ◽  
V. A. DiScala
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Structural Features ◽  
Toad Urinary Bladder ◽  
Luminal Membrane ◽  
Cautious Interpretation ◽  
Freeze Fracture Electron Microscopy ◽  
Induced Changes ◽  
Relationship Of ◽  
Fracture Electron

Recent observations utilizing freeze-fracturing electron microscopy are discussed which indicate that the membrane structural features visualized by this technique may in some instances be related to specialized membrane transport properties. The occurrence of organized aggregates of intramembrane particles observed in vasopressin or cAMP-treated toad urinary bladder has been found to be closely correlated with induced changes in the permeability of the luminal membrane. Although a cautious interpretation is considered appropriate, these observations raise the possibility that some aspects of hormone action may be restricted to limited regions of membrane. Difficulties in interpretation and some serious limitations of the freeze-fracture technique are discussed.

Effects of serosal hypertonicity on water permeability in toad urinary bladder

1990 ◽  
Vol 258 (5) ◽  
pp. C871-C878 ◽  
Author(s):  
W. A. Kachadorian ◽  
K. R. Spring ◽  
N. L. Shinowara ◽  
J. Muller ◽  
T. A. Palaia ◽  
...  
Keyword(s):  
Urinary Bladder ◽  
Water Permeability ◽  
Water Movement ◽  
Granular Cell ◽  
Toad Urinary Bladder ◽  
Morphological Examination ◽  
Tissue Water ◽  
Coated Pits ◽  
Thin Sections ◽  
Luminal Membrane

We studied in toad urinary bladder the effects of serosal hypertonicity on tissue water permeability, granular cell luminal membrane water permeability, and granular cell luminal membrane particle aggregates and compared them with effects of antidiuretic hormone (ADH). In tissues challenged by a hypertonic (447 mosmol/kgH2O) serosal bath, luminal membrane aggregates were structurally similar to those caused by ADH. The tissue water permeability increase induced by serosal hypertonicity was much less than that caused by a maximally stimulating concentration of ADH on tissue in isotonic serosal baths with approximately the same transmural gradient. The difference is explained not only by a reduced incidence of luminal membrane aggregates but also by an increased resistance to water movement at a postluminal membrane site. Measurements of luminal membrane water permeability showed a close correlation with luminal membrane aggregate frequency, indicating that the calculated permeability of an individual aggregate was a constant. Thus the relation of luminal membrane aggregates to tissue osmotic permeability is modified by serosal hypertonicity. Morphological examination of these tissues suggested that luminal membrane aggregates may be less stable in the absence of hormone. This was evident by the proportionally greater number of structures interpreted as aggregates captured in the process of disassembly ("patches"). Membrane depressions containing intramembrane particles ("craters") were also observed. They corresponded in terms of frequency and size to coated pits as seen in thin sections.

Comparison of effects of forskolin, cAMP, and vasopressin on Pf/Pd(w) of toad urinary bladder luminal membrane

1987 ◽  
Vol 252 (2) ◽  
pp. F357-F360
Author(s):  
S. D. Levine ◽  
M. Jacoby
Keyword(s):  
Electron Microscopy ◽  
Urinary Bladder ◽  
Freeze Fracture ◽  
Toad Urinary Bladder ◽  
Cyclic Monophosphate ◽  
Luminal Membrane ◽  
Flat Portion ◽  
Freeze Fracture Electron Microscopy ◽  
Rate Limiting ◽  
Fracture Electron

