2002 Fiscal Year Final Research Report Summary
Morphological and functional coupling of IP3 receptors with Na pumps in adrenal chromaffin cells
| Project/Area Number |
13670050
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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 | Fukuoka University |
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Principal Investigator |
INOUE Masumi Fukuoka University, School of Medicine, Associate Professor, 医学部, 助教授 (40223276)
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| Co-Investigator(Kenkyū-buntansha) |
OGAWA Kouichi Fukuoka University, School of Medicine, Associate Professor, 医学部, 助教授 (60078780)
FUJISHIRO Naoji Fukuoka University, School of Medicine, Research assistant, 医学部, 助手 (30173420)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Chromaffin cells / Ca store sites / Na pump / α subunit / Ca uptake / IP3 receptor / Catecholamine / secretion |
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| Research Abstract |
Adrenal chromaffin cells are exposed to high concentrations of cortical hormones, one of which is ouabain-like substance. Thus, the effects of ouabain on catecholamine secretion and distribution of Na^+, K^+-ATPase α subunits in chromaffin cells were examined using amperometry and immunocytochemistry. While exposure to 1 μM ouabain did not have a marked effect on resulting secretion, it induced an increase in the secretion due to mobilization of partially stored Ca^<2+>. Immunocytochemistry revealed that Na^+, K^+-ATPase α1 subunit-like immunoreactivity (IR) was distributed ubiquitously at cell periphery, whereas α2-like IR were present at part of cell periphery. Inositol trisphosphate receptor (InsP_3R) type 2-like IR was distributed perinuclearly and in the vicinity of the plasma membrane, consistent with that of BODIPY-FL-InsP_3 binding. Peripheral BODIPY-FL-InsP_3 binding sites underlay membranes with α2-like IR, indicating that the peripheral InsP_3R type 2-containing Ca^<2+> storage was juxtaposed to membranes with the α2 subunit. This close association may account for the facilitation of Ca^<2+> uptake into stores and the consequent increase in mobilization-dependent secretion in the presence of 1 μM ouabain.
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