银杏内酯B对内皮细胞的保护作用及分子机制研究

目的探讨银杏内酯B对氧化型低密度脂蛋白刺激脐静脉内皮细胞保护作用的分子机制。方法分别用银杏内酯B 0.2、0.4、0.6 g.L-1预孵育内皮细胞1 h,再加入ox-LDL(0.1 g.L-1)刺激细胞。用Western blot检测Lectin-likeoxidized LDL receptor-1(LOX-1)、PI3K、Nrf2、SIRT1表达及Akt磷酸化。结果 1.ox-LDL刺激内皮细胞LOX-1表达增加,银杏内酯B以剂量依赖方式抑制了LOX-1表达。2.银杏内酯B有效地抑制了ox-LDL刺激的Akt磷酸化,但对PI3K的表达无影响。3.ox-LDL刺激内皮细胞SIRT1表达降低,银杏内酯B有意义地增加了细胞SIRT1表达。4.ox-LDL刺激细胞抗氧化应激蛋白Nrf2表达明显增加,银杏内酯B下调了Nrf2的表达。结论银杏内酯B对内皮细胞保护作用与抑制LOX-1表达、Akt磷酸化,启动细胞内源性保护机制相关。     

银杏内酯B抑制高糖诱导内皮细胞TLR4及炎症蛋白表达

目的评价银杏内酯B对高糖诱导内皮细胞TLR4表达的影响以及分子机制。方法使用人原代脐静脉内皮细胞,用高糖刺激内皮细胞,用Western blot分析TLR4、炎症蛋白表达以及Akt磷酸化。免疫荧光检测NF-κB核转位。结果高糖(30 mmol·L-1)刺激内皮细胞TLR4和PAF受体表达明显增加,PAF受体抑制剂银杏内酯B(0.6 g·L-1)和CV3988(30μmol·L-1)分别抑制了TLR4及PAF受体表达。银杏内酯B有效地抑制了高糖刺激内皮细胞ICAM-1、VCAM-1表达。分子机制的研究表明,银杏内酯B明显抑制了高糖诱导的Akt磷酸化,以及NF-κB p65的核转位。结论高糖刺激内皮细胞TLR4和PAF受体表达增高,银杏内酯B能够抑制高糖刺激TLR4、PAF受体和炎症蛋白表达,分子机制与抑制Akt磷酸化以及NF-κB活化相关。     

银杏内酯B抑制中性粒细胞活化的研究

目的 研究银杏内酯B(GB,抗血小板聚集)抑制血小板活化因子(PAF)介导的中性粒细胞活化.方法 将银杏内酯B加入抗凝全血中,阻断PAF对中性粒细胞活化;用PAF及二磷酸腺苷(ADP)活化下述各组的中性粒细胞,包括对照组、PAF组、PAF+GB组、ADP组和ADP+GB组,用流式细胞术检测中性粒细胞整和素(CD11b)平均荧光强度.结果 PAF及ADP均可明显增加中性粒细胞CD11b的平均荧光强度,银杏内酯B可明显抑制PAF及ADP诱导的CD11b的平均荧光浓度.结论 银杏内酯B可明显抑制PAF介导的中性粒细胞活化.     

