EXERCISE TRAINING & THE MYOCARDIUM--CELLULAR ADAPTATIONS

描述：(改编自申请人的摘要)积极变化 耐力训练产生的内在心脏收缩能力似乎是 与训练引起的肌膜(SL)过程的改变有关 参与了跨膜钙动力学的调节。这 意味着内向钙电流的大小和/或时程 (ICa)和随后在EC偶联过程中的胞浆Ca~(2+)c动态 经过训练而改变的。(CA2)C规则的变化不仅会影响 心脏的收缩能力在细丝水平上，但也会 预计将影响其他依赖钙的过程。的主要目标 这项建议是为了检查训练对(1)ica和(Ca)c的影响。 EC偶联过程中的动力学和(2)钙依赖的磷酸化 心肌肌球蛋白P轻链(PLC)。建议的具体目标 实验是(A)直接评估收缩能力指数和 测量ICa和(Ca2)c发生变化的时间过程和大小 在电起搏的左心室(LV)心肌细胞中 久坐不动、训练有素的雌性老鼠。培训是否会导致变化 收缩能力与ICa和/或(钙)c动力学的变化有关 将变得显而易见。心肌细胞的收缩能力将由以下因素决定 用一种新的在线技术测量心肌细胞缩短动力学 解决平行变速的平行光学压力机 间距(肌肉条纹)。全细胞膜片钳技术将是 用来评估左室肌细胞和(钙)c的ICa特性 动力学将使用Fura-2和最近开发的 一种适用于(Ca~(2+))_c单次测量的荧光显微镜系统 细胞；(B)研究肌球蛋白PLC磷酸含量之间的关系 和完整心肌的收缩能力及训练对其的影响 两性关系。肌球蛋白PLC的钙依赖性磷酸化增强 在化学剥离的心脏纤维中产生次最大力； 实验旨在揭示完好无损的心脏的收缩能力 肌球蛋白PLC磷酸化和IF增强心肌 训练引起的心肌收缩能力改变与以下因素有关 PLC磷酸盐含量的变化。肌张力与PLC的磷酸化 将使用从训练中分离的左乳头肌来检查动力学 和久坐不动的大鼠；(C)利用AIMS(A)产生的信息 以及(B)为了测试和改进现有的动力学模型，该模型 描述负责的酶系统的协调动态行为 用于调节心脏PLC的磷酸含量。

DESCRIPTION: (Adapted from the applicant's abstract) Positive changes in intrinsic cardiac contractility produced by endurance training appear to be associated with training-induced changes in sarcolemmal (SL) processes that are involved in the regulation of transmembrane Ca2+ dynamics. This implies that the magnitude and/or timecourse of the inward Ca2+ current (Ica) and subsequent cytosolic Ca2+ (Ca2+)c dynamics during EC coupling are modified by training. Changes in (CA2+)c regulation would not only affect cardiac contractility at the level of the thin filament, but would also be expected to affect other Ca2+-dependent processes. Major objectives of this proposal are to examine the effect of training on (1)ICa and (Ca2+)c dynamics during EC coupling and (2) the Ca2+-dependent phosphorylation of cardiac myosin P-light chain (PLC). The specific aims of the proposed experiments are (a) to directly assess indices of contractility and to measure the timecourse and magnitude of ICa and (Ca2+)c changes occurring in electrically paced left ventricular (LV) cardiac myocytes isolated from sedentary and trained female rats. Whether or not training-induced changes in contractility are associated with changes in ICa and/or (Ca2+)c dynamics will become apparent. Myocyte contractility will be determined by measuring myocyte shortening dynamics using a novel on-line technique of parallel optical pressing which resolves high speed variation of parallel spacing (muscle striations). Whole cell patch clamp techniques will be used to assess the characteristics of ICa in LV myocytes and (Ca2+)c dynamics will be determined using fura-2 and a recently developed fluorescence microscopy system suitable for (Ca2+)c measurements in single cells; (b) to examine the relationship between myosin PLC phosphate content and contractility in intact myocardium and the effect of training on this relationship. The Ca2+-dependent phosphorylation of myosin PLC enhances submaximal force generation in chemically skinned cardiac fibers; experiments are designed to reveal if the contractility of intact myocardium is enhanced by myosin PLC phosphorylation and if training-induced changes in cardiac contractility are associated with changes in PLC phosphate content. Contractility and PLC phosphorylation dynamics will be examined using LV papillary muscles isolated from trained and sedentary rats; (c) to utilize the information resulting from Aims (a) and (b) in order to test and refine an existing kinetic model which describes the concerted dynamic behavior of the enzyme systems responsible for regulating cardiac PLC phosphate content.