Cell Kinetics in the Respiratory Tract of Hamsters Exposed to Cigarette Sidestream Smoke

Abstract

Male Syrian golden hamsters were exposed for 6 h/day, 7 days/wk for up to 3 wk to side-stream smoke generated from Kentucky 1R4F reference cigarettes. Monitoring showed that the chamber atmosphere contained 1 mg/m³ of total suspended particulate, 385 μg/m³ of nicotine, and 4 ppm carbon monoxide. Cumulative labeling indices were measured in the pulmonary parenchyma, intrapulmonary airways, trachea, and nasal passages with the bromodeoxyuridine osmotic minipump technique. Cells were labeled during wk 1, 2, and 3 of smoke exposure and for a 1-wk recovery period in air after 1, 2, or 3 wk of smoke exposure. In the airway epithelia, exposure to sidestream smoke did not increase cell proliferation as long as the animals were inhaling smoke, but did so upon removal of the animals from the chamber. In the nasal respiratory epithelium, cell proliferation was initially increased, but then, after removal of the animals into air, was inhibited relative to clean air controls. No changes in labeling index were seen in the trachea or in the pulmonary parenchyma. Although changes seen were only minimal, they nevertheless represent a biological response to the inhalation of sidestream smoke.