天麻成分对羟基苯甲醛抗血小板聚集作用及急性毒性研究

为探讨天麻成分对羟基苯甲醛的抗血小板聚集作用,本实验以二磷酸腺苷(ADP)、花生四烯酸(AA)、血小板活化因子(PAF)为诱导剂,探讨了对羟基苯甲醛的体外抗血小板聚集活性;采用ADP静脉注射致小鼠肺栓塞方法以及下腔静脉结扎致大鼠静脉血栓方法,考察了对羟基苯甲醛的体内抗血小板聚集活性;并对经口给药的对羟基苯甲醛的急性毒性进行了检测。结果表明,天麻成分对羟基苯甲醛对ADP诱导的家兔体外血小板聚集有明显的对抗作用,其半数抑制率(50%inhibitory concentration,IC50)为2mmol/L,对PAF诱导的家兔体外血小板聚集无明显影响;天麻成分对羟基苯甲醛能明显降低小鼠肺栓塞死亡率,并显著对抗大鼠下腔静脉血栓的形成。说明天麻成分对羟基苯甲醛在体外、体内均具有显著的抗血小板聚集活性。急性毒性研究结果表明天麻成分对羟基苯甲醛经口给药的小鼠半数致死量(lethal dose 50,LD50)为1.23 g/kg。     

滇产胡椒属植物醇提物抗血小板活性研究

采用Born氏比浊法观察了12种滇产胡椒属植物的乙醇提取物对血小板活化因子(PAF)、花生四烯酸(AA)和二磷酸腺苷(ADP)引起血小板活化聚集的影响.结果表明,这12种醇提物均明显抑制PAF诱导的血小板聚集,其中部分醇提物对AA和ADP引起的聚集亦有显著拮抗作用.结果提示,该12种滇产胡椒属植物醇提物具有较高的抗血小板活性     

蛇毒L-氨基酸氧化酶抗肿瘤作用研究进展

L-氨基酸氧化酶（LAAO）广泛地存在于各种蛇毒中。近年来许多文献报道了蛇毒L-氨基酸氧化酶具有与血小板相互作用、细胞毒性及诱导细胞凋亡作用,还报道它们具有出血或溶血活性、引起水肿及抗细菌、抗艾滋病病毒的特性。本文就其抗肿瘤方面的研究进行综述,介绍蛇毒L-氨基酸氧化酶的抑瘤机制、理化性质及国内外研究现状和应用前景。     

白藜芦醇甙对血小板聚集功能及内钙水平的影响

为了研究白藜芦醇甙(polydatin,PD)的抗血小板聚集作用及对细胞内钙水平的影响,并探讨其抗血栓形成作用的机制,应用Bom比浊法和Grynkiewicz方法分别测定PD对兔血小板聚集功能和血小板内钙水平的影响。PD在体外显著抑制花生四烯酸(arachidonic acid,AA)和腺苷二磷酸(adenosine diplrasphate,ADP)诱导的富血小板血浆中的血小板聚集,其半数抑制浓度(medium inhibitory concentration,IC50)分别为5．13及10．0μmol／L;5、10和20mg／kg的PD静注均明显降低兔血小板聚集率,且呈明显的剂量一效应关系;PD明显减少兔洗涤血小板内钙释放及外钙内流,本实验说明PD体内、外均有明显的抗血小板聚集作用,其机制与其降低血小板内钙浓度密切相关。     

