Role of inositol trisphosphate in preconditioning

描述(由申请人提供)：短暂的、非致命性的心肌梗塞发作 自相矛盾的是，缺血保护了心脏，并深刻地限制了梗死范围 是由随后持续的缺血侮辱引起的。大家普遍同意 这种现象，被称为“缺血预适应”，是由 短暂缺血刺激对G蛋白偶联受体的刺激作用。 然而，尽管经过深入的研究，第二信使途径(S)是由 受体的刺激和在这种深刻的内源性心脏中达到高潮 保护措施仍未得到解决。 我们实验室的证据表明肌醇(1，4，5)-三磷酸 (InsP3)信号--即第二信使InsP3的释放；刺激 InsP3受体及由此引起的细胞内钙离子变化 浓度--作为一种潜在的“触发器”缩小梗塞面积 兔心脏的预适应。此外，通过 预适应是由合成的、膜不渗透的类似物模拟的， +_ D-myo-InsP3，可能是通过刺激迄今尚未鉴定的 “外部”InsP3受体。我们目前的目标是：(1)记录存在 并阐明它们在降低InsP3受体中的作用 在短暂的预适应缺血和外源性心肌梗死面积中 D-myo-InsP3的应用；(2)确定缺血预适应 D-myo-InsP3通过共同的下行信号实现心肌保护 途径(重点是蛋白激酶C的可能作用(S)， 有丝分裂原激活的蛋白激酶和ATP敏感性钾通道)和 (3)确定Insp3是否代表物种间常见的细胞介体 用于通过预适应缩小梗塞面积。目标1和目标2将得到解决 在兔心脏局部缺血的隔离缓冲灌流模型中， 四唑盐染色显示心肌梗死面积及蛋白的参与 使用选择性药物拮抗剂和 定量生化分析。目标3将涉及脑梗塞的测量 用于体内生化分析的大小和集成组织采样 犬冠状动脉闭塞/再灌注模型。 如果InsP3被证明是导致脑梗塞的重要细胞介质 通过预适应缩小尺寸，这是对信号转导的洞察 由短暂的先天缺血触发的通路最终可能有助于 设计新的和良性的治疗策略以预防性呈现 人的心肌对缺血和梗塞具有抵抗力。

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.