Terasmaa A, Finnman U B, Owman C, Ferré S, Fuxe K, Rinken A
Institute of Chemical Physics, University of Tartu, Jakobi Str. 2, EE-51014, Tartu, Estonia.
Neurosci Lett. 2000 Feb 18;280(2):135-8. doi: 10.1016/s0304-3940(00)00776-x.
Rat dopamine D(2short) expressed in Chinese hamster ovary (CHO) cells were characterized by means of activation of [(35)S]-guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding and inhibition of [(3)H]raclopride binding. Among 18 dopaminergic ligands studied dopamine, NPA, apomorphine and quinpirole were full agonists in activation of [(35)S]GTPgammaS binding, while seven ligands were partial agonists with efficacies from 16 to 69% of the effect of dopamine and seven ligands were antagonists having no effect on the basal level of [(35)S]GTPgammaS binding, but inhibited dopamine-dependent activation in a dose-response manner. Despite the different efficacies, the potencies of all 18 ligands to modulate [(35)S]GTPgammaS binding revealed a good correlation with their potencies to inhibit [(3)H]raclopride binding in the CHO cell membranes. This indicates that the binding of the ligand to the receptor determines its potency, but has no direct correlation with its intrinsic activity.
通过激活[（35）S]-鸟苷5'-O-（γ-硫代三磷酸）（[（35）S]GTPγS）结合以及抑制[（3）H]雷氯必利结合来对表达于中国仓鼠卵巢（CHO）细胞中的大鼠多巴胺D（2短）进行表征。在所研究的18种多巴胺能配体中，多巴胺、NPA、阿扑吗啡和喹吡罗在激活[（35）S]GTPγS结合方面是完全激动剂，而7种配体是部分激动剂，其效力为多巴胺作用的16%至69%，7种配体是拮抗剂，对[（35）S]GTPγS结合的基础水平无影响，但以剂量反应方式抑制多巴胺依赖性激活。尽管效力不同，但所有18种配体调节[（35）S]GTPγS结合的效能与其在CHO细胞膜中抑制[（3）H]雷氯必利结合的效能显示出良好的相关性。这表明配体与受体的结合决定了其效力，但与其内在活性无直接相关性。
