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 会导致心脏功能的恶化， 冠状动脉疾病引起的。 从大多数模型来看， 心力衰竭是心室肌细胞经历相似表型， 基因型变化（定义为心肌病）， 代谢和系统压力。 这项调查旨在测试 对I型和2型糖尿病细胞反应趋同的假说 在疾病的早期，并表现在异常的心肌细胞内 钙调节。 申请人将通过确定 细胞内信号通路，有助于发展 异常兴奋-收缩（E-C）耦合在两个不同的模型， 糖尿病早期：1）在高血糖环境中培养肌细胞， 2)蔗糖喂养的动物引发胰岛素抵抗的发展。 肌细胞E-C偶联将使用生物物理测量（视频边缘）进行评价。 检测、电生理学和荧光分光光度法）和激酶活性， 使用生物化学和免疫印迹测定来表达特异性蛋白质。 将使用药理学干预（细胞培养和体内） 为了评价靶激酶的作用（即，PKC、PKA和CaMKII）在 E-C偶联受损的发病机制。 工作假设是， 调节蛋白活性先于离子基因表达的明显变化 通道和膜泵，这样这些变化是最初的原因 肌细胞功能障碍，而不是诱导的代偿性表型变化， 保持收缩功能。 本次调查将集中在细胞 导致糖尿病异常E-C偶联的机制， 与其他心力衰竭模型中的那些相同（例如，抑制K+ 电导和SR Ca 2+通量）。 细胞胰岛素的研究进展 抵抗可能是糖尿病病因学中的关键因素 心肌病并可能代表胎儿基因表达的重演， 如肥厚心肌所示。

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.