莽草酸对血小板聚集和凝血的抑制作用

目的：研究莽草酸(SA)对血小板聚集性的影响及其机制,并研究其对凝血时间的影响。 方法：采用比浊法测定血小板聚集功能,放射免疫法测定血小板TXB2和血浆6-keto-PGF_1α水平,玻管法测定凝血时间。结果：SA体外呈浓度依赖性抑制ADP、胶原诱导的兔血小板聚集,IC₅₀分别为9.25, 3.56 mmol.L^-1;在体内(ip)抑制脑血栓模型鼠由ADP诱导的血小板聚集; SA促进大鼠血浆6-keto-PGF_1α的生成并延长小鼠凝血时间。结论：SA对血小板聚集及凝血系统有显著的抑制作用。     

红花黄酮成分抑制血小板激活因子介导的血小板活化作用

目的　观察红花黄酮成分杨梅素(Myr)和山奈酚(Kae)对血小板激活因子(PAF)诱导的兔洗涤血小板聚集、5 HT释放及血小板内游离钙离子浓度升高的影响。方法　以比浊法测定家兔洗涤血小板(WRP)聚集,邻苯二甲醛(OPT)荧光法测定5-HT浓度,Fura-2荧光探针测定血小板内游离钙离子浓度。结果　Myr和Kae体外呈浓度依赖性地抑制PAF诱发的WRP聚集及5-HT释放。Myr抑制WRP聚集的IC₅₀ 为17.5 μmol·L^-1 ;抑制5-HT释放的IC₅₀ 为64.1μmol·L^-1 。Kae抑制聚集、释放作用的IC₅₀ 分别为73.7μmol·L^-1 和128μmol·L^-1 ;同时Myr和Kae均能明显抑制PAF引起的血小板内游离钙增高。结论　Myr和Kae可抑制PAF诱导的血小板活化作用     

Bakkenolide G,a Natural PAF-receptor Antagonist

Because platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) participates in many physiopathological responses, including inflammatory reaction, endotoxic shock, allergic diseases and platelet aggregation, PAF-receptor antagonists are important in the treatment of these diseases. A biologically active compound, bakkenolide G, extracted from the plant Petasites formosanus selectively and concentration-dependently inhibited PAF-induced platelet aggregation and ATP release. The IC50 of bakkenolide G for PAF (2 ng mL^?1)-induced platelet aggregation was 5.6 ± 0.9 μm . Bakkenolide G also concentration-dependently inhibited PAF-induced intracellular signal transductions, including thromboxane B₂ formation, and increased intra-cellular calcium concentration and phosphoinositide breakdown without affecting those caused by thrombin (01 units mL^?1), collagen (10 μg mL^?1), arachidonic acid (100 μm ) and U46619 (1 μm ). Bakkenolide G shifted the concentration-response curves of PAF-induced platelet aggregation parallel to the right; the Schild plot slope and the pA₂ value were 1.31 ± 0.31 and 6.21 ± 0.75, respectively. Moreover, bakkenolide G concentration-dependently competed with [³H]PAF binding to platelets, with an IC50 value of 2.5 ± 0.4 μm . These data strongly indicate that bakkenolide G is a specific PAF-receptor antagonist as an antiplatelet aggregatory agent.     

Inhibition of platelet aggregation by 5′-nucleotidase purified from Trimeresurus gramineus snake venom

