Nicholson N S, Smith S L, Fuller G C
Thromb Res. 1984 Jul 15;35(2):183-92. doi: 10.1016/0049-3848(84)90213-5.
The effects of the stable endoperoxide analog U46619 (U) on the regulation of prostacyclin (PGI2) formation and cyclic adenosine monophosphate (cAMP) were investigated in cultured bovine aortic endothelial (BAE) cells. Incubation of U (0.3, 3.0 and 30 microM) with BAE cells for 5 min results in a dose-dependent increase in PGI2. Cyclic AMP levels were not changed at 0.3 and 3.0 microM but were stimulated at 30 microM U. When cells were exposed to U for a second and third 5 min period, PGI2 formation at 0.3 and 3.0 microM U remained stimulated while at 30 microM, PGI2 was not increased. Five min incubation of BAE cells with the cyclooxygenase inhibitor indomethacin blocked the stimulation of PGI2 at all concentrations of U and also prevented the increase of cAMP levels at 30 microM. In cells prelabeled with 3H-arachidonate, U stimulated release of labeled products at 0.3 and 3.0 microM but not at 30 microM U. In cells treated with bradykinin in the presence of U, PGI2 production was stimulated at 0.3 and 3.0 microM but not 30 microM U. When cells were exposed to U and stimulated with PGI2 (with and without phosphodiesterase inhibition), U caused significant increases in cAMP. We conclude that incubation of BAE cells with U results in an initial dose-dependent increase in PGI2 formation. Cyclic AMP levels are increased at high concentrations of U. This increase in cAMP is mediated by the initial stimulated PGI2 and results in decreased PGI2 on further exposure to U. Data suggest that U stimulates phospholipase activity and, at high concentrations, inhibits phosphodiesterase.
在培养的牛主动脉内皮（BAE）细胞中研究了稳定的内过氧化物类似物U46619（U）对前列环素（PGI2）生成调节和环磷酸腺苷（cAMP）的影响。将U（0.3、3.0和30微摩尔）与BAE细胞孵育5分钟会导致PGI2呈剂量依赖性增加。在0.3和3.0微摩尔时cAMP水平未改变，但在30微摩尔U时受到刺激。当细胞再暴露于U 5分钟和第三次5分钟时，0.3和3.0微摩尔U时PGI2生成仍受到刺激，而在30微摩尔时PGI2未增加。将BAE细胞与环氧化酶抑制剂吲哚美辛孵育5分钟可阻断所有浓度U对PGI2的刺激，也可防止30微摩尔时cAMP水平升高。在用3H-花生四烯酸预标记的细胞中，0.3和3.0微摩尔U刺激标记产物释放，但30微摩尔U时无此作用。在U存在下用缓激肽处理的细胞中，0.3和3.0微摩尔U刺激PGI2生成，但30微摩尔U时无此作用。当细胞暴露于U并用PGI2刺激（有无磷酸二酯酶抑制）时，U导致cAMP显著增加。我们得出结论，将BAE细胞与U孵育会导致PGI2生成最初呈剂量依赖性增加。高浓度U时cAMP水平升高。cAMP的这种增加由最初刺激的PGI2介导，并且在进一步暴露于U时导致PGI2减少。数据表明U刺激磷脂酶活性，并且在高浓度时抑制磷酸二酯酶。