斑蝥素经PI3K/Akt/PKC通路对血小板功能的调控作用北大核心CSCD

目的 探讨斑蝥素(Cantharidin,CTD)对血小板功能的影响和抗血小板聚集的作用机制。方法 采集健康志愿者静脉血,提取洗涤血小板,聚集仪检测CTD(2.5、5、10μmol·L^(-1))对胶原、凝血酶、ADP和佛波酯(Phorbol-12-myristate-13-acetate,PMA,PKC激动剂)诱导的血小板聚集,和对ATP释放的影响。荧光显微镜拍照观察CTD对纤维蛋白原表面的血小板扩展功能和对血小板斑块回缩的影响。检测CTD联用740Y-P(PI3K特异性激动剂)对胶原诱导血小板的聚集率,Western blot检测PI3K蛋白磷酸化水平。小鼠腹腔注射CTD(0.35、0.7 mg·kg^(-1))和阿司匹林(30 mg·kg^(-1)),观察胶原诱导各组离体血小板聚集率,检测PI3K、Akt和PKC蛋白磷酸化水平,检测凝血指标凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)和小鼠断尾流血时间。结果 CTD抑制胶原、凝血酶和PMA诱导的血小板聚集和抑制ATP释放,对ADP诱导的血小板聚集无影响,CTD抑制血小板扩展和斑块回缩,740Y-P处理能够减弱CTD对胶原诱导的血小板聚集的抑制作用。CTD抑制离体血小板聚集功能和PI3K、Akt和PKC磷酸化水平,延长APTT和小鼠尾巴出血时间。结论 CTD抑制血小板聚集、释放、扩展、斑块回缩和影响止血功能,其机制与调控PI3K、Akt和PKC蛋白磷酸化水平有关。     

抑制PI3K/Akt信号通路对HER-2/neu诱导的Ishikawa细胞增殖的影响

目的研究抑制磷脂酰肌醇3激酶(PI3K)/蛋白激酶B(Akt)信号通路对表皮生长因子受体2(HER-2/neu)诱导的雌激素依赖性子宫内膜癌细胞增殖的拮抗作用。方法①表皮生长因子(EGF)处理Ishika-wa细胞株及转染HER-2/neu的Ishikawa细胞株,蛋白印迹法检测转染细胞前后总Akt(t-Akt)及磷酸化Akt(p-Akt)蛋白、环氧化酶(COX)-2蛋白的表达。酶联免疫吸附试验(ELISA)方法检测细胞培养上清液中雌二醇(E2)的含量。②用PI3K/Akt的抑制剂LY294002抑制信号通路,以不同时间(浓度为20μmol/L时,分别作用10,20,40和60min)和不同浓度(5,10,20和40μmol/L)作用30min后,再次检测COX-2的表达水平,ELISA检测E2水平。结果 HER-2/neu可引起子宫内膜癌细胞Akt活化,经EGF刺激后p-Akt/t-Akt比值、COX-2及细胞上清液中E2的表达量在转染组显著高于未转染组(P<0.05)。应用抑制剂抑制PI3K/Akt通路后,转染HER-2/neu的Ishikawa细胞株中COX-2的表达水平低于正常的Ishikawa细胞株,同时细胞上清液中肿瘤E2的含量于转染HER-2/neu的Ishikawa细胞株明显低于正常Ishikawa细胞株(P<0.05);随药物浓度的增加及作用时间的延长,2组细胞COX-2及E2的表达均逐渐减少,且抑制作用与浓度及作用时间呈依赖关系。结论 HER-2/neu可能通过PI3K/Akt通路来诱导COX-2的转录,进而导致雌激素的分泌增多,使子宫内膜癌细胞无限生长。     

去氢丹参新酮对神经炎症的抑制作用及机制研究

目的研究去氢丹参新酮对脂多糖(lipopolysaccharide,LPS)诱导小胶质细胞系BV2细胞产生炎症反应的抑制作用及其作用机制。方法不同浓度去氢丹参新酮预孵育BV2细胞后,用LPS刺激引起神经炎症相关反应。Griess试剂法检测去氢丹参新酮对活化的BV2细胞产生一氧化氮(nitric oxide,NO)的影响,ELISA检测细胞上清液中TNF-α和IL-6的释放量,Confocal观察小胶质细胞表面活化标志物MAC-1表达量的变化,Western blot检测炎症相关信号通路蛋白表达的变化。结果去氢丹参新酮可明显抑制LPS刺激BV2细胞产生的炎症因子包括NO、TNF-α和IL-6的水平,同时抑制一氧化氮合酶、环氧合酶-2等炎症相关蛋白的表达和小胶质细胞表面活化标志物MAC-1的表达。机制研究发现,去氢丹参新酮对PI3K/Akt的过度磷酸化以及NF-κB的过度活化都有明显的抑制作用。结论去氢丹参新酮具有很好的抑制神经炎症活性,其作用机制可能是通过PI3K/Akt信号通路抑制NF-κB的活化而实现的。     