天麻醒脑胶囊对家兔血小板聚集和花生四烯酸诱导大鼠脑血栓形成的影响

采用比浊方法测定天麻醒脑胶囊在体内和体外对腺苷二磷酸（ADP）、花生四烯酸（arachidonic acid,AA）和血小板活化因子（platelet activating factor,PAF）诱导家兔血小板活化聚集的影响。采用从经大鼠颈内动脉注射诱发同侧大脑半球脑血栓形成方法评价天麻醒脑胶囊的抗脑血栓形成作用。天麻醒脑胶囊在体外呈浓度依赖性明显抑制从和ADP引起的血小板聚集,其半数抑制浓度（50％of inhibitory concentration,IC50）分别为1．83和3．25g/L。0．5和1g/kg的天麻醒脑胶囊于灌胃后明显抑制从诱导的家兔血小板聚集,本品1g/kg时显著阻抑ADP引起的血小板聚集。天麻醒脑胶囊在体内外对PAF诱导的血小板聚集均无明显影响。1、2g/kg天麻醒脑胶囊组的右侧与左侧脑重差值均显著减小,显著降低右脑伊文思蓝吸光度与右脑重的比值。结果提示,天麻醒脑胶囊具有较强的抗血小板和减轻脑血栓形成作用,有利于血小板聚集性增高的血栓栓塞性疾病的防治。     

蛇毒L-氨基酸氧化酶酶学性质及对血小板功能的影响

L-氨基酸氧化酶(EC1·4·3·2)是一种黄素类蛋白酶,其酶活性为立体特异性催化L-氨基酸的氧化脱氨,生成α-酮酸,同时产生氨和过氧化氢。酶广泛存在于多种生物体种类中。蛇毒L-氨基酸氧化酶(LAAO)是该类酶中研究最为深入的一族,因其易于纯化而成为研究L-氨基酸氧化酶的酶学、结构生物学和药物学的有趣客体。近年来,越来越多的具有不同分子量、不同底物选择性的蛇毒LAAO被分离纯化,国内外文献越来越多的报道了蛇毒LAAO的特性,如准确的分子量、底物特性、与血小板的相互作用、诱发出血和凋亡。本文就蛇毒LAAO的性质及其对血小板功能的…     

华北绣线菊二萜生物碱抗血小板聚集活性研究

采用Born氏比浊法观察华北绣线菊小叶变种中分离得到的总碱和 9个hetisine型C2 0 二萜生物碱及其衍生物体外对血小板活化因子 (PAF)、花生四烯酸 (AA)和二磷酸腺苷 (ADP)三种诱导剂引起的血小板聚集活性的影响 ,并初步探讨了构效关系。结果表明 ,华北绣线菊小叶变种中总碱对PAF和ADP诱导的血小板聚集均有明显的抑制作用 ;9个hetisine型C2 0 二萜生物碱中 ,有 8个显著抑制PAF诱导的血小板聚集 ,其活性与分子结构明显相关 ;此外 ,hetisine型生物碱及其衍生物对ADP诱导的血小板聚集亦有一定的抑制作用 ,但总碱及生物碱对AA诱导的聚集影响不明显。提示hetisine型C2 0 二萜生物碱具有抗血小板聚集活性。     

尖吻蝮蛇毒活性肽K组分对血小板聚集和超微结构的影响

目的应用电镜研究尖吻蝮蛇毒活性肽(K组分)对血小板聚集和超微结构的影响,以探讨其抗血小板聚集的机制。方法取2周内未服任何药物健康志愿者静脉血,观察K组分对二磷酸腺苷(ADP)和胶原(collagen)诱导的血小板聚集作用的影响。将已调好的PRP分为5组,A组为空白对照组,B、D组为加入等体积的生理盐水组,C、E组为加K组分组。B、C组分别加血小板聚集诱导剂ADP,D、E组分别加血小板聚集诱导剂胶原,各组分别制成超薄切片样品进行电镜观察、摄片,测出其聚集抑制率。结果K组分能抑制由ADP和胶原诱导的血小板聚集,剂量与抑制率成量效关系,IC50经直线回归分别为0.067和0.088μmol/L。ADP和胶原组血小板形态不规则,突起明显增多。K组分组血小板形态基本规则,膜表面清晰光滑,颗粒较ADP与胶原组明显增加,胞浆空泡化现象减轻。结论K组分明显抑制ADP和胶原诱导的血小板聚集反应及其超微结构的改变。     

