scholarly journals FRACTURE FACES OF ZONULAE OCCLUDENTES FROM "TIGHT" AND "LEAKY" EPITHELIA

1973 ◽  
Vol 58 (2) ◽  
pp. 390-400 ◽  
Author(s):  
Philippa Claude ◽  
Daniel A. Goodenough
Keyword(s):  
Urinary Bladder ◽  
Large Fraction ◽  
Distal Tubule ◽  
Morphological Data ◽  
Physiological Data ◽  
Toad Urinary Bladder ◽  
Leaky Epithelia ◽  
Zonulae Occludentes ◽  
Zonula Occludens ◽  
Variable Morphology

Epithelia vary with respect to transepithelial permeability. In those that are considered "leaky", a large fraction of the passive transepithelial flux appears to follow the paracellular route, passing across the zonulae occludentes and moving down the intercellular clefts. In "tight" epithelia, the resistance of the paracellular pathway to passive flux is greatly increased. To see whether differences in the morphology of the zonula occludens could contribute to this variability in leakiness among epithelia, replicas of zonulae occludentes in freeze-fractured material from a variety of tight and leaky epithelia were examined. The junctions appear as a branching and anastomosing network of strands or grooves on the A and B membrane fracture faces, respectively. It was found that the zonula occludens from a "very leaky" epithelium, the proximal convoluted tubule of the mouse kidney, is extremely shallow in the apical-basal direction, consisting in most places of only one junctional strand. In contrast, the "very tight" frog urinary bladder exhibits a zonula occludens that is relatively deep (>0.5 µm) in the apical-basal direction, and consists of five or more interconnected junctional strands interposed between luminal and lateral membrane surfaces. Epithelia of intermediate permeabilities exhibited junctions with intermediate or variable morphology. Toad urinary bladder, mouse stomach, jejunum, and distal tubule, rabbit gallbladder, and Necturus kidney and gallbladder were also examined, and the morphological data from these epithelia were compared to physiological data from the literature.

scholarly journals THE STRUCTURE OF THE ZONULA OCCLUDENS

1974 ◽  
Vol 60 (1) ◽  
pp. 168-180 ◽  
Author(s):  
James B. Wade ◽  
Morris J. Karnovsky
Keyword(s):  
Urinary Bladder ◽  
Tight Junction ◽  
Cell Membranes ◽  
Adjacent Cell ◽  
Toad Urinary Bladder ◽  
Zonula Occludens ◽  
Single Set

Replicas of freeze-fractured toad urinary bladder and gallbladder were analysed in an attempt to determine the fracturing properties and structure of the zonula occludens (tight junction). Chalcroft and Bullivant have proposed that the junction has a double set of fibrils with one set associated with each of the adjacent cell membranes. However, the fracturing pattern that is observed might also result from only a single set of fibrils which is shared by the adjacent membranes if fracturing occurred around either side of the fibrils. These two models predict quite different structures at regions of the junction where tranl sitions are made between face A and face B. The relative heights of face A and face B and the shape of the transition from face A to face B do not agree with that expected according to the two fibril model but agree exactly with that expected if only a single set of fibrils existed. Further evidence for the single fibril model is derived from fractures of the mucosa membrane which cross the junction to the membrane of the adjacent cell without deflection. Such fractures reveal a single ridge which appears to be identical to the juxtaluminal fibril of the junction. In addition, small ridges are occasionally found in place of the grooves on face B which, although not consistent with the double fibril model, is expected if the single fibril model were correct. Although alternative explanations might account for these observations, we believe that the simplest and most consistent explanation is that the zonula occludens fractures as would be expected of a single set of fibrils shared by adjacent cells.

scholarly journals FRACTURE FACES OF OSMOTICALLY DISRUPTED ZONULAE OCCLUDENTES

1974 ◽  
Vol 62 (2) ◽  
pp. 344-350 ◽  
Author(s):  
James B. Wade ◽  
Morris J. Karnovsky
Keyword(s):  
Essential Role ◽  
Cell Attachment ◽  
Freeze Fracture ◽  
Toad Urinary Bladder ◽  
Mucosal Epithelium ◽  
Zonulae Occludentes ◽  
Ringer’S Solution ◽  
Zonula Occludens ◽  
A Site

Exposing the mucosal epithelium of the toad urinary bladder to 240 mM urea in Ringer's solution is known to cause a dramatic increase in the permeability of the zonulae occludentes and the appearance of distended, bubble-like compartments within these junctions. Examination of such osmotically disrupted junctions with the freeze-fracture technique reveals that these bubbles result from a distention of the compartments existing within the meshwork of interconnecting fibrils characteristic of the zonulae occludentes in this epithelium. Frequent discontinuities in the meshwork of fibrils are also found after osmotic disruption of the junction. These observations indicate the essential role of these fibrils in maintaining the characteristic properties of the zonula occludens as a site of cell-to-cell attachment and as a permeability seal.

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

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.

Action of steroids on H+ and NH 4 + excretion in the toad urinary bladder

1979 ◽  
Vol 49 (4) ◽  
pp. 297-308 ◽  
Author(s):  
Loy W. Frazier ◽  
N. Y. Zachariah
Keyword(s):  
Urinary Bladder ◽  
Toad Urinary Bladder

scholarly journals Vasopressin-stimulated movement of drugs and uric acid across the toad urinary bladder

1976 ◽  
Vol 9 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Sherman D. Levine ◽  
Nicholas Franki ◽  
Roland Einhorn ◽  
Richard M. Hays
Keyword(s):  
Uric Acid ◽  
Urinary Bladder ◽  
Toad Urinary Bladder

Cellular lithium and transepithelial transport across toad urinary bladder

1982 ◽  
Vol 70 (1) ◽  
pp. 69-88 ◽  
Author(s):  
Pauline M. Hughes ◽  
Anthony D. C. Macknight
Keyword(s):  
Urinary Bladder ◽  
Transepithelial Transport ◽  
Toad Urinary Bladder
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