五种海藻多糖体外抗血小板聚集作用观察

本文主要对海带（Laminaria japenioa Aresch)、鼠尾藻[Sargassum thunbergil(Mert)o‘Kuntge]、萱藻[Scytosiphon Lomentarius(Lyngb)J.Ag]、石莼[Ulva.lactucal]、刚毛[Cladophora kutzing]5种海藻多糖的硫酸基含量以及体外抗血小板聚集作用进行了观察。结果发现,萱藻多糖的硫酸基含量及抗血小板聚集作用显著高于其他海藻多糖,其他依次为鼠尾藻、海带、石莼。刚毛多糖的抗血小板聚集的作用不显著。5种海藻多糖的抗凝血活性与其硫酸基含量呈显著正相关。     

4，5－二氢－6－［（苯乙酰基－哌嗪基）苯基］－5－甲基－3（2H）－哒嗪酮对血小板聚集，花生四烯酸代谢及cAMP含量的影响

４，５－二氢－６－［（苯乙酰基－哌嗪基）苯基］－５－甲基－３（２Ｈ）－达嗪酮（ＳＭＤ。）０．１一２．５ｐｍｏｌ·Ｌ能使血小板激活因子（ＰＡｎ及血栓素Ａ，类似物Ｕ４６６１９诱导的兔血小板聚集剂量一效应曲线不移且最大反应降低。其ｐＤ２分别为６．０±ｓ０．４及６．１±ｓ０．３ＳＭⅡ４还能抑制ＡＤＬ花生四烯酸（ＡＡ）及Ｕ４６６１９诱导的人血小板聚集，其ＩＣ（５０）分别是１２，１３及１．６μｍｏｌ．Ｌ．用放射性薄层层折及放射免疫测定法分别检测血小板ＡＡ代谢产物及ｃＡＭＰ含量表明，ＳＭⅡ４对血小板ＡＡ代谢没有显著影响，但能剂量依赖性地升高血小板内ｃＡＭＰ含量，ＰＡＦμｍｏｌ·Ｌ不能改变此作用     

新型环氧化酶-2抑制剂--西利科斯

西利科斯（ｃｅｌｅｃｏｘｉｂ）是新一代非甾体抗炎药（ＮＳＡＩＤｓ）,化学名:４［５＿（４＿甲基苯基）＿３＿（三氟甲基）＿１Ｈ＿吡唑＿１＿基］苯磺酰胺,系吡唑衍生物,具有选择性抑制环氧化酶＿２（ｃｙｃｌｏｏｘｙｇｅｎａｓｅ＿２，ＣＯＸ＿２）的作用,用于治疗骨关节炎（ＯＡ）和类风湿性关节炎（ＲＡ）。临床研究表明,西利科斯的抗炎、镇痛作用似双氯芬酸钠、萘普生,但胃肠耐受性好,无传统ＮＳＡＩＤｓ的致胃肠道溃疡、出血和抗血小板聚集的作用。１９９８年１２月１日经美国关节炎咨询委员会推荐,同月３１日ＦＤＡ批准用于ＯＡ…     

海带低分子量岩藻聚糖硫酸酯的制备和抗血小板聚集活性研究

目的：研究低分子量海带岩藻聚糖硫酸酯的制备和纯化技术,筛选抗血小板聚集活性的低分子量海带岩藻聚糖硫酸酯。方法：以海带硫酸多糖为原料,采用自由基降解和强阴离子交换色谱技术,制备纯化出高硫酸根和高岩藻糖的低分子量岩藻聚糖硫酸酯;采用体外凝血酶诱导血小板聚集模型,筛选出抗血小板聚集活性的低分子量岩藻聚糖硫酸酯。结果：强阴离子交换色谱能够有效地将复杂的低分子量海带岩藻聚糖硫酸酯分离纯化,得到4个纯度较高的高硫酸根、高岩藻糖的低分子量多糖,其岩藻糖含量超过85% ~ 95%,硫酸根含量35%以上,分子量在20 ku ~ 30 ku。体外抗血小板聚集试验结果证明,这4个高硫酸根高岩藻糖组分的抗血小板聚集活性最高,而低硫酸根组分含有较高的半乳糖、甘露糖和糖醛酸,其抗血小板活性非常低。结论：采用自由基氧化降解和强阴离子交换色谱法,可获得抗血小板活性高的高硫酸根高岩藻糖的低分子量岩藻聚糖硫酸酯。     

