Ventricular and Cardiac Fiber Characterization and Integration Core

心室和心脏纤维表征和整合核心（核心B）将用于表征和整合MyBP-C磷酸化和肌动蛋白结合对工作小鼠左心室（LV）和化学皮肤心脏纤维的机械后果：小鼠LV的体内表型表征将由约翰霍普金斯大学的Kass和Takimoto博士使用小型体积电导导管系统进行，在接近生理条件下记录LV压力-容积环。这些测量将产生小鼠LV收缩和舒张功能的各种复杂参数，其与人类中的类似参数相关。将由佛蒙特大学的Palmer和Maughan博士在化学去皮的心脏纤维制备物中使用各种机械测定法评估心脏肌丝的体外表型表征。在LV和心脏纤维中进行的测量将用于提供数据，这些数据直接测试项目#2-Warshaw/VanBuren和#3-Robbins中提出的特定假设。这些假设是（i）MyBP-C磷酸化的机械结果需要特定位点和/或位点序列的磷酸化，（ii）MyBP-C的N-末端磷酸化， 与肌动蛋白相互作用并且可以影响细丝激活和/或对肌节施加机械负荷，和（iii）MyBP-C磷酸化和/或肌动蛋白相互作用改变肌动蛋白-肌球蛋白动力学，例如肌球蛋白时间。在肌丝水平的核心中进行的几个测量，包括肌球蛋白时间，预期与项目#2-Warshaw/VanBuren在单分子水平进行的测量直接相关。该核心的整合部分将证明在分子水平上发现的力学测量与心脏纤维和工作LV的肌丝网格几何结构的相关性。然后，将协调和比较本核心中进行的研究，以便系统地整合分子水平的研究结果（项目#2-Warshaw/VanBuren）与肌丝和肌纤维力学性能的测量结果。 心室水平（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).