川芎嗪对血小板聚集功能的影响及其作用机制的探讨

川芎嗪是从中药川芎根中提取的一种生物碱。祖国医学对其活血化瘀作用早有所知。其化学结构已查明,并有合成制品在市上销售。 临床试用表明,川芎嗪治疗冠心病、心绞痛和急性闭塞性脑血管病有效。本文研究证明,川芎嗪在体外对由诱导剂二磷酸腺苷、胶原、凝血酶诱导所致的家兔血小板聚集有强烈抑制作用,同时也能抑制血小板丙二醛的生成。对外源性花生四烯酸诱导的血小板聚集则无抑制作用。川芎嗪能加强家兔动脉环保温液对花生四烯酸诱导的血小板聚集的抑制作用。 给家兔静脉注射大剂量花生四烯酸钠盐,可使动物突然死亡。但如预先注射川芎嗪,则可使动物得到一定保护。     

L—精氨酸L—门冬氨酸盐对血小板功能的抑制

用血小板聚集、粘附、释放实验和出血时间测定观察L-精氨酸*L-门冬氨酸盐(DR)对血小板功能的作用。实验结果显示DR15mg/kg静脉给药,可明显抑制腺苷二磷酸(ADP)诱导的大鼠血小板聚集(P<0.01);15mg/kg单次口服给药可明显抑制ADP诱导的家兔血小板聚集;其药效可持续8h以上(P<0.01);DR7.5、15、30mg/kg灌胃给药(Bid×3.5d),可明显抑制ADP、胶原或凝血酶诱导的大鼠血小板聚集(P<0.01),并延长出血时间(P<0.05)。DR30mg/kg可明显抑制大鼠血小板粘附,并促进血管内皮释放前列环素(PGI2),但对活化的血小板释放血拴素(TXA2)无明显影响。本研究发现,DR可抑制血小板聚集和粘附功能,其作用机制不同于阿司匹林。这些作用部分是由于DR增加了血管内皮PGI2的释放。此结果为血小板功能的调节提供了新线索。     

葡萄籽中原花青素对实验动物主动脉收缩和血小板聚集的影响

目的:研究葡萄籽中原花青素(PA)对大鼠离体主动脉平滑肌收缩活动和兔血小板聚集的影响.方法:采用大鼠离体主动脉环灌流方法,记录主动脉环张力变化,观察PA对去甲肾上腺素(NA)和KCl预收缩大鼠离体主动脉平滑肌收缩反应的舒张作用以及对NA量效曲线的影响.比浊法测定兔血小板聚集.结果:PA能明显抑制NA(10-6mol/L)预收缩大鼠离体主动脉环的反应,使NA量效曲线压低,最大反应降低,此作用无内皮依赖性,但对KCl预收缩主动脉环的舒张作用无明显影响,也不影响花生四烯酸(AA),ADP和胶原(collagen)蛋白诱导的兔血小板聚集.结论:PA能对抗NA而不影响KCl诱导的大鼠离体主动脉平滑肌的收缩,不影响兔血小板聚集.     

Action mechanism of the platelet aggregation inducer and inhibitor from Echis carinatus snake venom

Platelet aggregation inducer and inhibitor were isolated from Echis carinatus snake venom. The venom inducer caused aggregation of washed rabbit platelets which could be inhibited completely by heparin or hirudin. The venom inducer also inhibit both the reversibility of platelet aggregation induced by ADP and the disaggregating effect of prostaglandin E₁ on the aggregation induced by collagen in the presence of heparin. The venom inhibitor decreased the platelet aggregation induced by collagen, thrombin, ionophore A23187, arachidonate, ADP and platelet-activating factor (PAF) with an IC₅₀ of around 10 μg/ml. It did not inhibit the agglutination of formaldehyde-treated platelets induced by polylysine. In the presence of indomethacin or in ADP-refractory platelets or thrombin-degranulated platelets, the venom inhibitor further inhibited the collagen-induced aggregation. Fibrinogen antagonized competitively the inhibitory action of the venom inhibitor in collagen-induced aggregation. In chymotrypsin-treated platelets, the venom inhibitor abolished the aggregation induced by fibrinogen. It was concluded that the venom inducer caused platelet aggregation indirectly by the conversion of prothrombin to thrombin, while the venom inhibitor inhibited platelet aggregation by interfering with the interaction between fibrinogen and platelets.     

