A study on the excitation-contraction coupling of myocardium - Analysis on isolated, perfused hearts using multi-nuclear NMR methods.

心肌兴奋-收缩耦合的研究 - 使用多核 NMR 方法对离体灌注心脏进行分析。

• 批准号: 62045020
• 负责人: INOUE Michitoshi
• 金额: $ 3.07万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Overseas Scientific Survey.
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62045020/
• 关键词: Myocardial Excitation-Contraction Coupling; Isolated, Perfused Heart; Intracellular Calcium Ion; Maximal Calcium-activated Force; Calcium Sensitivity; Ischemia; Reperfusion; Calcium Overload

This project aimed on the assessment of excitation-contraction (E-C) coupling in myocardium of isolated, perfused hearts.The following results were obtained in this University-to-University Cooperative Research. (1)Development of the methods to assess the endpoints in E-C coupling: The intracellular concentration of activator Ca^<2+> ([Ca^<2+>]_i) was measured in perfused heart using fluorine nuclear magnetic resonance spectroscopy (^<19>F-NMR) coupled with Ca^<2+> chelator, 5F-BAPTA. Calcium transients could be evaluated by this F-NMR technique with gating. Maximal Ca^<2+>-activated pressure (MCAP), the index of maximal Ca^<2+>-activated force in myofilament was evaluated by left ventricular isovolumic pressure during tetani elicited by the rapid pacing after exposure to ryanodine. (2)Mechanism of early contractile failure during ischemia: It was revealed that inorganic phosphate (Pi) decreases MCAP and proton (H^+) induces both the decrease in MCAP and the shift of Ca^<2+>-sensitivit … More y to higher Ca. Thus, these results indicate that the increase of Pi and H^+ during ischemia causes early contractile failure. (3)Pathophysiology of stunned myocardium: Reperfusion after a brief period of ischemia produces prolonged contractile failure without necrosis ("stunned myocardium"). In stunned myocardium, MCAP decreased and the amplitude of calcium transient increased compared with the control. Thus, these results indicate that this contractile dysfunction is due to the decrease in maximal Ca^<2+>-activated force and the shift of Ca^<2+>-sensitivity to higher Ca with paradoxical increase in amplitude of calcium transients. (4)Pathogenesis of stunned myocardium: Our data suggested that a transient calcium overload during ischemia and reperfusion causes the contractile failure in stunned myocardium. The changes in [Ca^<2+>]_i during ischemia and after reperfusion were also directly measured and the exist of calcium overload was confirmed. (5)Effect of non-ischemic calcium overload on contractility: Doxorubicin increased [Ca^<2+>]_i without ischemic changes and caused contractile disorder. Thus, these results indicate that calcium overload itself deteriorates the cardiac function. Less

本项目旨在评估离体灌注心脏心肌的兴奋-收缩（E-C）耦合。本次校际合作研究结果如下：(1) E-C耦合终点评估方法的发展：利用氟核磁共振波谱（^<19>F-NMR）与Ca^<2+>螯合剂5F-BAPTA偶联，测量灌注心脏中激活剂Ca^<2+> ([Ca^<2+>]_i)的细胞内浓度。采用门控的F-NMR技术可以对钙瞬态进行评价。最大Ca^<2+>-激活压力（MCAP），肌丝最大Ca^<2+>-激活力指数用左室等容压法测定ryanodine暴露后快速起搏引起的破伤风。(2)缺血早期收缩衰竭的机制：揭示了无机磷酸盐（Pi）降低MCAP，质子（H^+）诱导MCAP的降低和Ca^<2+>-敏感性的转变，从y向高Ca的转变，表明缺血时Pi和H^+的增加导致了早期收缩衰竭。(3)休克心肌的病理生理：短暂缺血后的再灌注产生不坏死的长时间收缩衰竭（“休克心肌”）。与对照组相比，休克心肌MCAP降低，钙瞬态振幅升高。因此，这些结果表明，这种收缩功能障碍是由于Ca^<2+>-最大激活力的降低和Ca^<2+>-敏感性随着钙瞬态振幅的矛盾增加而向更高的Ca转移。(4)休克心肌的发病机制：我们的数据提示缺血再灌注过程中短暂的钙超载导致休克心肌收缩衰竭。直接测定缺血和再灌注后[Ca^<2+>]_i的变化，证实钙超载的存在。(5)非缺血性钙超载对收缩力的影响：阿霉素使[Ca^<2+>]_i升高，但无缺血性改变，引起收缩障碍。因此，这些结果表明钙超载本身会使心功能恶化。少

项目成果

Proc.Natl.Acad.Sci.USA. 84ー8. (1987)

美国国家科学院。 84-8。

Kusuoka H: "Calcium oscillation in digitalis-induced ventricular fibrillation: pathogenetic role and metabolic consequences in isolated ferret hearts." Circulation research. 62. 609-619 (1988)

Kusuoka H：“洋地黄引起的心室颤动中的钙振荡：离体雪貂心脏的发病作用和代谢后果。”

Kusuoka H: "Excitation-contraction coupling in postischemic myocardium:does failure of activator Ca^<2+> transients underlie“stunning"?" Circulation Research. 66. (1990)

Kusuoka H：“缺血后心肌中的兴奋-收缩耦合：激活剂 Ca^<2+> 瞬变的失败是否导致“击晕”？”循环研究。66。（1990）

J.General Physiology. 90ー11. (1987)

J.普通生理学。90-11。

Porterfield JK: "Reperfusion and revascularization in acute myocardial infarction." Springer-Verlag, (1988)

Porterfield JK：“急性心肌梗死的再灌注和血运重建。”