By means of DEAE-Sephadex A-50 column chromatography and gel filtrations on Sephadex G-75, Sephacryl S-300 and Sephadex G-100, successively, a potent 5′-nucleotidase was purified from Trimeresurus gramineus venom. The venom 5′-nucleotidase is a single polypeptide chain and homogeneous as judged by SDS-polyacrylamide gel electrophoresis. It is a thermostable glycoprotein consisting of 589 amino acid residues. Its molecular weight was estimated to be 74,000 by SDS-polyacrylamide gel electrophoresis. It possessed nucleotidase activities toward adenosine monophosphate and adenosine diphosphate. The specific activities toward AMP and ADP were 504 ± 28 and 101 ± 8 μg P_i/min per mg, respectively. Pre-incubation of this venom's 5′-nucleotidase with ADP resulted in the cleavage of ADP and formation of adenosine. The 5′-nucleotidase activity was inhibited by EDTA. Both Zn²⁺ and Co²⁺ reversed the inhibitory effect of EDTA.In rabbit platelet-rich plasma, it inhibited completely the ADP (2 × 10^-5 g/ml)-induced platelet aggregation. It also inhibited the platelet aggregations induced by sodium arachidonate (100 μM), collagen (20 μg/ml) and ionophore A-23187 (5 μM). In rabbit platelet suspensions, it inhibited the platelet aggregation induced by ADP (2 × 10^-5 g/ml), sodium arachidonate (100 μM) and low concentration of thrombin (0.03 U/ml). The collagen (20 μg/ml)- and ionophore A-23187 (5 μM)-induced platelet aggregations were not affected significantly by this venom 5′-nucleotidase. In ADP-refractory platelet-rich plasma, the venom 5′-nucleotidase inhibited the platelet aggregations induced by collagen (20 μg/ml) or sodium arachidonate (100 μM). The venom 5′-nucleotidase showed a more pronounced inhibitory effect on sodium arachidonate-induced platelet aggregation than creatine phosphate/creatine phosphokinase and apyrase did. No lactate dehydrogenase was released by this venom 5′-nucleotidase, indicating that no platelet lysis occurred. It is concluded that removal of ADP, which is released by these platelet aggregation inducers, and the subsequent accumulation of adenosine are responsible for the inhibitory effect of the venom 5′-nucleotidase on platelet aggregations.     

Antiplatelet Effects of Some Aporphine and Phenanthrene Alkaloids in Rabbits and Man

Two aporphines (boldine and laurolitsine) and five phenanthrene alkaloids (litebamine, secoboldine, N-cyanosecoboldine, N-methylsecoglaucine and N-methylsecopredicentrine) were evaluated in-vitro for their ability to inhibit platelet aggregation. All seven alkaloids inhibited aggregation of rabbit platelets and inhibited the release of ATP induced by arachidonic acid and collagen in rabbit platelets. Those aggregations induced by platelet-activating factor (PAF), thrombin, U46619 and ADP were inhibited by the three N-substituted secoboldine derivatives only. Thromboxane B₂ formation caused by arachidonic acid was also suppressed by these compounds. They did not affect the generation of [³H]inositol monophosphate caused by collagen, PAF and thrombin in the presence of indomethacin. Platelet cyclic AMP level was unaffected by litebamine, but was increased by N-methyl-secoglaucine. Litebamine suppressed the secondary aggregation, but not the primary aggregation, induced by ADP and adrenaline in platelet-rich plasma from man, whereas N-methylsecoglaucine inhibited both primary and secondary aggregation. It is concluded that the antiplatelet effect of these seven aporphine and phenanthrene alkaloids is mainly a result of inhibition of thromboxane A₂ formation; N-methylsecoglaucine has additional antiplatelet activity as a result of increasing the levels of platelet cyclic AMP.     

姜黄素对高脂血症兔血液流变学、血小板聚集、抗氧化以及纤溶系统的影响

目的 观察姜黄素对高脂血症兔血液流变学、血小板聚集、抗氧化以及纤溶系统的影响。方法 新西兰兔摄取高脂饲料2周后,连续6周高脂饲料喂养并服用姜黄素。结果 各给药组兔的全血粘度、全血还原粘度、红细胞刚性指数和变型指数等指标有降低趋势,且随剂量的增加而增加(P<0.05, P<0.01),大剂量作用非常显著(P<0.01),对二磷酸腺苷(ADP)和胶原诱导的血小板聚集有一定的抑制作用,尤其大剂量组对胶原诱导的血小板聚集有明显的抑制作用(P<0.05),能使血清SOD水平显著提高,MDA和t-PA水平明显降低,对花生四稀酸诱导的血小板聚集未见明显影响。结论 姜黄素对高脂血症兔血液流变学可产生一定的有益作用,且具有抗氧化及促进纤溶的活性。     

