Effect of perinatal nicotine exposure on mesenchymal protein markers of airway reactivity and nicotinic acetylcholine receptors α3 and α7 in lungs of female F2 rats. Compared to the control group, with nicotine administration the protein levels of fibronectin, α-SMA, calponin, and collagens I and III (A) and nicotinic acetylcholine receptors α3 and α7 (B) increased significantly. Upper panels show representative Western blots for the markers and GAPDH. Lower panels show the densitometric values for these markers normalized to GAPDH. Values are means ± SE. n = 6 for each group. * P < 0.05, **P < 0.01, versus control group. GAPDH, glyceraldehyde 3-phosphate dehydrogenase; α-SMA, α-smooth muscle actin.