甲基莲心碱对兔血小板聚集功能的影响

用比浊法和放射免疫分析技术研究甲基莲心碱(Nef)抗血小板聚集作用及其对TXA₂/PGI₂与cAMP/cGMP浓度的影响。结果显示,Nef在体外明显抑制ADP,胶原,AA及PAF诱导的家兔血小板聚集,IC₅₀分别为16,22,193及103μmol·L^-1;Nef明显抑制AA诱导的血小板TXA₂的生成和释放,对动脉环PGI₂的生成有促进作用;Nef剂量依赖性地升高血小板cAMP浓度,对cGMP无明显影响。结果提示Nef抗血小板聚集作用的机理与抑制TXA₂生成,增加血管PGI₂及血小板cAMP含量有关。     

非普拉宗对环氧酶活性的影响

目的　研究非普拉宗(feprazone, Fep)对环氧酶-1和环氧酶-2活性的影响。 方法　用放免法测定PGE2含量反映环氧酶-2活性,测定6-酮-前列腺素F_1α含量反映环氧酶-1活性。 结果　Fep在0.1,1.0,10.0 μmol.L^-1能剂量依赖性抑制小鼠腹腔巨噬细胞PGE₂生成,在相同浓度下对小牛主动脉内皮细胞6-keto-PGF_1α生成抑制作用较弱。结论　Fep显著抑制PGE₂生成,对PGI₂生成影响较小,提示其对环氧酶-2有较强的抑制作用。     

人参总皂甙对14C-花生四烯酸在兔血小板中代谢的影响

本文报道人参总皂甙对花生四烯酸在免血小板中代谢的影响。方法采用放射薄层扫描、放射自显影及放射活性测定等同位素技术。结果表明,人参总皂甙抑制兔血小板血栓素A₂的生物合成,并呈量效关系。同时对前列腺素A₂也有抑制作用。这种抑制怍用的机理,可能是人参总皂甙抑制了血小板环氧酶和血栓素A₂合成酶的活性。     

4-{[2-(1H-咪唑基)-1-(4-取代苯基)乙氧基]甲基}苯甲酸类化合物的合成及其抑制血小板聚集的作用

根据咪唑类和吡啶类TXA₂合成酶抑制剂的构效关系和作用机制,设计合成了20个4-{[2-(1H-咪唑基)-1-(4-取代苯基)乙氧基]甲基}苯甲酸类化合物。初步体外药理试验结果表明,所有化合物都有不同程度的抑制TXA₂合成酶能力,从而抑制花生四烯酸(AA)诱导的血小板聚集。化合物15的抑酶活性最强,以IC₅₀值相比,其活性为Dazoxiben的55.6%。并初步探讨了这类化合物的构效关系。     

蝙蝠葛碱对血小板聚集及花生四烯酸代谢的影响

蝙蝠葛碱(Dau) 抑制AA及ADP诱导的大鼠血小板聚集,也能抑制AA,ADP及Adr诱导的人血小板聚集。这种抑制作用与Dau剂量呈依赖关系。Dau抑制大鼠洗涤血小板对[1-¹⁴C]AA经环氧酶途径的代谢,TXB₂与HHT的形成均呈剂量依赖性减少。当Dau浓度达到0.1 mmol/L时亦能抑制12-HETE的形成。Dau对AA代谢的上述影响可能是其抑制血小板聚集的机理之一。     

阿魏酸钠对花生四烯酸代谢的影响

利用放射薄层方法测定兔血小板花生四烯酸代谢产物TXB₂,PGE₂和PGF_2α。用放射免疫法测定兔血小板TXB₂及主动脉6-keto-PGF_1α。阿魏酸钠(SF,0.1～3.2 mmol/L),抑制¹⁴C-花生四烯酸转化为TXB₂,呈剂量效应关系,IC₅₀为0.762 mmol/L。SF在较高浓度(0.8～3.2mmol/L)时亦抑制PGE₂,PGF_2α的生成。用放免法观察到,SF对血小板TXB₂和动脉壁6-keto-PGF_1α的生成均有抑制作用,对TXB₂的作用较强。结果提示,SF可抑制兔血小板和动脉壁环氧酶活性。     

