2006 Fiscal Year Final Research Report Summary
Molecular basis for the regulation of the cardiac delayed rectifier K^+ channel by membrane PIP_2
| Project/Area Number |
17590185
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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 physiology
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
MATSUURA Hiroshi Shiga University of Medical Science, Physiology, Professor, 医学部, 教授 (60238962)
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| Co-Investigator(Kenkyū-buntansha) |
DING Wei-guang Shiga University of Medical Science, Physiology, Assistant Professor, 医学部, 助手 (80242973)
TOYODA Futoshi Shiga University of Medical Science, Physiology, Assistant Professor, 医学部, 助手 (90324574)
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| Project Period (FY) |
2005 – 2006
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| Keywords | PIP_2 / I_<ks> / α_1-adrenoceptor / P2Y-receptor / hyposmotic solution / membrane stretch / patch-clamp method / action potentials |
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| Research Abstract |
In this research project, we investigated the molecular basis for the regulation of the slowly activating component of delayed rectifier K^+ current (I_<ks>) by membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP_2), using the whole-cell patch-clamp method. The stimulatory action of α_1-adrenergic agonist phenylephrine (30μM) on I_<ks>, was partially (by 60%) inhibited by the protein kinase C inhibitor bisindolylymaleimide I(BIS-I) and was almost totally abolished by intracellular addition of PIP_2 (100μM) through a patch electrode. The potentiation of I_<ks>by the p2Y agonist ATP (50 μM) was scarcely affected by BIS-I but was largely blocked by intracellular application of PIP_2. The stimulation of I_<ks> by exposure to 70% hyposmotic external solution (200 mOsm) was significantly attenuated intracellular application of anti-PIP_2 monoclonal antibody(1:40 dilution) via a patch electrode. These results provide the experimental evidence for the involvement of PIP_2 metabolism in the potentiation of I_<ks>, evoked by stimulation a Gq-phospholipase C (PLC)-coupled receptors (e.g., α_1-and P2Y-receptors) or by hyposmotic cell swelling. The stimulation of M_1-muscarinic receptors (M_1-R) by acetylcholine (1 and 10 nM) in CHO cells transiently trasnfected with KCNQ1, KCNE1 and M_1-R increased the membrane current through the KCNQ1/KCNE1 channels, molecular constituents of cardiac I_<ks>, by 20%, supporting a functional role for membrane PIP_2 in the regulation of I_<ks>. These observation may also indicate the possibility that membrane PIP_2 plays a differential role in the potentiation of I_<ks> through the stimulation of distinct Gq-PLC-coupled receptors or various cellular stimuli.
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Research Products
(12 results)
