Ventricular and Cardiac Fiber Characterization and Integration Core

心室和心脏纤维特性和整合核心(核心B)将有助于表征和集成MyBP-C磷酸化和肌动蛋白结合在工作小鼠左心室和具有化学皮肤的心肌纤维上的力学后果：约翰霍普金斯大学的Kass和Takimoto博士将使用一种微型容量电导导管系统来记录近生理条件下的左心室压力-容量环，从而在体内对小鼠左室进行表型表征。这些测量将产生各种复杂的小鼠左室收缩和舒张期功能参数，这些参数与人类的相似参数有关。佛蒙特州大学的Palmer和Maughan博士将在体外对心肌纤维的表型特征进行评估，他们将在化学剥离的心脏纤维制剂中使用各种机械分析方法。对左心室和心脏纤维的测量将提供数据，直接检验项目2--Warshaw/Van布伦和#3--Robbins中提出的具体假设。这些假设是：(I)MyBP-C磷酸化的机械后果需要特定位点和/或位点序列的磷酸化，(Ii)MyBP-C的N末端 与肌动蛋白相互作用，可以影响细丝激活和/或给予肌节机械负荷，和(Iii)MyBP-C磷酸化和/或肌动蛋白相互作用改变肌球蛋白动力学，如肌球蛋白时间。Core在肌丝水平上所做的几项测量--包括肌球蛋白时间--预计将与2号项目--Warshaw/Van布伦在单分子水平上所做的测量直接相关。这个核心的整合部分将展示在分子水平上发现的机械测量与心脏纤维和工作左心室的肌丝晶格的几何形状的相关性。然后，将协调和比较在这个核心进行的调查，以便系统地将分子水平的研究结果(项目2--Warshaw/Van布伦)与肌丝和肌丝的机械性能测量相结合。 脑室水平(项目#3--罗宾斯)。

The Ventricular and Cardiac Fiber Characterization and Integration Core (Core B) will serve to characterize and integrate the mechanical consequences of MyBP-C phosphorylation and actin-binding on the working mouse left ventricle (LV) and the chemically-skinned cardiac fiber: In vivo phenotypic characterization of mouse LV will be performed by Drs. Kass and Takimoto at Johns Hopkins University using a miniaturized volume conductance catheter system to record LV pressure-volume loops under near physiological conditions. These measures will result in a variety of sophisticated parameters of mouse LV systolic and diastolic function, which relate to similar parameters in humans. In vitro phenotypic characterization of cardiac myofilaments will be assessed by Drs. Palmer and Maughan at the University of Vermont using a variety of mechanical assays in the chemically-skinned cardiac fiber preparation. The measurements made in the LV and cardiac fiber will serve to provide data, which directly test specific hypotheses raised in Projects #2-Warshaw/VanBuren and #3-Robbins. These hypotheses are (i) the mechanical consequences of MyBP-C phosphorylation requires phosphorylation of specific sites and/or sequence of sites, (ii) that the N-terminus of MyBP-C interacts with actin and can affect thin filament activation and/or impart a mechanical load on the sarcomere, and (iii) MyBP-C phosphorylation and/or actin interaction modifies acto-myosin kinetics such as myosin time-on. Several measures made in the Core at the myofilament level, -including myosin time-on, are expected to correlate directly to those made by Project #2-Warshaw/VanBuren at the single-molecule level. The integration portion of this Core will demonstrate the relevance of mechanical measures found at the molecular level to the geometry of the myofilament lattice of the cardiac fiber and the working LV. The investigations undertaken in this Core will then be coordinated and compared with the intent to systematically integrate findings at the molecular level (Project #2-Warshaw/VanBuren) with those measures of mechanical performance at the myofilament and ventricular levels (Project #3-Robbins).