| Project/Area Number |
14380405
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
SHIMIZU Jyuichiro (2003-2004) Okayama University, Graduate School of Medicine and Dentistry, Assistant Professor, 大学院・医歯学総合研究科, 講師 (80294403)
荒木 淳一 (2002) 岡山大学, 大学院・医歯学総合研究科, 助教授 (80271055)
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| Co-Investigator(Kenkyū-buntansha) |
KAJIYA Fumihiko Okayama University, Graduate School of Medicine and Dentistry, Professor, 大学院・医歯学総合研究科, 教授 (70029114)
MOHRI Satoshi Okayama University, Graduate School of Medicine and Dentistry, Research Associate, 大学院・医歯学総合研究科, 助手 (00294413)
NAKAMURA Kazufumi Okayama University, Graduate School of Medicine and Dentistry, Research Associate, 大学院・医歯学総合研究科, 助手 (10335630)
MIYASAKA Takehiro Okayama University, Graduate School of Medicine and Dentistry, Research Associate, 大学院・医歯学総合研究科, 助手 (60308195)
YAGI Naoto Japan Synchrotron Radiation Research Institute, Research & Utilization Division, Chief Scientist, 主席研究員 (80133940)
清水 壽一郎 岡山大学, 大学院・医歯学総合研究科, 助手 (80294403)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥13,000,000 (Direct Cost: ¥13,000,000)
Fiscal Year 2004: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2003: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2002: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | SPring-8 / X-ray Diffraction / Heart / Myofilament Lattice / Transmural Heterogeneity / Crossbridge / Contraction / Frank Starling Law / 心臓 / クロスブリッジ動態 / X線回折 / 筋線維 / 六角格子 / 筋節長 / アクチン・ミオシン / X線回折像解析 / 心筋線維配向 / マクロモレキュール / 心筋線維六角格子 / ミオシン格子間隔 / X線回析 / アクチン / ミオシン / クロスブリッジ |
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| Research Abstract |
Mechanism of volume dependent increase in cardiac performance (Frank-Starling law) is interesting theme in the cardiaovascular physiology. Possible mechanisms of the Frank-Starling law are decrease in the myofilamet lattice spacing, and increase in the calcium binding affinity to troponin and actin myosin interaction rate with strongly bound crossbrdge. However the heart has complex three-dimensional structure so the regional heterogeneities of myofilament orientation and strain may have important role in regulation of the cardiac performance.
We revealed the transmural difference of crossbridge dynamics using the SPring-8 synchrotron facility during cyclic heart beats. During contraction phase, epicardial and midcardial crossbridge dynamics were harmonized well with the left ventricular pressure development. However during relaxation phase, midcardial crossbridge decayed significantly earlier than epicardial one. The changes of the preload level did not affect on this regional differen
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ce of crossbridge decay.
We also found the myosin lattice spacing in the epicardial region was significantly smaller than that in the midcardial region at both high and low preload levels. With an assumption that the lattice volume is constant during stretch and release of the cardiomyocyte, decrease in the myosin lattice spacing means the lengthening of the sarcomere and vice versa. Thus the epicardial region would work with longer sarcomere length than the midcardial region regardless of preload levels.
Generally the duration of action potential in the endocardial or deeper region is longer than the epicardial region. The present results contradicts to this transmural heterogeneity of electrical activity. However the longer duration of twitch contraction is observed at the longer sarcomere length. Thus the duration of contraction with the long action potential and short sarcomere length in the midcardial region seemed to be comparable with the duration of contraction with the short action potential and long sarcomere length in the epicardial region. (297/300 words) Less
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