Anatomic localization of 24- and 96-h particle retention in canine airways

• Published in: Journal of applied physiology (1985) Vol. 87; no. 1; pp. 269 - 284
• Main Authors: Kreyling, W. G, Blanchard, J. D, Godleski, J. J, Haeussermann, S, Heyder, J, Hutzler, P, Schulz, H, Sweeney, T. D, Takenaka, S, Ziesenis, A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-07-1999; American Physiological Society
• Subjects: Aerosols; Anatomy & physiology; Animals; Biological and medical sciences; Blood gas. Hemoglobin. Myoglobin. Hemotissulary gas exchange. Acid-base balance; Dogs; Female; Fundamental and applied biological sciences. Psychology; Humans; Lung - anatomy & histology; Lung - diagnostic imaging; Lung - physiology; Lungs; Male; Particle Size; Pulmonary Alveoli - anatomy & histology; Pulmonary Alveoli - diagnostic imaging; Pulmonary Alveoli - physiology; Respiratory Mechanics - physiology; Respiratory system; Technetium; Time Factors; Tomography, Emission-Computed, Single-Photon; Vertebrates: respiratory system; Fissipedia; Carnivora; Single dose; Retention; Respiratory system; Long term; Inhalation; Particle; Respiratory tract; Vertebrata; Mammalia; Convective diffusion; Localization; Dog; Aerosol batcher
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1999.87.1.269

Institutes for 1  Inhalation Biology and
3  Pathology, GSF-National
Research Center for Environment and Health, D-85758 Neuherberg/Munich;
and
2  Harvard School of Public Health,
Department of Environmental Health, Boston, Massachusetts 02115
Long-term
retention of particles in airways is controversial. However, precise
anatomic localization of the particles is not possible in people. In
this study the anatomic location of retained particles after shallow
bolus inhalation was determined in anesthetized, ventilated beagle
dogs. Fifty 30-cm 3 boluses
containing monodisperse 2.5-µm polystyrene particles (PSL) were
delivered to a shallow lung depth of 81-129
cm 3 . At 96 h before euthanasia,
red fluorescent PSL were used; at 24 h, green fluorescent PSL and
99m Tc-labeled PSL were used.
Clearance of 99m Tc-PSL was
measured during the next 24 h. Sites of particle retention were
determined in systematic, volume-weighted random samples of
microwave-fixed lung tissue. Precise particle localization and
distribution was analyzed by using gamma counting, conventional fluorescence microscopy, and confocal microscopy. Within 24 h after
shallow bolus inhalation, 50-95% of the deposited
99m Tc-PSL were cleared, but the
remaining fraction was cleared slowly in all dogs, similar to previous
human results. The three-dimensional deposition patterns showed
particles across the entire cross-sectional plane of the lungs at the
level of the carina. In these locations, 33 ± 9.9% of
the retained particles were found in small, nonrespiratory airways
(0.3- to 1-mm diameter) and 49 ± 10% of the particles in alveoli; the remaining fraction was found in larger airways. After
96 h, a similar pattern was found. These findings suggest that
long-term retention in airways is at the bronchiolar level.
aerosol bolus inhalation; convective gas transport; particle
distribution in lungs; slow particle clearance from airways; fluorescent or radiolabeled polystyrene particles