Callado L F, Meana J J
Department of Pharmacology, University of the Basque Country, Leioa, Biscay, Spain.
Eur J Pharmacol. 1997 Jul 30;332(1):109-12. doi: 10.1016/s0014-2999(97)01105-9.
The mixture of 5'-guanylylimidodiphosphate (Gpp(NH)p)/EDTA/NaCl has been used to delineate low-affinity conditions for agonists binding to G-protein-linked receptors. The effects of this mixture on [3H]RX821002 (2-methoxyidazoxan) binding to alpha2-adrenoceptors were evaluated in different tissues. The density of alpha2-adrenoceptors in the presence of the mixture was 11, 78 and 60% higher in human cortex (predominant alpha2A), human caudate (alpha2A + alpha2C) and rat kidney (alpha2A + alpha2B), respectively, than in its absence. In rat kidney, masking of alpha2B-adrenoceptors by ARC239 (2-[2-[4-(o-methoxyphenyl)-piperazin-1-yl]-ethyl]-4,4-dimethyl-1,3 -(2H,4H)-isoquinolindione) (50 nM) or masking of alpha2A-adrenoceptors by BRL44408 (2-[2H-(1-methyl-1,3-dihydroisoindole)methyl]-4,5-dihydroimidaz ole) (100 nM) demonstrated that the increase was in the alpha2B-adrenoceptor but not in the alpha2A-adrenoceptor subtype.
5'-鸟苷酰亚胺二磷酸（Gpp(NH)p）/乙二胺四乙酸（EDTA）/氯化钠的混合物已被用于描绘激动剂与G蛋白偶联受体结合的低亲和力条件。在不同组织中评估了该混合物对[3H]RX821002（2-甲氧基咪唑克生）与α2-肾上腺素能受体结合的影响。与不存在该混合物时相比，在该混合物存在的情况下，人皮质（主要为α2A）、人尾状核（α2A + α2C）和大鼠肾脏（α2A + α2B）中α2-肾上腺素能受体的密度分别高出11%、78%和60%。在大鼠肾脏中，ARC239（2-[2-[4-(邻甲氧基苯基)-哌嗪-1-基]-乙基]-4,4-二甲基-1,3-(2H,4H)-异喹啉二酮）（50 nM）对α2B-肾上腺素能受体的掩盖或BRL44408（2-[2H-(1-甲基-1,3-二氢异吲哚)甲基]-4,5-二氢咪唑）（100 nM）对α2A-肾上腺素能受体的掩盖表明，增加的是α2B-肾上腺素能受体亚型，而非α2A-肾上腺素能受体亚型。
