Fig. 2. Generation of Adora2b bone marrow chimeric mice. Overview of the different bone marrow chimeric mice exposed to in situ  myocardial ischemia (MI) (fig. 3) (A ). Wild-type (WT) or adenosine receptor A2b minus (Adora2b^−/−) mice were irradiated with 12 Gy to eliminate all bone marrow derived cells. Next, 10⁷cells isolated from the WT or Adora2b^−/−bone marrow were injected into mice after irradiation as indicated in (A ). After 56 days, these mice were submitted to an in vivo  model of 60 min MI, followed by 120 min of reperfusion (B ). WT mice were treated with 12 Gy irradiation to ablate all bone marrow derived cells, and then reconstituted with 10⁷cells isolated from a donor animal bone marrow. Erythrocyte and leukocyte counts were performed to verify that the bone marrow ablation was successful. Erythrocyte cell count did not change over time. Leukocyte linage was absent on days 3 (0.1 ± 0.1 × 10⁶cells/μl; n = 4) and 4 (0.1 ± 0.1 × 10⁶cells/μl; n = 4) after irradiation treatment. Leukocytes were at the same concentration as the preirradiation value at day 56 after bone marrow transplantation (day −1: 10.1 ± 0.5 × 10⁶cells/μl; day 56: 9.3 ± 0.5 × 10⁶cells/μl; mean ± SD; n = 4 per group) (C ). WT mice underwent irradiation with 12 Gy to ablate all bone marrow derived cells. Then, irradiated WT mice received bone marrow from donor animal carrying the CD45.1 alloantigen on all bone marrow derived cells to reconstitute the leukocyte linage. Fluorescence-activated cell sorting analysis revealed that between 94 ± 0.6% (CD8+ T lymphocytes) and 98 ± 0.5% (B cell lineage) of bone marrow derived cells carried the CD45.1 alloantigen (mean ± SD; n = 5 per group) (D ). KO = knockout.