ELECTROPHYSIOLOGY OF DEVELOPING HEART CELLS

心脏细胞发育的电生理学

• 批准号: 3343120
• 负责人: NICHOLAS SPERELAKIS
• 金额: $ 26.59万
• 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 1992-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3343120
• 关键词: action potentials; animal age group; calcium channel; calmodulin; cardiotonic agents; chick embryo; cyclic AMP; electrophysiology; guanosine monophosphate; guinea pigs; heart cell; heart pharmacology; histogenesis; membrane channels; membrane proteins; microelectrodes; phosphorylation; protein kinase; single cell analysis; sodium channel; 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发生生化变化 这显然会影响心脏的功能特性。 的 年轻胚胎中电流的一致性和特性 动物并不了解。 鸡胚心脏 具有缓慢上升、钠依赖性、TTX不敏感的作用 潜力 快钠通道的数量在 发育，使老鸡胚心脏具有典型的 快速上升的钠依赖性动作电位 因此，类型和 在开发过程中，渠道数量会发生变化。 信道 性质和动力学也可在显影期间改变（例如， K通道在年轻人与老年人中显示较少的内向整流 鸡胚心脏）。 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Na通道的变化， 河豚毒素的光亲和探针 在这些研究中， 电压钳和膜片钳技术将被用于单 不同发育阶段鸡胚心脏的细胞 发展 在成人心脏中，cAMP依赖性 磷酸化调节慢钙通道的功能（和 其他渠道）。 其他蛋白激酶磷酸化 还可以调节通道功能。 例如，cGMP-， 钙调蛋白和磷脂依赖性磷酸化 与慢通道功能有关。 但是，作用 蛋白磷酸化在调节通道的过程中， 发展未知。 拟议的实验旨在 确定蛋白质磷酸化在发育过程中的作用 鸡的胚胎心脏 cAMP水平发生变化 在开发过程中; cGMP水平是否也发生变化， 知道的 钙调素水平、cGMP水平和各种蛋白激酶 将在不同的发展阶段衡量各项活动。 调节肌膜蛋白质的各种蛋白激酶将是 检查以确定磷酸化的模式是否 在发育过程中的变化，如cAMP所示， 依赖性磷酸化 去磷酸化的作用将 还可以进行电生理学和生化学检查。 到 鉴定并进一步研究钙通道蛋白， 一种特异性共价亲和试剂，（3 H）硝苯地平 异硫氰酸酯将用于标记通道。 生化和 电生理学实验将被关联以给出 更好地了解通道特性和功能 发展 这些研究很重要，因为 心脏到病理状态（例如，心肌缺血） 和心脏活性药物在很大程度上取决于类型， 通道的属性。