@article{oai:repo.qst.go.jp:00046275,
 author = {Kawamura, Kazunori and Yui, Joji and Konno, Fujiko and Yamasaki, Tomoteru and Hatori, Akiko and Wakizaka, Hidekatsu and Fujinaga, Masayuki and Kumata, Katsushi and Yoshida, Yuichirou and Ogawa, Masanao and Nengaki, Nobuki and Yanamoto, Kazuhiko and Fukumura, Toshimitsu and Zhang, Ming-Rong and 河村 和紀 and 由井 譲二 and 昆野 富士子 and 山崎 友照 and 羽鳥 晶子 and 脇坂 秀克 and 藤永 雅之 and 熊田 勝志 and 吉田 勇一郎 and 小川 政直 and 念垣 信樹 and 柳本 和彦 and 福村 利光 and 張 明栄},
 issue = {1},
 journal = {Nuclear Medicine and Biology},
 month = {Jan},
 note = {Introduction: To explore the possible use of positron emission tomography (PET) probes for imaging of I2-imidazoline receptors (I2Rs) in peripheral tissues, we labeled two new I2R ligands, 2-[2-(o-tolyl)vinyl]-4,5-dihydro-1H-imidazole (Ki for I2Rs, 3.7 nM) and 2-[2-(o-tolyl) ethyl]-4,5-dihydro-1H-imidazole (Ki for I2Rs, 1.7 nM) with 11C ([11C]metrazoline and [11C]TEIMD), respectively, and evaluated these
ligands and the recently developed I2R ligand 2-[3-fluoro-[4-11C]tolyl]-4,5-dihydro-1H-imidazole ([11C]FTIMD) by in vivo studies.
Methods: [11C]Metrazoline and [11C]TEIMD were prepared by a palladium-promoted cross-coupling reaction of the tributylstannyl precursor and [11C]methyl iodide. Their biodistribution in mice was investigated by tissue dissection. In addition, PET scans and metabolite analysis were performed.
Results: [11C]Metrazoline and [11C]TEIMD were successfully synthesized with a suitable radioactivity for injection. In the liver and pancreas expressing I2Rs, coinjection with the high-affinity I2R ligand, BU224, induced a reduction in the radioactivity level at 30 min after 
injection of [11C]metrazoline and [11C]FTIMD. However, the radioactivity level after injection of [11C]TEIMD was unchanged. In the PET
study, coinjection with BU224 induced a decrease in the radioactivity level in the liver and pancreas after more than 15 min of injection of
[11C]metrazoline and [11C]FTIMD as compared with the results obtained for controls. In metabolite analysis, coinjection with BU224 induced a significant reduction in the percentage of unchanged [11C]metrazoline at 30 min after injection as compared with that in the control, although no significant difference was observed in the percentage of unchanged [11C]FTIMD.
Conclusion: [11C]Metrazoline may be a more useful PET probe than [11C]FTIMD for imaging of I2Rs in peripheral tissues.},
 pages = {89--99},
 title = {Synthesis and evaluation of PET probes for the imaging of I2 imidazoline receptors in peripheral tissues},
 volume = {39},
 year = {2012}
}