MATERNAL EXPOSURE TO ENVIRONMENTAL TOBACCO-SMOKE ALTERS CLARA CELL SECRETORY PROTEIN EXPRESSION IN FETAL-RAT LUNG

We have previously demonstrated that aged and diluted sidestream cigar ette smoke (ADSS) alters the development of bronchiolar epithelial cel ls in postnatal animals (C. M. Ji, C. G. Flopper, H. P. Witschi, and K . E. Pinkerton. Am. J. Respir. Cell Mel. Biol. 11: 312-320, 1994). Thi s study was designed to examine the effects of maternal exposure to AD SS on the development of fetal Clara cells in rats with Clara cell 10- kDa protein (CC10; also designated Clara cell secretory protein) and C C10 mRNA as differentiation markers. Immunohistochemistry, Northern bl ots, and in situ hybridization were used to determine the abundance an d distribution of CC10 at gestational days 14, 18, and 21. CC10 and CC 10 mRNA were absent at gestational day 14 but were detectable at gesta tional day 18 and further increased by gestational day 21. Maternal ex posure to ADSS was found to significantly increase fetal expression of CC10 and CC10 mRNA by gestational day 21 but not by gestational day 1 4 or 18. These findings demonstrate that in utero exposure to ADSS alt ers the normal developmental expression of CC10 in the fetal rat lung.