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; 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节和 心脏钠钙交换的功能。 第二个目标是 对细胞 - 钙交换函数的了解得到了改善。 这 要获得的信息对于细胞生理和 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）新的大直径肌肉斑块中的当前测量 制备和2）跨膜钙运动的光学测量 在具有新钙染料的完整组织中。 在切除的肌膜膜贴片中（> 10mum直径，> 10 g-omega 密封件），将检验该假设，即钙激活钠钙 通过直接机制进行交换，而ATP通过磷酸化作用 机制。 基本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 胰凝乳蛋白酶，废除了次要交换调制并留下 高度刺激的交换器将允许研究分离的催化 钠钙交换的特性。 与次级损失有关 隔离膜囊泡期间的调节，将测试是否是否 心脏匀浆中的特定蛋白酶可能模仿 辣椒蛋白和/或轻度干预措施是否可以解散调节剂 从切除的补丁。 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，并与作用有关 潜力和收缩。 关于 将测试钠钙交换的生理作用。 动作 被认为是间接或直接通过钠起作用的肌力机制 钙交换将在细胞外钙瞬变和 与孤立交换电流的研究有关。