Effects of Repeated Exposure to Nitric Acid Vapor and Ozone on Respiratory Tract Clearance in the Rat

Mannix, Richard C.; Phalen, Robert F.; Oldham, Michael J.; Mautz, William J.; Kleinman, Michael T.

doi:10.3109/08958379609002574

Cited by 3 publications

(2 citation statements)

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“…Respiratory tract clearance of insoluble radioactive tracer particles was measured as 2 phases: a short-term early clearance of particles, largely mucociliary clearance from the upper airways, and a longer-term phase of particle clearance, largely from the deep lung (Mannix et al, 1983(Mannix et al, , 1996. Monodisperse 1.2 m diameter polystyrene latex tracer particles were labeled with tightly bound 51 Cr (Hinrichs et al, 1978).…”

Section: Respiratory Tract Clearancementioning

confidence: 99%

“…The lung activity for each rat was corrected for decay of the 51 Cr back to 50 h post-deposition and then normalized by dividing by the value obtained from a thoracic count of the same animal at 50 h post-deposition. The resulting values for uncleared radioactivity at 30 days constitute an index of late clearance termed the A 30 (Mannix et al, 1996).…”

Section: Respiratory Tract Clearancementioning

confidence: 99%

See 1 more Smart Citation

Respiratory Tract Responses to Repeated Inhalation of an Oxidant and Acid Gas-Particle Air Pollutant Mixture

Mautz

Kleinman

Bhalla

et al. 2001

Toxicological Sciences

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The purpose of this study was to examine a broad range of toxicologic responses in rats exposed to a multi-component pollutant atmosphere. Cumulative and adaptive respiratory tract responses to 3 concentrations of an inhaled particle-oxidant mixture were examined in Fisher 344 N rats exposed 4 h/day, 3 days/week for 4 weeks. The mixtures contained O3, NO2, NH4HSO4, carbon particles, and HNO3 vapor. Irritant-induced, rapid-shallow breathing responses were present during the first 4-h exposure to medium and high concentrations. Successive exposures showed diminished responses in medium concentrations and exacerbated responses in high concentrations. At the end of 4 weeks, rats exposed to high concentrations exhibited lung lesions. Lavaged pulmonary macrophages showed dose-dependent depressions of Fc-receptor binding and phagocytosis. Lung tissue macrophages showed dose-dependent increases in acid phosphatase staining density and carbon particles. Respiratory tract clearance of tracer particles was not significantly affected by the exposures. Broncho-alveolar epithelial permeability was increased by the high concentration. Epithelial cell-proliferation labeling showed a dose-dependent increase at all levels of the respiratory tract. Progressively exacerbated breathing-pattern responses at high concentrations were associated with lung lesions and high cell-proliferation labeling in the nose transitional epithelium and terminal bronchioles. Attenuating or adaptive breathing-pattern responses occurred in the presence of smaller, but in many cases still significant, compromise of respiratory functions. Either attenuating or exacerbated breathing-pattern responses can occur in the presence of a significant dose-dependent compromise of other respiratory functions and lung tissue injury.

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Section: Respiratory Tract Clearancementioning

confidence: 99%

Section: Respiratory Tract Clearancementioning

confidence: 99%