Effects of anagrelide on platelet cAMP levels, cAMP-dependent protein kinase and thrombin-induced Ca++ fluxes.
Effects of anagrelide on platelet cAMP levels, cAMP-dependent protein kinase and thrombin-induced Ca++ fluxes.
复制标题
阿那格雷对血小板 cAMP 水平、cAMP 依赖性蛋白激酶和凝血酶诱导的 Ca2+ 通量的影响。
DOI：
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发表时间：
1987
影响因子：
3.5
通讯作者：
H. C. Stanton
中科院分区：
文献类型：
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作者：
S. Seiler;A. Arnold;R. Grove;C. Fifer;S. L. Keely;H. C. Stanton
阿那格雷（BL-4162A，6,7-二氯-1,5-二氢咪唑[2, 1-6]喹唑啉-2[3H]单盐酸盐水合物）是一种有效的广谱血小板聚集抑制剂。先前的研究表明，阿那格雷抑制血小板环AMP（cAMP）磷酸二酯酶活性，但并未明显升高血小板cAMP水平。我们检查了阿那格雷对洗涤的人血小板的影响，发现阿那格雷导致 cAMP 水平显着升高。阿那格雷治疗还导致血小板cAMP依赖性蛋白激酶在阿那格雷浓度为0.1至1微克/ml时被激活，从而抑制血小板聚集，但仅导致血小板cAMP含量小幅增加。当整个血小板与放射性标记的磷酸盐一起孵育时，阿那格雷增加了相对分子量为 22、26、50 和 80 千道尔顿的血小板蛋白的磷酸化。阿那格雷处理刺激的蛋白质磷酸化模式与用毛喉素处理血小板时观察到的相似。使用装载 Fura-2 的血小板进行测量，阿那格雷还抑制凝血酶引起的细胞内 Ca++ 升高。细胞内 Ca++ 增加的抑制是由于凝血酶诱导的细胞内 Ca++ 动员受阻，以及阻止 Ca++ 通过质膜流入。阿那格雷本身对肌醇 1,4,5-三磷酸诱导的 Caz5++ 从分离的血小板膜囊泡中释放没有影响。这些研究表明，阿那格雷抑制完整血小板中的血小板磷酸二酯酶活性，导致 cAMP 水平升高，足以激活 cAMP 依赖性蛋白激酶并抑制激动剂激活的 Ca++ 通量。
Anagrelide (BL-4162A, 6,7-dichloro-1,5-dihydroimidazo[2, 1-6] quinazolin-2[3H]one monohydrochloride hydrate) is a potent and broad spectrum inhibitor of platelet aggregation. Prior studies showed that anagrelide inhibited platelet cyclic AMP (cAMP) phosphodiesterase activity but did not appreciably elevate platelet cAMP levels. We examined the effects of anagrelide on washed human platelets and found that anagrelide caused significant elevation of cAMP levels. Anagrelide treatment also resulted in activation of the platelet cAMP-dependent protein kinase at anagrelide concentrations of 0.1 to 1 microgram/ml, which inhibited platelet aggregation but caused only small increases in platelet cAMP content. When whole platelets were incubated with radiolabeled phosphate, anagrelide increased phosphorylation of platelet proteins with relative molecular weights of 22, 26, 50 and 80 kilodaltons. The pattern of protein phosphorylation stimulated by anagrelide treatment was similar to that observed when the platelets were treated with forskolin. Anagrelide also inhibited the rise in intracellular Ca++ caused by thrombin, as measured using Fura-2-loaded platelets. The inhibition of increased intracellular Ca++ resulted from block of thrombin-induced mobilization of intracellular Ca++, as well as prevention of Ca++ influx through the plasma membrane. Anagrelide itself had no influence on inositol 1,4,5-trisphosphate-induced Caz5++ release from isolated platelet membrane vesicles. These studies suggest that anagrelide inhibits platelet phosphodiesterase activity in intact platelets resulting in an elevation in cAMP levels sufficient to activate the cAMP-dependent protein kinase and inhibit agonist-activated Ca++ fluxes.