银杏内酯B抑制高糖诱导内皮细胞凋亡及机制研究

目的探讨银杏内酯B对高糖诱导的内皮细胞凋亡的影响及相关的分子机制。方法使用脐静脉血管内皮细胞作为细胞模型,分为对照组、高糖组、银杏内酯B处理组。用Transwell实验检测内皮细胞迁移,AnnexinⅤ试剂盒检测细胞凋亡,荧光试剂盒检测活性氧(reactive oxygen species,ROS)水平,Western blot检测Bax,Bcl-2,caspase-3的表达以及p53的磷酸化。结果高糖(30 mmol·L~(-1))处理组内皮细胞迁移数量明显降低,迁移率为(66.6±15.6)%,而银杏内酯B(0.6 g·L~(-1))处理增加了内皮细胞的迁移数量,迁移率为(94.8±11.4)%。高糖处理导致内皮细胞ROS水平增高2.75倍,与高糖处理组比较,0.6 g·L~(-1)银杏内酯B完全抑制了高糖诱导的ROS产生。流式细胞仪分析表明,高糖刺激内皮细胞凋亡率为(53.8±2.6)%,银杏内酯B处理组内皮细胞凋亡率为(44.0±3.1)%。对凋亡相关蛋白的分析表明,高糖组Bax、caspase-3表达增加,Bcl-2表达降低,银杏内酯B处理抑制了Bax、caspase-3表达,并增加了Bcl-2表达。此外,高糖处理增加了内皮细胞p53表达及磷酸化,而银杏内酯B抑制高糖刺激的p53活化。结论银杏内酯B能抑制高糖诱导的内皮细胞凋亡,改善内皮细胞迁移功能,对高糖引起的内皮细胞损伤具有保护作用。     

Apelin促大鼠血管平滑肌细胞增殖的PI3K／Akt信号通路研究

目的：研究G蛋白偶联受体APJ的内源性配体多肽apelin-13是否通过P13K／Akt信号通路影响血管平滑肌细胞（vascular smooth muscle cells,VSMCs）的牛长增殖,发现apelin—APJ系统促血管平滑肌细胞增殖的新的信号转导机制;方法：培养大鼠胸主动脉血管平滑肌细胞,噻唑蓝比色法（MTT）观察VSMCs增殖;Westernblot检测P13K等信号蛋门表达。结果：Western blot检测结果显尔,apelin-13（0、0．5、1、2、4gmol／L）刺激大鼠血管平滑肌细胞P13K磷酸化、Akt磷酸化增加,以1p．M最为明显;lgMapelin-13分别刺激大鼠VSMCs0、5、15、30、45、60min,P13K磷酸化、Akt磷酸化表达在30min时最为明显,P13K阻断剂LY294002明显抑制apelin-13诱导的P13K磷酸化及Akt磷酸化表达,Akt阻断剂1701．1明显抑制apelin—13诱导的Akt磷酸化、ERK1／2磷酸化及cyclinDl表达,MTT法显示P13K抑制剂LY294002和Akt抑制剂1701—1能明显抑制apelin--13诱导的VSMCs增殖;结论：Apelin-13通过P13K／Akt信号转导通路促进大鼠血管平滑肌细胞增殖。     

