NECA-induced airway responsiveness in a) wild-type study groups. Values for Fig. 4a are expressed as mean ± SEM, *p < 0.05 compared to WT CON; #p < 0.05 compared to WT SEN, n = 6 mice per group, and b) A2AKO study groups. Values for Fig. 4b are expressed as mean ± SEM, *p < 0.05 compared to A2AKO CON, n = 6 mice per group