Jard S, Guillon G, Balestre M N, Kirk C
J Cardiovasc Pharmacol. 1986;8 Suppl 7:S12-7.
WRK1 cells, an established cell line derived from a chemically induced mammary tumor in the rat, are sensitive to vasopressin. Binding studies with intact WRK1 cells indicated the presence of a single population of [3H]vasopressin binding sites (dissociation constant, Kd = 12.7 +/- 0.2 nM, maximal binding capacity = 75 +/- 6 fmole/10(6) cells). Competition experiments using a series of vasopressin analogs with enhanced selectivity for the three subtypes of receptors already characterized--that is, renal V2 receptors, V1 receptors of the vascular or hepatic subtype (V1a), and V1 receptors from rat adenohypophysis (V1b)--indicated that vasopressin receptors from WRK1 cells have a ligand specificity very similar, if not identical, to that of V1a receptors. Vasopressin induced a marked (up to tenfold) increase in the production of labeled inositol phosphate (Ins 1,4,5 P3, Ins 1,4 P2, and Ins P) by WRK1 cells prelabeled with [3H]inositol. Antagonists of the vasopressor effect of vasopressin inhibited vasopressin-induced inositol lipid breakdown in WRK1 cells. For the entire series of vasopressin analogs tested, there was a close correlation between the respective Kd values for binding of these peptides to WRK1 cells and the corresponding Ka or Ki values derived from the determination of dose-dependent stimulation of inositol phosphate production, or inhibition of vasopressin-induced stimulation.
WRK1细胞系源自大鼠化学诱导的乳腺肿瘤，对加压素敏感。对完整WRK1细胞进行的结合研究表明，存在单一群体的[3H]加压素结合位点（解离常数Kd = 12.7±0.2 nM，最大结合容量 = 75±6 fmol/10(6)个细胞）。使用一系列对已鉴定的三种受体亚型具有更高选择性的加压素类似物进行竞争实验，即肾V2受体、血管或肝亚型的V1受体（V1a）以及大鼠腺垂体的V1受体（V1b），结果表明WRK1细胞的加压素受体具有与V1a受体非常相似（即便不是完全相同）的配体特异性。加压素使预先用[3H]肌醇标记的WRK1细胞产生的标记肌醇磷酸（Ins 1,4,5 P3、Ins 1,4 P2和Ins P）显著增加（高达十倍）。加压素升压作用的拮抗剂抑制了WRK1细胞中加压素诱导的肌醇脂质分解。对于所测试的整个系列加压素类似物，这些肽与WRK1细胞结合的各自Kd值与通过剂量依赖性刺激肌醇磷酸产生或抑制加压素诱导的刺激测定得出的相应Ka或Ki值之间存在密切相关性。
