江浙蝗蛇毒酸性磷脂酶A_2抑制血小板作用的机理

江浙蝮蛇毒酸性磷脂酶Ａ２（ＡＰＬＡ２）对多种致聚剂引起的血小板聚集具有抑制作用，这种抑制并非是由于ＡＰＬＡ２与血小板膜结合，引起膜流动性降低造成。ＡＰＬＡ２不裂解血小板，电镜观察表明它能抑制血小板内部颗粒的中心化，使之不易被激活。进一步研究显示ＡＰＬＡ２是作用在细胞骨架上，使致聚剂引起的朋动蛋白单体聚合难以进行，ＡＰＬＡ２导致的ｃＡＭＰ浓度的升高正说明了这点。结果提示ＡＰＬＡ２首先作用于血小板细胞膜。引起ｃＡＭＰ浓度升高，影响到细胞骨架的正常功能，进而抑制了血小板的聚集。

Mechanism of Inhibition of Platelet Aggregation by Acidic Phospholipase A2 from Agkistrodon halys Pallas

Acidic phospholipase A2(APLA2)from Agkistrodon halys Pallas has an inhibitory effect on blood platelet aggregation caused by several inducers.This inhibition is not due to the binding of APLA2 to the platelet membrane with a decrease in its fluidity.APLA2 does not cause the lysis of platelets. Photographs of the ultrastructure show that APLA2 inhibit the centralization of platelet organelles,thus prevent their activation. Further investigation indicated that APLA2 acted on the cytoskeleton,inhibiting the induced polymerization of actin monomers and the increase of cAMP level was just in line with this result. Fromthese experiments we suggest that APLA2 first interacts with platelet membrane,leading to an increase in cAMP concentration,then affects the normal function of the cytoskeleton, thus inhibits platelet aggregation.