The Role of NO in the Regulation of Heart Contractility

NO 在调节心脏收缩力中的作用

• 批准号: 6399744
• 负责人: BEATA M. WOLSKA
• 金额: $ 31.17万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-30 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6399744
• 关键词: calcium flux; cardiac myocytes; cyclic GMP; enzyme activity; gene targeting; genetically modified animals; heart contraction; heart failure; immunocytochemistry; laboratory mouse; microfilaments; myocardium; nitric oxide; nitric oxide synthase; pathologic process; phospholamban; phosphorylation; protein kinase A; troponin; ventricular hypertrophy

Nitric oxide (NO) modulates cardiac muscle contraction via multiple pathways. Our long term objective is to understand the mechanisms by which NO and/or nitric oxides (NOx) alter cardiac contractility. We hypothesize that NO changes cardiac contractility by altering Ca2+ handling and the myofilament response to Ca2+ through both through cGMP-dependent and cGMP- independent mechanisms. During different stages of development of hypertrophy we will determine: 1) expression and activity of iNOS and eNOS in myocytes and whole heart and correlate these changes with alterations in contractility; 2) NO concentration in plasma; 3) mechanisms responsible for alterations in Ca2+ fluxes and myofilament response to Ca2+ by NO (NOx); and 4) the role of NO (NOx) in the altered response to adrenergic stimulation. We hypothesize that: 1) altered contractility by NO (NOx) is not only due to changes in Ca2+ current, but also due to changes in phosphorylation of phospholamban (PLB) and cardiac troponin I (cTnI), and 2) NO produced by iNOS plays a crucial role in the altered response to beta-adrenergic stimulation during different stages of development of hypertrophy. The studies employ hearts from control, iNOS knockout, and transgenic (TG) animals in which pressure overload is introduced by aortic banding, producing different phases of hypertrophy. The following TG mice are used: 1) TG mice which are deficient in PLB and either express native cTnl, or slow skeletal troponin I (ssTni) lacking phosphorylation sites for PKA and 2) TG mice that express normal level of PLB and either express cTnI or ssTnl. These TG mice allow us to separate the effect of alteration of TnI phosphorylation from PLB phosphorylation by NO (NOx). Our experiments provide new insights into the mechanisms and importance of NO (NOx) in alteration of cardiac contractility in physiological and pathological conditions.

一氧化氮（NO）通过多种途径调节心肌收缩。 我们的长期目标是了解NO和/或一氧化物（NOX）改变心脏收缩的机制。 我们假设没有通过CGMP依赖性和CGMP独立机制来改变Ca2+处理和对Ca2+的肌丝反应来改变心脏收缩性。 在肥大的不同阶段，我们将确定：1）iNOS和eNOS在心肌和心脏中的表达和活性，并将这些变化与收缩力的改变相关； 2）血浆中没有浓度； 3）导致Ca2+通量改变的机制和对Ca2+的肌丝反应的变化（NOX）； 4）NO（NOX）在对肾上腺素能刺激的反应改变中的作用。 我们假设：1）NO（NOX）的收缩性改变不仅是由于Ca2+电流的变化，而且还因为磷酸兰（PLB）（PLB）（PLB）和心脏肌动蛋白I（CTNI）的磷酸化变化以及INOS所产生的NO在beta-adadenrencrencrencrenren provery nose therfy thress offerstight offerty nose pronptir的反应中起着至关重要的作用。 该研究采用了对照，iNOS敲除和转基因（TG）动物的心脏，其中由主动脉谱带引入压力超负荷，从而产生不同的肥大阶段。 使用了以下TG小鼠：1）缺乏PLB和表达天然CTNL的TG小鼠，或者慢慢的骨骼肌钙蛋白I（SSTNI）缺乏PKA的磷酸化位点和2）表达PLB正常水平的TG小鼠，并且要么表达PLB的正常水平，要么是表达CTNI或SExtni或SSTNL。 这些TG小鼠使我们能够将TNI磷酸化改变与PLB磷酸化的影响通过NO（NOX）分开。 我们的实验为NO（NOX）在生理和病理条件下改变心脏收缩性的机制和重要性提供了新的见解。