Diffusion of nonelectrolytes in the canine trachea: Effect of tight junction

Steven George, A. L. Babb, M. E. Deffebach, M. P. Hlastala

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We recently demonstrated through theoretical modeling that the exhaled ethanol (EtOH) profile from humans is consistent with a molecular diffusion coefficient (cm2/s) in the bronchial mucosa (D(ti)) that is only 8% of the diffusion coefficient in water (D(w); J. Appl. Physiol. 75: 2439-2449, 1993). Because of the small oil-water partition coefficient (λ(o:w)) of EtOH (λ(o:w) = 0.074), the reduced diffusion coefficient may be due, in part, to the epithelial tight junction in the paracellular pathway. We hypothesized that opening the tight junction would open an aqueous pathway and increase the diffusion coefficient of small (mol wt <100) hydrophilic compounds. We mounted the mucosa from the membranous canine trachea in an Ussing-type diffusion cell and measured the diffusion coefficient of 2-ethoxyethanol (2- Ethx; λ(o:w) = 0.042), EtOH, and methyl ethyl ketone (MEK; λ(o:w) = 1.04) in the presence and absence of the epithelial tight junction. The tight junction was opened using a phosphate-buffered saline free of Ca2+ and Mg2+ with 0.5 mM ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'- tetraacetic acid, and its integrity was assessed by measuring the transepithelial electrical resistance. D(ti)/D(w) in the presence of Ca2+ and Mg2+ was 0.39, 0.34, and 0.39 for 2-Ethx, EtOH, and MEK, respectively, and increased 24.6, 11.7, and 1.11% in the absence of Ca2+ and Mg2+. We conclude that the effect of the tight junction on D(ti) increases with increasing water solubility but can account for only a small portion of the reduced D(ti) of EtOH as predicted by exhaled profiles.

Original languageEnglish (US)
Pages (from-to)1687-1695
Number of pages9
JournalJournal of Applied Physiology
Volume80
Issue number5
DOIs
StatePublished - Jan 1 1996

Fingerprint

Tight Junctions
Trachea
Canidae
Mitogen-Activated Protein Kinase Kinases
Water
Mucous Membrane
Ethylene Glycol
Electric Impedance
Ether
Solubility
Oils
Ethanol
Phosphates
Acids

Keywords

  • diffusion coefficient
  • lungs
  • modeling

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Diffusion of nonelectrolytes in the canine trachea : Effect of tight junction. / George, Steven; Babb, A. L.; Deffebach, M. E.; Hlastala, M. P.

In: Journal of Applied Physiology, Vol. 80, No. 5, 01.01.1996, p. 1687-1695.

Research output: Contribution to journalArticle

George, Steven ; Babb, A. L. ; Deffebach, M. E. ; Hlastala, M. P. / Diffusion of nonelectrolytes in the canine trachea : Effect of tight junction. In: Journal of Applied Physiology. 1996 ; Vol. 80, No. 5. pp. 1687-1695.
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