ELECTROPHYSIOLOGY OF DEVELOPING HEART CELLS

心脏细胞发育的电生理学

• 批准号: 3343111
• 负责人: NICHOLAS SPERELAKIS
• 金额: $ 28.45万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-07-01 至 1991-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3343111
• 关键词: action potentials; animal age group; cardiotonic agents; cyclic AMP; electrophysiology; guanosine monophosphate; heart cell; heart pharmacology; histogenesis; microelectrodes; phosphorylation; protein kinase; single cell analysis; tetrodotoxin

Important electrophysiological, pharmacological, and biochemical changes occur in myocardial cells during development of the heart, which obviously affect its functional properties. The identity and properties of the currents in young embryonic animals is not well understood. Young embryonic chick hearts have slowly-rising, Na-dependent, TTX-insensitive action potentials. The number of fast Na channels increases during development so that the old embryonic chick heart has a typical fast-rising Na-dependent action potential. Thus, the types and number of channels changes during development. Channel properties and kinetics may also change during development (e.g., K channels display less inward-rectification in young vs. old embryonic chick hearts). The identity and properties of the various cardiac channels will be examined at different stages of development, including changes in the Na channels using photoaffinity probes of tetrodotoxin. In these studies, whole-cell voltage clamp and patch clamp techniques will be used in single cells of embryonic chick hearts at different stages of development. In the adult heart, cAMP-dependent phosphorylation regulates the function of slow Ca channels (and perhaps other channels). Phosphorylation by other protein kinases may also regulate channel function. For example, cGMP-, calmodulin- and phospholipid-dependent phosphorylation have all been implicated in slow channel function. However, the role of protein phosphorylation in the regulation of channels during development is unknown. The proposed experiments seek to determine the role of protein phosphorylation during development of the embryonic chick heart. Changes in cAMP levels occur during development; whether cGMP levels also change is not known. Calmodulin levels, cGMP levels and various protein kinase activities will be measured at different stages of development. Regulation of sarcolemmal proteins various protein kinases will be examined to determine whether the pattern of phosphorylation changes during development, as has been shown for cAMP- dependent phosphorylation. The role of dephosphorylation will also be examined electrophysiologically and biochemically. To identify and further study the Ca channel protein(s) during development, a specific covalent affinity reagent, (3H)nifedipine isothiocyanate will be used to label the channel. Biochemical and electrophysiological experiments will be correlated to give a better understanding of channel properties and function during development. These studies are improtant, since the response of the heart to pathological conditions (e.g., myocardial ischemia) and to cardioactive drugs is largely determined by the types and properties of channels present.

重要的电生理学、药理学和 心肌细胞在发育过程中会发生生化变化 这显然会影响心脏的功能特性。这个 幼年胚胎电流的特性和特性 人们对动物的了解还不够深入。幼鸡胚胎心脏 有缓慢上升、钠依赖、TTX不敏感的作用 潜力。快钠通道的数量在 发展使老雏鸡的胚胎心脏具有典型的 快速上升的钠依赖动作电位。因此，类型和 频道的数量在开发过程中会发生变化。渠道 性质和动力学也可以在开发过程中改变(例如， K通道在年轻人和老年人中表现出较少的内向纠错 胚胎雏鸡心脏)。对象的标识和属性 不同的心脏通道将在不同的阶段进行检查 发展，包括钠通道的变化，使用 河豚毒素的光亲和探针。在这些研究中，全细胞 电压钳和膜片钳技术将在单个 鸡胚胎心脏不同发育阶段的细胞 发展。在成年人心中，依赖于cAMP 磷酸化调节慢钙通道的功能(和 也许是其他渠道)。其他蛋白激酶的磷酸化 也可以调节通道功能。例如，cGMP-， 钙调蛋白和磷脂依赖的磷酸化都有 与慢通道功能有关。然而，它的作用是 蛋白质磷酸化在通道调节中的作用 发展情况尚不清楚。拟议中的实验旨在 确定蛋白质磷酸化在发育过程中的作用 小鸡的胚胎心脏。CAMP水平发生变化 在发育过程中，cGMP水平是否也发生变化 为人所知。钙调素水平、cGMP水平和各种蛋白激酶 活动将在不同的发展阶段进行衡量。 肌膜蛋白的调节各种蛋白激酶将被 检查以确定磷酸化模式是否 发展过程中的变化，正如坎普所显示的那样- 依赖的磷酸化。去磷酸化的作用将 也要接受电生理和生化检查。至 钙通道蛋白(S)的鉴定和进一步研究 一种特殊的共价亲和试剂硝苯地平的研制 将使用异硫氰酸酯来标记通道。生化和 电生理实验将相互关联，以给出 更好地了解渠道属性和功能 发展。这些研究是重要的，因为 心脏对病理状态(如心肌缺血)的反应 而对心脏活性药物的使用在很大程度上取决于类型和 存在的频道属性。