Fig. 1. Matched high-resolution computed tomographic images of airways from one dog at control (upper left ), after a histamine challenge (upper right ), after administration of 0.5 μg/kg intravenous dexmedetomidine (Dex) (lower left ), and after a repetition of the histamine (Hist) challenge (lower right ). Nebulization of histamine led to marked bronchoconstriction. After intravenous administration of the α²-receptor agonist dexmedetomidine, the response to histamine was almost completely blocked.