Quantitation of peribronchiolar smooth muscle content in exposed rat lungs. (A) Quantitative assessment of the thickness of the smooth muscle layer in major airways of 15 d old rat lungs after exposure to air, DCB50 or DCB230. Data represent means ± SEM. n = 3 animals/group. *p < 0.05 vs Air and #p < 0.05 vs DCB50. (B, C, D) Representative micrographs demonstrating expression of α-smooth muscle actin (red) and E-cadherin (green) from 15 d old rat lungs exposed to air, DCB50, or DCB230, respectively. Cell nuclei stained with DAPI (blue).