CONTRACTILE FORCE AND CALCIUM HANDLING IN HEART FAILURE

充血性心力衰竭（CHE）与受损的心肌细胞 功能 含量和异构体分布的改变 收缩蛋白质和参与钙处理的关键蛋白质 在CHF中发现。 CHF中的力发展降低可能是由于 改变钙处理，减少收缩蛋白功能，或从 这些因素的组合。 之间的确切关系 蛋白质合成的改变和受损的心脏细胞功能， 然而，CHF仍然不确定。 当前的总体目标 研究建议是确定减少的细胞机制 CHF实验动物模型的心肌功能。 我们的数据 表示在两种电模式下，终末期CHF时的功能降低 刺激和皮肤的心脏小梁中， 心肌细胞 然而，最近的初步数据表明， 收缩的抽搐力先于被抑制的肌丝功能， 这表明在发育早期钙处理的改变 CHF诱导心功能降低，而肌丝的变化 与向明显心力衰竭的转变有关。 在 因此，我们将具体检验以下假设： 1)在CHF发展过程中降低心肌力发展 是由收缩期细胞内钙浓度降低引起的： 将直接测量准确和校准的细胞内钙 用荧光钙探针在离体心脏小梁中 严格的肌节长度控制条件，使用最近开发的 技术; 2）导致向失代偿终末期CHF的转变 通过降低最大力量发展，钙反应性和ATP 收缩器的水解率：力的发展，钙 反应性和ATP水解率将在 作为游离钙的函数的透化小梁。 激光衍射 技术将用于精确测量和控制肌节 长度，以便获得准确和明确的数据。 在整个 CHF、钙处理蛋白和肌丝蛋白的发展 水平以及基因表达将通过Western和 北方印迹，分别与原位功能和 血流动力学数据。 预计这些实验将提供 新的和明确的数据。 关于细胞的准确知识 参与CHF发展的过程对 制定创新的治疗策略，以解决这一问题。 衰弱综合征

Congestive heart failure (CHE) is associated with impaired cardiocyte function. Alterations in the content and isoform distribution of contractile proteins and key proteins involved in calcium handling have been found in CHF. Decreased force development in CHF may result from altered calcium handling, reduced contractile protein function, or from a combination of these factors. The precise relationship between alterations in protein synthesis and impaired cardiocyte function in CHF, however, is still uncertain. The overall goal of the present research proposal is to determine the cellular mechanisms of reduced myocardial function in an experimental animal model of CHF. Our data indicates depressed function at end-stage CHF in both electrically stimulated and in skinned cardiac trabeculae an single skinned cardiocytes. Recent preliminary data, however, indicates that depressed twitch force of contraction precedes depressed myofilament function, suggesting that alterations in calcium handling early in the development of CHF induces depressed cardiac function, while changes in myofilament function are associated with the transition to overt heart failure. In this proposal, therefore, we will specifically test the hypotheses that 1) reduced myocardial force development during the development of CHF is caused by reduced intracellular calcium concentration during systole: Accurate and calibrated intracellular calcium will be measured directly in isolated cardiac trabeculae by fluorescence calcium probe under conditions of strict sarcomere length control using a recently developed technique; 2) The transition to decompensated end-stage CHF is caused by reduced maximum force development, calcium responsiveness, and ATP hydrolysis rate of the contractile apparatus: Force development, calcium responsiveness, and ATP hydrolysis rate will be measured in permeabilized trabeculae as function of free calcium. Laser diffraction techniques will be used to accurately measure and control sarcomere length such that accurate and unambiguous data are obtained. Throughout the development of CHF, calcium handling protein and myofilament protein levels as well as gene expression will be assessed by Western and Northern blot, respectively, to correlate with in-situ functional and hemodynamic data. It is expected that these experiments will provide new and unambiguous data. Accurate knowledge regarding the cellular processes that participate in the development of CHF is critical to the development of innovative treatment strategies aimed to combat this debilitating syndrome.