| Project/Area Number |
62570046
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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 | Juntendo University |
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Principal Investigator |
OCHI R. Department of Physiology, School of Med.,Prof., 医学部, 教授 (10049025)
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| Co-Investigator(Kenkyū-buntansha) |
KAWASHIMA Y. Department of Physiology, School of Med., Assistant, 医学部, 助手 (10186091)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1988: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1987: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Ca channel / availability / slow gating process / blank sweeps / isoproterenol / acetylcholine / nitrendipine / patch clamp / チャネル / パッチクランプ |
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| Research Abstract |
The mechanisms of the modulation of Ca current by isoproterenol, a beta-adrenergic stimulant, and nitrendipine, a Ca channal blocker, were studied by recording single Ca channal currents from isolated guinea-pig ventricular muscles utilizing the cell-attached version of patch clamp technique. Isoproterenol increased the rate of current-containing sweeps (availability, Ps) by increasing the number of consecutive non-blanks. The efficacy of isoproterenol in increasing Ps was slightly enhanced by the depolarization of the holding potential. The increase in Ps was depressed by the addition of acetylcholine. Nitrendipine decreased Ps by increasing the number of consecutive blanks.
The action of nitrendipine was remarkable enhanced by the depolarization of the holding potential, resulting the shift of the availability-voltage curve in a hyperpolarizing direction. The fast gating process which plays a major role in the determination of the open probability in the current-containing sweeps was affected neither by isoproterenol nor by nitrendipine. We conclude that isoproterenol increases the Ca current by primarily increasing the duration of the available state and and decreasing the duration of the unavailable state and that nitrendipine depresses the current by increasing the duration of the unavailable state in a voltage-dependent manner.
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