3,4-二羟基苯乙酮对家兔血小板释放血栓素A2的影响

3,4-二羟基苯乙酮(DHAP)俸内体外给药,都明显抑制胶原或花生四烯酸诱导家兔血小板释放的血栓素B₂含量,剂量与效应相关,生物测定法与放射免疫分析所得结果相平行。实验结果还表明,AA较胶原诱导血小板释放TXB₂量强3～6倍。如不加诱导剂,血小板自发性释放TXB₂量甚微。此外,DHAP抑制AA诱导血小板释放TXB₂的作用也较胶原诱导时为强。DHAP是环加氧酶抑制剂,还是TXA₂合成酶抑制剂,有待进一步证实。     

几种抗炎药对白三烯B4生物合成的影响

白三烯B₄为花生四烯酸5-脂氧酶代谢产物,是炎症反应中的重要介质。目前抑制白三烯B₄生物合成的药物尚不多见。本文建立了测定白细胞来源白三烯B₄的反相高效液相色谱法,并初步探讨了几种抗炎药对白三烯B₄生物合成的影响。结果表明阿斯匹林、消炎痛、炎痛喜康、氢化可的松及麝香第一色带对白三烯B₄生物合成几无影响,而氟灭酸可明显抑制白三烯B₄生成,提示它可能是5-脂氧酶抑制剂。     

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。     

三乙酰莽草酸对血小板聚集的抑制作用

目的：研究三乙酰莽草酸（TSA）对血小板聚集功能的抑制作用及其作用机理。方法：用比浊法测定血小板聚集功能,分光光度法测定MDA的含量,放免法测定TXB₂,6-酮-PGF_1α,cAMP和cGMP的含量。结果：TSA 12.5,25,50,100和200 mg.kg^-1 ig明显抑制ADP和胶原诱导的大鼠血小板聚集;TSA 12.5,50和200　mg.kg^-1 ig显著增加大鼠血小板内cAMP水平,但不影响cGMP水平。TSA 200 mg.kg^-1对AA诱导的血小板中MDA的生成,ADP诱导的血小板中TXB2和腹主动脉壁6-酮-PGF_1α的生成有轻度抑制作用。结论：TSA抑制血小板聚集作用部分与血小板内cAMP水平升高有关。     

咪苯嗪酮对花生四烯酸环氧酶途径代谢产物的选择性影响

兔iv咪苯嗪酮(CI—914)20 mg/kg,用RIA法测定其血浆中TXB_2和6—kcto—PGF_(1α)含量,给药后30 min和60 min.6—keto—PGF_(1α)/TXB_2比值显著升高(p<0.05).在用放射性TLC法进行的洗涤大鼠血小板~(14)C—AA代谢实验中,CI—914在2～500 μmol/L范围内以剂量依赖方式抑制大鼠血小板TXB_2生成,IC_(50)为51.5μmol/L,对HHT生成的抑制明显弱于对TXB_2生成的抑制作用;在相同剂量范围内,CI—914同时以剂量依赖方式使PGE_2,PGF_(2α)和PGD_2生成增加.在相同实验条件下,50μmol/L的已知的TXA_2合成酶抑制剂DAZ,与大剂量CI—914的实验结果类似.上述结果提示,CI—914对血小板TXA_2合成酶可能具有选择性抑制作用.     

