Effect of perinatal nicotine exposure on mesenchymal protein markers of airway reactivity and nicotinic acetylcholine receptors α3 and α7 in lungs of male 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 these markers and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Lower panels show the densitometric values of the markers normalized to GAPDH. Values are means ± SE. n = 6 for each group. * P < 0.05, **P < 0.01, versus control group. α-SMA, α-smooth muscle actin.