Nakahodo K, Saitoh S, Nakamura M, Kosugi T
Department of Physiology, School of Medicine, University of The Ryukyus.
Arerugi. 1994 Mar;43(3):501-10.
In this study, we examined firstly whether PAF could activate washed platelets of rabbits and release ATP from the platelets, secondly whether activated platelets could release histamine, and thirdly whether certain antagonists of PAF could inhibit the release of histamine from platelets. The results obtained in these experiments may be summarized as follows. 1) Release of ATP was increased with enhanced platelet aggregation by PAF. At 3.4 x 10(-7) M of PAF, the maximal aggregation rate of platelets was about 70% and the concentration of released ATP was 1.6 x 10(-5) M. 2) After aggregated platelets induced by PAF had been sonicated and centrifuged, the resultant supernatant could cause contraction of the guinea pig ileum. This contraction was inhibited by the antihistaminic agents, cimetidine and pyrilamine. Furthermore, the histamine content of the supernatant was about 3.7 micrograms/ml (platelet count, 30 x 10(4)/microliter). 3) At 10(-5) M of CV-3988, the inhibitory ratio of PAF-induced aggregation was 35% and that of histamine release was 50%. On the other hand, at 5 x 10(-7) M of CV-6209, the inhibitory ratio of PAF-induced aggregation was 35% and that of histamine release was about 30%. From the above results, it was clear that PAF-activated platelets could release histamine. In addition, it is suggested that a direct relationship between PAF and platelets may exist in the process of allergic reactions, and histamine from PAF-activated platelets may modify allergic reactions.
在本研究中，我们首先检测了血小板活化因子（PAF）是否能激活兔洗涤血小板并促使血小板释放三磷酸腺苷（ATP），其次检测了活化的血小板是否能释放组胺，最后检测了某些PAF拮抗剂是否能抑制血小板释放组胺。这些实验得到的结果可总结如下：1）PAF增强血小板聚集时，ATP释放增加。在3.4×10⁻⁷M的PAF作用下，血小板的最大聚集率约为70%，释放的ATP浓度为1.6×10⁻⁵M。2）PAF诱导聚集的血小板经超声处理和离心后，所得上清液可引起豚鼠回肠收缩。这种收缩被抗组胺药西咪替丁和吡拉明抑制。此外，上清液中的组胺含量约为3.7微克/毫升（血小板计数为30×10⁴/微升）。3）在10⁻⁵M的CV - 3988作用下，PAF诱导的聚集抑制率为35%，组胺释放抑制率为50%。另一方面，在5×10⁻⁷M的CV - 6209作用下，PAF诱导的聚集抑制率为35%，组胺释放抑制率约为30%。从上述结果可知，PAF激活的血小板能释放组胺。此外，提示在过敏反应过程中PAF与血小板之间可能存在直接关系，且PAF激活的血小板释放的组胺可能会改变过敏反应。