牛蒡子苷元通过抑制PI3-K/Akt信号通路诱导肝癌细胞凋亡

目的 探讨天然木脂素类化合物牛蒡子苷元对肝癌细胞生长的抑制作用及其可能机制。方法 采用不同浓度的牛蒡子苷元处理HepG2 和Hep3B 细胞,通过MTT 法检测细胞增殖情况,流式细胞术检测细胞凋亡及细胞周期,免疫印迹检测细胞中caspase-9 和caspase-3 的活化情况以及抗凋亡蛋白的表达。进一步通过转染Akt 质粒以及使用PI3K 抑制剂,探讨牛蒡子苷元对肝癌细胞PI3K/Akt 信号通路的影响。结果 牛蒡子苷元能以浓度依赖性方式显著抑制肝癌细胞增殖并促进其凋亡,同时抑制肝癌细胞中PI3K/Akt 信号通路活化,降低抗凋亡蛋白Bcl-xL、Mcl-1 和survivin 的表达,抑制mTOR 和S6K 的磷酸化;细胞过表达Akt 活化蛋白后可抑制牛蒡子苷元的上述效应,而PI3K 抑制剂联合作用可增强上述效应。结论 牛蒡子苷元可通过抑制PI3K/Akt 信号通路下调抗凋亡蛋白的表达进而促进肝癌细胞凋亡。     

银杏内酯B对脂多糖刺激的小鼠腹腔巨噬细胞TNFα生成及大鼠胸腔多形核白细胞NF-кB活化的影响

目的研究银杏内酯B对脂多糖刺激的小鼠腹腔巨噬细胞TNFα生成及大鼠胸腔多形核白细胞NF-κB活化的影响.方法用L929细胞结晶紫染色法检测TNFα的含量,用电泳迁移率改变检测法检测NF-κB的结合活性.结果1和10 μmol·L-1银杏内酯R能够显著抑制LPS刺激的小鼠腹腔巨噬细胞TNFα的生成,其IC50为0.26μmol·L-1:1 mg·L-1LPS和1 nmol·L-1PAF均可活化大鼠胸腔多形核白细胞NF-κB;银杏内酯B能够抑制LPS或PAF刺激的NF-κR活化.结论银杏内酯B能够抑制LPS刺激的小鼠腹腔巨噬细胞TNFα生成及大鼠胸腔多形核白细胞NF-κB的活化.PAF参与LPS激活NF-κB的过程.     

Amyloid beta peptide-activated signal pathways in human platelets

Amyloid beta peptide (amyloid-beta), which accumulates in the cerebral microvessels in an age-dependent manner, plays a key role in the pathogenesis of cerebral amyloid angiopathy. Platelets are an important cellular element in vasculopathy of various causes. Amyloid-beta may activate or potentiate platelet aggregation. The present study explored the signaling events that underlie amyloid-beta activation of platelet aggregation. Platelet aggregometry, immunoblotting and assays to detect activated cellular events were applied to examine the signaling processes of amyloid-beta activation of platelets. Exogenous amyloid-beta (1-2 microM) potentiated platelet aggregation caused by collagen and other agonists. At higher concentrations (5-10 microM), amyloid-beta induced platelet aggregation which was accompanied by an increase in thromboxane A2 (TxA2) formation. These amyloid-beta actions on platelets were causally related to amyloid-beta activation of p38 mitogen-activated protein kinase (MAPK). Inhibitors of p38 MAPK and its upstream signaling pathways including proteinase-activated receptor 1 (PAR1), Ras, phosphoinositide 3-kinase (PI3-kinase), or Akt, but not extracellular signal-regulated kinase 2 (ERK2)/c-Jun N-terminal kinase 1 (JNK1), blocked amyloid-beta-induced platelet activation. These findings suggest that the p38 MAPK, but not ERK2 or JNK1 pathway, is specifically activated in amyloid-beta-induced platelet aggregation with the following signaling pathway: PAR1 --> Ras/Raf --> PI3-kinase --> Akt --> p38 MAPK --> cytosolic phospholipase A2 (cPLA2)--> TxA2. In conclusion, this study demonstrates amyloid-beta activation of a p38 MAPK signaling pathway in platelets leading to aggregation. Further studies are needed to define the specific role of amyloid-beta activation of platelets in the pathogenesis of vasculopathy including cerebral amyloid angiopathy.     

