CARDIAC SODIUM-CALCIUM EXCHANGE REGULATION & FUNCTION

心脏钠钙交换调节

• 批准号: 3473264
• 负责人: DONALD W HILGEMANN
• 金额: $ 9.21万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-07-01 至 1993-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3473264
• 关键词: action potentials; adenosine triphosphate; bioenergetics; biological transport; calcium; calmodulin; chymotrypsin; guinea pigs; heart contraction; heart function; heart pharmacology; heart ventricle; hormone regulation /control mechanism; ion transport; magnesium; membrane transport proteins; muscle relaxants; muscle stimulant; myocardium; phosphorylation; protein kinase; proteolysis; sarcolemma; sodium; stoichiometry

The major project goal is an understanding of the molecular regulation and function of cardiac sodium-calcium exchange. A secondary goal is an improved understanding of cellular sodium-calcium exchange function. The information to be gained is of basic importance to cellular physiology and is essential to an understanding of pathological cardiac function. Two unique methods will be used for molecular and cellular work, respectively; 1) current measurements in a new large-diameter sarcolemmal patch preparation, and 2) optical measurements of transmembrane calcium movements in intact tissues with new calcium dyes. In excised sarcolemmal membrane patches (>10mum diameter with >10 G-omega seals), the hypothesis will be tested that calcium activates sodium-calcium exchange by a direct mechanism, while ATP acts via a phosphorylation mechanism. The underlying mechanisms will be identified and characterized by specific biochemical interventions. Limited proteolysis by chymotrypsin, which abolishes secondary exchange modulation and leaves the exchanger highly stimulated, will allow studies of the isolated catalytic properties of sodium-calcium exchange. Relevant to the loss of secondary regulation during isolation of membrane vesicles, it will be tested whether a specific proteinase in cardiac homogenates may mimic effects of chymotrypsin and/or whether mild interventions may dissociate regulators from excised patches. In intact cardiac ventricle, fast extracellular calcium transients will be monitored with newly improved calcium-sensitive dyes and related to action potentials and contraction. Long-standing hypotheses about the physiological role of sodium-calcium exchange will be tested. The actions of inotropic mechanisms thought to act indirectly or directly via sodium- calcium exchange will be evaluated in extracellular calcium transients and related to studies of the isolated exchange current.

主要项目目标是了解分子调控和 心脏钠钙交换功能。 次要目标是 提高对细胞钠钙交换功能的了解。 这 所获得的信息对于细胞生理学具有基本重要性 对于理解病理心脏功能至关重要。 二 独特的方法将分别用于分子和细胞工作； 1) 新的大直径肌膜片的电流测量 准备，以及 2) 跨膜钙运动的光学测量 在完整的组织中使用新的钙染料。 在切除的肌膜膜片中（>10mm 直径，>10 G-omega 密封），将检验钙激活钠钙的假设 通过直接机制进行交换，而 ATP 通过磷酸化作用 机制。 潜在的机制将被识别和表征 通过特定的生化干预措施。 有限的蛋白水解作用 胰凝乳蛋白酶，它消除了二次交换调节并留下 交换器受到高度刺激，将允许研究分离的催化 钠钙交换特性。 与二次丢失相关 膜囊泡分离过程中的调节，将测试是否 心脏匀浆中的特定蛋白酶可能模仿 胰凝乳蛋白酶和/或温和的干预是否可能解离调节剂 来自切除的补丁。 在完整的心室中，快速的细胞外钙瞬变将是 用新改进的钙敏感染料进行监测并与作用相关 潜力和收缩。 长期以来关于 将测试钠钙交换的生理作用。 行动 正性肌力机制被认为通过钠间接或直接起作用 钙交换将通过细胞外钙瞬变进行评估， 与孤立交换电流的研究有关。