Effects of tobacco smoke on respiratory epithelial clearance of DTPA and on lung histology in rats.

The respiratory epithelial clearance of 99mTc-(DTPA) diethylenetriamine penta-acetate (RC-DTPA) was measured in rats before and after sham or cigarette smoke exposures. RC-DTPA was increased by cigarette smoke exposure (p less than 0.001); the amount and duration of the exposure had no significant effect. In smoker animals, the number of bronchoalveolar macrophages was decreased after one or five smoke exposures a day for one day (p less than 0.001) and the number of bronchoalveolar neutrophils was increased after five exposures a day for ten days (p less than 0.001). No abnormality was found in the lung parenchyma on light microscopy. We conclude that in rats RC-DTPA is increased by exposure to tobacco smoke, whatever the amount and duration of exposure; however, no gross parenchymal lung abnormality explains the increase in RC-DTPA.