1996 Fiscal Year Final Research Report Summary
Exploration of ryanodine receptor in isolated microsomal vesicles prepared from exocrine acinar cells.
| Project/Area Number |
07670046
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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 | Tohoku University |
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Principal Investigator |
OZAWA Terutaka Tohoku University School of Medicine Associate Professor, 医学部, 助教授 (30160857)
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| Project Period (FY) |
1995 – 1996
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| Keywords | ryanodine receptor / parotid acinar cells / pancreatic acinar cells / isolated microsomal veicles / Ca^<2+> releasing mechanism / caffeine / cyclic ADP-ribose |
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| Research Abstract |
To investigate the characterization of a ryanodine-sensitive Ca^<2+> release mechanism which may be present in rat parotid and pancreatic acinar cells, Ca^<2+> flux by isolated microsomal vesicles and Ca^<2+> activated K^+ or Cl^- currents by isolated cells were measured. 1. Measurements of ^<45>Ca^<2+> release from microsomal vesicles of parotid acinar cells : 1) Caffeine (10-40 mM), a low concentration (10 muM) of ryanodine and cyclic ADP-ribose (cADPR : 1-10 muM) released ^<45>Ca^<2+> from microsomal vesicles. 2) Caffeine (40 mM)-induced ^<45>Ca^<2+> release was enhanced by a pretreatment of 10 muM ryanodine. 3) Caffeine (40 mM)-and cADPR (4 muM)-induced ^<45>Ca^<2+> release were inhibited by the presence of a higher concentration (500 muM) of ryanodine or ruthenium red (50 muM). 4) A lower concentration of cADPR (0.5 muM) shifted the dose-response curve for caffeine-induced ^<45>Ca^<2+> release. 2. Measurements of Ca^<2+> flux by microsomal vesicles of pancreatic acinar cells : 1)
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Caffeine (10-40 mM), a low concentration (10 muM) of ryanodine and cADPR (0.1-4 muM) released ^<45>Ca^<2+> from microsomal vesicles preloaded with ^<45>Ca^<2+>.2) By using a Ca^<2+> -sensitive electrode, it was shown that addition of Ca^<2+> into the medium at a final concentration of 50 mu M released Ca^<2+> from microsomal vesicles. 3. Measurements of Ca^<2+> activated K^+ or Cl^- currents by isolated parotid acinar cells : 1) Caffeine (1-40 mM) induced Ca^<2+> -activated K^+ or Cl^- currents in a dose dependent manner. 2) Intracellular injection of ryanodine (20 muM) or cADPR (2 muM) potentiated caffeine (40 mM)-and acetylcholine (30 nM)-induced Ca^<2+> currents. 3) The injection of 200 muM ryanodine or 50 muM ruthenium red inhibited the caffeine-evoked currents. These results suggest that a ryanodine-sensitive Ca^<2+> release mechanism, whose features are similar to the ryanodine receptor described in muscle or neuronal tissue, is present in the endoplasmic reticulum of parotid and pancreatic acinar cells and this mechanism is involved in acetylcholine-induced Ca^<2+> mobilization. Less
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