1987 Fiscal Year Final Research Report Summary
Pharmaco-mechanical coupling in the iris sphincter muscle
| Project/Area Number |
61571059
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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 |
Biological pharmacy
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| Research Institution | Nagoya City University |
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Principal Investigator |
WATANABE Minoru Faculty of Phamaceut. Sciences, Nagoya City University, 薬学部, 教授 (50012638)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAI Tomoyuki Faculty of Pharmaceut. Sciences, Nagoya City University, 薬学部, 助手 (60152906)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Iris sphincter / Patch clamp / イオン電流 |
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| Research Abstract |
Ionic currents in single smooth muscle cells isolated from rabbit iris sphincter were investigated using the single suction electrode voltage clamp method. By depolarization from holding potential of -60mV, only outward currents were activated. The main component of the outward currents was blocked by 3mM tetraethylammonium (TEA) or withdrawal of extracelular Ca. The transient component of residual outward currents was inhibited by 3mM 4-aminopyridine (4-AP). Outward currents were totally abolished by 50mM TEA and 5mM 4-AP. The inward current could be unmasked by the treatment with 50mM TEA and 5mM 4-AP, but was still quite small (<20pA). When extracellular Ca concentration was elevated from 2.2 to 10mM, the inward current was enhanced by about threefold. The replacement of Ca with Ba enlarged the peak inward current and decreased the decaying time course. The large outward currents in comparison with the small inward current can explain the lack of excitability of this smooth muscle under physiological conditions.
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