Institut für Pharmakologie, Universitätsklinikum Essen, Essen, Germany.
Thromb Haemost. 2010 Mar;103(3):662-78. doi: 10.1160/TH09-06-0341. Epub 2010 Feb 2.
Membrane-permeable 8-(4-chlorophenylthio)-2'-O-methyl cyclic AMP (8-pCPT-2'-O-Me-cAMP) has been shown to specifically activate cAMP-regulated Epac proteins, without direct effects on protein kinase A and protein kinase G. During isometric tension measurements in thoracic aortic rings from Wistar rats, we observed that 8-pCPT-2'-O-Me-cAMP selectively induced a rightward shift of the concentration response curve for the thromboxane mimetic U46619, without altering the contractile response to noradrenaline. We hypothesised that 8-pCPT-2'-O-Me-cAMP and similar compounds may function as direct thromboxane receptor antagonists. Indeed, in addition to 8-pCPT-2'-O- Me-cAMP, also 8-pCPT-cAMP, 8-(4-chlorophenylthio)-adenosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-CPT-cAMPS) and 8-CPT-adenosine, but not 8-Bromo-2'-O-Me-cAMP, induced rightward shifts of the contractile response to U46619. Likewise, 8-pCPT-2'-O- Me-cAMP and Rp-8-CPT-cAMPS, but not 8-Bromo-2'-O-Me-cAMP, specifically reduced U46619-induced aggregation of human platelets. In addition, 8-pCPT-2'-O-Me-cAMP and Rp-8-CPT-cAMPS completely reversed U46619-induced reduction of intercellular adhesion molecule-1 expression and migration of human coronary artery endothelial cells. Most important, the cAMP analogs that reduced the contractile response to U46619 also concentration-dependently inhibited binding of the thromboxane receptor radioligand [5,6-3H]SQ29548 to human platelets. We conclude that 8-pCPT-conjugated cAMP analogs exert competitive thromboxane receptor antagonistic properties.
膜透性 8-(4-氯苯基硫代)-2'-O-甲基环 AMP（8-pCPT-2'-O-Me-cAMP）已被证明可特异性激活 cAMP 调节的 Epac 蛋白，而对蛋白激酶 A 和蛋白激酶 G 无直接作用。在 Wistar 大鼠胸主动脉环的等长张力测量中，我们观察到 8-pCPT-2'-O-Me-cAMP 选择性地诱导血栓烷类似物 U46619 的浓度反应曲线向右移位，而不改变去甲肾上腺素的收缩反应。我们假设 8-pCPT-2'-O-Me-cAMP 和类似化合物可能作为直接血栓烷受体拮抗剂发挥作用。事实上，除了 8-pCPT-2'-O-Me-cAMP 外，8-pCPT-cAMP、8-(4-氯苯基硫代)-腺苷-3'，5'-环单磷酸硫代酯、Rp-异构体（Rp-8-CPT-cAMPS）和 8-CPT-腺苷也可引起 U46619 收缩反应曲线向右移位，但 8-Bromo-2'-O-Me-cAMP 则不然。同样，8-pCPT-2'-O-Me-cAMP 和 Rp-8-CPT-cAMPS 可特异性减少 U46619 诱导的人血小板聚集，但 8-Bromo-2'-O-Me-cAMP 则不然。此外，8-pCPT-2'-O-Me-cAMP 和 Rp-8-CPT-cAMPS 完全逆转了 U46619 诱导的人冠状动脉内皮细胞细胞间黏附分子-1 表达减少和迁移。最重要的是，降低 U46619 收缩反应的 cAMP 类似物也浓度依赖性地抑制了血栓烷受体放射性配体 [5,6-3H]SQ29548与人血小板的结合。我们得出结论，8-pCPT 缀合的 cAMP 类似物具有竞争性血栓烷受体拮抗特性。
