Fig. 5
a Effect of dopamine D1 receptor agonists on MUC5AC mRNA expression in NCI-H292 cells. The cells were treated for 48 h with dopamine (1 μM), the dopamine D1 receptor agonist A68930 (1 μM), the Gs protein-coupled β2 adrenoceptor agonist isoproterenol (ISO; 1 μM), or cigarette smoke extract (CSE; 10%: positive control). Data represent means ± SEM. *P < 0.05, **P < 0.01 compared with basal. n = 14. b NCI-H292 cell viability analysis with MTT assay after 48 h treatment with CSE (10 or 20%); n = 13. Data are shown as percentages of absorbance at 570 nm compared with no treatment control and represent means ± SEM. n.s. compared with no treatment control