Ariyoshi H, Salzman E W
Department of Surgery, Beth Israel Hospital, Harvard Medical School, Boston, Mass 02215, USA.
Arterioscler Thromb Vasc Biol. 1996 Feb;16(2):230-5. doi: 10.1161/01.atv.16.2.230.
We monitored the intracellular distribution of ionized free Ca2+ concentration ([Ca2+]i) in individual human platelets by digital imaging fluorescence microscopy with fura 2 during platelet activation induced by surface contact or a soluble platelet agonist (thrombin). Contact of platelets with glass resulted in pseudopod formation and spreading, accompanied by a nonuniform rise in [Ca2+]i. The rise in [Ca2+]i was maximal during pseudopod formation. Locally elevated [Ca2+]i was frequently found in pseudopodia and at the edge and core of spread platelets. This pattern was faithfully duplicated by the local pattern of distribution of the cytoskeletal components F-actin, gelsolin, and surface glycoproteins (GP) IIb-IIIa but not by calmodulin. Platelets stimulated by thrombin also showed an inhomogeneous rise in [Ca2+]i, which was well correlated with the staining of F-actin and GPIIb-IIIa. Cytochalasin D, an inhibitor of actin polymerization, inhibited the inhomogeneous increase or redistribution of F-actin and GPIIb-IIIa but did not inhibit the rise in mean [Ca2+]i. These observations suggest that a localized change in [Ca2+]i may be associated with cytoskeletal reorganization and redistribution of GPIIb-IIIa in activated platelets.
我们通过使用fura 2的数字成像荧光显微镜，在由表面接触或可溶性血小板激动剂（凝血酶）诱导的血小板活化过程中，监测了个体人类血小板中游离钙离子浓度（[Ca2+]i）的细胞内分布。血小板与玻璃接触导致伪足形成和铺展，同时伴有[Ca2+]i的不均匀升高。[Ca2+]i的升高在伪足形成过程中达到最大值。在伪足以及铺展血小板的边缘和核心部位经常发现局部[Ca2+]i升高。这种模式与细胞骨架成分F-肌动蛋白、凝溶胶蛋白和表面糖蛋白（GP）IIb-IIIa的局部分布模式一致，但与钙调蛋白的分布模式不同。凝血酶刺激的血小板也显示出[Ca2+]i的不均匀升高，这与F-肌动蛋白和GPIIb-IIIa的染色密切相关。细胞松弛素D，一种肌动蛋白聚合抑制剂，抑制了F-肌动蛋白和GPIIb-IIIa的不均匀增加或重新分布，但不抑制平均[Ca2+]i的升高。这些观察结果表明，[Ca2+]i的局部变化可能与活化血小板中细胞骨架的重组以及GPIIb-IIIa的重新分布有关。