Inhibition of platelet aggregation by S-(1,2-dicarboxyethyl)glutathione, intrinsic tripeptide in liver, heart, and lens

S-(1,2-Dicarboxyethyl)glutathione (DCE-GS) found in animal tissues or baker's yeast showed strong inhibitory effects on blood coagulation and platelet aggregation. The inhibitory effect of blood coagulation was almost the same as those of EDTA, oxalate, and citrate. DCE-GS did not show chelating activity. As for ADP- or thrombin-induced platelet aggregations, DCE-GS exerted a potent effect on the secondary aggregation, while it was less active in the primary aggregation. DCE-GS gave a distinct lag period in the time course of the secondary aggregation induced by collagen and inhibited most strongly the aggregation induced by arachidonic acid compared with those elicited by ADP, thrombin, and collagen. The peptide, however, did not inhibit the platelet aggregation induced by 12-O-tetradecanoylphorbol-13-acetate. Although both DCE-GS and EDTA inhibited the platelet aggregation which was triggered by ADP, their inhibitory manners were entirely different.     

Modulation of platelet activation by native DNA.

Native DNA (dsDNA) was found to induce the aggregation of isolated human platelets and the release of platelet 5HT; this activation was inhibited by both theophylline and TYA, suggesting a role for cAMP and metabolic products formed from arachidonate. By contrast, nonaggregating amounts of dsDNA inhibited platelet activation induced by collagen or thrombin. This inhibition, which could be overcome by use of greater amounts of the stimulatory agents, was not associated with the loss of platelet viability. Activation of platelets by dsDNA was not observed in plasma or in isolated platelet systems to which small amounts of cell-free plasma were added. However, dsDNA maintained in plasma its ability to inhibit platelet aggregation induced by collagen and thrombin. RNA and single-stranded DNA failed to induce platelet aggregation or release of 5HT and to block the platelet activation stimulated by dsDNA. Further, dsDNA did not significantly inhibit platelet aggregation in platelet-rich plasma stimulated by ADP or epinephrine. These data implicate dsDNA as a selective and potentially important activator and modulator of platelet responsiveness.     

Effect of low doses of ethanol on platelet function in long-life abstainers and moderate-wine drinkers

In vitro, high concentrations of ethanol (EtOH) reduce platelet aggregation. Less is known about the effect of low EtOH doses on platelet function in a selected human population of long-life abstainers and low moderate-wine drinkers to avoid rebound effect of EtOH on platelet aggregation. Results of our experiments suggest that moderate-wine drinkers have higher levels of high density lipoprotein (HDL) than long-life abstainers while fibrinogen levels are unchanged. Furthermore, platelets obtained from these individuals do not differ in their response when stimulated by agonists such as AA and collagen. The effect of in vitro exposure of low doses of EtOH has been studied in PRP and in washed platelets. EtOH (0.1-10 mM) inhibits platelet aggregation induced by collagen at its ED50 while is ineffective when aggregation was triggered by U-46619 and by 1 microM adenosine diphosphate (ADP). 5-10 mM EtOH partially reduces the second wave of aggregation induced by 3 microM ADP. 0.1-10 mM EtOH dose-dependently lowers the aggregation induced by AA at its ED50 but it is less effective at ED75 of AA. The antiaggregating effect of EtOH on aggregation induced by AA is unchanged by inhibitor of nitric oxide synthase. In addition, 10 mM EtOH reduces thromboxane (Tx) formation. In washed platelets, 1-10 mM EtOH partially inhibits platelet aggregation induced by thrombin. In washed resting platelets, 10 mM EtOH does not change the resting [Ca++]i while significantly reduces the increase in [Ca++]i triggered by AA. The results of ex vivo experiments have demonstrated that wine increases the HDL. However, this observation may or may not influence the response of platelets to agonists. Results of our studies demonstrate that low doses of alcohol reduces platelet function.     

