A3 Adenosine Receptors Cardioprotective Mechanisms

描述（由申请人提供）：本研究的目的是确定A3腺苷受体（AR）保护心肌缺血/再灌注损伤的机制。 我们将检验A3 AR通过多种机制具有保护作用的假设，包括保护线粒体功能、减少细胞凋亡和减轻炎症。 我们预测，A3 AR信号通过激酶信号传导途径，最终导致保护线粒体KATP通道的激活。 我们假设的一个关键特征是，我们预测A3 AR在心肌细胞中表达。 我们将通过检查选择性A3 AR激动剂在离体小鼠全脑缺血/再灌注心脏模型和临床相关的体内犬梗死模型中的作用来测试这些假设。 将使用离体小鼠心脏模型来关联缺血后收缩功能（左心室压力）和细胞坏死（LDH释放）与代谢状态（高能磷酸盐），线粒体完整性（线粒体膜电位、呼吸和ATP合成速率）、细胞凋亡（DNA片段化、TUNEL染色、半胱天冬酶活化）和促炎细胞因子信号传导（NF κ B活化、TNF α产生）。 将使用体内犬梗死模型比较梗死大小与炎症标志物（中性粒细胞浸润）。 线粒体特异性KATP通道阻滞剂5-羟基癸酸钠将用于描述线粒体KATP通道在保护线粒体和心脏功能中的作用。 将进行实验以确定A3 AR是否通过特异性蛋白激酶（PKC-β或δ; PI-3/akt激酶）和/或活性氧物质的产生发出信号。 从这些研究中获得的信息将促进对细胞保护所涉及的基本问题的理解。 这些研究的结果也应该为靶向A3 AR在缺血性心脏病患者中的治疗效用提供新的见解。

DESCRIPTION (provided by applicant): The goal of this research is to define the mechanisms by which A3 adenosine receptors (ARs) protect against myocardial ischemia/reperfusion injury. We will test the hypothesis that A3ARs are protective by multiple mechanisms including preservation of mitochondrial function, reduction of apoptosis, and attenuation of inflammation. We predict that the A3AR signals via kinase signaling pathways that ultimately results in protection by activation of mitochondrial KATP channels. A key feature of our hypothesis is that we predict that A3ARs are expressed in cardiac myocytes. We will test these hypotheses by examining the effect of selective A3AR agonists in an isolated mouse heart model of global ischemia/reperfusion and a clinically relevant in vivo dog model of infarction. The isolated mouse heart model will be used to correlate post-ischemic contractile function (left ventricular pressure) and cell necrosis (LDH released) with metabolic state (high-energy phosphates), mitochondrial integrity (mitochondrial membrane potential, respiration, and rate of ATP synthesis), apoptosis (DNA fragmentation, TUNEL staining, caspase activation), and pro-inflammatory cytokine signaling (NF kappa B activation, TNF alpha production). The in vivo dog model of infarction will be used to compare infarct size with markers of inflammation (neutrophil infiltration). The mitochondrial specific KATP channel blocker sodium 5-hydroxydecanoate will be used to delineate the role of mitochondrial KATP channels in preserving mitochondrial and cardiac function. Experiments will be performed to determine whether A3ARs signal via specific protein kinases (PKC-epsilon or delta; PI-3/akt kinase) and/or generation of reactive oxygen species. Information obtained from these studies will advance the understanding of the fundamental questions involved in cellular protection. The results of theses studies should also provide new insights into the therapeutic utility of targeting A3ARs in patients with ischemic heart disease.