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ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia.

Publication ,  Journal Article
Blaug, S; Hybiske, K; Cohn, J; Firestone, GL; Machen, TE; Miller, SS
Published in: Am J Physiol Cell Physiol
August 2001

Mammary epithelial 31EG4 cells (MEC) were grown as monolayers on filters to analyze the apical membrane mechanisms that help mediate ion and fluid transport across the epithelium. RT-PCR showed the presence of cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial Na(+) channel (ENaC) message, and immunomicroscopy showed apical membrane staining for both proteins. CFTR was also localized to the apical membrane of native human mammary duct epithelium. In control conditions, mean values of transepithelial potential (apical-side negative) and resistance (R(T)) are -5.9 mV and 829 Omega x cm(2), respectively. The apical membrane potential (V(A)) is -40.7 mV, and the mean ratio of apical to basolateral membrane resistance (R(A)/R(B)) is 2.8. Apical amiloride hyperpolarized V(A) by 19.7 mV and tripled R(A)/R(B). A cAMP-elevating cocktail depolarized V(A) by 17.6 mV, decreased R(A)/R(B) by 60%, increased short-circuit current by 6 microA/cm(2), decreased R(T) by 155 Omega x cm(2), and largely eliminated responses to amiloride. Whole cell patch-clamp measurements demonstrated amiloride-inhibited Na(+) currents [linear current-voltage (I-V) relation] and forskolin-stimulated Cl(-) currents (linear I-V relation). A capacitance probe method showed that in the control state, MEC monolayers either absorbed or secreted fluid (2--4 microl x cm(-2) x h(-1)). Fluid secretion was stimulated either by activating CFTR (cAMP) or blocking ENaC (amiloride). These data plus equivalent circuit analysis showed that 1) fluid absorption across MEC is mediated by Na(+) transport via apical membrane ENaC, and fluid secretion is mediated, in part, by Cl(-) transport via apical CFTR; 2) in both cases, appropriate counterions move through tight junctions to maintain electroneutrality; and 3) interactions among CFTR, ENaC, and tight junctions allow MEC to either absorb or secrete fluid and, in situ, may help control luminal [Na(+)] and [Cl(-)].

Duke Scholars

Published In

Am J Physiol Cell Physiol

DOI

ISSN

0363-6143

Publication Date

August 2001

Volume

281

Issue

2

Start / End Page

C633 / C648

Location

United States

Related Subject Headings

  • Sodium Channels
  • Reference Values
  • Polymerase Chain Reaction
  • Physiology
  • Patch-Clamp Techniques
  • Models, Biological
  • Mice
  • Mammary Glands, Animal
  • Immunohistochemistry
  • Epithelial Sodium Channels
 

Citation

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Blaug, S., Hybiske, K., Cohn, J., Firestone, G. L., Machen, T. E., & Miller, S. S. (2001). ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia. Am J Physiol Cell Physiol, 281(2), C633–C648. https://doi.org/10.1152/ajpcell.2001.281.2.C633
Blaug, S., K. Hybiske, J. Cohn, G. L. Firestone, T. E. Machen, and S. S. Miller. “ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia.Am J Physiol Cell Physiol 281, no. 2 (August 2001): C633–48. https://doi.org/10.1152/ajpcell.2001.281.2.C633.
Blaug S, Hybiske K, Cohn J, Firestone GL, Machen TE, Miller SS. ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia. Am J Physiol Cell Physiol. 2001 Aug;281(2):C633–48.
Blaug, S., et al. “ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia.Am J Physiol Cell Physiol, vol. 281, no. 2, Aug. 2001, pp. C633–48. Pubmed, doi:10.1152/ajpcell.2001.281.2.C633.
Blaug S, Hybiske K, Cohn J, Firestone GL, Machen TE, Miller SS. ENaC- and CFTR-dependent ion and fluid transport in mammary epithelia. Am J Physiol Cell Physiol. 2001 Aug;281(2):C633–C648.

Published In

Am J Physiol Cell Physiol

DOI

ISSN

0363-6143

Publication Date

August 2001

Volume

281

Issue

2

Start / End Page

C633 / C648

Location

United States

Related Subject Headings

  • Sodium Channels
  • Reference Values
  • Polymerase Chain Reaction
  • Physiology
  • Patch-Clamp Techniques
  • Models, Biological
  • Mice
  • Mammary Glands, Animal
  • Immunohistochemistry
  • Epithelial Sodium Channels