Kugelmass A D, Oda A, Monahan K, Cabral C, Ware J A
Charles A. Dana Research Institute, Beth Israel Hospital, Boston, MA 02215.
Circulation. 1993 Sep;88(3):876-83. doi: 10.1161/01.cir.88.3.876.
Cocaine ingestion has been associated with thrombosis of coronary as well as peripheral arteries, but the mechanism by which cocaine promotes thrombus formation is unknown. Accordingly, we determined whether cocaine activates human platelets by flow cytometric analysis of whole blood to which cocaine was added.
Activated platelets were detected by "two-color" flow cytometric analysis of the binding of fluorescently labeled antibodies directed against either platelet-associated fibrinogen or P-selectin, which are found on the surface of platelets only after stimulation. Platelets were distinguished from other constituents of whole blood by their ability to bind an anti-glycoprotein Ib antibody bound to both activated and resting platelets. Incubation of whole blood with cocaine, in concentrations of 10 microM to 13 mM, induced significant increases in both platelet-associated fibrinogen (range of increase, 45 +/- 12% to 125 +/- 40%) and P-selectin expression (36 +/- 15% to 112 +/- 24%). In platelets suspended in either buffer or plasma, however, P-selectin expression was detected only at the highest cocaine concentration (85 +/- 13% increase in plasma and 59 +/- 7% in buffer). Neither aspirin nor the ADP scavenger apyrase inhibited cocaine-induced P-selectin expression. Cocaine inhibited the uptake of 14C-radiolabeled serotonin by platelets (IC50, 8.7 microM). P-selectin expression and fibrinogen binding were found after the addition of cocaine alone to blood taken from some but not all donors; however, platelet activation in response to submaximal concentrations of the agonists ADP or epinephrine was enhanced by a low concentration of cocaine added to blood from every donor.
Cocaine, in concentrations similar to those found clinically, induces activation of individual platelets studied in whole blood from some but not all donors, and platelet response to physiological agonists is enhanced by cocaine. Thus, cocaine-induced platelet activation may contribute to thrombosis following cocaine ingestion.
摄入可卡因与冠状动脉及外周动脉血栓形成有关，但可卡因促进血栓形成的机制尚不清楚。因此，我们通过对添加了可卡因的全血进行流式细胞术分析，来确定可卡因是否激活人血小板。
通过对针对血小板相关纤维蛋白原或P-选择素的荧光标记抗体的结合进行“双色”流式细胞术分析来检测活化血小板，这些抗体仅在刺激后才会出现在血小板表面。通过其结合与活化和静息血小板均结合的抗糖蛋白Ib抗体的能力，将血小板与全血的其他成分区分开来。用浓度为10微摩尔/升至13毫摩尔/升的可卡因孵育全血，可导致血小板相关纤维蛋白原（增加范围为45±12%至125±40%）和P-选择素表达（36±15%至112±24%）均显著增加。然而，在悬浮于缓冲液或血浆中的血小板中，仅在最高可卡因浓度下才检测到P-选择素表达（血浆中增加85±13%，缓冲液中增加59±7%）。阿司匹林和ADP清除剂阿哌沙班均未抑制可卡因诱导的P-选择素表达。可卡因抑制血小板对14C放射性标记5-羟色胺的摄取（IC50为8.7微摩尔/升）。单独向部分但并非所有供体的血液中添加可卡因后，可发现P-选择素表达和纤维蛋白原结合；然而，向每个供体的血液中添加低浓度可卡因可增强对亚最大浓度激动剂ADP或肾上腺素的血小板活化反应。
可卡因浓度与临床发现的浓度相似时，可诱导部分但并非所有供体全血中单个血小板的活化，且可卡因可增强血小板对生理性激动剂的反应。因此，可卡因诱导的血小板活化可能导致摄入可卡因后发生血栓形成。
