Abstract
ABSTRACT
Regional variations in epithelial permeability may be important in assessing damage from inhaled toxic agents that are absorbed or deposited nonuniformly in the respiratory tract. To measure baseline values and reproducibility of regional differences in epithelial permeability, small volumes (50 uL) of 99mTc-diethylenetriaminepentacic acid (DTPA) were placed in the airways of six anesthetized Beagle dogs using a fiberoptic bronchoscope.
Elimination of the 99mTc-DPTA from the 4 instillation sites was described by first order kinetics with the following halftimes ([unk] ± SE): 1) 159 ± 30 min in the nasal cavity, 2) 165 ± 34 min in the trachea, 3) 140 ± 31 min in a 5th generation airway, and 4) 134 ± 20 min in a periperheral airway (approximately 10th generation). There were no significant differences (P < 0.05) among the halftimes for the different sites. These results showed considerable variability in repeat measurements and lack of substantial differences in permeability from upper to lower airways.
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