Regulation of power output in cardiac myocytes

心肌细胞功率输出的调节

• 批准号: 6556764
• 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/6556764
• 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。 这一建议的一个主要重点是确定如何可变表达的两个心肌肌球蛋白重链（MyHC）亚型调节心肌细胞的收缩特性。 将通过大鼠中MyHC同种型的甲状腺激素依赖性表达在100% α-MyHC至100% β-MyHC的整个范围内操纵MyHC含量。 通过SDS-PAGE分析功能测量后单个肌细胞的蛋白质组成，将获得MyHC含量和机械性能之间的因果关系。 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Ca 2+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力学步骤，这些步骤在确定肌细胞在宽范围负荷下的功率输出中是最重要的。 这些实验将利用增加特定交叉桥状态的试剂，以检查特定化学机械状态如何改变功率负载曲线。 另一个目的是确定在α-MyHC和β-MyHC肌细胞之间，在响应于蛋白激酶A（PKA）诱导的肌原纤维蛋白磷酸化的力和功率输出的心肌变化是否不同，并确定肌球蛋白结合蛋白-C的磷酸化是否是β-肾上腺素能刺激后增加肌原纤维功率输出所必需的。 最终目的是确定PKCe诱导的磷酸化对肌原纤维功率输出的影响。 总的来说，这些实验应该提供重要的见解到细胞和分子的因素，调节功率输出的心脏，并应提高我们的理解减少表达的α-MyHC和改变的肌原纤维蛋白磷酸化状态的功能性后果，这两者都发生在人类心力衰竭的进展。