EXERCISE TRAINING & THE MYOCARDIUM--CELLULAR ADAPTATIONS

描述：（改编自申请人摘要） 耐力训练产生的内在心肌收缩力似乎 与训练引起的肌膜（SL）过程的变化有关， 参与跨膜Ca 2+动力学的调节。 这 这意味着内向Ca 2+电流的大小和/或时程 (Ica)EC偶联过程中随后的胞质Ca 2+（Ca 2+）c动态是 通过训练进行修改。 （CA 2+）c调节的变化不仅会影响 心脏收缩力在细丝的水平，但也将是 预计会影响其他钙依赖过程。 大目标 本研究的目的是探讨训练对（1）伊卡和（Ca ~（2+））c的影响 EC偶联过程中的动力学和（2）Ca 2+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）直接评估收缩性指数， 测量伊卡和（Ca 2+）c变化发生的时间过程和幅度 在电起搏的左心室（LV）心肌细胞中， 久坐不动且受过训练的雌性大鼠。 是否由培训引起的变化 收缩力的变化与伊卡和/或（Ca 2+）c动力学的变化有关 将变得明显。 肌细胞收缩性将通过以下测定： 使用一种新的在线技术测量肌细胞缩短动力学， 平行光冲压，解决了平行光的高速变化， 间隔（肌肉条纹）。 全细胞膜片钳技术将是 用于评估LV心肌细胞中的伊卡和（Ca 2+）c的特征 动力学将使用fura-2和最近开发的 荧光显微镜系统适用于（Ca 2+）c测量在单一的 （B）检测肌球蛋白PLC磷酸盐含量 以及训练对心肌收缩力的影响 关系 肌球蛋白PLC的Ca 2+依赖性磷酸化增强 在化学皮肤化的心脏纤维中产生次最大力; 实验的目的是揭示，如果收缩性的完整的 心肌通过肌球蛋白PLC磷酸化而增强， 训练引起的心肌收缩力变化与 PLC磷酸盐含量的变化。 收缩和PLC磷酸化 将使用从训练的左心室乳头肌中分离的左心室乳头肌检查动力学。 （c）利用从目标（a）中获得的信息， 和（B）为了测试和改进现有的动力学模型，该动力学模型 描述了酶系统的协调动力学行为， 调节心脏PLC磷酸盐含量。

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.