1987 Fiscal Year Final Research Report Summary
The electrical transfer properties of basolateral-, luminal-, and gap junctional cell membrane in exocrine gland acinar cells.
| Project/Area Number |
61570038
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General physiology
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| Research Institution | University of Tokyo, Fculty of Medicine |
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Principal Investigator |
MARUYAMA Yoshio University of Tokyo, Faculty of Medicine, 医学部(医), 助手 (00133942)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Pancreatic acxinar cells / Cell membrane capacitance / Cell membrane conductance / GTP-binding protein / カルシウム |
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| Research Abstract |
1. Single acinar cells, enzymatically isolated from the rat pancrease, were subjected to tight-seal whole-cell recordings. Changes in cell membrane capacitance and conductance were simultaneously recorded using a phas-sensitive detection method.
2. Acetylcholine (ACh, 0.08 - 0.5 uM) and cholecystokinin - octapeptide (CCK, 10 - 50 pM) concomitantly induced transient increases in cell membrane current, capacitance and conductance only when cytosolic Ca was weakly chelated by EGTA (70 uM). These responses were prolonged when the cells were dialyzed with a solution containing GTP-rS (a stable analogue of GTP, 50 - 100 uM) whereas they were inhibited by dialyzing with that containing GDP-bS (a stable analogue of GDP). These results suggest that a type of guanine-nucleotide binding proteins (G-protein) could be involved in ACh-or CCK-receptor signalling.
3. The ACh- or CCK-induced responses (with or without GTP-rS in the cytosol) were all abolished when a high dose of EGTA(1 - 2 mM) was injected into the acinar cells. In addition, A23187 induced sustained responses when the cytosolic Ca was weakly buffered by 70 uM EGTA. These results suggest that the secretagogoues regulate the changes in cell membrane capacitance and conductance via an increase and decrease of cytosolic Ca concentration.
4. The peak amplitude of changes in cell membrane capacitance induced by ACh or CCK, with or without GTP-rS in the cytosol, varied between 200 and 1000 fF, thereby suggesting that 20 to 100 zymogen granules can fuse with the luminal cell membrane in response to these agonists, in rat exocrine pancreatic acinar cells.
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Research Products
(4 results)
