Adenosine A3 Receptor induced Delayed Preconditioning: Essential Role of Nuclear Factor κB, Nitric Oxide Synthase and Mitochondrial KATP channels
We investigated the signaling mechanism of adenosine A3 receptor (A3AR) induced delayed cardioprotection. Mice pretreated with selective A3AR agonist, N6-(3-iodobenzyl) adenosine-5′-N-methyluronamide (IB-MECA) demonstrated significant reduction in necrosis and improvement in post-ischemic myocardial performance 24hrs later as compared to vehicle-treated controls. Pretreatment with A3AR antagonist, MRS1191 abolished delayed cardioprotection while selective adenosine A1 receptor antagonist, 8-8-cyclopentyl-1,3-dipropyl xanthine (DPCPX) had no effect. Electrophoretic mobility shift assay demonstrated increased nuclear factor-κB (NF-κB) binding in nuclear extracts following A3AR stimulation, which was diminished by MRS1191 and NF-κB inhibitor, pyrro-lidinediethyldithiocarbamate (PDTC). Also, the cardioprotection was abrogated by PDTC as well as targeted ablation of p50 subunit of NF-κB in mice. The inhibition of inducible nitric oxide synthase (iNOS) with S-methylisothiourea and targeted disruption of iNOS gene abolished the protective effect of A3AR stimulation. Expression of iNOS mRNA and NO production were enhanced after 6 and 24hrs of IB-MECA treatment respectively. MRS1191 and PDTC but not DPCPX blocked NO generation after A3AR stimulation. MitoKATP channel blocker, 5-hydroxydecanoate abolished the protective effect of A3AR. These studies suggest that signaling cascade involving NF-κB activation, synthesis of NO from iNOS and subsequent opening of mitoKATP channel play an essential role in A3AR-induced delayed phase of ischemic protection in the heart. We propose that selective activation of A3AR with its pharmacological drugs can potentially be used to enhance the endogenous defense mechanisms that may provide long lasting ischemic protection of the ischemic heart.
Key wordsAdenosine nuclear factor κ-B nitric oxide mito-KATP channel ischemia reperfusion myocardial infarction
Unable to display preview. Download preview PDF.
- 6.Auchampach, JA, Bolli R. 1999. Adenosine receptor subtypes in the heart: therapeutic opportunities and challenges. Am J Physiol 276:1113–1116.Google Scholar
- 7.Auchampach JA, Qiu Y, Tang XL, Maldonado C, Teschner S, Bolli R. 1997. Selective activation of A3 adenosine receptors with N6-(3-iodobenzyl)adenosine-5′-N-methyluronamide protects against myocardial stunning and infarction without hemodynamic changes in conscious rabbits. Circ Res 80:800–809.PubMedCrossRefGoogle Scholar
- 16.Dana A, Skarli M, Papakrivopoulou J, Yellon DM. 2000. Adenosine A1 receptor induced delayed preconditioning in rabbits: induction of p38 mitogen-activated protein kinase activation and Hsp27 phosphorylation via a tyrosine kinase- and protein kinase C-dependent mechanism. Circ Res 86:921–932.CrossRefGoogle Scholar
- 17.Zhao TC, Hines DS, Kukreja RC. 2001. Adenosine-induced late preconditioning in mouse hearts: role of p38 MAP kinase and mitochondrial KATP channels. Am J Physiol 280:278–285.Google Scholar
- 19.Hu K, Li GR, Nattel S. 1999. Adenosine-induced activation of ATP-sensitive K+ channels in excised membrane patches is mediated by PKC. Am J Physiol 276:488–495.Google Scholar
- 53.Hoag JB, QianY-Z, Nayeem MA, D’Angelo M, Kukreja RC. 1997. ATP-sensitive potassium channel mediates delayed ischemic protection by heat stress in rabbit heart. Am J Physiol 42:H861–H868.Google Scholar