Ward J V, Radojewski-Hutt A M, Packham M A, Haslam R J, Mustard J F
Lab Invest. 1976 Oct;35(4):337-42.
Rabbit platelets were labeled in vivo by intravenous injection of 35SO4=60 hours before the animals were exsanguinated. The labeled platelets were washed and resuspended in Tyrode's solution containing 0.35 per cent albumin. The aggregated normally upon the addition of ADP and during aggregation 14.0 +/- 2.7 per cent (mean +/- standard deviation) of the labeled material was lost into the suspending medium. The extent of loss was dependent on ADP concentration and was inhibited by inhibitors of ADP-induced aggregation (AMP, ATP, adenosine, prostaglandin E1, parachloromercuribenzensulfonate and lack of calcium). Since neither release of granule contents nor lysis occurs when rabbit platelets are aggregated by ADP, it was concluded that the labeled material that was lost had been part of the surface coat of the platelets. The labeled material has been identified in other studies as a proteoglycan in which the mucopolysaccharide is principally chondroitin sulfate A. Loss of this material did not make the platelets unresponsive to ADP. The platelets did not reincorporate labeled proteoglycan from plasma. Thrombin caused the release of 50 to 80 per cent of the total platelet-labeled material, presumably from both the granules and the surface. The functional significance of the loss of surface proteoglycan during platelet aggregation is unknown.
在处死动物前60小时，通过静脉注射35SO4对兔血小板进行体内标记。将标记的血小板洗涤后，重悬于含0.35%白蛋白的台氏液中。加入ADP后血小板正常聚集，聚集过程中14.0±2.7%（平均值±标准差）的标记物质丢失到悬浮介质中。丢失程度取决于ADP浓度，并受到ADP诱导聚集的抑制剂（AMP、ATP、腺苷、前列腺素E1、对氯汞苯磺酸盐和缺钙）的抑制。由于当兔血小板被ADP聚集时既不发生颗粒内容物释放也不发生裂解，因此得出结论，丢失的标记物质曾是血小板表面 coat 的一部分。在其他研究中已将该标记物质鉴定为一种蛋白聚糖，其中粘多糖主要是硫酸软骨素A。这种物质的丢失并未使血小板对ADP无反应。血小板不会从血浆中重新摄取标记的蛋白聚糖。凝血酶导致50%至80%的总血小板标记物质释放，推测来自颗粒和表面。血小板聚集过程中表面蛋白聚糖丢失的功能意义尚不清楚。
