| Project/Area Number |
11470129
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Gastroenterology
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| Research Institution | Nagoya University |
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Principal Investigator |
HAYAKAWA Tetsuo Graduate School of Medicine, Nagoya University, Professor, 大学院・医学研究科, 教授 (80022838)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIGURO Hiroshi Research Center Health, Physical Fitness, and Sports, Assistant Professor, 総合保健体育科学センター, 助手 (90303651)
KITAGAWA Motoji University Hospital, Assistant Professor, 医学部・附属病院, 助手 (80262898)
NARUSE Satoru Graduate School of Medicine, Nagoya University, Associate Professor, 大学院・医学研究科, 助教授 (50180550)
FURUYA Sonoko National Institute for Physiological Sciences, Assistant Professor, 生理学研究所, 助手 (20096952)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1999: ¥3,200,000 (Direct Cost: ¥3,200,000)
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| Keywords | pancreatic duct cell / bicarbonate transport / aquaporin / enterochromaffm cell / ethanol / fluid hypersecretion / alcoholic chronic pancreatitis / 単離小葉間膵管 / 細胞内C1^-濃度 / HCO_3^-分泌 / 5-hydroxytriptamine / Na^+-HCO_3^- cotransport / マイクロパーフュジョン / 細胞内pH測定 / HCO_3^-透過性 / Na^+-HCO_3^-共輸送体 / Cl^- / HCO_3^-交換輸送体 / マイクロパーフュージョン / プリン受容体 / バゾプレッシン / CFTR / 単離膵導管細胞 / PLA_2 / Ca^<2+>オシレーション |
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| Research Abstract |
1. To investigate the secretory mechanism of HCO_3^-, across the luminal membrane of pancreatic duct cell we have measured intracellular concentrations of HCO_3^- ([HCO_3^-]_i) and of Cl^- ([Cl^-]_i) in microperfused interlobular duct segments isolated from guinea-pig pancreas. When the HCO_3^- concentration in the lumen was raised to 125 mM (24 mM Cl^-) under cAMP stimulation, pH_i did not increase above 7.2 ([HCO_3^-]_i = 〜 20 mM), indicating that luminal Cl^--HCO_3^- exchange was inhibited. Under the same condition, [Cl^-]_i was kept very low at 〜7 mM, which would tend to favor HCO_3^-' secretion via a luminal anion conductance.
2. 5-hydroxytryptamine (5-HT, serotonin) at 0. 1μM strongly inhibited fluid secretion in isolated ducts via 5-HT_3 receptor. The action is mediated by the inhibition of basolateral HCO_3^- accumulation via Na^+-HCO_3^- cotransport. 5-HT released from pancreatic ductal enterochromaffin cells may regulate fluid secretion in a paracrine fashion.
3. RT-PCR analysis and immunohistochemistry of isolated ducts revealed the expression of AQP1 in duct cells. The osmotic water permeability of the ductal epithelium was reduced by 80-90% with either basolateral or luminal application of HgCl_2. AQP1 of the known water channels appears to be the main water pathway in pancreatic ductal epithelium.
4. Although ethanol abuse is the most common cause of acute and chronic pancreatitis, the mechanism by which ethanol causes the disease is not well understood. Ethanol at 1 mM, the concentration observed after an occasional social drinking, significantly augmented the maximal rate of fluid secretion and induced a transient increase in intracellular Ca^<2+> concentration in ducts stimulated with secretin or dibutyryl cAMP. When the flow of pancreatic juice is disturbed by protein plug or stones, fluid hypersecretion induced by ethanol would elevate the intraductal pressure in the proximal part of the duct, leading to edema formation or pancreatitis.
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