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From the Department of Anatomy, Physiology and CellBiology*
and the Department of MolecularBiosciences,
School of Veterinary Medicine,University of California Davis, Davis, California; and the Departmentof Environmental Health Sciences,
School ofPublic Health, University of Alabama at Birmingham,Birmingham, Alabama
Repeated exposures to the Clara cell cytotoxicant naphthalene (NA)
result in target cell populations that become refractory to further
injury. To determine whether tolerance occurs from specific adaptations
favoring glutathione (GSH) resynthesis without broad shifts in cellular
phenotype, mice were administered NA for 21 days. We found that
-glutamylcysteine synthetase (
-GCS) was induced in tolerant Clara
cells by repeated exposures to NA. Treating tolerant mice with
buthionine sulfoximine, a
-GCS inhibitor, eliminates
resistance acquired by repeated exposures to NA. Broad phenotypic
shifts were not present. Marker proteins of differentiation declined
over the first 3 days in the development of tolerance, but
returned to control levels at 14 and 21 days. Epithelial organizational
structure and internal organelle composition in Clara cells from
tolerant mice were similar compared to corn oil-treated
controls, while subtle shifts in organelle distribution were
present. We conclude that induction of
-GCS expression is
coordinated with the development of NA tolerance, but induction
of NA tolerance does not markedly alter Clara cell
differentiation, epithelial organization, or organelle
composition in bronchiolar epithelium.
This article has been cited by other articles:
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J. A. A. West, L. S. Van Winkle, D. Morin, C. A. Fleschner, H. J. Forman, and C. G. Plopper Repeated Inhalation Exposures to the Bioactivated Cytotoxicant Naphthalene (NA) Produce Airway-Specific Clara Cell Tolerance in Mice Toxicol. Sci., September 1, 2003; 75(1): 161 - 168. [Abstract] [Full Text] [PDF] |
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