1997 Fiscal Year Final Research Report Summary
Studies on changes in the pancreatic B cell function during development and aging assessed by computer-aided fluorescent microscopy
| Project/Area Number |
08672523
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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 |
Biological pharmacy
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| Research Institution | Kitasato University (1997)
University of Shizuoka (1996) |
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Principal Investigator |
ISHI Kunio Kitasato Univ.Sch. of Pharmaceut. Sci., Professor, 薬学部, 教授 (90137993)
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| Co-Investigator(Kenkyū-buntansha) |
TANABE Yoshiyuki Univ. of Shizuoka Sch. of Pharmaceut. Sci., Assistant Professor, 薬学部, 助手 (10275109)
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| Project Period (FY) |
1996 – 1997
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| Keywords | pancreatic B cell / Ca^<2+> concentration / fura 2 / nitric oxide(NO) / L-arginine / cyclic GMP / mambrane potential / development |
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| Research Abstract |
In pancreatic B cells isolated from normal adult and normal young rats, the intracellular free Ca^<2+> concentration ([Ca^<2+>]i) and the membrane potential were measured by fluorescent microscopy using fura 2 and patch clamp technique, respectively. Furthermore, the possibility that denervation of the sympathetic nervous system affects responsiveness of B cells to drugs was examined.
In the presence of partially stimulating concentrations of glucose or tolbutamide, agents that facilitate NO production or augment intracellular cyclic GMP content, such as 8-bromo-cyclic GMP,human atrial natriuretic peptide, L-arginine, sodium nitroprusside, NOC 5 and NOC 7, increased [Ca^<2+>]i of B cells isolated from normal adult rats, as observed with cyclic AMP.However, these agents failed to increase [Ca^<2+>]i of B cells when tested under depolarization of the plasma membrane with high concentrations of K^+. The increase in [Ca^<2+>]i was considered to be mainly due to Ca^<2+> influx through the plasma membrane. In the case of B cells isolated from normal young or sympathectomized adult rats, effects of the NO-cyclic GMP-related agents were similar to those observed with B cells isolated from normal adult rats.
These results suggest that activation of the NO-cyclic GMP system positively medullates the release of insulin from pancreatic B cells under the physiological conditions. Possible changes in the B cell function during aging need to be elucidated.
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