White J G, Burris S, Smith C M
University of Minnesota Medical School, Department of Laboratory Medicine, Minneapolis, USA.
Eur J Clin Invest. 1995 Apr;25(4):241-9. doi: 10.1111/j.1365-2362.1995.tb01555.x.
The present study has evaluated the influence of high concentrations of cytochalasins B and E on the detergent-resistant actin levels in fully spread platelets by PAGE gel electrophoresis, and the effects of the two inhibitors of new actin filament assembly on translocation of fibrinogen gold (Fgn/Au) labelled GPIIb-IIIa receptors on the surface-activated cells. Concentrations of 10(-4) M and 10(-5) M cytochalasin B and E reduced detergent-resistant actin in fully spread platelets to levels present in resting discoid platelets in suspension. Despite reduction of actin filaments to levels in resting cells, cytochalasin B did not prevent translocation of Fgn/Au from platelet margins into channels of the open canalicular system (OCS). Similar concentrations of cytochalasin E completely blocked translocation of receptor-ligand complexes and produced a patching phenomenon not observed in previous studies. Rinsing of the spread cells to remove cytochalasin, followed by incubation of the treated platelets in Hank's buffered salt solution (HBSS) restored levels of detergent-resistant actin to those found in untreated, spread platelets. Resting grids of 10(-5) M cytochalasin E-treated platelets on drops of HBSS for 15 min restored their ability to clear FGN/Au linked to GPIIb-IIIa from exposed surfaces to the OCS, but 10(-4) M cytochalasin E-treated cells remained anergic after incubation on drops of HBSS. Thus a fully assembled cytoplasmic actin filament cytoskeleton does not appear to be essential for translocating receptor-ligand complexes on the platelet surface to the OCS, nor does its presence guarantee that the ability to clear GPIIb-IIIa receptors will be restored.
本研究通过聚丙烯酰胺凝胶电泳评估了高浓度的细胞松弛素B和E对完全铺展血小板中抗去污剂肌动蛋白水平的影响，以及两种新的肌动蛋白丝组装抑制剂对表面活化细胞上纤维蛋白原金（Fgn/Au）标记的糖蛋白IIb-IIIa受体转位的影响。10⁻⁴M和10⁻⁵M浓度的细胞松弛素B和E将完全铺展血小板中的抗去污剂肌动蛋白降低至悬浮状态下静息盘状血小板中的水平。尽管肌动蛋白丝减少至静息细胞中的水平，但细胞松弛素B并未阻止Fgn/Au从血小板边缘向开放小管系统（OCS）通道的转位。类似浓度的细胞松弛素E完全阻断了受体-配体复合物的转位，并产生了先前研究中未观察到的斑块现象。冲洗铺展细胞以去除细胞松弛素，然后将处理过的血小板在汉克斯缓冲盐溶液（HBSS）中孵育，可使抗去污剂肌动蛋白水平恢复至未处理的铺展血小板中的水平。将10⁻⁵M细胞松弛素E处理的血小板在HBSS液滴上静置网格15分钟，可恢复其将与糖蛋白IIb-IIIa相连的FGN/Au从暴露表面清除至OCS的能力，但10⁻⁴M细胞松弛素E处理的细胞在HBSS液滴上孵育后仍无反应。因此，完全组装的细胞质肌动蛋白丝细胞骨架似乎对于将血小板表面的受体-配体复合物转位至OCS并非必不可少，其存在也不能保证恢复清除糖蛋白IIb-IIIa受体的能力。
