Suzaki S, Suzaki A, Yamamoto Y
Department of Emergency and Critical Care Medicine, Nippon Medical School, Tokyo, Japan.
Nihon Ika Daigaku Zasshi. 1993 Aug;60(4):223-30. doi: 10.1272/jnms1923.60.223.
High affinity binding sites for endothelin (ET)-1 were identified on mouse parenchymal hepatocytes. The binding of 125I-ET-1 at its site was specific, saturable, and time dependent, but dissociation of the receptor-bound ligand was minimal. Scatchard analysis of the binding data revealed the presence of a non-interacting, single class of high-affinity binding sites on hepatocytes. The dissociation binding constant (Kd) and the maximal binding capacity (Bmax) were determined as 2.1 x 10(-10) M and 3.0 x 10(2) sites/cell, respectively. Unlabeled ET-1 competitively inhibited the binding of 125I-ET-1 to primary cultured mouse hepatocytes with a concentration for half-maximal inhibition (IC50) of 2.0 x 10(-10) M. ET-1 apparently enhanced total protein synthesis in primary cultured mouse hepatocytes concentration ranging from 3 x 10(-11) M to 3 x 10(-8) M in a dose-dependent manner. These data indicate that specific receptor for ET-1 is present in the mouse liver and suggest for the first time that hepatocyte protein synthesis is involved in its direct, agonistic effect.
在小鼠实质肝细胞上鉴定出了内皮素（ET）-1的高亲和力结合位点。125I-ET-1在其位点的结合具有特异性、饱和性和时间依赖性，但受体结合配体的解离极少。对结合数据进行Scatchard分析显示，肝细胞上存在一类非相互作用的高亲和力结合位点。解离结合常数（Kd）和最大结合容量（Bmax）分别测定为2.1×10（-10）M和3.0×10（2）个位点/细胞。未标记的ET-1竞争性抑制125I-ET-1与原代培养的小鼠肝细胞的结合，半数最大抑制浓度（IC50）为2.0×10（-10）M。ET-1在浓度范围为3×10（-11）M至3×10（-8）M时，以剂量依赖方式明显增强原代培养的小鼠肝细胞中的总蛋白合成。这些数据表明，ET-1的特异性受体存在于小鼠肝脏中，并首次表明肝细胞蛋白合成参与了其直接的激动作用。
