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  • 1970-1974  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Iodination (125I) of the apical plasma membrane of toad bladder epithelium: Electron-microscopic autoradiography and physiological effects (1973)
    Springer
    The journal of membrane biology 14 (1973), S. 17-32 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The apical plasma membrane of toad bladder epithelial cells has been enzymatically iodinated, using lactoperoxidase, H2O2 (generated by a glucose-glucose oxidase system) and NaI. The site of labeling was demonstrated by electron-microscopic autoradiography; the silver grains (125I) were found exclusively overlying the luminal plasma membranes of the epithelium. The iodination reaction reached completion in less than 5 min. The dependence of the degree of iodination on NaI concentrations (range=6.3×10−8 to 6.3×10−2 m) in the mucosal medium was determined. The results suggest that three classes of sites are iodinated within this concentration range. At concentrations of NaI of 6.3×10−6 m or less, iodination of the apical membrane had no significant effect on either the fine structure of the epithelium or on electrophysiological properties. The baseline short-circuit current (SCC) remained steady and the response to vasopressin was unimpaired. At concentrations of 6.3×10−5 m NaI and greater, the baseline SCC was depressed and the response to vasopressin was partially inhibited. The results indicate that125I may serve as a covalent marker (specific for tyrosine and histidine residues) of the apical plasma membrane of epithelia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868066
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The membrane surfaces of the toad bladder: Scanning and transmission electron-microscopy (1974)
    Springer
    The journal of membrane biology 16 (1974), S. 279-295 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The SEM permits analysis of large areas of the surface of epithelia and facilitates the study of cell-to-cell relationships, as pointed out by Fenguson and Heap (Z. Zellforsch.109:297, 1970). The short method of preparation described here yields good results when the critical point method is used for drying (freeze-drying was less satisfactory). Cell counts reveal that theBufo marinus toad bladder epithelium contains 3 or 4 granular (GR) cells to 1 mitochondria-rich (MR) cell. Whether these cell membrane contacts are permeable to the diffusion of high energy compounds and whether the MR cells serve as a source of energy for the GR cells are hypotheses that require further study. In view of the wide variations in the cell number per unit area even in single hemibladders, experimental measurements should probably be expressed either in terms of cell counts of DNA content, rather than per unit surface area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01872419
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fine structure of the urinary bladder of the bullfrog, (Rana catesbiana)With the financial aid of U.S.P.H.S., National Heart and Lung Institute, grant HL 06285 and NIAMD grant AM 13659. (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 178 (1974), S. 15-39 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The urinary bladder of the bullfrog, Rana catesbiana has been studied by light and electron microscopy. Three epithelial cell types were found: (1) granular cells, (2) mitochondria-rich cells, and (3) basal cells. The structure of the Rana catesbiana bladder differs from that of the toad Bufo marinus, in several respects: it lacks a mucous (goblet) cell type, its granular cells do not contact the underlying basement membrane, it has specialized, smooth-muscle cell-basal epithelial cell contacts, not previously described in amphibian bladders, and its mucosa is richly innervated. Mitochondria-rich cells within the bullfrog bladder epithelium were occasionally observed touching the basement membrane. The specialized smooth muscle-basal cell contacts provide anatomical evidence for how regulatory vasoactive substances such as neurohypophyseal peptides might alter epithelial geometry. Many nerve endings invest the mucosa just beneath the epithelial basement membrane in proximity to mitochondriarich cells and basal cells. The possible role of neural regulation in epithelial transport was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091780104
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative analysis of surface charges on luminal epithelial membranes of urinary bladders from toad, frog, turtle, and tortoiseWith the financial aid of U.S.P.H.S., National Institute of Arthritis, Metabolism, and Digestive Diseases, Grant AM 13659, and National Heart and Lung Institute, Grant HL 06285. (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 509-519 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cationized ferritin was used to analyze the surface charges on the luminal epithelial cell membranes of urinary bladders from toad (Bufo marinus), bullfrog (Rana catesbiana), turtle (Pseudemys scripta and Clemmys caspica), and tortoise (Geochelone carbonaria and Testudo graeca). The labeling, done at a physiological pH on fixed or unfixed bladders, revealed differences in the distribution and density of negative charges along the luminal membrane surfaces. The epithelial surface of toad bladder did not label with cationized ferritin. Frog bladder labeled lightly and the labeling pattern varied between cell types. The epithelial membrane surfaces of reptile bladders were heavily labeled, in contrast to amphibian bladders. Luminal surfaces from fresh water turtles were not as heavily labeled as those from land tortoises. The degree of labeling varied from cell type to cell type in all reptile bladders except Pseudemys scripta. An analysis of the degree and pattern of labeling by cationized ferritin in bladders of all species studied might reflect a difference in the nature of the glycocalyx of a particular membrane, the presence or absence of negative surface charges or their availability (i.e., interference by mucus), and/or the nature of the chemical groups comprising the surface structure of the membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091800310
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    Paper (German National Licenses)
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