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 language | English (US) |
|---|---|
| Pages (from-to) | 1687-1695 |
| Number of pages | 9 |
| Journal | Journal of Applied Physiology |
| Volume | 80 |
| Issue number | 5 |
| DOIs | |
| State | Published - Jan 1 1996 |
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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 journal › Article
}
TY - JOUR
T1 - Diffusion of nonelectrolytes in the canine trachea
T2 - Effect of tight junction
AU - George, Steven
AU - Babb, A. L.
AU - Deffebach, M. E.
AU - Hlastala, M. P.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - 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.
AB - 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.
KW - diffusion coefficient
KW - lungs
KW - modeling
UR - http://www.scopus.com/inward/record.url?scp=0029989209&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029989209&partnerID=8YFLogxK
U2 - 10.1152/jappl.1996.80.5.1687
DO - 10.1152/jappl.1996.80.5.1687
M3 - Article
C2 - 8727556
AN - SCOPUS:0029989209
VL - 80
SP - 1687
EP - 1695
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 5
ER -