| Project/Area Number |
10670996
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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 |
Kidney internal medicine
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| Research Institution | Osaka University |
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Principal Investigator |
HORIO Masaru Osaka University, Faculty of Medicine, Associate Professor, 医学部, 助教授 (20273633)
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| Co-Investigator(Kenkyū-buntansha) |
福永 恵 大阪大学, 医学部, 助手 (40283775)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | osmolyte / betaine / amino acid / osmolality / apoptosis / MDCK cell / System A / ストレス |
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| Research Abstract |
Many type of cells, exposed to hyperonic medium accumulate small osmotically active organic solutes, which are called osmolytes. To investigate the osmoregulation in rat mesothelial cells, the content of amino in the cells and the activity of system A was measured after switching to hypertonic medium. Total content of 20 amino acids increased from 306 to 757 nmol/mg protein and peaked after 12 h of hypertonicity. The content of neutral amino acids accounted for 81% of the increased amount of the total amino acids. System A transport activity increased 36-fold relative to the uptake in isotonic cells after 4 h of hypertonicity. Theses data suggested that neutral amino acids and system A transport play an important role in early-phase osmoregulation in rat peritoneal mesothelial cell.
Hypertonicity-induced cell damage and apoptosis were investigated in MDCK cells. Viabilities of MDCK cells were decreased osmolality dependent manner after hypertonic exposure. When the cells were exposed to 700 mOsm medium for 24h, DNA laddering and TUNEL positive cells were demonstrated in both the detached and the adherent cells, indicating that apoptosis involved in the hypertonicity-induced cell death in MDCK cells. Twelve percent of the adherent cells were TUNEL positive determined by flow cytometry analysis. Caspase-3 activity of the adherent cells exposed to 700 mOsm for 24h increased about 20 fold the value of isotonic cells. Addition of 1mM betaine, one of the predominant osmolytes in kidney medulla, protected the hypertonicity-induced cell damage assessed by MTT assay. Betaine significantly reduced the hypertonicity-induced apoptosis and the induction of caspase-3 activity. We concluded that caspase-3-related apoptosis is at least partly responsible for the hypertonicity-induced cell death in MDCK cells. Betaine had a potent protective effect on the hypertonicity induced apoptosis.
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