Packham M A, Guccione M A, Kinlough-Rathbone R L, Mustard J F
Blood. 1980 Nov;56(5):876-80.
Some investigators have reported recently that platelet surface sialic acid is decreased during ADP-induced aggregation, whereas others have reported an increase. Since removal of sialic acid from the platelet surface shortens platelet survival, we have determined the survival of platelets that have been aggregatad by ADP. We have also measured the amount of sialic acid in the suspending fluid of platelets after ADP-induced aggregation. ADP-induced aggregation did not cause the loss of sialic acid from rabbit platelets (which do not undergo a release reaction in response to ADP) nor from washed human platelets in a medium containing physiologic concentrations of calcium in which granule contents are not released. In a medium without added calcium, ADP caused the release of 14C-serotonin (42.5% +/- 3%) from human platelets, but less than 4% of the sialic-acid-containing material was released. It seems likely that little of the releasable sialic acid of platelets is in the dense granules or the alpha-granules. Thrombin (5 U/ml) released 90.0% +/- 3.4% of the serotonin from human platelets but only 20.6% +/- 7.4% of the total sialic-acid-containing material. Neuraminidase removed 42.3% of the total sialic acid, presumably from the platelet surface. Rabbit platelets that had been aggregated by ADP and deaggregated survived normally when returned to the circulation. This observation also provides evidence that they had not lost membrane sialic acid during aggregation and deaggregation.
最近一些研究者报道，在二磷酸腺苷（ADP）诱导的血小板聚集过程中，血小板表面唾液酸含量降低，而另一些研究者则报道其含量增加。由于从血小板表面去除唾液酸会缩短血小板存活时间，我们测定了经ADP诱导聚集的血小板的存活情况。我们还测量了ADP诱导血小板聚集后其悬浮液中唾液酸的含量。ADP诱导的聚集并未导致兔血小板（对ADP不发生释放反应）以及在含有生理浓度钙的培养基中洗涤过的人血小板（其中颗粒内容物不会释放）表面唾液酸的丢失。在无添加钙的培养基中，ADP可使人血小板释放14C - 5 - 羟色胺（42.5%±3%），但含唾液酸物质的释放量不到4%。血小板中可释放的唾液酸似乎很少存在于致密颗粒或α颗粒中。凝血酶（5 U/ml）可使人血小板释放90.0%±3.4%的5 - 羟色胺，但仅释放20.6%±7.4%的总含唾液酸物质。神经氨酸酶去除了42.3%的总唾液酸，推测是从血小板表面去除的。经ADP诱导聚集然后解聚的兔血小板重新回到循环中后能正常存活。这一观察结果也证明它们在聚集和解聚过程中并未丢失膜唾液酸。
