Inflammatory lung injury after cardiopulmonary bypass is attenuated by adenosine A_2A receptor activation

Objective: Cardiopulmonary bypass has been shown to exert an inflammatory response within the lung, often resulting in postoperative pulmonary dysfunction. Several studies have shown that adenosine A_2A receptor activation attenuates lung ischemia-reperfusion injury; however, the effect of adenosine A_2A receptor activation on cardiopulmonary bypass-induced lung injury has not been studied. We hypothesized that specific adenosine A_2A receptor activation by ATL313 would attenuate inflammatory lung injury after cardiopulmonary bypass. Methods: Adult male Sprague-Dawley rats were randomly divided into 3 groups: 1) SHAM group (underwent cannulation + heparinization only); 2) CONTROL group (underwent 90 minutes of normothermic cardiopulmonary bypass with normal whole-blood priming solution; and 3) ATL group (underwent 90 minutes of normothermic cardiopulmonary bypass with ATL313 added to the normal priming solution). Results: There was significantly less pulmonary edema and lung injury in the ATL group compared with the CONTROL group. The ATL group had significant reductions in bronchoalveolar lavage interleukin-1, interleukin-6, interferon-γ, and myeloperoxidase levels compared with the CONTROL group. Similarly, lung tissue interleukin-6, tumor necrosis factor-α, and interferon-γ were significantly decreased in the ATL group compared with the CONTROL group. There was no significant difference between the SHAM and ATL groups in the amount of pulmonary edema, lung injury, or levels of proinflammatory cytokines. Conclusion: The addition of a potent adenosine A_2A receptor agonist to the normal priming solution before the initiation of cardiopulmonary bypass significantly protects the lung from the inflammatory effects of cardiopulmonary bypass and reduces the amount of lung injury. Adenosine A_2A receptor agonists could represent a new therapeutic strategy for reducing the potentially devastating consequences of the inflammatory response associated with cardiopulmonary bypass.