乙酰丹酚酸 A──一种新型血栓素合成酶抑制剂

乙酰丹酚酸Ａ一种新型血栓素合成酶抑制剂吁文贵徐理纳（中国医学科学院、中国协和医科大学药物研究所，北京１０００５０）乙酰丹酚酸Ａ（ａｃｅｔｙｌｓａｌｖｉａｎｏｌｉｃａｃｉｄＡ，ＡＳＡＡ）有抗血小板功能作用［１］，且能明显抑制花生四烯酸（ＡＡ）代谢产物血...     

硫酸多糖与动脉粥样硬化

动脉粥样硬化（ＡＳ）的发生、发展是一个十分复杂的病理过程。它涉及到血管内皮细胞（ＥＣ）、平滑肌细胞（ＳＭＣ）、炎性细胞（如单核细胞、巨噬细胞等）、淋巴细胞、血小板等多种细胞及相关细胞因子。许多研究发现硫酸多糖与ＡＳ存在密切的关系。大多报道表明硫酸多糖可保护ＥＣ免受各种刺激因子的损伤作用,从而阻断ＡＳ形成的起始环节;另外,硫酸多糖也可通过抑制ＶＳＭＣ增殖、迁移;减少炎性细胞、淋巴细胞、血小板等粘附、聚集到血管内膜;抑制补体的激活等多种途径来达到抗ＡＳ目的。但也有文献报道部分硫酸多糖反而促进ＡＳ形成。而且硫酸多糖的抗ＡＳ活性与其分子结构有关,所以ＡＳ与硫酸多糖的关系是一直存在争议的问题。     

4,5—二氢—6—[（苯乙酰基—哌嗪基）苯基]—5—甲基—3（2H）—哒…

４，５－二氢－６－［（苯乙酰基－哌嗪基）苯基］－５－甲基－３（２Ｈ）－达嗪酮（ＳＭⅡ４）０．１－２．５μｍｏｌ．Ｌ＾－＾１能使血小板激活因子（ＰＡＦ）及血栓素Ａ２类似物Ｕ４６６１９诱导的兔血小板聚集剂量一效应曲线左移且最大反应降低。其ｐＤ２分别为６．０±ｓ０．４及６．１±ｓ０．３．ＳＭⅡ４还能抑制ＡＤＰ，花生四烯酸（ＡＡ）及Ｕ４６６１９诱导的人血小板聚集，其ＩＣ５０分别是１．２，１．３及１．６．．     

中药海藻及数种同属植物的药理作用

对中药海藻海蒿子、羊栖菜及马尾藻科植物匐枝马尾藻、半叶马尾藻、鼠尾藻、铜藻和海黍子进行了药理研究。结果表明:7种海藻的LD_(50)>40g/kg;抗血小板聚集实验仅海黍子表现出较弱的抗凝活性(抑制率20.3％);抗肿瘤试验半叶马尾藻和匐枝马尾藻对小鼠S_(180)实体瘤抑制率分别为55.7％、53.1％;免疫药理实验海蒿子总多糖使小鼠肝脾的重量显著增加,胸腺增长受到显著抑制;海蒿子总多糖和羊栖菜总多糖对单核巨噬细胞的吞噬功能无显著作用。     

Dual effects of 5-hydroxytryptamine on stable analogue of thromboxane A~(2~_) induced aggregation and release reaction in rabbit platelets

