Role of inositol trisphosphate in preconditioning

描述（由申请人提供）：短暂的非致死性心肌梗死发作 缺血矛盾地保护心脏和深刻地限制梗死面积 是由随后持续的缺血性损伤引起的人们普遍同意 这种被称为“缺血预适应”的现象是由 在短暂的缺血刺激期间刺激G蛋白偶联受体。 然而，尽管进行了深入的研究，但由 受体的刺激，并最终在这个深刻的内源性心脏 保护问题仍未解决。 我们实验室的证据表明肌醇（1，4，5）-三磷酸 （InsP 3）信号传导-即，第二信使InsP 3的释放; InsP 3受体;以及由此引起的细胞内钙离子的改变 浓度-作为一个潜在的“触发”，为梗死面积减少， 预处理此外，通过以下方式实现的心脏保护 预处理被合成的、膜不可渗透的类似物模仿， + ____________________ D-myo-InsP 3，可能是通过刺激尚未充分表征的 “外部”InsP 3受体。我们目前的目标是：（1）记录存在 的“外部”InsP 3受体，并阐明其贡献的减少 在短暂预处理缺血和外源性 D-myo-InsP 3的给药;（2）确定缺血预处理是否 和D-myo-InsP 3通过共同的下游信号传导实现心脏保护 途径（强调蛋白激酶C的可能作用， 丝裂原活化蛋白激酶和ATP敏感性钾通道）， (3)确定BMP 3是否代表物种间的共同细胞介质 用预处理减少梗死面积。目标1和2将得到解决 在局部缺血的离体缓冲液灌注兔心脏模型中， 四氮唑染色和蛋白质参与描绘的梗死面积 使用选择性药理学拮抗剂评估激酶C等， 定量生化分析。目标3将涉及梗死的测量 尺寸和用于生化分析的整合组织取样， 犬冠状动脉闭塞/再灌注模型。 如果InsP 3被证明是一种重要的细胞介质， 通过预处理减小体积， 由短暂的先行缺血触发的通路可能最终有助于 设计新的良性治疗策略， 抗缺血和梗塞的人心肌。

DESCRIPTION (provided by applicant): Brief, nonlethal episodes of myocardial ischemia paradoxically protect the heart and profoundly limit infarct size caused by a subsequent sustained ischemic insult. There is general agreement that this phenomenon, termed "ischemic preconditioning," is initiated by stimulation of G-protein coupled receptors during the brief ischemic stimulus. However, despite intensive study, the second messenger pathway(s) initiated by receptor stimulation and culminating in this profound endogenous cardiac protection remain unresolved. Evidence from our laboratory has implicated inositol (1,4,5)-trisphosphate (InsP3) signaling - i.e., release of the second messenger InsP3; stimulation of InsP3 receptors; and resultant alterations in intracellular calcium concentration - as a potential "trigger" for infarct size reduction with preconditioning in rabbit heart. Moreover, the cardioprotection achieved with preconditioning is mimicked by the synthetic, membrane-impermeable analog, + ____________________ D-myo-InsP3, presumably via stimulation of as-yet poorly characterized 'external' InsP3 receptors. Our current aims are to: (1) document the existence of 'external' InsP3 receptors and elucidate their contribution to the reduction in infarct size seen with brief preconditioning ischemia and exogenous administration of D-myo-InsP3; (2) determine whether ischemic preconditioning and D-myo-InsP3 achieve cardioprotection via common downstream signaling pathways (with emphasis on the possible role(s) of protein kinase C, mitogen-activated protein kinases, and ATP-sensitive potassium channels) and (3) determine whether Insp3 represents a common cellular mediator among species for infarct size reduction with preconditioning. Aims 1 and 2 will be addressed in the isolated buffer-perfused rabbit heart model of regional ischemia, with infarct size delineated by tetrazolium staining and the involvement of protein kinase C, etc assessed using selective pharmacologic antagonists and quantitative biochemical assays. Aim 3 will involve the measurement of infarct size, and integrated tissue sampling for biochemical analysis, in the in vivo canine model of coronary artery occlusion/reperfusion. If InsP3 proves to be an important cellular mediator contributing to infarct size reduction with preconditioning, this insight into the signal transduction pathways triggered by brief antecedent ischemia may ultimately assist in the design of novel and benign therapeutic strategies to prophylactically render human myocardium resistant to ischemia and infarction.