丰城鸡血藤总黄酮抗血小板聚集及抗血栓作用研究

目的 研究丰城鸡血藤总黄酮对实验性大鼠血小板聚集和血栓形成的影响。方法 以二磷酸腺苷(adenosine diphosphate,ADP)、胶原和凝血酶作诱导剂诱导大鼠血小板聚集,丰城鸡血藤总黄酮按25,50,100 mg·kg^-1的剂量灌胃给药,测定大鼠血小板聚集率,计算聚集抑制率;用血栓法测定大鼠血栓形成重量。结果 丰城鸡血藤总黄酮各剂量均能抑制ADP、胶原和凝血酶诱导的大鼠血小板聚集,并能减少血栓形成的重量。结论 丰城鸡血藤总黄酮具有明显的抗血小板聚集及抗血栓形成的作用。     

CV3988 inhibits in vivo platelet aggregation induced by PAF-acether and collagen

Platelet activating factor (PAF-acether) was shown to cause a fall in the circulating platelet count and blood pressure (BP) in anaesthetised rabbits. CV3988 caused a dose-dependent inhibition of these responses to a low dose of PAF-acether (150 ng · kg⁻¹). CV3988 itself was found to cause a fall in both BP and platelet count in vivo. Collagen (40 μg · kg⁻¹) i.v. caused sudden death in rabbits and pretreatment with CV3988 (5 mg · kg⁻¹) caused a 62% inhibition of the platelet count response to collagen without significantly increasing the survival rate. In the rat, collagen (40 μg · kg⁻¹) was not lethal and CV3988 caused a dose-dependent inhibition of the fall in platelet count due to collagen, but this action was short-lived. CV3988 also caused agonist actions in the rat. These results show that CV3988 inhibits the effects of PAF-acether in vivo and suggests that PAF-acether may play a role in mediating collagen-induced platelet aggregation in vivo.     

Ex-vivo and In-vivo Antithrombotic Effect of Triflavin,an RGD-containing Peptide

Abstract— Triflavin, an Arg-Gly-Asp-containing snake venom peptide, inhibits platelet aggregation through the blockade of fibrinogen binding to the activated platelets. It binds to fibrinogen receptors associated with the glycoprotein IIb/IIIa complex with a K_d value of 7 × 10^?8 m. In this study, we found that ¹²⁵I-triflavin reached the maximal binding to human platelets within 5 min at 25°C. In addition, when triflavin was intravenously administered at 1·0 mg kg^?1 to rabbits, it reversibly impaired the platelet aggregation of platelet-rich plasma caused by ADP (20 μm) ex-vivo over 30 min. The platelet counts of the experimental rabbits remained unchanged. Triflavin was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice when administered intravenously at a dose of 2 μg g^?1. Therefore, triflavin was proven to be an effective antithrombotic agent in preventing ADP-induced acute pulmonary thromboembolism in mice and impairing reversibly the platelet function of rabbits when given intravenously.     

槲皮素在试管内对血小板功能和膜脂质流动性的影响

本文报道槲皮素对血小板聚集释放反应以及膜脂质流动性的影响。槲皮素浓度为300μmol时对PAF诱导和600μmol时对凝血酶诱导的大鼠血小板聚集几乎完全抑制;也明显地抑制ADP诱导的大鼠血小板聚集及凝血酶诱导的兔血小板³H-5 HT释放;在槲皮素浓度为30μmol时,即明显降低血小板膜脂质流动性。     

