Wojenski C M, Schick P K
Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson Medical College, Philadelphia, PA 19107-5099.
J Lab Clin Med. 1991 Oct;118(4):370-6.
The capacity for thromboxane A2 synthesis in response to exogenous arachidonic acid, calcium ionophore A23187, thrombin, and collagen was studied during megakaryocyte maturation. Studies were performed in (1) isolated megakaryocytes not separated, (2) isolated megakaryocytes separated into subgroups at different stages of maturation, and (3) washed platelets. When comparisons were based on equal amounts of cell protein (10(5) megakaryocytes vs 10(8) platelets), isolated megakaryocytes, not separated into subgroups, responded to exogenous arachidonic acid with synthesis of thromboxane A2 equal to that of platelets from the same animals at their respective times of maximum synthesis (30 minutes vs 10 minutes). In similar fashion, megakaryocytes and platelets synthesized thromboxane A2 from endogenous arachidonic acid at the same minimum concentration of A23187, 0.1 mumol/L, and showed equal maximum synthesis at 1 mumol/L (167 +/- 9 pmol and 150 +/- 18 pmol, respectively). In contrast, maximum thromboxane A2 synthesis in response to thrombin (10 U/ml) was three times higher in platelets than in megakaryocytes (230 +/- 15 pmol and 74 +/- 5 pmol, respectively), and synthesis in response to collagen (20 micrograms/ml) was 20 times higher in platelets (130 +/- 20 pmol vs 7 +/- 1.2 pmol). When synthesis was studied in isolated megakaryocytes at different stages of maturation, the capacity for thromboxane A2 synthesis was established in immature megakaryocytes but was not fully developed in the most immature megakaryocytes. Synthesis in response to thrombin was not significantly enhanced by megakaryocyte maturation. Thus the ability to metabolize arachidonic acid occurs early during megakaryocyte maturation, but the ability to respond to thrombin and collagen is only fully established in platelets.
在巨核细胞成熟过程中，研究了其对外源性花生四烯酸、钙离子载体A23187、凝血酶和胶原的血栓素A2合成能力。研究在以下三种情况下进行：（1）未分离的分离巨核细胞；（2）分离为不同成熟阶段亚组的分离巨核细胞；（3）洗涤过的血小板。当基于等量的细胞蛋白进行比较时（10⁵个巨核细胞对10⁸个血小板），未分离为亚组的分离巨核细胞对外源性花生四烯酸的反应是，血栓素A2的合成量与来自相同动物的血小板在各自最大合成时间（30分钟对10分钟）时的合成量相等。以类似方式，巨核细胞和血小板在相同的最低A23187浓度（0.1μmol/L）下从内源性花生四烯酸合成血栓素A2，并在1μmol/L时显示出相等的最大合成量（分别为167±9 pmol和150±18 pmol）。相比之下，血小板对凝血酶（10 U/ml）的最大血栓素A2合成量比对巨核细胞高3倍（分别为230±15 pmol和74±5 pmol），对胶原（20μg/ml）的合成量在血小板中比对巨核细胞高20倍（130±20 pmol对7±1.2 pmol）。当在不同成熟阶段的分离巨核细胞中研究合成时，未成熟巨核细胞已具备血栓素A2合成能力，但在最不成熟的巨核细胞中尚未完全发育。巨核细胞成熟并未显著增强对凝血酶的合成反应。因此，代谢花生四烯酸的能力在巨核细胞成熟早期就已出现，但对凝血酶和胶原的反应能力仅在血小板中完全确立。
