| Project/Area Number |
04660330
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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 |
基礎獣医学
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| Research Institution | Kitasato University |
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Principal Investigator |
TEMMA Kyosuke Kitasato Univ., School of Vet. Med., Associate Professor, 獣医畜産学部, 助教授 (50050654)
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| Co-Investigator(Kenkyū-buntansha) |
KONDO Hiroshi Kitasato Univ., Schol of Vet. Med., Professor, 獣医畜産学部, 教授 (60050407)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Ca^<2+> transient / Single cell / Heart / Digital image analysis |
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| Research Abstract |
To examine the origin and spreading of the Ca^<2+> transients following electrical stimulation of isolated myocyte, a system capable of recording intracellular Ca^<2+> distribution with sufficient temporal and spatial resolution was constructed. The system consists of an inverted epifuorescent microscope with a computer-controlled CCD camera and a digital image analyzer. With ths system, it is possible to collect a fluorescent picture every 4 msec. In this study, single myocytes obtained from guinea pig or rat hearts were used. Ca^<2+> transient was monitored using fura-2 as the Ca^<2+> indicator. This was a two year study conducted from 1992 throught 1993. Experimental results are summarized as follows.
Ca^<2+> transients triggered by electrical stimulation originated from one or a few sites, or almost entire part of a myocyte. When the Ca^<2+> transient initiated at one site, it took approximately 30 msec to propagate to the other end of the myocyte. A peak of the Ca^<2+> transient was observed about 80 msec after electrical stimulation. The mumber of the initiating sites was increased by isoproterenol which stimulates Ca^<2+> channels, and decreased by verapamil which inhibits Ca^<2+> channels. Ouabain, which increases intracellular Ca^<2+> concentration but has n direct effect on Ca^<2+> channels, failed to alter the number of initiating sites. Doxorubicin, shown to inhibit the Ca^<2+> release mechanism of sarcoplasmic reticulum, did not alter the number of initiating sites athough this agent delayd time to peak Ca^<2+> transients remarkably.
These results ndicate that each cell has preferential site(s) at which Ca^<2+> transients originate responding to membrane depolarization. Cz^<2+> transients may be initiated by Ca^<2+> influx via Ca^<2+> channels, and propagate within a cell as the wave of Ca^<2+> induced Ca^<2+> release from sarcoplasmic reticulum.
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