COMPARTMENTAL ANALYSIS OF DIPRENORPHINE BINDING TO OPIATE RECEPTORS IN THE RAT INVIVO AND ITS COMPARISON WITH EQUILIBRIUM DATA INVITRO
COMPARTMENTAL ANALYSIS OF DIPRENORPHINE BINDING TO OPIATE RECEPTORS IN THE RAT INVIVO AND ITS COMPARISON WITH EQUILIBRIUM DATA INVITRO
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DOI：
10.1038/jcbfm.1991.1
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发表时间：
1991-01-01
影响因子：
6.3
通讯作者：
JONES, AKP
中科院分区：
文献类型：
--
作者：
CUNNINGHAM, VJ;HUME, SP;JONES, AKP
阿片受体配基异丙诺啡在体内和体外的大鼠脑内的区域结合已经被检测。静脉注射[H-3]地丙诺啡后2 h内观察特定脑区总标记的时程变化，30min时分别给予或不给予未标记丙泊诺啡。此外，在注射非示踪剂浓度的标记双丙诺啡30分钟后，在一系列特定的活性范围内测量总标记。将每个区域的总数据集同时拟合到一个分室模型中，以估计最大结合容量(B(Max))、二阶表观结合速率常数和一阶受体-配体复合体的解离速率常数。该模型结合了具有低特异性结合的参照区(小脑)的使用。在37℃、pH 7.4、有无纳洛酮存在的平衡条件下，测定了异丙诺啡与大鼠脑匀浆的结合，给出了相应的区域B(Max)和半饱和常数K(D)的估计值。结果表明，在很大范围内，B(Max)的体外和体内区域估计值之间存在密切的相关性。无论是体外的K(D)，还是来自体内分析的K(D)，都没有显著的地区间差异，尽管体外和体内的估计有一个数量级的差异。这项工作是作为验证性研究的一部分进行的，目的是在对一系列特定活动的后续研究不可行的情况下，将间隔模型应用于使用正电子发射断层扫描在人体内获得的数据。仅限于示踪剂和脉冲追踪法的老鼠数据表明，间隔模型给出了与使用完整数据集获得的估计一致的区域联合前进速率常数的估计。
The regional binding of the opiate receptor ligand diprenorphine has been examined in rat brain both in vivo and in vitro. The time course of total label in specific brain regions was followed up to 2 h after intravenous bolus injection of [H-3]diprenorphine, with or without a pulse chase of unlabelled diprenorphine at 30 min. In addition, total label was measured 30 min after injection of labelled diprenorphine at nontracer concentrations over a range of specific activities. Total data sets for each region were fitted simultaneously to a compartmental model to give estimates of maximal binding capacity (B(max)), the second-order apparent association rate constant, and the first-order dissociation rate constant of the receptor-ligand complex. The model incorporated the use of a reference region with low specific binding (cerebellum). The binding of diprenorphine to rat brain homogenates was measured in vitro under equilibrium conditions at 37-degrees-C, pH 7.4, in the presence and absence of naloxone, to give corresponding regional estimates of B(max) and the half-saturation constant K(d). The results showed a close correlation between in vitro and in vivo regional estimates of B(max) over a wide range. There were no significant interregional differences either in K(d) in vitro or in the K(d) derived from the in vivo analysis, although in vitro and in vivo estimates differed by an order of magnitude. This work was carried out as part of a validation study with a view to the application of the compartmental model to data obtained in vivo in humans using positron emission tomography, when successive studies over a range of specific activities are not feasible. Restriction of the rat data to tracer alone and pulse chase protocols showed that the compartmental model gave regional estimates of the combined forward rate constant consistent with estimates obtained using the complete data set.