Shiue C Y, Shiue G G, Cornish K G, O'Rourke M F
Department of Radiology, University of Pennsylvania, Philadelphia 19104, USA.
Nucl Med Biol. 1995 Apr;22(3):321-4. doi: 10.1016/0969-8051(94)00104-r.
Carbon-11 labeled (-)-methamphetamine and (-)-3,4-methylenedioxy-N-methamphetamine were synthesized by methylation of the corresponding desmethyl precursors with [11C]H3I in 40-60% yield in a synthesis time of 30 min from EOB with a specific activity of 0.5-1.2 Ci/microM. PET studies in a Rhesus monkey revealed that the uptakes of both compounds in different brain regions were similar, and the retention of radioactivity in these brain regions remained constant throughout the study for the former while it was washed out slowly for the latter. The half-life of (-)-3,4-methylenedioxy-N-methamphetamine in monkey brain was approximately 70 min. Analyses of arterial plasma by HPLC revealed that 50% of radioactivity in the plasma remained as (-)-methamphetamine while only 3% remained as (-)-3,4-methylenedioxy-N-methamphetamine at 60 min post-injection. These results suggest that the uptakes of both compounds in monkey brain are probably not receptor mediated. Rather, blood flow, lipophilicity of the compounds or other transport mechanisms may play a role in their uptakes.
用[11C]H3I使相应的去甲基前体甲基化，合成了碳-11标记的(-)-甲基苯丙胺和(-)-3,4-亚甲基二氧基-N-甲基苯丙胺，产率为40-60%，从EOB开始的合成时间为30分钟，比活度为0.5-1.2 Ci/μM。对一只恒河猴进行的PET研究显示，两种化合物在不同脑区的摄取相似，在整个研究过程中，前一种化合物在这些脑区的放射性滞留保持恒定，而后一种化合物的放射性则缓慢清除。(-)-3,4-亚甲基二氧基-N-甲基苯丙胺在猴脑中的半衰期约为70分钟。通过HPLC对动脉血浆进行分析发现，注射后60分钟时，血浆中50%的放射性仍以(-)-甲基苯丙胺的形式存在，而只有3%以(-)-3,4-亚甲基二氧基-N-甲基苯丙胺的形式存在。这些结果表明，两种化合物在猴脑中的摄取可能不是由受体介导的。相反，血流、化合物的亲脂性或其他转运机制可能在它们的摄取过程中起作用。
