Figure 2.

CS exposure affects PDE contributions to cAMP hydrolysis under basal conditions in the in vivo model. (A) Experimental design. Mice were exposed to the mainstream smoke of cigarettes for 4 days. Lung slices were prepared for FRET measurements with PDE3 and PDE4 selective inhibitors under basal conditions. β₂‐AR, β₂‐adrenoceptor; AC, adenylyl cyclase. (B) PCLS from smoke‐exposed mice showed a decreased baseline FRET ratio compared to those from air‐exposed animals, indicating decreased cAMP levels. (C) Quantification of FRET data indicated that clear effects of both PDE3 and PDE4 inhibitors on basal cAMP levels were detected after CS in vivo exposure. Representative FRET traces from slices of air‐exposed mice (D, F) or CS‐exposed mice (E, G). PDE3 and PDE4 were inhibited by cilostamide (10 μM; D, E) and rolipram (10 μM; F, G) respectively. Number of slices and mice is indicated above the bars. On average n = 19–23 independent slices from six to seven mice. Data are expressed as mean ± SEM. *P < 0.05; significantly different from air. One‐way ANOVA was used for simple two groups comparison; IBMX, 100 μM; fenoterol, 1 μM.