1999 Fiscal Year Final Research Report Summary
Having an Anesthetic without adverse effects : The binding sites of dexmedetomidine on adrenoceptor
| Project/Area Number |
09470335
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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 |
Anesthesiology/Resuscitation studies
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| Research Institution | Department of Anesthesiology Kyoto Prefectural University of Medicine |
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Principal Investigator |
MIZOBE Toshiki M.D., Ph.D. Associate Professor, Department of Anesthesiology, Kyoto Prefectural University of Medicine, 医学部, 講師 (50239266)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Yoshifumi M.D., Ph.D. Professor of Chair, Department of Anesthesiology, Kyoto Prefectural University of Medicine, 医学部, 教授 (50079935)
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| Project Period (FY) |
1997 – 1999
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| Keywords | dexmedetomdine / adrenergic receptor / chimeric receptor / point-mutant receptor / PCR / anesthesia |
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| Research Abstract |
Dexmedetomidine (DEX) is a subtype non-selective, alpha2 adrenergic agonist developed for anesthetic management because of its sedative/hypnotic, anestheticsparing, analgesic and sympatholytic properties. Each of these properties are thought to be mediated by activation of the alpha2A adrenoceptor subtype. We sought to determine the TMDs on the human alpha2A adrenoceptor subtype which are responsible for binding to DEX in order to design novel subtype selective alpha2A agonists. Chimeric receptor were constructed to replace defined TMDs of the wild-type human alpha2A adrenoceptor with homologous sequence from the human beta2 adrenoceptor which itself has no affinity for DEX.
Chimerae of the human alpha2A and human beta2 adrenoceptors were constructed from genes encoding human alpha2A (or C10) and beta adrenoceptors. COS-7 cells were transfected with 12 new constructs as well as the wild-type human alpha2A and human beta2 adrenoceptors. Cells were harvested and membranes prepared for radiolabeled ligand binding using 3H-atipamezole and DEX as the displacing ligand.
TMD#7 is pivotal for DEX binding since CRS 25 (alpha2 TMD#7) has > 10,000 for higher affinity than CRT3 (beta2 TMD#7). To a lesser extent TMD#2 is involved in DEX binding since CRS16 (alpha2 TMD#2) has >100 fold higher affinity for DEX than does beta2 adrenoceptor. TMD#6 may be involved in DEX binding since CRS 25(alpha2 TMD#6) has 10 fold higher affinity for DEX than does CR8 (beta2 TMD#6).
The next generation of alpha2 adrenergic agonists needs to be alpha2A subtype selective. To better understand the amino acid residues responsible for subtype selectivity, further site-directed mutagenesis studies of the differences in amino acid residues in TMD#7 and 2 (and 6) between the three adrenoceptor subtypes need to be undertaken. This will facilitate target-based drug design of the novel alpha2A subtype selective agonists for use in anesthesia.
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Research Products
(14 results)
