Molecular Basis of Preconditioning

描述（由申请人提供）：拟议研究的长期目标是阐明缺血和药理学预处理的分子基础。已经反复观察到，短时间的缺血保护心脏组织免受长时间的缺血损伤，并且这种作用被多种药理学试剂模拟。虽然预适应及其阻断被认为分别通过线粒体K（ATP）通道的开放和关闭介导，但总体机制特征并不明确。我们的初步数据表明，5-羟基癸酰辅酶A（潜在的K（ATP）通道阻滞剂5-羟基癸酸的辅酶A衍生物）通过中链酰基辅酶A脱氢酶以及线粒体脂肪酸氧化途径的后续酶代谢。所提出的研究是基于我们的假设，即药理学预处理及其阻断的起源在于线粒体途径的酶活性的调节（即，脂肪酸氧化和TCA循环）和电子转移系统。拟议研究的具体目标是：（1）阐明5-羟基癸酰辅酶A代谢的详细机制（2）为了确定5-HD-CoA及其代谢产物对选定的线粒体酶的作用，（3）探讨选择性预适应调节剂对活性氧（reactive oxygen species，ROS）产生/抑制的作用机制。这些具体目标将通过采用酶动力学、热力学、涉及分离的酶和完整的线粒体制剂的模型建立研究的技术来实现。这些研究的结果将揭示预处理的分子基础，并可能导致心脏保护药物的开发。

DESCRIPTION (provided by applicant): The long term goal of the proposed research is to deleneate the molecular basis of ischemic and pharmacological preconditioning. It has been repeatedly observed that short period of ischemia protects heart tissues from prolonged ischemic insult, and such an effect is mimicked by a variety of pharmacological agents. Although preconditioning and its blockage are believed to be mediated via openining and closing of the mitochondrial K(ATP) channels, respectively, overall mechanistic feature is not unequivocal. Our preliminary data suggest 5-hydroxydecanoyI-CoA (the CoA-derivative of the potential K(ATP) channel blocker 5-hydroxydecanoic acid) is metabilized via medium chain acyI-CoA dehydrogenase, as well as by the subsequent enzymes of the mitochondrial fatty acid oxidative pathway. The proposed research is based on our hypothesis that the origin of pharmacological preconditioning and its blockage lies in the modulation of enzyme activities of the mitochondrial pathways (viz., fatty acid oxidation and TCA cycle) and the electrontransfer system. The specific aims of the proposed research are: (1) To elucidate the detailed mechanism for the metabolism of 5-hydroxydecanoyI-CoA (5-HD-CoA) via the enzymes of the mitochondrial oxidative pathway, (2) To determine the effects of 5-HD-CoA and its metabolized products on selected mitochrondrial enzymes, and (3) To investigate the mechanism of production/suppression of reactive oxygen species (ROS) under the influence of selective preconditioning modulators. These specific aims will be accomplished by employing the techniques of enzyme kinetics, thermodynamics, model building studies involving isolated enzymes and intact mitochonrial preparations. The outcomes of the proposed studies will throw light on the molecular basis of preconditioning and may lead to the development of cardioprotective drugs.