Cazenave J P, Reimers H J, Kinlough-Rathbone R L, Packham M A, Mustard J F
Lab Invest. 1976 May;34(5):471-81.
Removal of N-acetylneuraminic acid from the platelet surface causes rapid removal of platelets from the circulation but causes little change in other platelet functions. We have now investigated the effects of sodium periodate which is thought to oxidize the sialic acid of glycoproteins on cell surfaces and has been shown to affect the functions of other cells. NaIO4 (1 to 10 mm) caused aggregation of stirred suspensions of washed platelets from rabbits. Calcium was required in the suspending medium for NaIO4-induced aggregation. Aggregation was not accompanied by the release of amine storage granule contents nor by cell lysis. Aggregation induced by NaIO4 was not inhibited by creatine phosphate-creatine phosphokinase, by platelet inhibitors that raise platelet cyclic AMP levels such as prostaglandin E1 or methylxanthines, by agents that modify platelet surface--SH groups (N-ethylmaleimide, p-chloromercuribenzene sulfonate), nor by cytochalasin B and/or colchicine which interfere with platelet contractile processes. Drugs such as acetylsalicyclic acid, penicillin G, or cephalothin had no effect on NaIO4-induced aggregation. NaIO4-induced aggregation was practically independent of platelet metabolism since it was not affected by low temperatures and was only slightly inhibited by a combination of antimycin and iodoacetate. Periodate treatment enhanced CO2 production by platelets. When rabbit platelets were pretreated, without stirring, with NaIO4 (0.01 to 1 mm), they did not aggregate. They retained their disc shape and granule contents. However, this pretreatment with NaIO4 inhibited aggregation induced by ADP and inhibited both aggregation and release induced by collagen, thrombin, arachidonic acid, and the ionophore A23,187. The extent of inhibition corresponded to the concentration of NaIO4 used to pretreat the platelets. In contrast, concanavalin A-induced aggregation was unchanged by NaIO4 pretreatment. When NaIO4 oxidation was followed by sodium borohydride (NaBH4) reduction, the effects caused by NaIO4 pretreatment on ADP-induced aggregation and collagen- or thrombin-induced aggregation and release were partially reversed. Pretreatment with NaIO4 also diminished the rate of serotonin uptake and decreased the ability of platelets to adhere to collagen-coated surfaces or to the subendothelial structures of the rabbit aorta. Platelets which had been treated with NaIO4 and then reinfused into rabbits did not survive, and in this way were similar to platelets from which surface sialic acid had been removed by neuraminidase treatment. Since NaIO4 has been shown to oxidize sialic acid on red cell membranes, it seems probably that alteration of surface sialic acid resulted in recognition of the periodate-treated platelets as "foreign" by the reticuloendothelial system. When NaIO4 oxidation was followed by NaBH4 reduction, platelet survival returned toward normal values.
从血小板表面去除N-乙酰神经氨酸会导致血小板迅速从循环中清除，但对其他血小板功能影响不大。我们现在研究了高碘酸钠的作用，高碘酸钠被认为可氧化细胞表面糖蛋白的唾液酸，并且已证明会影响其他细胞的功能。NaIO4（1至10毫米）可引起兔洗涤血小板搅拌悬浮液的聚集。悬浮介质中需要钙才能使NaIO4诱导聚集。聚集过程中不伴有胺储存颗粒内容物的释放，也不伴有细胞裂解。NaIO4诱导的聚集不受磷酸肌酸-肌酸磷酸激酶、升高血小板环磷酸腺苷水平的血小板抑制剂（如前列腺素E1或甲基黄嘌呤）、修饰血小板表面-SH基团的试剂（N-乙基马来酰亚胺、对氯汞苯磺酸盐）以及干扰血小板收缩过程的细胞松弛素B和/或秋水仙碱的抑制。乙酰水杨酸、青霉素G或头孢菌素等药物对NaIO4诱导的聚集没有影响。NaIO4诱导的聚集实际上与血小板代谢无关，因为它不受低温影响，仅被抗霉素和碘乙酸的组合轻微抑制。高碘酸盐处理可增强血小板的二氧化碳产生。当兔血小板在不搅拌的情况下用NaIO4（0.01至1毫米）预处理时，它们不会聚集。它们保持盘状和颗粒内容物。然而，这种用NaIO4预处理会抑制ADP诱导的聚集，并抑制胶原、凝血酶、花生四烯酸和离子载体A23187诱导 的聚集和释放。抑制程度与用于预处理血小板的NaIO4浓度相对应。相比之下，伴刀豆球蛋白A诱导的聚集不受NaIO4预处理的影响。当NaIO4氧化后用硼氢化钠（NaBH4）还原时，NaIO4预处理对ADP诱导的聚集以及胶原或凝血酶诱导的聚集和释放所产生的影响会部分逆转。用NaIO4预处理还会降低血清素摄取率，并降低血小板粘附于胶原包被表面或兔主动脉内皮下结构的能力。用NaIO4处理后再回输到兔体内的血小板无法存活，在这方面与用神经氨酸酶处理去除表面唾液酸的血小板相似。由于已证明NaIO4可氧化红细胞膜上的唾液酸，因此表面唾液酸的改变似乎可能导致网状内皮系统将经高碘酸盐处理的血小板识别为“异物”。当NaIO4氧化后用NaBH4还原时，血小板存活率恢复到正常水平。