目的：研究５ＨＴ对ＳＴＡ２血小板聚集和释放反应的影响及可能的分子机制．方法：以透光法，介质中ＡＴＰ含量及荧光图像法评价血小板变形，聚集反应和［Ｃａ２］ｉ水平．结果：（１）５ＨＴ预处理可消除ＳＴＡ２的血小板变形，ＳＴＡ２０３μｍｏｌ·Ｌ－１的聚集增强，ｌ－３μｍｏｌ·Ｌ－１的聚集不变，释放反应抑制．（２）５ＨＴ预处理增加ＳＴＡ２０３μｍｏｌ·Ｌ－１的［Ｃａ２＋］ｉ，降低３μｍｏｌ·Ｌ－１的［Ｃａ２＋］ｉ降低．（３）延长加入５ＨＴ和ＳＴＡ２的间隔，ＳＴＡ２０３μｍｏｌ·Ｌ－１的聚集增强，３μｍｏｌ·Ｌ－１的聚集不变，释放反应抑制．结论：５ＨＴ对ＳＴＡ２介导的聚集和释放反应有双重影响．对ＳＴＡ２［Ｃａ２＋］ｉ的调节可能是上述反应的分子机制．     

得自小根蒜及薤中的几种含氮化合物

从中药薤白的主要基源植物小根蒜（ＡｌｌｉｕｍｍａｃｒｏｓｔｅｍｏｎＢｕｎｇｅ）鳞茎中首次分得５种化合物。它们是腺苷（Ａｄｅｎｏｓｉｎｅ，１）、胸苷（Ｔｈｙｍｉｄｉｎｅ，２）、２，３，４，９－四氢－１－甲基－１Ｈ－吡啶骈［３，４－ｂ］吲哚－３－羧酸（２，３，４，９－ｔｅｔｒａｈｙｄｒｏ－１－ｍｅｔｈｙｌ－１Ｈ－ｐｙｒｉｄｏ［３，４－ｂ］ｉｎｄｏｌｅ－３－ｃａｒｂｏｘｙｌｉｃａｃｉｄ，３）、２，３，４，９－四氢－１Ｈ－吡啶骈［３，４－ｂ］吲哚－３－羧酸（２，３，４，９－ｔｅｔｒａｈｙｄｒｏ－１Ｈ－ｐｙｒｉｄｏ［３，４－ｂ］ｉｎｄｏｌｅ－３－ｃａｒｂｏｘｙｌｉｃａｃｉｄ，４）和丁香甙（Ｓｙｒｉｎｇｉｎ，５）．从另一种基源植物薤（Ａ．ｃｈｉｎｅｎｓｅＧ．Ｄｏｎ）鳞茎中分得腺苷（１）、色氨酸（Ｔｒｙｐｔｏｐｈａｎ，６）和化合物（４）．     

Inhibitory mechanism of ifenprodil tartrate on rabbit platelet aggregation

The effects of dl-erythro-4-benzyl-alpha-(4-hydroxyphenyl)-beta-methyl-l-piperidine-eth anol tartrate (ifenprodil tartrate) on rabbit platelet aggregation in vitro and ex vivo were studied. Ifenprodil tartrate inhibited platelet aggregation in vitro induced by ADP, collagen and epinephrine. It also inhibited 5-hydroxytryptamine (5-HT) uptake into platelets and 5-HT release from platelets. Since these inhibitory effects of ifenprodil tartrate on the functions of rabbit platelets were similar to the effects of imipramine, the effects of ifenprodil tartrate may be due to the stabilizing action of ifenprodil tartrate on the platelet membrane. The platelet aggregation by ADP was significantly inhibited in rabbits after oral administration of ifenprodil tartrate, the maximal plasma level of ifenprodil being reached at 20 ng/ml ex vivo, while the maximal level was only 1/40 of the minimal concentration of ifenprodil tartrate necessary to inhibit platelet aggregation in vitro. These results indicate that factors other than ifenprodil tartrate acting directly on the platelets (e.g., PGI2 which is an endogenous inhibitor of platelet aggregation) are involved in inducing the inhibitory effects of ifenprodil tartrate on platelet aggregation ex vivo. The effects of ifenprodil tartrate on both PGI2 release from the aorta and the inhibitory effects of PGI2 on platelet aggregation in vitro were investigated: PGI2 was found to intensify the inhibitory effects of ifenprodil tartrate on platelet aggregation in vitro, but there was little effect, if any, on PGI2 release. Therefore, it is considered that the ex vivo effects of ifenprodil tartrate might be due to its interaction with endogenous PGI2 in the blood.     

