Pullen M, Brown G, Nambi P
Department of Renal Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, PA 19406-0939, USA.
Neuropeptides. 1997 Aug;31(4):345-9. doi: 10.1016/s0143-4179(97)90070-6.
The data presented in this manuscript describe the binding characteristics of the ETA-selective antagonist, [125I]TTA 386 (hexamethylenelmino carbonyl-Leu-Tri-Ala-beta-Ala-Tyr-Phe). This radioligand bound with high affinity and specificity to cloned human ETA receptors and rat mesenteric artery ETA receptors. The apparent dissociation constants (KdS) and maximum binding capacities were 1.0 nM and 8.5 pmol/mg for cloned human ETA receptors and 0.8 nM and 170 fmol/mg for rat mesenteric artery membranes respectively. Binding of [125I]TTA 386 was fast reaching equilibrium by 45 min and 15 min for human ETA and rat mesenteric artery membrane, respectively. Addition of excess unlabeled ligand resulted in the dissociation of bound radioligand from both preparations. Competition of [125I]TTA 386 binding by unlabeled ET-1, ET-3, TTA 386 and BQ123 revealed appropriate ETA pharmacology. This radioligand did not display any binding to cloned human ETB receptors.
本手稿中呈现的数据描述了ETA选择性拮抗剂[125I]TTA 386（六亚甲基氨基羰基-亮氨酸-三丙氨酸-β-丙氨酸-酪氨酸-苯丙氨酸）的结合特性。这种放射性配体与克隆的人ETA受体和大鼠肠系膜动脉ETA受体具有高亲和力和特异性结合。对于克隆的人ETA受体，表观解离常数（KdS）和最大结合容量分别为1.0 nM和8.5 pmol/mg；对于大鼠肠系膜动脉膜，分别为0.8 nM和170 fmol/mg。[125I]TTA 386与人ETA和大鼠肠系膜动脉膜的结合分别在45分钟和15分钟时快速达到平衡。加入过量未标记的配体导致两种制剂中结合的放射性配体解离。未标记的ET-1、ET-3、TTA 386和BQ123对[125I]TTA 386结合的竞争显示出合适的ETA药理学特性。这种放射性配体与克隆的人ETB受体没有任何结合。
