CALCIUM ION CONTROL IN CARDIAC FUNCTION

心脏的收缩激活或舒张状态， 骨骼肌是由Ca2+的升高或降低控制的 在肌浆中的浓度。 该计划的目的是 表征Ca2+从细胞中去除的机制。 肌浆产生松弛，或者释放到 使肌浆产生收缩激活。 其中一部分涉及肌浆网， 这是一个膜系统，涉及钙离子的去除， 主动运输。 Ca~（2+）的催化和转运循环 肌浆网依赖的ATP酶将在 详细地说，部分反应的特点是平衡和 动力学方法和催化机理研究 反应性酶残基的化学修饰。 方法 免疫学和分子遗传学也将用于产生 单克隆抗体，克隆和分析cDNA和 编码ATP酶的基因，研究ATP酶的表达 在哺乳动物系统中进行基因转移， 改变编码ATP酶的DNA， 用于结构-功能和生物调节研究的材料。 该计划的另一部分涉及的机制， 肌浆网钙释放。 纤维制备物 和微粒体组分，它们来自于 将测试肌管膜系统的能力， 释放Ca2+作为收缩激活所需。 性质 信号触发释放和特性的 将调查涉及释放的渠道。 的动力学 将通过测量放射性示踪剂来研究释放 通量，并记录电流在重组 膜双层和膜片钳实验。 分离 将尝试通道蛋白。

The state of contractile activation or relaxation of cardiac and skeletal muscle is controlled by rise or reduction of the Ca2+ concentration in the myoplasm. The aim of this program is to characterize the mechanism by which Ca2+ is removed from the myoplasm to produce relaxation, and alternatively released into the myoplasm to produce contractile activation. One section of the program deals with sarcoplasmic reticulum, which is the membrane system involved in Ca2+ removal by active transport. The catalytic and transport cycle of the Ca2+ dependent ATPase of sarcoplasmic reticulum will be studied in detail, the partial reactions characterized by equilibrium and kinetic methods, and the catalytic mechanism investigated by chemical modification of reactive enzyme residues. Methods of immunology and molecular genetics will be also used to generate monoclonal antibodies, clone and analyze the cDNAs and the genes encoding the ATPase, study the expression of the ATPase following gene transfer in mammalian systems, and obtain alterations of the DNAs encoding the ATPase to generate material for structure-function and bioregulation studies. Another section of the program deals with the mechanism of Ca2+ release from sarcoplasmic reticulum. Fiber preparations and microsomal fractions derived from various sections of the sarcotubular membrane system will be tested for their ability to release Ca2+ as required for contractile activation. The nature of the signal triggering release and the characteristics of the channels involved in release will be investigated. The kinetics of release will be studied by measurements of radioactive tracer fluxes, and recording electrical currents in reconstituted membrane bilayers and patch clamp experiments. Isolation of channel protein will be attempted.