Wong D F, Gjedde A, Wagner H N, Dannals R F, Douglass K H, Links J M, Kuhar M J
J Cereb Blood Flow Metab. 1986 Apr;6(2):147-53. doi: 10.1038/jcbfm.1986.28.
A method for estimating receptor density (Bmax) in the living human brain by positron emission tomography was exemplified by a ligand, 3-N-[11C]methylspiperone ([11C]NMSP), that binds to D2 dopamine receptors with high affinity. The ligand binds essentially irreversibly (i.e., with very little dissociation) to the receptors during the 2-h scanning period. Transfer constants were estimated at steady state. In a previous article, we presented a method for the determination of k3, the rate of binding of the labeled ligand. In the present work, we varied k3 by reducing the number of available receptors with a previously administered receptor blocking agent, haloperidol. We calculated a receptor density of 9.2 pmol g-1 in the caudate nucleus of four normal volunteers, and an inhibitory constant of haloperidol of 1.4 nM by comparing tracer accumulation in the absence and the presence of the blocking agent. The values agreed with measurements of NMSP receptor density and haloperidol inhibitory potency in vitro in brain homogenates from human autopsy material.
一种通过正电子发射断层扫描估计活体人脑中受体密度（Bmax）的方法，以一种与D2多巴胺受体具有高亲和力的配体3-N-[11C]甲基螺哌隆（[11C]NMSP）为例进行说明。在2小时的扫描期间，该配体与受体的结合基本不可逆（即解离极少）。在稳态下估计转移常数。在之前的一篇文章中，我们提出了一种测定标记配体结合速率k3的方法。在本研究中，我们通过用先前给予的受体阻断剂氟哌啶醇减少可用受体的数量来改变k3。通过比较在不存在和存在阻断剂的情况下示踪剂的积累，我们计算出四名正常志愿者尾状核中的受体密度为9.2 pmol g-1，氟哌啶醇的抑制常数为1.4 nM。这些值与用人尸检材料的脑匀浆进行的体外NMSP受体密度测量和氟哌啶醇抑制效力一致。
