2004 Fiscal Year Final Research Report Summary
Analysis of coronary microcirculation and myocardial crossbridge dynamic using SPring-8 synchrotron facility
| Project/Area Number |
13854030
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| Research Category |
Grant-in-Aid for Scientific Research (S)
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| Allocation Type | Single-year Grants |
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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 |
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)
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| Co-Investigator(Kenkyū-buntansha) |
SUGA Hiroyuki National Cardiovascular Center, Research Institute, Director General, 所長 (90014117)
YAGI Naoto Research & Utilization Division, Japan Synchrotron Radiation Research Institute, Chief Scientist, 主席研究員 (80133940)
OHE Toru Okayama University, Graduate School of Medicine and Dentistry, Professor, 大学院・医歯学総合研究科, 教授 (70263556)
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)
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)
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| Project Period (FY) |
2001 – 2004
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| Keywords | SPring-8 / Physiome / Coronary Circulation / Cardiac Contraction / Crossbridge Dynamics / Intravital CCD / Transmural characteristics / Vascular regUlation |
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| Research Abstract |
Global dynamics of coronary circulation and cardiac contraction have been well documented in cardiology and circulatory physiology. Recently, transmural, i.e., from epicardial to endocardial heterogeneities have been getting more important for better understanding of the cardiac pathophysiology. Thus the objective of this study was to reveal the detailed transmural characteristics of the myocardial crossbridge dynamics and the coronary micro-circulation.
Firstly, we found that the diastolic predominant flow pattern was common throughout myocardial layers. During systolic phase, significant systolic reverse flow was observed in subendocardial arterioles, whereas a remarkable forward flow was observed in subepicardial arterioles. Intramural pressure gradient and myocardial stiffness (elastance) cause these transmural dissociations in systolic flow direction. We also found the vessel size dependent coronary vascular regulation system, and spatial and temporal myocardial flow heterogeneity using the SPring-8, custom-made intravital CCD microscopes, and molecular isotope tracers.
Secondly, we revealed the transmural difference of crossbridge dynamics using the SPring-8. During contraction phase, subepicardial and midcardial crossbridge dynamics were harmonized well each other and synchronized with the left ventricular pressure development. However the crossbridge of deeper myocardium decayed earlier than that of subepicardium during relaxation phase. Earlier relaxation in the myocardium in deeper regions seemed to be beneficial for diastolic blood inflow into deeper myocardium.
We are now going to promote the "Physiome" as the quantitative and integrated description of the functional behavior of the physiological state. We believe that the present studies contribute to the cardiovascular physiome in the sense that it clarified the close coupling between coronary microcirculation and actin-myosin macromolecular dynamics. (256/300 words)
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