We have reported that Pf/Pd(w) (the ratio of osmotic and diffusional water permeabilities) for the luminal membrane of toad urinary bladder is approximately 17 for tissues stimulated with either vasopressin or 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP). In a recent abstract, Kachadorian and co-workers have shown that tissues stimulated with adenosine 3',5'-cyclic monophosphate (cAMP) or forskolin have a lower Pf than would be anticipated from the frequency of aggregates visualized on the flat portion of the luminal membrane using freeze-fracture electron microscopy. We report here measurements of Pf/Pd(w) for the luminal membrane of tissues receiving these agents: Pf/Pd(w) for submaximally stimulated tissues was the same, regardless of whether the stimulant was vasopressin (12.7 +/- 0.3), forskolin (13.7 +/- 0.9), or cAMP (12.0 +/- 1.3). The calculated Pd(w)'s for the series barrier were also identical (6.8 +/- 0.5, 6.5 +/- 0.3, and 8.2 +/- 1.0 X 10(-4) cm/s respectively). Our data, taken together with those of Kachadorian et al. are consistent with a number of possibilities: because our methodology does not permit estimation of Pf for the series barrier, we cannot rule out the possibility of a "post-luminal barrier" that is rate-limiting for Pf, but not for Pd(w) in forskolin- and cAMP-stimulated tissues, Pf and Pd(w) of the luminal surface aggregates could decrease in parallel, so that luminal membrane Pf/Pd(w) remains constant, and there could be a diminished frequency of fused aggregate-rich aggrephores, but not of aggregates that are on the flat portion of the luminal membrane. Only the latter can be unequivocally quantitated using freeze-fracture electron microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of quantified coated pit profiles in thin sections and freeze-fracture replicas of granular epithelial cells of the toad urinary bladder

1992 ◽  
Vol 50 (1) ◽  
pp. 720-721
Author(s):  
Nancy L. Shinowara ◽  
Jenchang Yu ◽  
Thomas A. Palaia
Keyword(s):  
Apical Membrane ◽  
Unit Area ◽  
Collecting Duct ◽  
Freeze Fracture ◽  
Toad Urinary Bladder ◽  
Granular Cells ◽  
Coated Pits ◽  
Thin Sections ◽  
Membrane Changes ◽  
Apical Membranes

It is well known that stimulation of granular cells by arginine vasopressin (AVP) results in apical membrane changes, including an increased water permeability and an associated exocytotic delivery of aggregates of intramembrane particles, Endocytotic clathrin-coated pits appear in stimulated collecting duct principal cells, which transport water in mammalian kidneys. Recently, presumptive coated pits (CPs), identified in replicas, were reported in apical membranes of stimulated granular cells. This study describes the comparison of structurally defined sectioned-CPs (s-CPs per unit membrane length with presumptive, replicated-CPs (r-CPs) per unit area in bladders when initial CP formation was expected.

Aggregate-carrying membranes during ADH stimulation and washout in toad bladder

1984 ◽  
Vol 247 (1) ◽  
pp. C90-C98 ◽  
Author(s):  
J. Muller ◽  
W. A. Kachadorian
Keyword(s):  
Water Flow ◽  
Cytochalasin B ◽  
Multivesicular Body ◽  
Osmotic Gradient ◽  
Luminal Surface ◽  
Granular Cells ◽  
Body Type ◽  
Fusion Frequency ◽  
Luminal Membrane ◽  
Cytoplasmic Structures

Aggregates of intramembrane particles are found in cytoplasmic structures that we now term “aggrephores.” Antidiuretic hormone (ADH) causes aggrephores to fuse with the luminal membrane. Aggregates subsequently become dispersed in the membrane and behave as sites for water flow. In the present studies we examined further the behavior of aggrephores. 1) Bladders stimulated for 10, 30, or 60 min in the absence of an osmotic gradient had two to three times more fusions as those stimulated in the presence of a gradient, indicating that aggrephore fusion frequency is influenced by water flow. 2) ADH stimulation did not change the projected luminal surface area of granular cells. Thus fused aggrephores remain fixed while aggregates move from the aggrephore to flat areas of luminal membrane. 3) Horseradish peroxidase, present in the mucosal baths of bladders stimulated with and then washed of ADH, was found in the lumen of cytoplasmic aggrephores; aggrephores therefore detach from the luminal membrane during washout. The same bladders had about twice as many multivesicular body-type lysosomes as unstimulated bladders, suggesting that, after detachment, aggrephores may join or become lysosomes. 4) Colchicine did not affect the rate of disappearance of fusion sites during washout, whereas cytochalasin B slowed it, suggesting that aggrephore detachment depends of microfilaments, but not microtubules.

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