A model of metabolism and clearance of organic compounds from the respiratory tract
In cases where inhalants induce toxicity in the airway epithelium, the mechanism of absorption is an important determinant of target dose. Absorption of organic solutes in the lungs occurs mainly by two consecutive mechanisms; molecular diffusion drives the chemicals into the tissues, and blood perfusion of the tissues removes the chemicals into the systemic circulation. Solutes having lipophilicities ranging from equally soluble in lipids and water to moderately more lipid-soluble are limited by the perfusion during clearance from the lungs. The perfusion-limited solute enters the blood circulation from all regions of the lungs within minutes and is distributed to other organs via the systemic circulation. In contrast, clearance of highly lipophilic toxicants, such as benzo(a)pyrene, from the lungs is diffusion-limited. The limiting process refers to the slowest transport mechanism of either perfusion or diffusion. Because of the short distance from the surface of the alveolar region to the capillary network, diffusion-limited clearance of highly lipophilic solutes occurs within minutes. In the thicker epithelium of the conducting airways, however, clearance may take hours. The purpose of the current modeling effort was to encompass both mechanisms of clearance in a single model in order to explore the influence of toxicant lipophilicity and local metabolism on the dosimetry at the airway portal-of-entry.
- Research Organization:
- Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States). Inhalation Toxicology Research Inst.
- DOE Contract Number:
- AC04-76EV01013
- OSTI ID:
- 54797
- Report Number(s):
- ITRI-144; ON: DE95007526; CNN: Grant R01-ES05910; TRN: 95:012742
- Resource Relation:
- Other Information: PBD: Nov 1994; Related Information: Is Part Of Inhalation Toxicology Research Institute annual report, October 1, 1993--September 30, 1994; Belinsky, S.A.; Hoover, M.D.; Bradley, P.L. [eds.]; PB: 211 p.
- Country of Publication:
- United States
- Language:
- English
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