An inhibitor selective for collagen-stimulated platelet aggregation from the salivary glands of hard tick Haemaphysalis longicornis and its mechanism of action  

作　　者：程远国 吴厚永 李德昌 

出　　处：《Science China(Life Sciences)》1999年第5期457-464,共8页中国科学（生命科学英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant No. 39170591)

摘　　要：Soluble materials of salivary glands from Haemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin- stimulated platelet aggregation. One inhibitory component was purified to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longicomin, is a protein of molecular weight 16 000 on SDS-PAGE under both reduced and nonreduced conditions. Collagen-mediated aggregation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effectors, including ADP, arachidonic acid, thrombin, risto-cetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-0-phorbol-13-myristate acetate, was observed . Longiconin had no effect on platelet adhension to collagen. Not only platelet aggregation but also release reaction, and increase of intracellar Ca2+ level of platelets in response to collagen were completely eliminated by longicomin . Increasing amounts of collagen are able to overcome the inhibition of aggregation by longicomin, indicating that longicomin probably shares with collagen a common receptor. In addition, collagen fibers did not emit fluorescence after incubation with isothocyanate-conjugated longicomin, indicating that longicomin did not bind directly to collagen fibers. The identification and isolation of longicomin demonstrates the existence of a new type of platelet inhibitor that should be useful to better understand the mechanism of collagen stimulation of platelets.Soluble materials of salivary glands from Haemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C₈ reverse phase HPLC. The purified activity, named longieornin, is a protein of moleeular weight 16 000 on SDS-PAGE under both reduced and nonredueed conditions. Collagen-mediated aggregation of platelets in plasma and of washed platelets (IC₅₀ was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effeetors, including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate acetate, was observed. Longieonin had no effect on platelet adhension to collagen. Not only platelet aggregation but also release reaction, and increase of intraeellar Ca²⁺ level of platelets in response to collagen were

关 键 词：Haemaphysalis longicornis SALIVARY GLAND longicornin collagen antiplatelet. 

分 类 号：R181.3[医药卫生—流行病学]