Holmsen H, Kaplan K L, Dangelmaier C A
Biochem J. 1982 Oct 15;208(1):9-18. doi: 10.1042/bj2080009.
Previous studies have indicated different energy requirements for some platelet responses; these differences could, however, be due to inadequate methodology and differences in platelet preparation. The present study describes the effect of decreasing ATP availability on seven platelet responses measured in gel-filtered human platelets. The cells, prelabelled with 5-hydroxy[(3)H]tryptamine, [(3)H]- or [(14)C]adenine, [(32)P]P(i) or [(3)H]arachidonate, were incubated with antimycin A and 2-deoxy-d-glucose. Platelet responses induced by thrombin and collagen (secretion only), level of metabolic ATP and the adenylate energy charge (AEC) were determined at various times during incubation. Platelet aggregation was rapidly inhibited after a lag of 5-15 min and with 50% inhibition at AEC = 0.55-0.60. Secretion of 5-hydroxy[(14)C]tryptamine and ATP + ADP from dense granules and of fibrinogen and beta-thromboglobin from alpha-granules were inhibited in parallel, without a lag and with 50% inhibition at AEC = 0.65-0.70. The inhibition of secretion of platelet factor 4 from the alpha-granules followed another pattern with 50% inhibition at AEC = 0.70-0.80. Breakdown of [(3)H]-phosphatidylinositol, formation of [(3)H]- and [(32)P]-phosphatidate, liberation of [(3)H]arachidonate and secretion of acid hydrolases were inhibited in parallel and inhibition was present at the start of incubation with 50% inhibition at AEC = 0.80-0.87. These results suggest that the responses have different energy requirements, increasing in the order: aggregation < dense granule and alpha-granule secretion < acid hydrolase secretion, phosphatidylinositol breakdown, phosphatidate formation and arachidonate liberation. The powerful inhibition of phosphatidylinositol breakdown by metabolic inhibitors suggests that energy-requiring steps are involved in the activation of phospholipase C.
以往的研究表明，某些血小板反应所需的能量不同；然而，这些差异可能是由于方法不当以及血小板制备方法的差异所致。本研究描述了降低ATP可用性对凝胶过滤的人血小板中所测定的7种血小板反应的影响。用5-羟基[（3）H]色胺、[（3）H]-或[（14）C]腺嘌呤、[（32）P]无机磷酸盐或[（3）H]花生四烯酸预标记的细胞，与抗霉素A和2-脱氧-D-葡萄糖一起孵育。在孵育过程中的不同时间测定凝血酶和胶原诱导的血小板反应（仅分泌）、代谢ATP水平和腺苷酸能荷（AEC）。血小板聚集在滞后5-15分钟后迅速受到抑制，在AEC = 0.55-0.60时抑制率为50%。致密颗粒中5-羟基[（14）C]色胺和ATP + ADP的分泌以及α颗粒中纤维蛋白原和β-血小板球蛋白的分泌受到平行抑制，无滞后，在AEC = 0.65-0.70时抑制率为50%。α颗粒中血小板因子4分泌的抑制遵循另一种模式，在AEC = 0.70-0.80时抑制率为50%。[（3）H]-磷脂酰肌醇的分解、[（3）H]-和[（32）P]-磷脂酸的形成、[（3）H]花生四烯酸的释放以及酸性水解酶的分泌受到平行抑制，在孵育开始时就存在抑制，在AEC = 0.80-0.87时抑制率为50%。这些结果表明，这些反应具有不同的能量需求，其顺序增加为：聚集＜致密颗粒和α颗粒分泌＜酸性水解酶分泌、磷脂酰肌醇分解、磷脂酸形成和花生四烯酸释放。代谢抑制剂对磷脂酰肌醇分解的强烈抑制表明，需要能量的步骤参与了磷脂酶C的激活。
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