甲基莲心碱对高脂血症患者及健康成人血小板聚集的影响

目的观察甲基莲心碱（ｎｅｆｅｒｉｎｅ，Ｎｅｆ）体外给药对高脂血症患者及健康成人血小板聚集功能的影响。方法用比浊法测定血小板聚集率。结果Ｎｅｆ在体外呈剂量依赖性明显抑制ＡＤＰ、胶原、盐酸肾上腺素注射液（Ａｄｒ）诱导的人血小板聚集。高脂血症患者组，Ｎｅｆ对ＡＤＰ、Ａｄｒ诱聚的１ｍｉｎ时的ＩＣ５０分别为４５、３８μｍｏｌ·Ｌ－１；对ＡＤＰ、Ａｄｒ、胶原诱聚的５ｍｉｎ时的ＩＣ５０分别为３６、２７和１６μｍｏｌ·Ｌ－１。健康成人组，对ＡＤＰ、Ａｄｒ诱聚的１ｍｉｎ时的ＩＣ５０分别为５９和３６μｍｏｌ·Ｌ－１；对ＡＤＰ、Ａｄｒ、胶原诱聚的５ｍｉｎ时的ＩＣ５０分别为４２，８９和１１０μｍｏｌ·Ｌ－１。结论体外给药，Ｎｅｆ可明显抑制多种诱聚剂诱导的高脂血症患者和健康成人血小板聚集，且作用强于阿斯匹林。提示Ｎｅｆ对高脂血症患者并发血栓性疾病有一定的防治作用     

Anticoagulant, anti-aggregation and antithrombotic effects of a novel hexapeptide

Objectives Hexapeptide is a novel synthetic oligopeptide with a structure similar to that of eptifibatide. This study was designed to investigate the anticoagulant, anti‐aggregation, disaggregation and anti‐thrombogenesis effects of hexapeptide. Methods The effects of antiplatelet aggregation induced by adenosine diphosphate (ADP), arachidonic acid (AA) and thrombin, and the effect of disaggregation of platelet aggregation induced by ADP were determined. The anticoagulation indexes were determined by different kits. Key findings Hexapeptide 1 × 10^?5–1 × 10^?4m could significantly prolong rabbit blood clotting time, thrombin time, prothrombin time and activated partial thromboplastin enzyme time, and reduce the length, wet weight, dry weight and the index of thrombus in a concentration‐dependent manner. Hexapeptide 1 × 10^?4m decreased platelet adhesion rate by 40.2%. The platelet aggregation inhibition of hexapeptide in dogs and humans was more obvious than in rabbits and rats. The aggregation inhibition rate of 1 × 10^?5m hexapeptide in dogs, rabbits, rats and humans induced by ADP was 93.9 ± 1.3%, 66.2 ± 1.4%, 76.1 ± 3.2% and 99.8 ± 0.2%, respectively; the 50% inhibitory concentration (IC50) of hexapeptide was 7.24 × 10^?8, 3.24 × 10^?6, 6.61 × 10^?6 and 8.91 × 10^?8m , respectively. For the aggregation inhibition rate of hexapeptide in dogs, rabbits and humans induced by AA, the IC50 was 1.29 × 10^?9, 1.32 × 10^?6 and 9.33 × 10^?8m , respectively; the IC50 of aggregation inhibition rates induced by thrombin was 2.88 × 10^?6, >1 × 10^?5 and 4.17 × 10^?6m , respectively. The disaggregation rate of 1 × 10^?4m hexapeptide in dog induced by ADP was 68.8 ± 7.4%. Conclusions Hexapeptide has anticoagulant, antiplatelet aggregation, disaggregation and antithrombotic effects in vitro.     

