Noda M, Shibouta Y, Inada Y, Ojima M, Wada T, Sanada T, Kubo K, Kohara Y, Naka T, Nishikawa K
Pharmaceutical Division, Takeda Chemical Industries, Ltd., Osaka, Japan.
Biochem Pharmacol. 1993 Jul 20;46(2):311-8. doi: 10.1016/0006-2952(93)90420-2.
The angiotensin II (AII) antagonistic action of CV-11974 (2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl] benzimidazole-7-carboxylic acid) was investigated in an AII-receptor binding assay using rabbit aortic membranes and an AII-induced contraction assay using rabbit aortic strips. A single class of [125I]AII-(Sar1,Ile8) binding sites was found in the membranes with a dissociation constant (Kd) of 0.15 nM and a receptor concentration (Bmax) of 86.9 fmol/mg protein. CV-11974 markedly reduced Kd without affecting Bmax. The specific binding of [125I]AII-(Sar1,Ile8) in this preparation was inhibited completely by CV-11974 [the inhibition constant (Ki) = 0.64 nM], DuP 753 [an angiotensin II type I (AT1) receptor-selective antagonist] (Ki = 51 nM) and EXP3174 (an active metabolite of DuP 753) (Ki = 6.8 nM), but was not affected by PD123177 (an AT2 receptor-selective antagonist). These results suggest that the single binding site in rabbit aortic membranes is an AT1 receptor subtype. The affinity of CV-11974 to these AT1 receptors was approximately 80 and 10 times higher than that of DuP 753 and EXP3174, respectively. CV-11974 showed no appreciable affinity for the AT2 receptors found in bovine cerebellum. In the in vitro functional study, CV-11974 markedly reduced the AII-induced maximal contractile response of rabbit aortic strips (pD'2 = 9.97). In contrast, Compound 7-H, which lacks the carboxyl group at the benzimidazole ring of CV-11974, inhibited the contraction in a competitive manner. The inhibition by CV-11974 was long lasting. These results suggest that CV-11974 is a potent and long-acting AT1 receptor-selective, competitive antagonist. The carboxyl group at the benzimidazole ring plays an important role in the interaction between CV-11974 and the AT1 receptor.
在使用兔主动脉膜的血管紧张素II（AII）受体结合试验以及使用兔主动脉条的AII诱导收缩试验中，研究了CV - 11974（2 - 乙氧基 - 1 - [[2' - (1H - 四氮唑 - 5 - 基)联苯 - 4 - 基]甲基]苯并咪唑 - 7 - 羧酸）的AII拮抗作用。在膜中发现了一类[125I]AII - (Sar1,Ile8)结合位点，其解离常数（Kd）为0.15 nM，受体浓度（Bmax）为86.9 fmol/mg蛋白质。CV - 11974显著降低Kd而不影响Bmax。CV - 11974完全抑制了该制剂中[125I]AII - (Sar1,Ile8)的特异性结合[抑制常数（Ki）= 0.64 nM]、DuP 753 [一种血管紧张素II 1型（AT1）受体选择性拮抗剂]（Ki = 51 nM）和EXP3174（DuP 753的活性代谢物）（Ki = 6.8 nM），但不受PD123177（一种AT2受体选择性拮抗剂）影响。这些结果表明兔主动脉膜中的单一结合位点是AT1受体亚型。CV - 11974对这些AT1受体的亲和力分别比DuP 753和EXP3174高约80倍和10倍。CV - 11974对牛小脑中发现的AT2受体没有明显亲和力。在体外功能研究中，CV - 11974显著降低了AII诱导的兔主动脉条最大收缩反应（pD'2 = 9.97）。相比之下，在CV - 11974苯并咪唑环上缺乏羧基的化合物7 - H以竞争性方式抑制收缩。CV - 11974的抑制作用持久。这些结果表明CV - 11974是一种强效且长效的AT1受体选择性竞争性拮抗剂。苯并咪唑环上的羧基在CV - 11974与AT1受体的相互作用中起重要作用。
