CARDIAC ION TRANSPORT AND ULTRASTRUCTURE

心脏离子转运和超微结构

• 批准号: 2214636
• 负责人: ERNEST PAGE
• 金额: $ 33.82万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-05-01 至 1998-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2214636
• 关键词: X ray crystallography; atrial natriuretic peptide; calcium; edema; electron microscopy; fluorescence microscopy; freeze etching; gel electrophoresis; heart Purkinje's fiber; heart contraction; hypertension; image enhancement; immunoelectron microscopy; intercellular connection; ion transport; laboratory rat; membrane permeability; membrane potentials; membrane reconstitution /synthesis; membrane structure; membrane transport proteins; monoclonal antibody; myocardial ischemia /hypoxia; myofibrils; myogenesis; sarcoplasmic reticulum; second messengers; sodium; vascular smooth muscle; voltage /patch clamp; X ray crystallography; atrial natriuretic peptide; calcium; edema; electron microscopy; fluorescence microscopy; freeze etching; gel electrophoresis; heart Purkinje's fiber; heart contraction; hypertension; image enhancement; immunoelectron microscopy; intercellular connection; ion transport; laboratory rat; membrane permeability; membrane potentials; membrane reconstitution /synthesis; membrane structure; membrane transport proteins; monoclonal antibody; myocardial ischemia /hypoxia; myofibrils; myogenesis; sarcoplasmic reticulum; second messengers; sodium; vascular smooth muscle; voltage /patch clamp

Although the atrial natriuretic polypeptide (ANP) hormone secreted by atria plays a major role in the medically important function of fluid, electrolyte, and blood pressure homeostasis, the cellular mechanisms by which stretching atria stimulates hormone secretion are unknown. The long-term goal of this proposal is to investigate the mechanisms of stretch-secretion coupling in atria and its interaction with atrial contraction by studying in detail the Ca2+-sensitive mechanotransducer relationship between stretch-activated atrial ion transport and ANP secretion demonstrable in intact rat atria. The relationship will be examined (a) by in vitro studies on intact atria stretched by a physiological range of distending pressures in which stretch- activated cellular net Na efflux, Ca influx, depolarization, and ANP secretion can be measured together during variations of passive stretch and contraction frequency while conditions determining Ca2+ influx across the plasma membrane or Ca2+ release from sarcoplasmic reticulum (SR) can be separately varied; (b) by single channel patch-clamp studies on cultured and freshly dissociated cardiac myocytes to identify and characterize stretch-activated channels and/or second messenger systems; (c) by applying fura-2 fluorescence microscopy interfaced with digital computer-aided image analysis to single atrial myocytes (both cultured myocytes and freshly dissociated myocytes) to investigate the time course and subcellular localization of the changes in cytoplasmic Ca2+ associated with changes in ANP secretion due to variations in ionic environment, membrane stretch, contraction rate, activation or inhibition of second messenger systems, and other variables; (d) by correlating stretch-activated ANP secretion with stretch-activated changes in tension and in plasmalemmal Na-Ca exchange using measurements of tension and intracellular Na+ activity in quiescent and contracting rat atrial trabeculae; and (e) by correlating ANP secretion rates of atrial myocytes cultured from adult rats with observations of microtubule-associated cytoplasmic translocation of atrial granules from the Golgi to the plasma membrane using electron microscopy and double immunofluorescence microscopy while stretch, Ca influx, and SR Ca release can be separately varied and second messenger systems can be stimulated or blocked in different ways.

虽然心房纳特里二肽（ANP）激素 Atria的分泌在医学上重要的 液体，电解质和血压稳态的功能， 伸展心房刺激激素的细胞机制 分泌是未知的。 该提议的长期目标是 研究心房中拉伸分泌耦合的机制 以及通过详细研究与房屋收缩的相互作用 Ca2+ - 敏感机械转换器之间的关系 拉伸激活的心房离子运输和ANP分泌 在完整的大鼠心房中证明。 关系将是 通过对完整心房的体外研究进行了检查（a） 扩张压力的生理范围 活化的细胞净Na外排，CA涌入，去极化和 可以在变化期间一起测量ANP分泌 被动拉伸和收缩频率，而条件 确定质膜或Ca2+的CA2+涌入 可以单独从肌质网（SR）释放 多样化； （b）通过单通道斑块钳研究培养和 新鲜分离的心肌细胞以识别和表征 伸展激活的通道和/或第二会使系统； （C） 通过应用Fura-2荧光显微镜与 数字计算机辅助图像分析对单个心房心肌细胞 （培养的心肌细胞和新鲜分离的心肌细胞） 研究时间过程和亚细胞定位 与ANP变化相关的细胞质Ca2+的变化 由于离子环境，膜的变化引起的分泌 第二次伸展，收缩率，激活或抑制 Messenger系统和其他变量； （d）通过关联 拉伸激活的ANP分泌，拉伸激活变化 在张力和浆膜Na-Ca交换中 张力和细胞内Na+活性的测量 静止和收缩的大鼠心房小梁； （e） 将培养的心肌细胞的ANP分泌率相关联 与微管相关的成年大鼠 心房颗粒从高尔基人到胞质易位 使用电子显微镜和双重质膜 免疫荧光显微镜，伸展时，CA涌入和SR CA释放可以分开变化，第二使者 可以以不同的方式刺激或阻止系统。