2000 Fiscal Year Final Research Report Summary
Roles of c-kit in functional development of Ca^<2+> release mechanism in smooth muscle cells
| Project/Area Number |
11670094
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General pharmacology
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| Research Institution | KUMAMOTO UNIVERSITY |
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Principal Investigator |
TOKUTOMI Yoshiko Kumamoto University, School of Medicine, Assistant Professor, 医学部, 助手 (90253723)
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| Co-Investigator(Kenkyū-buntansha) |
TOKUTOMI Naofumi Kumamoto University, School of Medicine, Associate Professor, 医学部, 助教授 (30227582)
NISHI Katsuhide Kumamoto University, School of Medicine, Professor, 医学部, 教授 (00040220)
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| Project Period (FY) |
1999 – 2000
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| Keywords | smooth muscle / Ca^<2+> storage / c-kit / mouse / Patch-clamp technique / fura-2 / ryanodine / caffeine |
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| Research Abstract |
To clarify the roles of c-kit, a receptor-type tyrosine kinase, in the functional development of smooth muscle cells, we investigated the property of the Ca^<2+>-induced Ca^<2+> release in smooth muscle cells freshly dissociated from gastrointestinal tract of BALB/c mice treated with neutralizing anti-c-kit-monoclonal antibody (ACK2). Under voltage-clamped conditions with the nystatin-perforated patch-clamp technique, c-kit-expressing (c-kit^+) cells developed rhythmic Ca^<2+>-activated Cl^- currents and smooth muscle cells from the control animals developed spontaneous outward currents and caffeine-and carbachol-induced transient outward currents. In smooth muscle cells from the ACK2-treated mice, dysfunction in the ryanodine-sensitive Ca^<2+> storage in the cytoplasm was suggested when tested with caffeine-induced Ca^<2+>-activated K^+ currents and fura-2 fluorometric measurements of intracellular Ca^<2+> concentration. The Ca^<2+> release and caffeine-induced Ca^<2+>-activated K^+ currents in smooth muscle cells from the control animals were ryanodine-sensitive and had great dependence upon the activity of L-type voltage-gated Ca^<2+> channels. In measurements of isometric tension, caffeine-induced relaxation was significantly accelerated in smooth muscles precontracted with high K^+ depolarization or carbachol. Altogether, it is suggested that ryanodine-sensitive Ca^<2+> release is an important modifier of Ca^<2+> homeostasis in the cytoplasm and the contractility of gastrointestinal smooth muscle of mice and that the c-kit^+ cells play important roles in the development of smooth muscle through the rhythmic excitation and Ca^<2+>-fluctuation in the cytoplasm.
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