Delforge J, Syrota A, Lançon J P, Nakajima K, Loc'h C, Janier M, Vallois J M, Cayla J, Crouzel C
Service Hospitalier Frédéric Joliot, Commissariat à l'Energie Atomique, Orsay, France.
J Nucl Med. 1991 Apr;32(4):739-48.
The in vivo quantification of myocardial beta-adrenergic receptor has been obtained in five closed-chest dogs using positron emission tomography (PET). The ligand was racemic (+/-)[11C] CGP 12177, a very potent hydrophilic antagonist of the beta-adrenergic receptor. A kinetic method appeared unsuitable because of the presence of metabolites which made the input function difficult to measure and also inaccurate. Therefore, a graphical method, based on a particular protocol, was proposed. The animals were injected with a trace amount of (+/-)[11C]CGP 12177, which was followed 40 min later by a second injection of radioligand with a low-specific activity. An additional injection of an excess of unlabeled CGP 12177 was administered after 90 min and allowed for the estimation of the dissociation rate constant. The main advantage of this graphical approach is that the results are obtained without having to measure the input function and therefore without estimating the metabolites. The average value of Bmax was 31 +/- 4 pmole/ml of tissue and the dissociation constant was 0.014 +/- 0.002 min-1.
利用正电子发射断层扫描（PET）技术，在五只开胸犬体内对心肌β - 肾上腺素能受体进行了定量分析。所用配体为外消旋（±）[¹¹C]CGP 12177，一种非常有效的β - 肾上腺素能受体亲水性拮抗剂。由于存在代谢产物，使得输入函数难以测量且不准确，因此动力学方法似乎并不适用。于是，提出了一种基于特定方案的图形化方法。给动物注射微量的（±）[¹¹C]CGP 12177，40分钟后再注射一次低比活度的放射性配体。90分钟后额外注射过量的未标记CGP 12177，用于估计解离速率常数。这种图形化方法的主要优点是无需测量输入函数，因此也无需估计代谢产物即可获得结果。Bmax的平均值为31±4 pmole/ml组织，解离常数为0.014±0.002 min⁻¹。
