| Project/Area Number |
01570497
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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 |
Circulatory organs internal medicine
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| Research Institution | Oita Medical University |
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Principal Investigator |
IMANISHI Sunao Oita Medical University, Department of Medicine, Associate Professor, 医学部, 助教授 (90108689)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | human atrial muscles / abnormal automaticity / intracellular K^+ activity / intracellular Na^+ activity / single human artial cells / acetylcholine / nicorandil / atrial natriuretic peptide / 病的ヒト心房筋 / Triggered Activity / 単離ヒト心房細胞 / パッチクランプ |
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| Research Abstract |
A human atrial trabecula(0.8xl. 5mm)was dissected from a small piece of right atrial appendage excised from patients undergoing cardiac surgery. We first attempted to elucidate the ionic mechanisms for the low resting membrane potential(Vm)of human atrial preparations using double-barreled K^+- and Na^+-sensitive microelectrodes. Because various types of abnormal automaticities observed at a rate of about 70% in the ppecimens may be mainly caused by partial depolarizations of Vm. The intracellular K^+ activity(a^i_averaged 99.7<plus-minus>1.3mM(n=33), intracellular Na^+ activity(a^i_, 6.9<plus-minus>1.7mM(n=9)and Vm, 43.6<plus-minus>3.2(n=42). These findings suggest that the depolarization of Vm is neither due to a decrease in a^i_ nor an increase in a^i_ but probably due to a decrease in K^+ permeability for the membrane. We secondly examined the effects of atrial natriuretic peptide(ANP)on action potential characteristics and contractile tension of the human preparations. However, we found no significant effect of ANP on those parameters. So we intended to test the effects of ANP on the ionic current in single human atrial myocytes using whole cell voltage-clamp technique. However, there was only one isolated cell tolerable to do experiment among 31 human atrial tissues undergone cell-isolation procedures. Therefore, we could not obtain available informations about electrophysiologic effects of ANP on single human atrial cell, though we observed electrophysiologically reasonable actions of acetylcholine and nicorandil on it.
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