ELECTROPHYSIOLOGY OF NEONATAL AND ADULT HEART

这项研究建议主要涉及调解过程。 心肌的机电耦合。具体地说，实验是 提出将探索钙离子进入、释放和释放的过程 心肌细胞的重摄取。试验性工作将沿着六个方向进行 主要方向：前两个项目涉及钙染料的测量 单个分离细胞和完整的脑室小梁内有信号。CA++ 信号以及SR活动的固有光学指示器将是 在电压钳条件下测量不同心脏的已知 超微结构差异。通过这种方式，我们希望建立 各种钙离子转运系统的贡献以及钙离子转运系统的作用 Ca~(++)释放和再吸收循环中的SR。第三个项目成交 直接与钙离子电流通过钙离子通道。单细胞研究 以及对大鼠心肌膜片的钳制研究。 哺乳动物和青蛙的心脏都计划确定ISI是否 青蛙和哺乳动物的心脏中的经络是真正不同的，或者如果 差异与细胞内钙离子储存的存在有关 哺乳动物的心脏。第四个项目涉及的实验探索了 肾上腺素松弛作用的分子机制 心。计划进行具体的实验来确定Na+泵的作用 刺激和环磷酸腺苷在这一过程中的中介作用。感光的 笼式cAMP和离子选择性Na+和K+电极将用于测试 交替使用两种方案。第五个项目将探索 使用光敏“笼状”化合物进行心肌收缩 EGTA、Ca++、cAMP和有机钙拮抗剂。这些药物的使用 将使逐步改变离子或药物浓度成为可能 探讨钙离子通道的动力学和张力的发展。 在不同超微结构的心脏上进行这样的实验 组件将提供有关 钙循环途径和激活剂钙的来源。在第六届 我们将继续研究(钙)i的作用并发布 Ca++储存在SA结细胞起搏电流的产生过程中。我们希望 这些研究将提供对过程的更好的理解 它们控制着心肌的兴奋和收缩。

This research proposal deals primarily with the processes which mediate electromechanical coupling in heart muscle. Specifically, experiments are proposed which will probe processes of Ca++ entry, Ca++ release and reuptake in the myocardial cell. Experimental work will proceed along six major directions: The first two projects deal with measurements of Ca-dye signal in single isolated cells and in intact ventricular trabeculae. Ca++ signals, as well as intrinsic optical indicators of SR activity, will be measured under voltage clamp conditions in different hearts with well known ultrastructural differences. In this way we hope to establish the contribution of various Ca++ transporting systems as well as the role of the SR in the Ca++ release and reuptake cycle. The third project deals directly with Ca++ current through the Ca++ channel. Single cell studies as well as clamp studies on isolated patches of myocardial membranes in both mammalian and frog heart are planned to identify whether the Isi channel is truly different in frog and mammalian heart, or if the difference is related to the presence of intracellular Ca++ stores in mammalian heart. The fourth project deals with experiments which probe the molecular mechanisms which mediate the relaxant effect of adrenaline on the heart. Specific experiments are planned to determine the role of Na+ pump stimulation and cyclic AMP in mediating this process. Light-sensitive caged cAMP and ion-selective Na+ and K+ electrodes will be used to test the alternate two schemes. The fifth project will probe the kinetics of myocardial contraction by using light-sensitive "caged" compounds such as EGTA, Ca++, cAMP and organic Ca++ antagonists. The use of these agents will make it possible to do step changes of ionic or drug concentrations to probe the kinetics of the Ca++ channel and development of tension. Performing such experiments on hearts with different ultrastructural components will provide structure-function information regarding the pathway of the Ca++ cycle and the source of activator Ca++. In the sixth project we shall continue our studies on the role of (Ca)i and releasable Ca++ stores in generation of pacemaker current in SA nodal cell. We hope that these studies will provide a better understanding of the processes which control myocardial excitation and contraction.