| Project/Area Number |
63570045
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General physiology
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| Research Institution | National Cardiovascular Center Research Institute |
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Principal Investigator |
SUGA Hiroyuki National Cardiovascular Center Research Institute, Department of Cardiovascular Dynamics, Chairman, 循環動態機能部, 部長 (90014117)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAGUCHI Osamu National Cardiovascular Center Research Institute, Department of Cardiovascular, 循環動態機能部, 室員 (80214609)
OHGOSHI Yuichi National Cardiovascular Center Research Institute, Department of Cardiovascular, 循環動態機能部, 室員 (90203752)
FUTAKI Shiho National Cardiovascular Center Research Institute, Department of Cardiovascular, 循環動態機能部, 室員 (60190112)
GOTO Yoichi National Cardiovascular Center Research Institute, Department of Cardiovascular, 循環動態機能部, 室長 (40142179)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1989: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1988: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Heart / Myocardium / Circulation / Pump function / Contraction / Contractility / Mechanical efficiency / Optimality / 心室 / Emax / 酸素消毒量 / 機械的エネルギー / 全容積面積 |
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| Research Abstract |
The heart consumes oxygen to generate free energy for the mechanical pump performance. The mechanical efficiency of the heart is 10-20% under normal loading and contractile conditions. The factors which decrease this efficiency are 1) significant level of basal metabolism, 2) oxygen wasting effect of enhanced, contractility, and 3) loss in the energy conversion from total I mechanical energy to effective mechanical work. We considered that the mechanical efficiency of the heart could be improved by 1) increasing the contractile efficiency of the heart, and 2) improving the load matching of the heart. In this project, we searched for possible methods to improve the mechanical efficiency of the heart. Through a series of appropriately designed dog heart experiments, we have found the followings: 1) Various acute positive inotropic agents increases the energy utilization for activation (membrane excitation and excitation-contraction coupling) without affecting the contractile efficiency. 2) Myocardial cooling is so far the only positive inotropic intervention which does not increase energy for activation. 3) Systolic pressure-volume area (PVA) as a measure of the total mechanical energy generated by contraction has been established as a reliable predictor of myocardial oxygen consumption (MVo_2). 4) The peak myocardial force and the time integral of force (FTI) which have been recognized to be reliable predictors of MVo_2 were shown not to be go reliable as believed. 5) Linear addition of FTI to PVA does not help improving the predictability of MVo_2.6) Epinephrine and calcium have the same oxygen cost of contractility despite their different pharmacological mechanisms of positive inotropism. These findings together impress us that it would not be easy to find methods to improve mechanical efficiency of the heart which has been usually maximized under normal loading conditions.
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