Mürer E H, Stewart G J, Rausch M A, Day H J
Thromb Diath Haemorrh. 1975 Sep 30;34(1):72-82.
The addition of 0.1 muM ionophore A23187 to washed platelets incubated in citrated saline caused massive release of stored serotonin accompanied by intracellular accumulation of inosine monophosphate, but produced no detectable influx of externally added calcium or abnormal structural alterations. With increasing ionophore concentration there was a significant influx of calcium and a drastic alteration in the platelet ultrastructure. The increase in ionophore concentration was accompanied by the conversion of the major part of metabolic adenine nucleotides to inosine monophosphate and an almost complete blockage of further conversion to inosine and hypoxanthine. The metabolic changes were accentuated by the addition of calcium at concentrations less than 1/10 of the citrate concentration. In the presence of Ca++, or when citrate was omitted, there was a substantial leakage of cytoplasmic material, which at times suggested complete exchangeability between cytoplasm and extracellular medium. Our findings are consistent with the hypothesis that the platelet release reaction is triggered by intracellularly bound calcium. They also suggest that the application of high ionophore concentration has a toxicologic rather than a physiologic effect on platelets, and that a weak chelator added during incubation with the ionophore can in the absence of divalent cations prevent cell destruction, but not the toxic effect on cell metabolism.
向枸橼酸盐缓冲盐溶液中洗涤过的血小板悬液中添加0.1 μM离子载体A23187，会导致储存的5-羟色胺大量释放，同时伴有肌苷一磷酸在细胞内蓄积，但未检测到细胞外钙的内流，也未出现明显的结构改变。随着离子载体浓度增加，钙大量内流，血小板超微结构发生显著改变。离子载体浓度增加的同时，大部分代谢性腺嘌呤核苷酸转化为肌苷一磷酸，且进一步转化为肌苷和次黄嘌呤的过程几乎完全受阻。当添加的钙浓度低于枸橼酸盐浓度的1/10时，代谢变化更为明显。在有Ca++存在时，或省略枸橼酸盐时，会出现大量细胞质物质泄漏，有时提示细胞质与细胞外介质之间完全可交换。我们的研究结果与血小板释放反应由细胞内结合钙触发这一假说相符。研究结果还表明，高浓度离子载体对血小板产生的是毒理学而非生理学效应，并且在与离子载体共同孵育期间添加弱螯合剂，在无二价阳离子的情况下可防止细胞破坏，但不能防止对细胞代谢的毒性作用。