In-vitro and Ex-vivo Inhibition of Blood Platelet Aggregation by Naftazone

Because of the considerable interest in the role of platelets and antiplatelet therapy in cardiovascular disease, including the aggregation of platelets to each other during arterial thrombosis and atherogenesis, we have studied the effect of naftazone (Etioven), an original vasculotropic drug on platelet aggregation. Rat and human platelets were prepared and incubated in-vitro with different concentrations of naftazone. We found that naftazone inhibited both platelet secretion and aggregation in platelet-rich plasma (PRP) and washed platelets after stimulation with thrombin or ADP. Rats were also treated intraperitoneally for five days with various naftazone doses (0.125-10 mg kg^?1) and ex-vivo platelet aggregation compared, at various times after the last injection, with that of control animals. Inhibition by naftazone was dose-dependent in both PRP and isolated platelets. The inhibition was transient, a maximum value (～ 50%) being obtained about 3–6 h after the last injection, with a return to near-control values after 24 h. Naftazone also facilitated platelet deaggregation after in-vitro stimulation with thrombin or ADP. In another series of experiments, rats were treated intraperitoneally for five days with 10 mg kg^?1 of aspirin, ticlopidine, dipyridamole or naftazone. Platelets were prepared and tested for aggregation 90 min after the last injection. Thrombin-induced aggregation in PRP and washed platelets was significantly reduced after in-vivo treatment with ticlopidine and naftazone. Except for dipyridamole, all the drugs inhibited ex-vivo ADP-induced aggregation in PRP. In isolated platelet preparation, only naftazone induced a significant inhibition of ADP-or thrombin-stimulated aggregation. We conclude that naftazone inhibits platelet aggregation in-vitro and ex-vivo.     

Rolipram inhibits airway microvascular leakage induced by platelet-activating factor,histamine and bradykinin in guinea-pigs

Abstract— Rolipram (0·1–1000 μg kg^?1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg^?1, i.v.) at different sites of the guinea-pig airways. Rolipram (1–100μg kg^?1, i.v.) inhibited histamine (30μg kg^?1, i.v.)-and bradykinin (0·3 μg kg, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7–20 μg kg^?1 min^?1)-induced bronchoconstriction (IC50 = 3 ± 1 μg kg, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg^?1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.     

酸枣仁皂苷A的抗血小板聚集活性研究

目的 研究酸枣仁皂苷A的抗血小板聚集活性。方法 采用兔体外血小板聚集实验方法,结合酶联免疫吸附法测定血清血小板活化因子（platelet activating factors,PAF）、P-选择素和血小板因子-4（platelet factor-4,PF-4）的含量,探讨不同浓度的酸枣仁皂苷A对二磷酸腺苷（adenosine diphosphate,ADP）、花生四烯酸（arachidonic acid,AA）和PF-4诱导血小板聚集的抑制活性。结果 酸枣仁皂苷A能有效抑制AA、ADP和PF-4诱导的血小板聚集,能显著降低PAF、P-选择素和PF-4的含量。结论 酸枣仁皂苷A具有明显的抗血小板聚集活性。     

Effect of 2(1-piperazinyl)-4H-pyrido[1,2-a]pyrimidin-4-one (AP155) on human platelets in vitro

The effect on human platelets of 2-(1-piperazinyl)-4H-pyrido[1,2-a]pyrimidin-4-one (AP155) was tested in vitro by measuring cyclic adenosine monophosphate (cAMP) level, cytosolic Ca⁺⁺, [¹²⁵I]fibrinogen binding as well as aggregation induced by several agonists. AP155 dose-dependently inhibited aggregation both in platelet rich plasma (PRP) and in washed platelets (WP), exerting its maximal power in the presence of collagen, ADP and platelet activating factor (PAF). It specifically inhibited the activity of cAMP high affinity phosphodiesterase (PDE), resulting in a sufficient increase in cAMP levels to activate cAMP-dependent protein kinase. AP155 was able to inhibit aggregation, the increase in cytosolic Ca⁺⁺ induced by thrombin, and fibrinogen binding to ADP or thrombin-stimulated platelets. Thus, this new pyridopyrimidine derivative exerts its antiplatelet activity by increasing cAMP intracellular concentration.     