Effect of salvianolic acids from Radix Salviae miltiorrhizae on regional cerebral blood flow and platelet aggregation in rats.

This study was conducted to observe the effect of salvianolic acids (SA) on regional cerebral blood flow (rCBF) in rats and on platelet aggregation in vitro and in vivo. Cerebral ischemia was produced in rats by occluding of the right middle cerebral artery, together with the right common carotid artery. rCBF was monitored by H2 clearance method with a tissue blood-flow meter. Platelet aggregation induced by collagen, ADP, and AA was measured in vitro and in vivo by platelet aggregometer. Doses of SA at 6 and 10 mg/kg body wt. (i.v.) improved rCBF in rats after ischemia, but had no obvious effect on normal rCBF. In vitro, SA inhibited significantly the platelet aggregation induced by collagen, ADP, and AA with IC50 values of 0.197, 2.22 and 3.29 x 10(3) mg/l, respectively. In vivo, doses of SA at 6 and 10 mg/kg body wt. inhibited significantly the platelet aggregation induced by collagen, and SA at 10 mg/kg body wt. inhibited remarkably platelet aggregation induced by ADP. The results suggest that SA could improve rCBF in the ischemic hemisphere and inhibit platelet aggregation in rats.     

Antiplatelet effects of acidamides isolated from the fruits of Piper longum L.

The inhibitory effects of four acidamides, piperine, pipernonaline, piperoctadecalidine, and piperlongumine, isolated from the fruits of Piper longum L. on washed rabbit platelet aggregation were examined. All of the four tested acidamides showed dose-dependent inhibitory activities on washed rabbit platelet aggregation induced by collagen, arachidonic acid (AA), and platelet-activating factor (PAF), except for that induced by thrombin. Piperlongumine, in particular, showed stronger inhibitory effects than other acidamides to rabbit platelet aggregation induced by collagen, AA and PAF.     

Reversal of platelet aggregation by aortic microsomes

The microsomal fraction of dog aortas inhibited human platelet aggregation induced by arachidonic acid, ADP, or thrombin. When aortic microsomes were added to a preparation of irreversibly aggregated platelets, the aggregates dispersed after 4–6 minutes. The fact that aortic microsomes inhibit platelet aggregation induced by ADP suggests that its effect is probably on the cellular function of platelets and not in direct competition against thromboxane A₂.     

Differential effects of dimethyl sulfoxide on human platelet aggregation and arachidonic acid metabolism

DMSO inhibited human platelet aggregation induced by ADP, AA, PAF, or collagen in a concentration-related manner, in vitro. DMSO was a more effective inhibitor for aggregation induced by ADP and collagen than PAF or AA. However, in vivo experiments on rabbits showed that DMSO did not protect rabbits against death from pulmonary platelet thrombosis induced by AA. On the other hand, DMSO (1-30% v/v) had no effect on thromboxane production by platelets incubated with [14C]AA. Moreover, DMSO stimulated PGE2 production by bovine seminal vesicle PG synthase. DMSO also stimulated the production of 12-HETE but inhibited the production of tri-HETE produced via lipoxygenase pathway. Since lipoxygenase products play an important role in inflammation, our data suggest that the anti-inflammatory effects of DMSO are probably not mediated via its action on AA metabolism.     

Effect of heparin on platelet aggregation in vitro

Heparin added to citrated platelet rich plasma influences shape change and aggregation of platelets in different ways. In the presence of heparin neither ADP nor collagen induces shape change, while shape change after thrombin or arachidonic acid remains unaltered. Heparin potentiates the first aggregation step induced by ADP and epinephrine but inhibits aggregation induced by thrombin and ristocetin. The second phase of aggregation and the release reaction are not directly influenced by heparin no matter which aggregation agent is used.