Inhibitory effect of 8-bromo cyclic GMP on an extracellular Ca2+-dependent arachidonic acid liberation in collagen-stimulated rabbit platelets

The inhibitory effect of cyclic GMP on collagen-induced platelet activation was studied using 8-bromo cyclic GMP (8brcGMP) in washed rabbit platelets. Addition of collagen (1 micrograms/ml) to platelet suspension caused shape change and aggregation associated with thromboxane (TX) A2 formation. 8brcGMP (10-1000 microM) inhibited collagen-induced platelet aggregation and TXA2 formation in a concentration-dependent manner. 8brcGMP did not affect platelet cyclooxygenase pathways, but markedly inhibited collagen-induced arachidonic acid (AA) liberation from membrane phospholipids in [3H]AA-prelabeled platelets, indicating that the inhibitory effect of 8brcGMP on collagen-induced aggregation is due to an inhibition of AA liberation. In [32P]orthophosphate-labeled platelets, collagen stimulated phosphorylation of a 20,000 dalton (20-kD) and 40-kD proteins. 8BrcGMP stimulated phosphorylation of a specific protein having molecular weight of 46-kD and inhibited collagen-induced both 20- and 40-kD protein phosphorylation. Collagen could stimulate the AA liberation without activation of phospholipase C or Na+-H+ exchange, but could not in the absence of extracellular Ca2+. These findings suggest that cyclic GMP inhibits collagen-induced AA liberation which is mediated by an extracellular Ca2+-dependent phospholipase A2. However, cyclic GMP seems to inhibit the Ca2+-activated phospholipase A2 indirectly, since 8brcGMP had no effect on Ca2+ ionophore A23187-induced platelet aggregation or AA liberation. It is therefore suggested that cyclic GMP may regulate collagen-induced increase in an availability of extracellular Ca2+ which is responsible for phospholipase A2 activation in rabbit platelets.     

Strains of Group B streptococci from septic patients induce platelet activation via Toll‐like Receptor 2

Group B Streptococcus (GBS) causes life‐threatening bacterial sepsis, especially in newborns and pregnant women. Patients suffering from sepsis often display low platelet counts, characterized by thrombocytopenia, because of platelet activation. In the present study, the roles of six GBS strains from septic patients in platelet aggregation, as well as the underlying mechanisms, were investigated. Incubation of platelets with three of the strains induced platelet aggregation, increased the secretion of cellular adhesin molecule CD62P and activation of GPIIb/IIIa. Furthermore, the GBS strains that induced platelet activation also caused an increase in the expression of Toll‐like receptor (TLR) 2 in platelets. Pre‐incubation of platelets with anti‐TLR2 monoclonal antibody, but not anti‐TLR4 monoclonal antibody, inhibited these functional responses induced by GBS. TLR2 stimulation also activated the phosphoinositide 3‐kinase (PI3‐K)/Akt signalling pathway in platelets, and inhibition of PI3‐K significantly reduced GBS‐induced platelet responses. Our results indicate that three of the GBS strains from the septic patients can trigger platelet activation by interacting with platelets, which involves the elevation of platelet TLR2 expression.     

Sphingosylphosphorylcholine,a naturally occurring lipid mediator,inhibits human platelet function

1 The lysophospholipids, lysophosphatidic acid and sphingosine 1-phosphate, have been reported to activate platelets. Here we examined effects of the naturally occurring related sphingosylphosphorylcholine (SPC) on human platelet function. 2 Platelet activation was determined as aggregation, elevation of intracellular Ca(2+) concentrations, surface expression of P-selectin, GP 53, and GP IIb/IIIa neoepitope PAC-1, and of fibrinogen binding to the platelet surface. 3 Platelets were activated by ADP (5 and 20 micro M), the thrombin receptor-activating peptide TRAP-6 (5 and 20 micro M), the thromboxane A(2) mimetic U-46619 (1 micro M) and collagen (20 and 50 micro g ml(-1)) but not by SPC (up to 20 micro M). 4 SPC concentration-dependently (IC(50) approximately 1-10 micro M) inhibited activation of washed human platelets in response to all of the above agonists, with almost complete inhibition occurring at 20 micro M SPC. 5 The SPC stereoisomers, D-erythro SPC and L-threo SPC, exhibited similar concentration-response curves in inhibiting 20 micro M ADP-induced platelet aggregation, suggesting that SPC did not act via specific lysophospholipid receptors. 6 Although SPC slightly activated platelet protein kinase A (as assessed by VASP phosphorylation), this effect could not explain the marked platelet inhibition. Possible protein kinase C inhibition also did not explain the inhibition of platelet activation by SPC. On the other hand, SPC suppressed agonist-induced Ca(2+) mobilization and phospholipase C stimulation. 7 These results indicate that the lysophospholipid SPC is an effective inhibitor of human platelet activation, apparently primarily by uncoupling agonist-activated receptors from their effectors.     

