Regulation of power output in cardiac myocytes

心肌细胞功率输出的调节

• 批准号: 7006622
• 负责人: Kerry S McDonald
• 金额: $ 10.13万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7006622
• 关键词: SDS polyacrylamide gel electrophoresis; biomechanics; cardiac myocytes; isozymes; laboratory mouse; laboratory rat; muscle contraction; muscle proteins; muscle strength; myofibrils; myosins; neuromuscular transmission; phosphorylation; protein kinase A; protein structure function

DESCRIPTION (provided by applicant): The overall purpose of this project is to determine the cellular mechanisms that determine power output of me heart. A major focus of this proposal is determination of how variable expression of the two cardiac myosin heavy chain (MyHC) isoforms regulates contractile properties of cardiac myocytes. MyHC content will be manipulated over the entire range of 100% alpha-MyHC to 100% beta-MyHC by thyroid hormone-dependent expression of MyHC isoforms in rats. Definitive relationships between MyHC content and mechanical properties will be achieved by SDS-PAGE analysis of protein composition of individual myocytes following functional measurements. The specific aims of this study include determination of the effects of MyHC on Ca2+ sensitivity of stead:-state isometric force, loaded shortening velocity and power output. Another aim is to assess the chemomechanical steps of the myosin cross-bridge cycle that are most important in determining myocyte power output over a wide range of loads. These experiments will utilize reagents that increase the population of specific cross-bridge states, to examine how specific chemomechanical states alter power-load curves. Another aim is to determine if myocardial variations in force and power output in response to protein kinase A (PKA)-induced phosphorylation of myofibrillar proteins differ between alpha-MyHC and beta-MyHC myocytes and to determine whether phosphorylation of myosin binding protein-C is necessary for increased myofibrillar power output following beta-adrenergic stimulation. A final aim is determine the effects of PKCe-induced phosphorylation on myofibrillar power output. Overall, these experiments should provide important insights into the cellular and molecular factors that regulate power output in the heart and should improve our understanding the functional consequences of reduced expression of alpha-MyHC and altered phosphorylation states of myofibrillar proteins, which both occur during the progression of human heart failure.

描述（由申请人提供）： 该项目的总体目的是确定决定心脏功率输出的细胞机制。 该提案的一个主要焦点是确定两种心肌肌球蛋白重链 (MyHC) 亚型的可变表达如何调节心肌细胞的收缩特性。 MyHC 含量将通过大鼠中 MyHC 亚型的甲状腺激素依赖性表达在 100% α-MyHC 至 100% beta-MyHC 的整个范围内进行控制。 MyHC 含量和机械特性之间的明确关系将通过功能测量后对单个肌细胞的蛋白质组成进行 SDS-PAGE 分析来实现。 本研究的具体目的包括确定 MyHC 对稳态等长力、负载缩短速度和功率输出的 Ca2+ 敏感性的影响。 另一个目的是评估肌球蛋白跨桥循环的化学机械步骤，这对于确定各种负载下的肌细胞功率输出最为重要。 这些实验将利用增加特定跨桥状态数量的试剂，以检查特定化学机械状态如何改变功率负载曲线。 另一个目的是确定 α-MyHC 和 β-MyHC 肌细胞之间对蛋白激酶 A (PKA) 诱导的肌原纤维蛋白磷酸化反应的力和功率输出的心肌变化是否存在差异，并确定肌球蛋白结合蛋白 C 的磷酸化是否是 β 肾上腺素刺激后肌原纤维功率输出增加所必需的。 最终目标是确定 PKCe 诱导的磷酸化对肌原纤维功率输出的影响。 总的来说，这些实验应该为调节心脏功率输出的细胞和分子因素提供重要的见解，并应该提高我们对α-MyHC表达减少和肌原纤维蛋白磷酸化状态改变的功能后果的理解，这两种情况都发生在人类心力衰竭的进展过程中。