The mode for the manifestation of the inhibitory effects of ifenprodil tartrate on platelet aggregation in vivo and ex vivo

The mode for the manifestation of the inhibitory effect of ifenprodil tartrate on platelet aggregation in vivo and ex vivo was studied in mice and men, respectively. The ifenprodil level in plasma reached the maximum in 20 min after oral administration of 30 mg ifenprodil tartrate/kg in mice, and it decreased over a 3 hr period after the administration. On the other hand, the maximal inhibitory effect was observed 60 min after the administration. Thus ifenprodil tartrate manifested its inhibitory effect on platelet aggregation only after the maximum plasma concentration of ifenprodil was reached. The same phenomenon was observed with the inhibitory effects of ifenprodil tartrate on platelet aggregation ex vivo in man. To clarify the reason for the delay in the manifestation of the inhibitory effects of ifenprodil, the ifenprodil contents in mouse platelets after the oral administration of the drug was measured. The pattern of change in the ifenprodil contents in platelets was found to resemble closely the pattern of the change in its inhibitory effects, suggesting that the manifestation of the inhibitory effects on platelet aggregation by oral administration of ifenprodil tartrate was directly related to the ifenprodil contents in platelets rather than the ifenprodil level in plasma.     

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.     

Aggregation of human peripheral blood mononuclear cells by calcium ionophore A23187. Comparison with the aggregation of platelets and defective response in Glanzmann's thrombasthenia

Following exposure to calcium ionophore A23187, washed peripheral blood mononuclear cells (MNC) aggregated and formed thromboxane, like platelets. However, while aspirin strongly inhibited platelet aggregation and thromboxane formation, it had a little effect on the aggregation of MNC. In about 50% of the samples studied, aggregation of MNC was associated with the secretion of ATP. However studies in which exogenous ATP or ADP were used, suggested that the aggregation of MNC is independent of the secretion of nucleotides. MNC from 2 thrombasthenic patients failed to aggregate and bound 9-10 fold less radiolabelled fibrinogen than those from normals when challenged with A23187. However, fibrinogen, which plays a major role in the aggregation of platelets, did not appear to be involved in the aggregation of MNC. A differing behavior of these two types of cells was also found when the effect of plasma was studied on the aggregation response to A23187. Indeed, citrated plasma greatly enhanced the aggregation of platelets while it suppressed the response to MNC. This inhibitory effect of plasma was not detected when heparinized plasma was substituted for citrated plasma. We conclude that the aggregation of MNC in response to A23187 does not involve basic events known to play a major role in the aggregation of platelets. The response to A23187 may be an important probe for understanding basic mechanisms and pathophysiological significance of the aggregation of MNC.     

The influence of acetysalicylic acid on changes in platelet function due to physical exertion

The influence of acetylsalicylic acid (ASA) on alterations of the platelets resulting from physical exertion was studied in 10 healthy volunteers. Before and 2 h after the administration of placebo or 1 g ASA, venous blood samples were taken for platelet counts, thrombelastography (TEG) and tests of ADP- and epinephrine-induced platelet aggregation. The blood in which the 2-h values were determined was sampled at the highest work-load during sub-maximum exercise on a bicycle ergometer (5 min each at 50, 100 and 150 watts). ASA had no effect on the alterations of the platelets due to physical effort: the increase in the first phase of epinephrine-induced aggregation, the elevation of the platelet count and the hypercoagulability demonstrable by TEG still persisted after the administration of ASA. Some effects were noted, however, that are also observed after the administration of ASA at rest: the second phase of epinephrine-induced aggregation was suppressed and disaggregation after induction with ADP was accelerated.     

