A1adenosine receptor knockout mice exhibit increased renal injury following ischemia and reperfusion

Abstract
Controversy exists regarding the effect of A1adenosine receptor (AR) activation in the kidney during ischemia and reperfusion (I/R) injury. We sought to further characterize the role of A1ARs in modulating renal function after I/R renal injury using both pharmacological and gene deletion approaches in mice. A1AR knockout mice (A1KO) or their wild-type littermate controls (A1WT) were subjected to 30 min of renal ischemia. Some A1WT mice were subjected to 30 min of renal ischemia with or without pretreatment with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) or 2-chrolo-cyclopentyladenosine (CCPA), selective A1AR antagonist and agonist, respectively. Plasma creatinine and renal histology were compared 24 h after renal injury. A1KO mice exhibited significantly higher creatinines and worsened renal histology compared with A1WT controls following renal I/R injury. A1WT mice pretreated with the A1AR antagonist or agonist demonstrated significantly worsened or improved renal function, respectively, after I/R injury. In addition, A1WT mice pretreated with DPCPX or CCPA showed significantly increased or reduced markers of renal inflammation, respectively (renal myeloperoxidase activity, renal tubular neutrophil infiltration, ICAM-1, TNF-α, and IL-1β mRNA expression), while demonstrating no differences in indicators of apoptosis. In conclusion, we demonstrate that endogenous or exogenous preischemic activation of A1ARs protects against renal I/R injury in vivo via mechanisms leading to decreased necrosis and inflammation.