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Permeability properties of the mammalian bladder apical membrane.

Publication ,  Journal Article
Chang, A; Hammond, TG; Sun, TT; Zeidel, ML
Published in: Am J Physiol
November 1994

The luminal surface of mammalian bladder is exposed to urine with a composition widely different from that of plasma that bathes the basolateral surface of epithelium. Therefore we predict that the bladder permeability barrier, which is likely located in the apical membrane (AM), will exhibit low permeabilities to water, urea, NH3, H+, and small nonelectrolytes. AM surface area increases as the bladder fills with urine and decreases during emptying, a process that involves cyclical endocytosis and reinsertion of membrane from a pool of AM endosomes (AME). Rigid-appearing plaques composed of three proteins, uroplakins, have been identified and occupy 70-90% of AM surface area. To determine permeability properties of the AM permeability barrier, we purified AME and measured their permeabilities. Rabbit urinary bladders were removed, and their apical surface was exposed to carboxyfluorescein (CF) or horseradish peroxidase (HRP). Exposure to hypotonic and then isotonic basolateral solutions induced endocytosis of luminal CF or HRP into AME. Electron microscopy of bladders after this treatment revealed HRP entrapped within AME bordered by plaques. AME were purified by differential and sucrose-gradient centrifugation, and CF-containing AME were purified 17.0 +/- 3-fold (SD) with respect to homogenate. Analysis of purified AME by flow cytometry showed that > 95% of vesicles contained CF entrapped from luminal solution and were selectively labeled with anti-uroplakin antibody. AME osmotic water permeability averaged 2.3 +/- 0.66 x 10(-4) cm/s and exhibited a high activation energy, indicating that AM contains no water channels. Permeability to urea and NH3 averaged 7.8 +/- 3.7 x 10(-7) and 1.5 +/- 0.3 x 10(-3) cm/s, respectively, which are exceptionally low and similar to permeabilities of other water-tight membranes, including toad urinary bladder and gastric mucosa. AME behaved as a single population in all permeability studies, which will permit future characterization of protein and lipid structure responsible for these unique permeability properties.

Duke Scholars

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

November 1994

Volume

267

Issue

5 Pt 1

Start / End Page

C1483 / C1492

Location

United States

Related Subject Headings

  • Water
  • Urinary Bladder
  • Urea
  • Rabbits
  • Proton-Translocating ATPases
  • Organelles
  • Male
  • Horseradish Peroxidase
  • Fluorescent Dyes
  • Fluoresceins
 

Citation

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ICMJE
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Chang, A., Hammond, T. G., Sun, T. T., & Zeidel, M. L. (1994). Permeability properties of the mammalian bladder apical membrane. Am J Physiol, 267(5 Pt 1), C1483–C1492. https://doi.org/10.1152/ajpcell.1994.267.5.C1483
Chang, A., T. G. Hammond, T. T. Sun, and M. L. Zeidel. “Permeability properties of the mammalian bladder apical membrane.Am J Physiol 267, no. 5 Pt 1 (November 1994): C1483–92. https://doi.org/10.1152/ajpcell.1994.267.5.C1483.
Chang A, Hammond TG, Sun TT, Zeidel ML. Permeability properties of the mammalian bladder apical membrane. Am J Physiol. 1994 Nov;267(5 Pt 1):C1483–92.
Chang, A., et al. “Permeability properties of the mammalian bladder apical membrane.Am J Physiol, vol. 267, no. 5 Pt 1, Nov. 1994, pp. C1483–92. Pubmed, doi:10.1152/ajpcell.1994.267.5.C1483.
Chang A, Hammond TG, Sun TT, Zeidel ML. Permeability properties of the mammalian bladder apical membrane. Am J Physiol. 1994 Nov;267(5 Pt 1):C1483–C1492.

Published In

Am J Physiol

DOI

ISSN

0002-9513

Publication Date

November 1994

Volume

267

Issue

5 Pt 1

Start / End Page

C1483 / C1492

Location

United States

Related Subject Headings

  • Water
  • Urinary Bladder
  • Urea
  • Rabbits
  • Proton-Translocating ATPases
  • Organelles
  • Male
  • Horseradish Peroxidase
  • Fluorescent Dyes
  • Fluoresceins