2004 Fiscal Year Final Research Report Summary
Analyses of transmural difference of myocardial crossbridge dynamics using SPring-8 synchrotron facility
| 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 Okayama University, Graduate School of Medicine and Dentistry, Assistant Professor, 大学院・医歯学総合研究科, 講師 (80294403)
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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)
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| Project Period (FY) |
2002 – 2004
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| Keywords | SPring-8 / X-ray Diffraction / Heart / Myofilament Lattice / Transmural Heterogeneity / Crossbridge / Contraction / Frank Starling Law |
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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
… More
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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Author(s)
Kiyooka T, Hiramatsu O, Shigeto F, Nakamoto H, Tachibana H, Yada T, Ogasawara Y, Kajiya M, Morimoto T, Morizane Y, Mohri S, Shimizu J, Ohe T, Kajiya F
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Am J Physiol Heart Circ Physiol. 288(3)
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[Journal Article] Sarcomere-length dependence of lattice volume and radial mass transfer of myosin cross-bridges in rat papillary muscle.2004
Author(s)
Yagi N, Okuyama H, Toyota H, Araki J, Shimizu J, Iribe G, Nakamura K, Mohri S, Tsujioka K, Suga H, Kajiya F
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Pflugers Arch. 448(2)
Pages: 153-160
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[Journal Article] X-ray diffraction from a left ventricular wall of rat heart.2004
Author(s)
Yagi N, Shimizu J, Mohri S, Araki J, Nakamura K, Okuyama H, Toyota H, Morimoto T, Morizane Y, Kurusu M, Miura T, Hashimoto K, Tsujioka K, Suga H, Kajiya F
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Biophys J. 86(4)
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