Extracellular NAADP affords cardioprotection against ischemia and reperfusion injury and involves the P2Y11-like receptor

Background and purpose: Extracellular nucleotides may play important regulatory roles within the cardiovascular system and notably in cardioprotection. We aimed to look for a possible pharmacological preconditioning effect of extracellular NAADP ([NAADP](e)) against ischemia/reperfusion injury. [NAADP](e) has been recently reported to be a full agonist of the P2Y11 receptor. Therefore, we characterized the involvement of the P2Y11-like receptor in mediating ischemic/reperfusion tolerance induced by [NAADP](e). Experimental approach: The cardioprotective effects of [NAADP](e) were evaluated in a model of ischemia/ reperfusion carried out on Langendorff perfused rat hearts. This model was also instrumented with a microdialysis probe. Furthermore, using isolated cardiomyocytes, we assessed cAMP, inositol phosphate accumulation and prosurvival protein kinases activation induced by [NAADP](e) pretreatement. Results: Pretreatment with 1 mu M [NAADP](e), induced cardioprotective effects with regards to functional recovery, necrosis and arrhythmogenesis (p <0.05). These effects were completely suppressed with NF157, an antagonist of the P2Y11 receptor. Moreover, global ischemia induced a time-dependent increase in interstitial concentration of adenosine, NAADP and UTP. In cardiomyocyte cultures, NF157 suppressed cAMP and inositol phosphate accumulation induced by [NAADP](e). [NAADP](e), induced phosphorylation of ERK 1/2, AKT and its downstream target GSK-3 beta (p <0.05). These activations were also suppressed by NF157. Conclusions: Evidence suggests that NAADP signalling at the P2Y11-like receptor affords significant cardioprotection against ischemia/reperfusion injury. Besides adenosine and UTP, microdialysis study supports a potential endogenous role of [NAADP](e). (C) 2013 Elsevier Inc. All rights reserved.