| Project/Area Number |
63480347
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
麻酔学
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
TOYOOKA Hidenori Tokyo Medical and Dental Univ. Faculty of Mad, Associate, 医学部, 助教授 (80010362)
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| Co-Investigator(Kenkyū-buntansha) |
FUJII Yoshitaka Tokyo Medical and Dental Univ. Faculty of Med. Research Fellow, 医学部, 大学院生 (90292557)
OHSHIMA Tsutomu Tokyo Medical and Dental Univ. Faculty of Med. Assistant, 医学部, 助手 (50223805)
AMAHA Keisuke Tokyo Medical and Dental Univ. Faculty of Med. Professor, 医学部, 教授 (30045992)
SAWA Takeshi Tokyo Medical and Dental Univ. Faculty of Med. Lecturer, 医学部, 講師 (40013982)
YOKOYAMA Kuninori Tokyo Medical and Dental Univ. Faculty of Med. Assistant, 医学部, 助手 (00014176)
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1990: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Keywords | Respiratory muscle / Diaphragm / Muscle fatigue / Respiratory failure / Dobutamine / Ca* blocker / 疲労 |
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| Research Abstract |
Dysfunction of respiratory muscle, as seen in fatigued diaphragm, is known to play an important role in development of respiratory failure. This series of studies was conducted to investigate the pathophysiology of respiratory muscle dysfunction as a cause of respiratory failure, and to develop some preventive or therapeutic measures of diaphragmatic fatigue. The followings are main results of this research.
1) The involvement of neuromuscular transmission failure as a possible mechanism of diaphragmatic fatigue was investigated in canine model. It was demonstrated that this transmission failure plays considerable role in development of low frequency as well as high frequency fatigue.
2) Effects of cardiac output on diaphragmatic blood flow and diaphragmatic fatigue and its recovery were studied in canine models with controlled obstruction of vena cava. There was a significant posi tive correlation between cardiac output and left inferior phrenic arterial blood flow. Diaphragmatic fatigability was significantly greater in animals with low cardiac output (i. e. 60% of control).
3) In animals with severely depressed' Cardiae output (30% of control), the failure of neuromuscular transmission played a significant role in production of diaphragmatic fatigue.
4) Dobutamine (10 mug/kg/min) increased contractility in non-fatigued diaphragm. This positive inotropic effect was observed without any change of cardiac output, and was antagonized by concomitant administration of nicardipine. Thus, involvement of Ca channels was suggested in inotropic mechanism of dobutamine.
5) Dobutamine also increased contractility of fatigued canine diaphragm. This maybe due to direct inotropic effect of dobutamine on diaphragm, or to secondary effect through improvement of diaphragmatic blood flow.
6) The time constant of decline of transdiaphragmatic pressure after tetanic stimulation of phrenic nerve was a sensitive indicator, and may be useful for early detection of diaphragmatic fatigue.
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