Prednisolone exerts exquisite inhibitory properties on platelet functions

We have previously reported presence of the glucocorticoid (GC) receptor (GR) alpha on blood platelets, and its ability to modulate platelet aggregation when activated by the synthetic GC prednisolone (Pred). In the present study we investigated the effects of Pred on broader aspects of platelet functions to unveil novel non-genomic actions on this cell type. Using whole blood assay we demonstrated that Pred was the only GC able to inhibit platelet aggregation and platelet–monocyte interactions. This latter effect was due to regulation of platelets, not monocytes. We next examined the effects of Pred on physiological actions of platelets, observing inhibition of platelet adhesion and spreading on collagen under static conditions. Moreover Pred inhibited thrombus formation under flow, suggesting potential important effects in haemostasis and thrombosis. Pred was unable to regulate platelet reactivity under conditions where the effects of platelet-derived ADP and TxA₂ were blocked, suggesting that the GC targeted the activation-dependent component of the adhesion and aggregation response. The effects of Pred were not mediated through cyclic nucleotide signaling, but rather seemed to evolve around selective regulation of P2Y₁₂ ADP receptor signaling, intimating a novel mode of action. This study details the actions of Pred on platelets unveiling novel properties which could be relevant for this GC in controlling unwanted vascular and thrombotic diseases.     

Inhibition of human platelet aggregation by a novel S-nitrosothiol is abolished by haemoglobin and red blood cells in vitro: implications for anti-thrombotic therapy

1. S-Nitrosothiols are nitric oxide (NO) donor drugs that have been shown to inhibit platelet aggregation in platelet rich plasma (PRP) in vitro and to inhibit platelet activation in vivo. The aim of this study was to compare the platelet effects of a novel S-nitrosated glyco-amino acid, RIG200, with an established S-nitrosothiol, S-nitrosoglutathione (GSNO) in PRP, and to investigate the effects of cell-free haemoglobin and red blood cells on S-nitrosothiol-mediated inhibition of platelet aggregation. 2. The effects of GSNO and RIG200 in collagen (2.5 microg ml(-1))-induced platelet aggregation in PRP and whole blood were investigated in vitro. Both compounds were found to be powerful inhibitors of aggregation in PRP, and RIG200 was significantly more potent (IC(50)=2.0 microM for GSNO and 0.8 microM for RIG200; P=0.04). 3. Neither compound inhibited aggregation in whole blood, even at concentrations of 100 microM. Red blood cell concentrations as low as 1% of the haematocrit, and cell-free haemoglobin (> or = 2.5 microM), significantly reduced their inhibitory effects on platelets. 4. Experiments involving measurement of cyclic GMP levels, electrochemical detection of NO and electron paramagnetic resonance of haemoglobin in red blood cells, indicated that scavenging of NO generated from S-nitrosothiols by haemoglobin was responsible for the lack of effect of S-nitrosothiols on platelets in whole blood. 5. These studies suggest that scavenging of NO by haemoglobin in blood might limit the therapeutic application of S-nitrosothiols as anti-platelet agents.     

Adhesion of blood platelets to electric-featuring polymers]

The authors studied the effect of electric potential arising on the plastic surface upon the blood clotting process. The study was performed according to the Breddin method. The study concerned fluorosilicone rubber, fluoroplast, polyester, polyethylene and polyvinyl chloride with various surface potentials. The authors found that the negatively charged blood platelets adhere to negatively charged plastic surfaces only to a low extent and undergo no disintegration and agglomeration. To the surfaces of the same plastics being electrically neutral, only small aggregates of blood platelets adhere. On the other hand, on the positively charged surfaces the accumulation of blood platelets takes place with concurrent aggregation and disintegration, thus initiating the thrombus formation. The authors observed the intensity of these changes using blood platelet adhesion index and fluorescence microscope.     

A comparative study of platelets behaviour in controls and acute myocardial infarction patients

Acute myocardial infarction is one of the leading vascular diseases. Platelet-endothelium plays a crucial role in its etiopathogenesis. The present study was undertaken to compare the platelet aggregability in controls and acute myocardial infarction patients along with its effect on the peripheral platelet count. The work was conducted in five patients from ICCU and 5 controls between the age group of 40-60 years by using Chronolog Dual Channel Aggrometer with ADP and epinephrine as agonists. The platelets were counted by hemocytometry. The results were statistically analysed by Student's 't' test which was found to be significant. There was increase in the aggregation index in patients compared to controls. It was also observed that the degree of increase was more with ADP than epinephrine. Relatively, there was tendency of low platelet count. The increase in the aggregation index can be attributed to the hyperreactiveness of the platelets to ADP than epinephrine. The relative thrombocytopenia can be accounted to the sequestration of platelets in the coronary microvasculature. In conclusion, balance between EDRF and EDCF determines the platelet activation.