Ginkgolide C reduced oleic acid-induced lipid accumulation in HepG2 cells

Ginkgolide C, isolated from Ginkgo biloba, is a diterpene lactone that has multiple biological functions and can improve Alzheimer disease and platelet aggregation. Ginkgolide C also inhibits adipogenesis in 3T3-L1 adipocytes. The present study evaluated whether ginkgolide C reduced lipid accumulation and regulated the molecular mechanism of lipogenesis in oleic acid-induced HepG2 hepatocytes. HepG2 cells were treated with 0.5?mM oleic acid for 48?h to induce a fatty liver cell model. Then, the cells were exposed to various concentrations of ginkgolide C for 24?h. Staining with Oil Red O and the fluorescent dye BODIPY 493/503 revealed that ginkgolide C significantly reduced excessive lipid accumulation in HepG2 cells. Ginkgolide C decreased peroxisome proliferator-activated receptor γ and sterol regulatory element-binding protein 1c to block the expression of fatty acid synthase. Ginkgolide C treatment also promoted the expression of adipose triglyceride lipase and the phosphorylation level of hormone-sensitive lipase to enhance the decomposition of triglycerides. In addition, ginkgolide C stimulated CPT-1 to activate fatty acid β-oxidation, significantly increased sirt1 and phosphorylation of AMP-activated protein kinase (AMPK), and decreased expression of acetyl-CoA carboxylase for suppressed fatty acid synthesis in hepatocytes. Taken together, our results suggest that ginkgolide C reduced lipid accumulation and increased lipolysis through the sirt1/AMPK pathway in oleic acid-induced fatty liver cells.     

Effects of Ginkgolide A on Okadaic Acid-induced Tau Hyperphosphorylation and the PI3K-Akt Signaling Pathway in N2a Cells

Alzheimer's disease is the most common form of dementia leading to the irreversible loss of neurons, and Tau hyperphosphorylation has an important role in the pathology of Alzheimer's disease. Ginkgolide A is one of the active components of Ginkgo biloba extracts which has been proven to have neuroprotective effects, but the effect of ginkgolide A on Tau hyperphosphorylation has not yet been reported. In this study, the effects of ginkgolide A on cell viability, Tau hyperphosphorylation, and the PI3K-Akt signaling pathway in N2a cell lines were explored, and methods such as the MTT assay, ELISA, and Western blots techniques were used. The results showed that ginkgolide A could increase cell viability and suppress the phosphorylation level of Tau in cell lysates, meanwhile, GSK3β was inhibited with phosphorylation at Ser9. Moreover, treatment of the cells with ginkgolide A promoted phosphorylation of PI3K and Akt, suggesting that the activation of the PI3K-Akt signaling pathway may be the mechanism for ginkgolide A to prevent the intracellular accumulation of p-Tau induced by okadaic acid and to protect the cells from Tau hyperphosphorylation-related toxicity.     

