Mitsui T, Yokoyama S, Shimizu Y, Katsuura M, Akiba K, Hayasaka K
Department of Pediatrics, Yamagata University, School of Medicine, Japan.
Thromb Haemost. 1997 May;77(5):991-5.
We describe an 11-year-old girl with a mild bleeding disorder since early childhood. The disorder was characterized by a prolonged bleeding time, and the patient's platelets showed defective aggregation responses to thromboxane A2 (TXA2) mimetic U46619 and arachidonic acid. In contrast, the platelets showed normal responses to thrombin and Ca ionophore A23187. When the platelet TXA2 receptor was examined with the [3H]-labeled TXA2 agonist U46619, the equilibrium dissociation rate constants (kd) and the maximal concentration of binding sites (Bmax) of the patient's platelets were within normal ranges. Normal GTPase activity was also induced in the patient's platelets by stimulation with U46619, however, inositol 1,4,5-triphosphate (IP3) formation was not induced by U46619. These results suggests that the patient's platelets had a defect in phospholipase C activation beyond TXA2 receptors.
我们描述了一名自幼年起就患有轻度出血性疾病的11岁女孩。该疾病的特征是出血时间延长，患者的血小板对血栓素A2（TXA2）模拟物U46619和花生四烯酸的聚集反应存在缺陷。相比之下，血小板对凝血酶和钙离子载体A23187的反应正常。当用[3H]标记的TXA2激动剂U46619检测血小板TXA2受体时，患者血小板的平衡解离速率常数（kd）和结合位点的最大浓度（Bmax）在正常范围内。用U46619刺激也能在患者血小板中诱导出正常的GTP酶活性，然而，U46619并不能诱导肌醇1,4,5-三磷酸（IP3）的形成。这些结果表明，患者的血小板在TXA2受体以外的磷脂酶C激活方面存在缺陷。
