Preconditioning and adenosine protect human proximal tubule cells in an in vitro model of ischemic injury

Abstract

Renal ischemic reperfusion injury results in unacceptably high mortality and morbidity during the perioperative period. It has been recently demonstrated that ischemic preconditioning or adenosine receptor modulations attenuate renal ischemic reperfusion injury in vivo. An in vitro model of ischemic renal injury was used in cultured human proximal tubule (HK-2) cells to further elucidate the protective signaling cascades against renal ischemic reperfusion injury. ATP depletion preconditioning (1 h of antimycin A and 2-deoxyglucose treatment followed by 1 h of recovery), adenosine, an A1 adenosine receptor selective agonist or an A2a adenosine receptor selective agonist significantly attenuated subsequent severe ATP depletion injury of HK-2 cells. In contrast, an adenosine receptor antagonist failed to prevent protection induced by ATP depletion preconditioning. Cytoprotection by ATP depletion preconditioning or A1 adenosine receptor activation was prevented by inhibitors of extracellular signal-regulated mitogen-activated kinases, protein kinase C, and tyrosine kinases. The A1 and A2a adenosine receptor-mediated cytoprotection were also dependent on Gi/o proteins and PKA activation, respectively. It is concluded that ATP depletion preconditioning and A1 and A2a adenosine receptor activation protect HK-2 cells against severe ATP depletion injury via distinct signaling pathways.