Alvarez-Guerra Miriam, Hernandez Maria Rosa, Escolar Ginés, Chiavaroli Carlo, Garay Ricardo P, Hannaert Patrick
INSERM U400, Faculté de Médecine, 8 rue du Général Sarrail, 94010 Créteil Cédex, France.
Thromb Res. 2002 Sep 15;107(6):329-35. doi: 10.1016/s0049-3848(02)00353-5.
Ethamsylate possesses antihemorrhagic properties, but whether or not it directly activates blood platelets is unclear. Here we investigated the platelet activation potential of ethamsylate, by measuring membrane P-selectin expression with flow cytometry in human whole blood and also by immunofluorescence imaging of isolated human platelets. Moreover, we measured membrane P-selectin expression in the SV40-transformed aortic rat endothelial cell line (SVAREC) and 14C-ethamsylate membrane binding and/or uptake in platelets and endothelial cells. Whole blood flow cytometry showed a modest, but statistically significant increase by ethamsylate in the percentage of platelets expressing P-selectin (from 2% to 4-5%, p < 0.05). Immunofluorescence showed a sizable (39%) and significant (p < 0.01) enhancement of P-selectin expression at the lowest concentration of ethamsylate tested (1 microM), with maximal enhancement of P-selectin expression (75-90%) at 10 microM ethamsylate. Similar results were obtained in SVAREC endothelial cells. 14C-ethamsylate specifically bound to platelets and endothelial cell membranes, without significant uptake into the cell interior. In conclusion, ethamsylate enhances membrane P-selectin expression in human platelets and in cultured endothelial cells. Ethamsylate specifically binds to some protein receptor in platelet and endothelial cell membranes, receptor which can signal for membrane P-selectin expression. These results support the view that ethamsylate acts on the first step of hemostasis, by improving platelet adhesiveness and restoring capillary resistance.
酚磺乙胺具有抗出血特性，但它是否直接激活血小板尚不清楚。在此，我们通过流式细胞术检测人全血中膜P-选择素的表达以及对分离的人血小板进行免疫荧光成像，研究了酚磺乙胺的血小板激活潜力。此外，我们还检测了SV40转化的大鼠主动脉内皮细胞系（SVAREC）中膜P-选择素的表达以及血小板和内皮细胞中14C-酚磺乙胺的膜结合和/或摄取情况。全血流式细胞术显示，酚磺乙胺使表达P-选择素的血小板百分比有适度但具有统计学意义的增加（从2%增至4 - 5%，p < 0.05）。免疫荧光显示，在测试的最低酚磺乙胺浓度（1 microM）下，P-选择素表达有显著（39%）且有统计学意义（p < 0.01）的增强，在10 microM酚磺乙胺时P-选择素表达增强最大（75 - 90%）。在SVAREC内皮细胞中也获得了类似结果。14C-酚磺乙胺特异性结合血小板和内皮细胞膜，未大量摄取进入细胞内部。总之，酚磺乙胺可增强人血小板和培养的内皮细胞中膜P-选择素的表达。酚磺乙胺特异性结合血小板和内皮细胞膜中的某些蛋白质受体，该受体可引发膜P-选择素的表达信号。这些结果支持了酚磺乙胺通过改善血小板黏附性和恢复毛细血管阻力作用于止血第一步的观点。
