Sharif N A, Davis T L, Williams G W
Molecular Pharmacology Unit, Alcon Laboratories, Inc., Fort Worth, TX 76134-2099, USA.
J Pharm Pharmacol. 1999 Jun;51(6):685-94. doi: 10.1211/0022357991772989.
AL-5848 (5Z,13E)-(9 S,11R,15S)-9,11,15-trihydroxy-5,13-prostadienoic acid) is the carboxylic acid of travoprost (AL-6221), a single (+)-isomer of (+/-)-fluprostenol, an FP-class prostaglandin agonist which lowers intraocular pressure. We have prepared a radioligand from this selective prostaglandin and demonstrated its utility for studying the pharmacology and autoradiographic location of the FP-receptor. Specific [3H]AL-5848 binding (84% of total) was linearly related to bovine corpus luteum tissue concentration and reached equilibrium within 275 min at 23 degrees C. Scatchard analysis of saturation isotherms indicated interaction of [3H]AL-5848 with a single class of high-affinity (dissociation constant, Kd, = 33.8+/-2.9 nM, n = 4) and saturable (Bmax = 37.3+/-3.0 pmol (g wet weight tissue)(-1)) FP receptor-binding sites in bovine corpus luteum. Specific [3H]AL-5848 binding was potently inhibited by the FP-receptor ligands 16-phenoxyPGF2alpha (inhibition constant Ki = 17.3 nM); cloprostenol (Ki = 56.8 nM); 17-phenyl PGF2alpha (Ki = 87.0 nM); AL-5848 (Ki = 52.1 nM); PGF2alpha (Ki = 195 nM); PHXA85 (Ki = 223 nM); (n = 3-11) but very weakly by PGD2, ZK118182, BW245C, PGE2, PGI2 and U-46619. The pharmacology of specific [3H]AL-5848 binding correlated well with the pharmacology of [3H]PGF2alpha binding in the bovine corpus luteum preparation (r = 0.98, n = 14, P<0.0001) and also with functional responses in Swiss 3T3 and rat vascular smooth muscle cells (A7r5) (r = 0.96) expressing FP receptors. Autoradiographic studies revealed high levels of specific FP-receptor binding with [3H]AL-5848 on granulosa cells in the bovine corpus luteum sections, and on longitudinal ciliary muscle, the ciliary process, the iris sphincter and the retina in eye sections from man. These studies show [3H]AL-5848 to be a high-affinity agonist radioligand capable of selectively labelling the FP prostaglandin receptor.
AL-5848（(5Z,13E)-(9S,11R,15S)-9,11,15-三羟基-5,13-前列腺二烯酸）是曲伏前列素（AL-6221）的羧酸，曲伏前列素是(+/-)-氟前列醇的单一(+)-异构体，一种能降低眼压的FP类前列腺素激动剂。我们从这种选择性前列腺素制备了一种放射性配体，并证明了其在研究FP受体的药理学和放射自显影定位方面的效用。特异性[3H]AL-5848结合（占总量的84%）与牛黄体组织浓度呈线性相关，在23℃下275分钟内达到平衡。对饱和等温线的Scatchard分析表明，[3H]AL-5848与牛黄体中一类单一的高亲和力（解离常数Kd = 33.8±2.9 nM，n = 4）且可饱和（Bmax = 37.3±3.0 pmol/(g湿重组织)）的FP受体结合位点相互作用。FP受体配体16-苯氧基PGF2α（抑制常数Ki = 17.3 nM）、氯前列醇（Ki = 56.8 nM）、17-苯基PGF2α（Ki = 87.0 nM）、AL-5848（Ki = 52.1 nM）、PGF2α（Ki = 195 nM）、PHXA85（Ki = 223 nM）（n = 3 - 11）能有效抑制特异性[3H]AL-5848结合，但PGD2、ZK118182、BW245C、PGE2、PGI2和U-46619的抑制作用非常弱。特异性[3H]AL-5848结合的药理学与牛黄体制剂中[3H]PGF2α结合的药理学相关性良好（r = 0.98，n = 14，P<0.0001），也与表达FP受体的瑞士3T3和大鼠血管平滑肌细胞（A7r5）中的功能反应相关性良好（r = 0.96）。放射自显影研究显示，在牛黄体切片的颗粒细胞上，以及在人眼切片的纵行睫状肌、睫状体、虹膜括约肌和视网膜上，[3H]AL-5848有高水平的特异性FP受体结合。这些研究表明[3H]AL-5848是一种能够选择性标记FP前列腺素受体的高亲和力激动剂放射性配体。
