2003 Fiscal Year Final Research Report Summary
Analysis on opening modes of ryanodine receptore-Ca^<2+> release channel
| Project/Area Number |
14570084
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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 pharmacology
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| Research Institution | Saitama Medical School |
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Principal Investigator |
IKEMOTO Takaaki Saitama Medical School, Medicine, Assistant professor, 医学部, 助手 (30275854)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Calcium ion / Ryanodine receptor / Skeletal muscle / Sarcoplasmic reticulum / Ca^<2+> -induced Ca^<2+> release / Dantrolene / Antihyperlipidemic agent / rhabdomyolysis |
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| Research Abstract |
We analyzed the effect of HMG-CoA reductase inhibitors on Ca^<2+> release from the sarcoplasmic reticulum (SR) using chemically skinned skeletal muscle fibers. Cerivastatin (Cer, > 20μM) released Ca^<2+> from the SR, while pravastatin showed only a little effect. The rates of Ca^<2+> release were increased by Cer at all Ca^<2+> concentrations tested. Cer-induced Ca^<2+> release in the presence of Ca^<2+> was affected by adenosine monophosphate, Mg^<2+> and procaine in essentially the same way as for caffeine-induced Ca^<2+> release. The Ca^<2+>-uptake capacity of the SR was reduced after co-treatment with ryanodine and Cer at pCa6.0 to a much grater extent than with ryanodine alone. Thus, Cer-induced Ca^<2+> release in the presence of Ca^<2+> must be a result of the activation of the Ca^<2+>-induced Ca^<2+> release (CICR) mechanism of the ryanodine receptor. However, even under the condition that CICR was maximally inhibited by Mg^<2+> and procaine, or in the practical absence of Ca^<2+>, Cer still caused Ca^<2+> releases. These results indicate that Cer causes Ca^<2+> release also by activating some other mechanism(s) in addition to the activation of CICR. Either or both of these effects might be related to its adverse effect, rhabdomyolysis
A novel method for radioisotope-free photoaffinity labeling was developed, in which a bifunctional ligand is connected to a target protein by activation of a photoreactive group, such as an aromatic azido or 3-trifluoromethyl-3H-diazirin-3-yl group, and identification of the ligated product is achieved by anchoring of a detectable tag through the Staudinger-Bertozzi reaction with an alkyl azido moiety that survives photolysis. The chemical ground of this method was confirmed using model compounds with the bifunctional group under photoirradiation in the presence of trapping agents for reactive intermediates. The utility of the method has been demonstrated by specific labeling of the catalytic portion of human HMG-CoA reductase.
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Research Products
(12 results)
