DEVELOPMENT OF CARDIAC EXCITATION/CONTRACTION COUPLING

尽管最近在对钙的总体理解上取得了许多进展 在心脏兴奋-收缩(EC)偶联期间的处理，很少是 关于各种分子的功能组装的已知 胚胎学过程中的EC偶联成分 发展。这是非常重要的信息，因为很多药物 用于治疗心脏病的药物在某种程度上影响了钙的调节 而且，对于怀孕的母亲来说，这些很可能会影响胎儿 不同的。其次，很可能这些因素的正常发展 先天性心脏病的发病机制发生了改变。在这份提案中， 这些实验旨在测试心脏的功能方面 EC偶联与心脏连接复合体平行发展， 特定蛋白在胚胎心脏中的表达。交汇性 复合体是EC偶联的结构表现形式，具有 最近详细报道了在鸡胚中的电子和 共聚焦显微镜。预计，时间进程 电子商务耦合的发展将与其出现和表达平行 关键的蛋白质成分。将使用的方法包括 膜片钳、钙瞬变测量、荧光共聚焦 显微镜和Western blotting。这些研究将在#年进行。 鸡胚是胚胎学研究最多的模型 大多数蜂窝系统的开发，包括EC耦合。平行 实验将在发育中的小鼠心脏中进行 与哺乳动物物种相比。具体目标是：1) 确定钙诱导的钙释放的正常发育 肌浆网；2)测定肌浆网的正常发育 从细胞质中去除钙的机制；以及3)确定 心脏内皮细胞中关键蛋白的相对表达和组装 耦合。这项工作的长期目标是理解 细胞内钙离子调控的关键机制研究进展 从最早的心脏导管到成熟的四个- 有心腔的。

Despite many recent advances in the general understanding of Ca2+ handling during cardiac excitation-contraction (EC) coupling, little is known regarding the functional assembly of the various molecular components of EC coupling during the course of embryological development. This is critical information considering that many drugs used in the treatment of heart disease affect Ca2+ handling in some way and, in the pregnant mother, these are likely to affect the fetus differently. Secondly, it is likely that the normal development of these mechanisms is altered in congenital heart disease. In this proposal, the experiments are designed to test how functional aspects of cardiac EC coupling develop in parallel with cardiac junctional complexes and expression of specific proteins in embryonic heart. Junctional complexes are the structural manifestations of EC coupling which have recently been reported in detail in the chick embryo with electron and confocal microscopy. It is anticipated that the time course of development of EC coupling will parallel the appearance and expression of the key protein components. The approaches that will be used include patch clamping, measurements of Ca2+ transients, fluorescence confocal microscopy, and Western blotting. These studies will be carried out in the chick embryo which is the most studied model for embryological development of most cellular systems including EC coupling. Parallel experiments will be conducted in the developing mouse heart for comparison with a mammalian species. The Specific Aims are: 1) to determine the normal development of Ca-induced-Ca-release from the sarcoplasmic reticulum; 2) to determine the normal development of the mechanisms which remove Ca2+ from the cytoplasm; and 3) to determine the relative expression and assembly of the key proteins in cardiac EC coupling. The long term objective of this work is to understand the development of the critical mechanisms which regulate cytosolic Ca2+ on a beat-to-beat basis from the earliest heart tube to the mature four- chambered heart.