Interspecies comparisons of particle deposition and mucociliary clearance in tracheobronchial airways
Inhaled insoluble particles that deposit along normal healthy tracheobronchial airways of humans and other mammals are transported on the proximally moving mucous lining to the larynx, where they are swallowed. The transit time from the most distal ciliated airways varies from 0.1 to 1 d, with each individual having a relatively constant, characteristic time. The exact time course of clearance depends on the distributions of both particle deposition and mucus velocities along the airways. As compared to commonly used experimental animals, humans have larger lungs and a more symmetric upper bronchial airway branching pattern. In addition, humans do considerable oral breathing, thus bypassing the effective air cleaning capability of the nasal airways. These differences contribute to a greater amount of upper bronchial airway particle deposition in humans, as well as to greater concentrations of deposition on localized surfaces near airway bifurcations. Airborne irritants that deposit in small ciliated airways may produce marked changes in mucociliary transport. Such materials include cigarette smoke, submicrometer-sized sulfuric acid mist, nitrogen dioxide, and ozone. For cigarette smoke and sulfuric acid, which have been studied for transient effects following single brief exposures in animals, both of these irritants produce persistant alterations in clearance rates and airway morphometry. Studies of the effects of ozone on mucociliary clearance have, up to now, been limited to tests of the responses of rats to single exposures. The similarities between the known effects of various irritants suggests a nonspecific response.
- Research Organization:
- New York Univ. Medical Center, New York
- OSTI ID:
- 6219512
- Journal Information:
- J. Toxicol. Environ. Health; (United States), Vol. 13:2-3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NITROGEN DIOXIDE
BIOLOGICAL EFFECTS
OZONE
PARTICULATES
DEPOSITION
LUNG CLEARANCE
RESPIRATORY SYSTEM
MORPHOLOGICAL CHANGES
SULFURIC ACID
TOBACCO SMOKES
BIOLOGICAL VARIABILITY
COMPARATIVE EVALUATIONS
KINETICS
LABORATORY ANIMALS
MAN
AEROSOLS
ANIMALS
CHALCOGENIDES
CLEARANCE
COLLOIDS
DISPERSIONS
EXCRETION
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MAMMALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PRIMATES
RESIDUES
SMOKES
SOLS
VERTEBRATES
560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)
560306 - Chemicals Metabolism & Toxicology- Man- (-1987)