DIABETIC CARDIOMYOPATHY - ROLE OF INSULIN RESISTANCE

申请人摘要 临床和实验研究表明，糖尿病本身 会导致心功能恶化，而不仅仅是 可归因于冠状动脉疾病。从大多数模型中可以明显看出 心力衰竭是指心室肌细胞经历类似的表型和 基因类型改变(定义为心肌病)对不同的 新陈代谢和全身压力。这项调查旨在测试 I型和2型糖尿病细胞反应趋同的假说 在疾病的早期，并表现为心肌细胞内的异常 CA2的调控。申请者将通过以下方式检验这一假设： 细胞内信号转导通路促进血管紧张素转换酶 两种不同模型的异常兴奋-收缩(E-C)耦合 糖尿病的早期阶段：1)在高血糖环境中培养心肌细胞 2)喂食蔗糖的动物会引发胰岛素抵抗。 将使用生物物理方法(视频边缘)评估心肌细胞的E-C偶联 检测、电生理学和荧光分光光度法)，以及激酶活性和 利用生物化学和免疫印迹分析表达特定的蛋白质。 将使用药物干预(包括细胞培养和体内)。 目的：探讨靶蛋白激酶(即PKC、PKA和CaMKII)在脑缺血再灌注损伤中的作用。 E-C偶联受损的发病机制。工作假设是，改变 调节蛋白活性先于离子基因表达的显性变化 通道和膜式泵，因此这些变化是导致 心肌细胞功能障碍而不是代偿性表型改变 保留收缩功能。这项调查将集中在蜂窝 导致糖尿病患者E-C偶联异常的机制有 在其他心力衰竭模型中常见的(例如，压抑的K 电导和SR钙通量)。细胞胰岛素的研究进展 耐药性很可能是糖尿病病因中的一个关键因素。 心肌病，可能代表胎儿基因表达的重现， 如肥大心肌所示。

Applicant's Abstract Clinical and experimental investigations have indicated that diabetes per se can lead to a deterioration of cardiac function that cannot be solely attributable to coronary artery disease. What is apparent from most models of heart failure is that ventricular myocytes undergo similar phenotypic and genotypic changes (defined as a cardiomyopathy) in response to various metabolic and systemic stresses. This investigation is designed to test the hypothesis that cellular responses to type I and type 2 diabetes converge early on in the diseases, and manifest in abnormal cardiomyocyte intracellular Ca2+ regulation. The applicants will test this hypothesis by determining intracellular signaling pathways that contribute to the development of abnormal excitation- contraction (E-C) coupling in two distinct models of early stages of diabetes: 1) culturing myocytes in a hyperglycemic milieu and 2) sucrose-feeding animals triggering the development of insulin resistance. Myocyte E-C coupling will be evaluated using biophysical measures (video-edge detection, electrophysiology and spectrofluorometry), and kinase activity and expression of specific proteins using biochemical and immunoblot assays. Pharmacological interventions (both in cell culture and in vivo) will be used to evaluate the roles of target kinases (i.e., PKC, PKA and CaMKII) in the pathogenesis of impaired E-C coupling. The working hypothesis is that changes in regulatory protein activity precede overt changes in gene expression of ion channels and membrane pumps, such that these changes are the initial cause of myocyte dysfunction rather than a compensatory phenotypic change induced to preserve contractile function. This investigation will focus on cellular mechanisms which contribute to abnormal E-C coupling in diabetes and are common to those in other models of heart failure (e.g., depressed K+ conductance and SR Ca2+ fluxes). The development of cellular insulin resistance is likely to be a key factor in the etiology of diabetic cardiomyopathy and may represent the recapitulation of fetal gene expression, as shown for hypertrophic myocardium.