CELL-KINETICS IN THE RESPIRATORY-TRACT OF HAMSTERS EXPOSED TO CIGARETTE SIDESTREAM SMOKE

Male Syrian golden hamsters were exposed for 6 h/day, 7 days/wk for up to 3 wk to sidestream smoke generated from Kentucky IR4F reference ci garettes. Monitoring showed that the chamber atmosphere contained 1 mg /m(3) of total suspended particulate, 385 mu g/m(3) of nicotine, and 4 ppm carbon monoxide. Cumulative labeling indices were measured in the pulmonary parenchyma, intrapulmonary airways, trachea, and nasal pass ages with the bromodeoxyuridine osmotic minipump technique. Cells were labeled during wk 1, 2, and 3 of smoke exposure and for a 1-wk recove ry period in air after 1, 2, or 3 wk of smoke exposure. In the airway epithelia, exposure to sidestream smoke did not increase cell prolifer ation as long as the animals were inhaling smoke, but did so upon remo val of the animals from the chamber. In the nasal respiratory epitheli um, cell proliferation was initially increased, but then, after remova l of the animals into air, was inhibited relative to clean air control s. No changes in labeling index were seen in the trachea or in the pul monary parenchyma. Although changes seen were only minimal, they never theless represent a biological response to the inhalation of sidestrea m smoke.