Ozaki Y, Jinnai Y, Yatomi Y, Kume S
Department of Clinical and Laboratory Medicine, Yamanashi Medical College, Japan.
Eur J Pharmacol. 1993 Apr 28;235(2-3):255-65. doi: 10.1016/0014-2999(93)90144-7.
Changes in the shape of human platelets and the biochemical mechanism responsible were evaluated, using the shape-change parameter. Neither the Na+/H+ exchanger, nor intracellular or extracellular calcium ions (Ca2+) affected disc-sphere changes induced by low doses of thrombin. Treatment with inhibitors of Ca2+ mobilization, calmodulin or mysoin light-chain kinase had no significant effect on the shape change of platelets. Staurosporine and H-7, both of which are inhibitors of protein kinase C, inhibited disc-sphere changes at low concentrations. Moreover, calphostin C, a specific inhibitor of protein kinase C, effectively inhibited thrombin-induced shape change, as assessed by the shape-change parameter, in a dose-dependent manner. 1-Oleoyl-2-acetyl-glycerol and 1,2-dioctanoyl-glycerol, which are synthetic protein kinase C activators, induced shape changes similar to those induced by thrombin. A decrease in the surface area of platelet images on scanning electron micrographs was used to quantify the disc-sphere transformation. The mean platelet areas was significantly decreased after stimulation with thrombin or 1-oleoyl-2-acetyl-glycerol. Pretreatment with H-7 inhibited the thrombin-induced disc-sphere change, as assessed by changes in the platelet surface area. Our results obtained with various inhibitors suggest that thrombin-induced platelet change, as assessed by the shape-change parameter, are associated with activation of protein kinase C.
利用形状改变参数评估了人类血小板形状的变化及其相关的生化机制。钠氢交换体、细胞内或细胞外钙离子（Ca2+）均未影响低剂量凝血酶诱导的盘状-球状变化。用钙离子动员抑制剂、钙调蛋白或肌球蛋白轻链激酶处理对血小板的形状变化无显著影响。蛋白激酶C抑制剂星形孢菌素和H-7在低浓度时抑制盘状-球状变化。此外，蛋白激酶C的特异性抑制剂钙磷蛋白C以剂量依赖方式有效抑制了凝血酶诱导的形状变化，这通过形状改变参数进行评估。合成蛋白激酶C激活剂1-油酰基-2-乙酰甘油和1,2-二辛酰甘油诱导的形状变化与凝血酶诱导的相似。扫描电子显微镜下血小板图像表面积的减少用于量化盘状-球状转变。用凝血酶或1-油酰基-2-乙酰甘油刺激后，平均血小板面积显著减小。用H-7预处理可抑制凝血酶诱导的盘状-球状变化，这通过血小板表面积的变化进行评估。我们使用各种抑制剂获得的结果表明，通过形状改变参数评估的凝血酶诱导的血小板变化与蛋白激酶C的激活有关。
