Effects of repeated inhalation of sulfuric acid aerosol on tracheobronchial structure and function in rabbits

This investigation evaluated the responses of the rabbit tracheobronchial system to daily exposures of sulfuric acid aerosol, in an attempt to correlate in vivo physiologic responses with structural changes determined histologically. The changes in tracheobronchial mucociliary clearance of /sup 99m/Tc tagged iron oxide particles was evaluated in 40 New Zealand White rabbits exposed to 250 ug/m3 1 hr/day, with sacrifices of 5 acid and 5 control rabbits, after 4, 8, and 12 months of acid exposure; remaining rabbits were allowed a three month recovery from acid exposure. Sulfuric acid produced a slowing in mucociliary clearance in the first week of exposure, that became significantly worse as the number of acid exposures continued. An increase in the slope of the slowing of clearance with increased number of exposures occurred by the twelfth month of acid exposure and this increase in slope of slowed clearance continued to worsen for the recovery group