Niida K, Ejiri K, Suga K, Kudo T, Yamamura H
Department of Obstetrics and Gynecology, Okayama University Medical School, Japan.
Acta Med Okayama. 1996 Feb;50(1):47-52. doi: 10.18926/AMO/30511.
Aggregation activity of platelets in umbilical blood is lower than that in adult blood, but the reason for this is not well understood. It has recently been clarified that calcium plays a role as a second messenger of platelet aggregation, and that glycoproteins of platelet surface membrane such as glycoprotein I b and IIb/IIIa are receptors for agonists inducing aggregation. We examined the concentrations of intracellular calcium and the membrane glycoproteins of platelets in umbilical and adult blood. The increase of intracellular calcium in umbilical platelets was lower than that in adult platelets when the aggregation was induced by ADP, collagen, thrombin and epinephrine. Only calcium ionophore A23187 induced aggregation of both umbilical and adult platelets. On the other hand, there were no qualitative differences between glycoproteins I b and IIb/IIIa of these two groups. Therefore, the low aggregation activity of umbilical platelets seems to be due to low responsiveness of the intracellular calcium system, not to the disorder of functional surface membrane glycoprotein.
脐血中血小板的聚集活性低于成人血液中的血小板聚集活性，但其原因尚不完全清楚。最近已阐明，钙作为血小板聚集的第二信使发挥作用，并且血小板表面膜糖蛋白如糖蛋白Ib和IIb/IIIa是诱导聚集的激动剂的受体。我们检测了脐血和成人血液中血小板的细胞内钙浓度和膜糖蛋白。当由ADP、胶原、凝血酶和肾上腺素诱导聚集时，脐血血小板中细胞内钙的增加低于成人血小板。只有钙离子载体A23187能诱导脐血和成人血小板的聚集。另一方面，这两组的糖蛋白Ib和IIb/IIIa在质量上没有差异。因此，脐血血小板聚集活性低似乎是由于细胞内钙系统反应性低，而非功能性表面膜糖蛋白紊乱所致。
