Effects of submicrometer XXXX aerosols on mucociliary transport and respiratory mechanics in asymptomatic asthmatics.

@entity4197 @entity25050 @entity8316 @entity1514
The effects of a 1-hr inhalation of submicrometer @entity8316 ( @entity4197 ) aerosols via nasal mask on tracheobronchial mucociliary particle clearance and respiratory mechanics were studied in ten subjects with asthmatic histories. A brief inhalation of monodisperse 3.9-micron 99mTc-tagged @entity25050 aerosol preceded the 1-hr @entity4197 (at 100, 300, and 1000 micrograms/m3) or a sham exposure. @entity1514 retention of the gamma-tagged @entity25050 was measured using external radiation detectors. Respiratory function was measured before, and 15 min and 3 hr after the @entity4197 or sham exposure. After exposure to 1000 micrograms/m3 of @entity4197 , the six subjects not on routine medication exhibited a transient slowing of mucociliary clearance and also decrements in sGaw, FEV1/FVC, MMEF, and V25 (P less than 0.05) in both sets of measurements. The four asthmatics on daily medication exhibited stepwise mucociliary clearance that was too variable to allow detection of any @entity4197 effect on clearance. The 1000 micrograms/m3 of @entity4197 did produce decrements in V25 (P less than 0.05), but the variability of the other respiratory parameters in this small group was too great to permit detection of changes. Mucociliary clearance rates in both groups in the sham exposure tests were significantly slower than those of healthy nonsmokers studied previously using the same protocols. The extent of mucociliary clearance slowing following the 1000 micrograms/m3 exposure in the nonmedicated subjects was similar to that in the healthy nonsmokers. This similar change, from a reduced baseline rate of clearance, together with the significant change in respiratory function, indicate that asymptomatic asthmatics may respond to @entity4197 exposures with functional changes of greater potential health significance than do healthy nonsmokers.
