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| Titel |
Kinetic multi-layer model of the epithelial lining fluid (KM-ELF): Reactions of ozone and OH with antioxidants and surfactant molecules |
| VerfasserIn |
Pascale Lakey, Ulrich Pöschl, Manabu Shiraiwa |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106112
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| Publikation (Nr.) |
 EGU/EGU2015-5765.pdf |
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| Zusammenfassung |
| Oxidants cause damage to biosurfaces such as the lung epithelium unless they are effectively
scavenged. The respiratory tract is covered in a thin layer of fluid which extends from the
nasal cavity to the alveoli and contain species that scavenge ozone and other incoming
oxidants. The kinetic multi-layer model of the epithelial lining fluid (KM-ELF) has been
developed in order to investigate the reactions of ozone and OH with antioxidants (ascorbate,
uric acid, glutathione and α-tocopherol) and surfactant lipids and proteins within
the epithelial lining fluid (ELF). The model incorporates different processes: gas
phase diffusion, adsorption and desorption from the surface, bulk phase diffusion
and known reactions at the surface and in the bulk. The ELF is split into many
layers: a sorption layer, a surfactant layer, a near surface bulk layer and several bulk
layers.
Initial results using KM-ELF indicate that at ELF thicknesses of 80 nm and 1
x 10-4cm the ELF would become rapidly saturated with ozone with saturation
occurring in less than a second. However, at an ELF thickness of 1 x 10-3cm
concentration gradients were observed throughout the ELF and the presence of
antioxidants reduced the O3 reaching the lung cells and tissues by 40% after 1
hour of exposure. In contrast, the antioxidants were efficient scavengers of OH
radicals, although the large rate constants of OH reacting with the antioxidants
resulted in the antioxidants decaying away rapidly. The chemical half-lives of the
antioxidants and surface species were also calculated using KM-ELF as a function of
O3 and OH concentration and ELF thickness. Finally, the pH dependence of the
products of reactions between antioxidants and O3 were investigated. The KM-ELF
model predicted that a harmful ascorbate ozonide product would increase from 1.4
x 1011cm-3at pH 7.4 to 1.1 x 1014 cm-3 at pH 4after 1 hour although a uric
acid ozonide product would decrease from 2.0 x 1015cm-3to 5.9 x 1012cm-3. |
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