Regulation of Work Capacity in Cardiac Myocytes

心肌细胞工作能力的调节

• 批准号: 6370411
• 负责人: Kerry S McDonald
• 金额: $ 17.94万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6370411
• 关键词: SDS polyacrylamide gel electrophoresis; biological signal transduction; biomechanics; calcium flux; cardiac myocytes; heart contraction; laboratory rat; muscle function; myocardium; myosins; phosphorylation; protein isoforms; protein kinase A; protein structure function; sarcomeres; thyroid hormones; tissue /cell culture

The ability of the heart to perform work is essential for moving blood throughout the circulatory system and appears to be depressed in conditions of heart disease. The overall goal of this project is to investigate potential molecular mechanisms that regulate the work capacity of cardiac mycocytes. Experiments will specifically test how variable expression of the two cardiac myosin heavy chain (MyHC) isoforms regulates myocyte contractible properties. MyHC content will be manipulated over the entire range of 100 percent alpha-MyHC to 100 percent 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 MyHC composition in single mycocytes following functional measurements. The first aim is to determine how altered alpha: beta MyHC ratios affect the important relationship between isometric force and [Ca2+]. The second aim will investigate how varied expression of alpha:beta MyHC ratios affect dynamic mechanical properties by correlating MyHC content with unloaded shortening velocities of the same individual myocyte. The third aim will determine the role that MyHC plays in determining power output by measuring power-load curves in myocytes expressing variable ratios of alpha:beta MyHC. Effects of variable expression of MyHC on power-load curves will also address the fourth aim, which is to provide insights into the steps(s) (i.e., detachment or attachment) of the myosin cross-bridge cycle that limit peak power output of myocytes. Further experiments will utilize reagents that increase specific cross-bridge states as a means assess which chemomechanical steps limit myocyte power output. The final aim to determine if the myocardial variations in both force and power output following protein kinase A (PKA)- induced phosphorylation differ between alpha-MyHC and beta-MyHC myocytes. Overall, these experiments should provide important insights into the role that cardiac MyHC plays in regulating myocardial contraction and determining the work capacity of individual myocytes. These experiments are important in elucidating the molecular mechanisms that determine work capacity of myocardium as well as improving our understanding of the functional consequences associated with reduced expression of alpha-MyHC as increased expression of beta-MyHC, which occurs during the progression of human heart failure.

心脏做功的能力对于血液在整个循环系统中的流动至关重要，并且在心脏病的情况下似乎受到抑制。 本项目的总体目标是研究调节心肌真菌细胞工作能力的潜在分子机制。实验将专门测试两种心肌肌球蛋白重链（MyHC）亚型的可变表达如何调节肌细胞收缩特性。 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真菌细胞中的MyHC组成，将获得MyHC含量和机械性能之间的因果关系。 第一个目的是确定α：β MyHC比例的改变如何影响等长力和[Ca 2 +]之间的重要关系。 第二个目标将调查如何不同的表达α：β MyHC的比例影响动态力学性能相关的MyHC内容与卸载缩短速度相同的个体肌细胞。 第三个目标是通过测量表达不同比例α：β MyHC的肌细胞的功率-负荷曲线，确定MyHC在确定功率输出中的作用。 MyHC的可变表达对功率-负荷曲线的影响也将解决第四个目标，即提供对步骤（即，分离或附着），限制肌细胞的峰值功率输出。 进一步的实验将利用增加特定交叉桥状态的试剂作为评估哪些化学机械步骤限制肌细胞功率输出的手段。 最终目的是确定蛋白激酶A（PKA）诱导磷酸化后，α-MyHC和β-MyHC心肌细胞之间的力和功率输出的心肌变化是否不同。 总的来说，这些实验应该提供重要的见解，心脏心肌细胞在调节心肌收缩和确定单个心肌细胞的工作能力的作用。 这些实验对于阐明决定心肌工作能力的分子机制以及提高我们对与在人类心力衰竭进展期间发生的α-MyHC表达减少和β-MyHC表达增加相关的功能后果的理解是重要的。