Isofraxidin ameliorated influenza viral inflammation in rodents via inhibiting platelet aggregation

Platelets have been proved to exacerbate influenza infection and its complications. Inhibition of platelet activation may be a feasible method for preventing severe infection and secondary acute lung injury (ALI). Isofraxidin (IFD) is a natural coumarin isolated from the plants Sarcandra glabra and Siberian ginseng, and exerts anticancer, antioxidant and antiinflammatory effects. In the present study, we examined the therapeutic effects of IFD in ADP- or arachidonic acid (AA)-induced platelet aggregation model and in influenza A virus (IAV)-induced ALI mouse model. The results showed that IFD significantly inhibited platelet aggregation induced by ADP and AA in vitro in a concentration-dependent manner as well as the release of soluble P-selectin and platelet factor 4. Moreover, IFD significantly relieved IAV-induced lung inflammation, reduced the expressions of platelet activation biomarkers (P-selectin and CD61), decreased the serum levels of TNF-α, IL-1β, IL-6 and MIP-2, suppressed peripheral platelet aggregation and prolonged the survival time of infected mice. The western blotting results also demonstrated that IFD reduced the phosphorylation levels of PI3K, AKT and p38 in the activated platelets stimulated by ADP and IAV infection. But IFD did not have any effects on IAV replication. It indicated that IFD ameliorated IAV-induced severe lung damage and lethal infection by suppressing platelet aggregation via regulating PI3K/AKT and MAPK pathways.     

Ginkgolide C inhibits platelet aggregation in cAMP- and cGMP-dependent manner by activating MMP-9

In this report, we investigated the effect of ginkgolide C (GC) from Ginkgo biloba leaves in collagen (10 mug/ml)-stimulated platelet aggregation. It has been known that matrix metalloproteinase-9 (MMP-9) is released from human platelets, and that it significantly inhibited platelet aggregation stimulated by collagen. Zymographic analysis confirmed that pro-MMP-9 (92-kDa) was activated by GC to form an activated MMP-9 (86-kDa) on gelatinolytic activities. And then, GC dose-dependently inhibited platelet aggregation, intracellular Ca(2+) mobilization, and thromboxane A(2) (TXA(2)) formation in collagen-stimulated platelets. In addition, GC significantly increased the formation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which have an anti-platelet function in both resting and collagen-stimulated platelets. Therefore, we demonstrate that the inhibitory effect of GC on platelet aggregation might be involved into the following pathways. GC may increase intracellular cAMP and cGMP production and MMP-9 activity, inhibit intracellular Ca(2+) mobilization and TXA(2) production, thereby leading to inhibition of platelet aggregation. These results strongly indicate that GC is a potent inhibitor of collagen-stimulated platelet aggregation. It may be a suitable tool for a negative regulator during platelet activation.     

LC-MS/MS法测定Wistar大鼠组织中银杏内酯B的浓度

目的建立LC-MS/MS法测定大鼠组织中银杏内酯B的浓度,并将此方法应用于银杏内酯B注射液在Wistar大鼠体内的组织分布研究。方法色谱柱:AQVASIL C18柱(100 mm×2.0 mm I.D.,5μm),流动相:乙腈-水-甲酸(体积比为60.0∶40.0∶0.4),流速:0.4 mL.min-1,离子源为电喷雾电离(electrospray ionization,ESI)源,负离子化方式,以选择反应监测(selective reaction monito-ring,SRM)方式进行扫描定量,用于定量分析的离子反应分别为m/z 423→m/z 367(银杏内酯B)和m/z 444→m/z 138(格列吡嗪)。测定了18只Wistar大鼠静脉注射给予银杏内酯B(给药剂量为3.75 mg.kg-1)后大鼠体内各组织和脏器中银杏内酯B的质量浓度。结果测定大鼠组织匀浆液中银杏内酯B的线性为1.0～500.0μg.L-1,定量下限为1.00μg.L-1。低、中、高3个质量浓度质控样品的日内和日间精密度分别小于6.4%和14.5%,准确度为97.3%～103.6%。银杏内酯B在心、肝、脾、肺、肾、胰、胃、小肠、脑、肌肉、脂肪、子宫、卵巢和睾丸14种组织中(除脑组织6 h时间点外)均被检出。银杏内酯B在大鼠各组织中分布广泛,自各组织中消除也较快。结论该方法适用于银杏内酯B注射液在Wistar大鼠体内的组织分布研究。