眼镜蛇毒金属蛋白酶atrase A抗血小板聚集作用及机制

目的研究中华眼镜蛇毒金属蛋白酶atrase A对血小板聚集的影响及其相关的机制。方法测定atrase A对二磷酸腺苷、胶原、血小板活化因子、花生四烯酸、瑞斯托霉素、凝血酶诱导血小板聚集的影响情况,并通过蛋白质免疫印迹检测atrase A对血小板膜糖蛋白和血管假血友病因子的酶切情况。结果中华眼镜蛇毒金属蛋白酶atrase A能明显抑制由瑞斯托霉素和凝血酶诱导的血小板聚集,这种抑制作用呈量效、时效关系。而atrase A和血小板预孵5min后对二磷酸腺苷、胶原、血小板活化因子、花生四烯酸诱导的血小板聚集有微弱的抑制作用,预孵时间延长至30min对血小板聚集有明显的抑制作用。蛋白质免疫印迹结果显示atrase A能特异性酶切血小板膜糖蛋白GPIb,但对vWF几乎没有酶切作用。结论中华眼镜蛇毒金属蛋白酶atrase A对二磷酸腺苷、胶原、血小板活化因子、花生四烯酸、瑞斯托霉素、凝血酶诱导的血小板聚集均有抑制作用,其中对瑞斯托霉素和凝血酶诱导的血小板聚集具有明显的抑制作用,其机制是通过酶切血小板膜糖蛋白GPIb。     

Inhibition of Platelet Thromboxane Formation and Phosphoinositides Breakdown by Diisoeugenol

Abstract— Diisoeugenol inhibited the platelet aggregation and ATP release of rabbit platelets caused by ADP, arachidonic acid, platelet-activating factor (PAF), collagen and thrombin. Prolongation of the incubation time of platelets with diisoeugenol did not cause further inhibition and the aggregability of platelets could not be restored after washing. In human platelet-rich plasma, diisoeugenol inhibited the biphasic aggregation and ATP release induced by adrenaline and ADP in a concentration-dependent manner. Thromboxane B₂ formation caused by arachidonic acid, collagen and thrombin was markedly inhibited by diisoeugenol in a concentration-dependent manner. Diisoeugenol also inhibited the formation of inositol monophosphate caused by collagen, PAF and thrombin. The cAMP level of washed platelets was not changed by diisoeugenol. It is concluded that the antiplatelet effect of diisoeugenol is due to the inhibition of thromboxane formation and phosphoinositides breakdown.     

Increased ex-vivo colonic generation of PAF induced by diphenylmethane stimulant laxatives in rats,mice, guinea-pigs and rabbits

Abstract— The effects of in-vivo treatment with bisacodyl, phenolphthalein, picosulphate, sulphosuccinate, mannitol and lactulose laxatives were examined on the ex-vivo formation of platelet-activating factor (PAF) by duodenum and colon of rat, mouse, guinea-pig and rabbit. Bisacodyl (10 mg kg^?1), phenolphthalein (20 mg kg^?1) and picosulphate (10 mg hg^?1), but not sulphosuccinate (40 mg kg^?1), mannitol (50 mg kg^?1) or lactulose (50 mg kg^?1), at doses that all caused laxation, markedly increased PAF in the colon (P < 0·01) but not in the duodenum. Intraluminal release of acid phosphatase was also significantly increased in the colon of rats treated with bisacodyl, phenolphthalein and picosulphate, but not in colons of animals treated with sulphosuccinate, mannitol or lactulose. The data show that enhanced generation of PAF is associated with the colonic damage induced by diphenylmethane laxatives, but do not show whether this is a cause or a consequence of the pathophysiological changes.     

小檗碱对局灶性脑缺血大鼠血小板聚集及血浆TXB2和6-keto-PGF1a水平的影响

以大鼠可逆性大脑中动脉梗塞(MCAO)致局灶性脑缺血为模型,观察小檗碱对大鼠MCAO24h后血小板粘附、聚集、血栓形成及血浆TXB2和PGI₂生成的影响。结果表明,小檗碱20mg·kg^-1·d^-1ipl,3或5d,明显降低MCAo24h后血小板粘附性及ADP、胶原和花生四烯酸诱导的血小板聚集率,抑制血浆TXB₂水平。同剂量ip3或5d,则抑制血栓形成。提示小檗碱可能通过其抗血小板粘附和聚集及影响花生四烯酸代谢而发挥抗脑缺血作用。