Pulmonary A2BAR expression increases after exposure to hypoxia in vivo. Wild-type mice were subjected to normoxia or 4 hours of ambient hypoxia (8% oxygen). Whole lungs were fixed with 10% formalin at total lung capacity. Lungs were stained with antibody for the A2BAR. Normal goat IgG was used in controls at identical concentration and staining conditions as the target primary Ab (arrow marks vascular, asterisk alveolar structures). Evaluation of the histologic and immunohistochemical stainings and photographic documentation was performed using an Olympus Vanox AH-3 light microscope (Hamburg, Germany), original magnification, ×400.