Effects of CI-930, a novel phosphodiesterase III inhibitor, on platelet aggregation and arachidonic acid metabolism

In the platelet-rich plasma of rabbits, 4,5-dihydro-6-[4-(1H-imidazol-1-yl)phenyl]-5-methyl-3(2H)-pyridazinone (CI-930) inhibited platelet aggregation triggered by AA, U-46619, ADP, collagen and PAF, with the IC50 values of 0.91, 0.73, 2.12, 2.35 and 7.15 mumols/L, respectively. The inhibitory effect of CI-930 on AA-induced aggregation was potentiated by PGE1, an adenylate cyclase activator, and antagonized by SQ-22536, an adenylate cyclase inhibitor. The contents of cAMP in washed rabbit platelets were increased by CI-930 5-50 mumols/L. In the concentration range of 0.5-500 mumols/L, CI-930 reduced the synthesis of TXB2 by either washed rat or rabbit platelets or rat pleural neutrophils. At the same time, CI-930 induced a dose-dependent increase of PGE2, PGF2a, and PGD2 biosynthesis by rat platelets and had no significant influence on the formation of 6-keto-PGF1a by the neutrophils. It is showed that CI-930 is an anti-platelet agent with a wide-spectrum activity and its anti-aggregating action may be exerted by dual mechanisms, both increasing cAMP contents and selectively inhibiting TXA2 synthesis in platelets.     

Effects of dauricine on the metabolism of arachidonic acid in rat pleural neutrophils

The effects of dauricine (Dau), an isoquinoline alkaloid and anti-arrhythmic agent used in China recently, on the biosynthesis of metabolites of arachidonic acid in rat pleural neutrophils, comparing with dazoxiben, indomethacin and BW-755 c, were studied. The major products of metabolism by 5-lipoxygenase (5-LPO), measured by HPLC, were LTB4 and 5-HETE, whereas the major cyclooxygenase products measured by HPLC and RIA, were HHT and TXB2. The formation of all products by neutrophils was significantly depressed by Dau in a dose-dependent manner. The concentration of Dau required to obtain 50% inhibition (IC50) of formation of HHT, TXB2, LTB4 and 5-HETE was 25.3, 59.3, 31.8 and 59.5 mumol/L, respectively. These results indicate that the two major metabolic pathways of arachidonic acid in rat pleural neutrophils are inhibited by Dau.     

山莨菪碱对大鼠胸水中性白细胞花生四烯酸代谢的影响

本文研究了654-2对大鼠胸水中性白细胞代谢[1-¹⁴C]AA及内源性AA的影响。大鼠白细胞AA经5-LPO代谢途径形成的主要产物为LTB₄及5-HETE,经CO途径的主要产物为HHT及TXB₂。654-2对白细胞代谢[1-¹⁴C]AA无抑制作用,但显著减少白细胞从内源性AA形成的LTB₄,5-HETE,HHT及TXB₂。这种抑制作用与654-2呈剂量依赖关系。本实验结果表明,654-2抑制PG及LT的形成可能是影响了AA从胞膜的释放,而并非直接抑制CO及5-LPO。     

咪苯嗪酮对血小板聚集、血栓形成和血小板环磷酸腺苷含量的影响

本文观察了新型强心剂咪苯嗪酮(Cl-914)对血小板聚集、血栓形成和血小板cAMP含量的影响。用比浊法测定Cl-914体外抑制AA,ADP和胶原诱导兔血小板聚集的IC_(50),分别为2.6,8.9和15.8μM;大鼠iv Cl-914 1.25mg/kg能抑制实验性血栓形成,20 mg/kg能抑制上述三种诱导剂引起的血小板聚集。在体外,用竞争性蛋白结合法测定,CI-914可使洗涤兔血小板cAMP含量明显升高。CI-914能以剂量依赖方式协同PGE_1抑制血小板聚集和升高血小板cAMP的含量。提示CI-914升高血小板cAMP含量可能是其抑制血小板聚集和抗血栓形成的主要机理。     

丹酚酸B镁盐对兔洗涤血小板聚集和5-HT释放反应的影响(英文)

AIM: To study the effects and mechanism of magnesium lithospermate B(MLB) on rabbit platelet aggregation and 5-HT release. METHODS: The platelet aggregation was determined by Born's method. Release of serotonin (5-HT) and formation of thromboxane A2 (TXA2) were measured by fluorophotometry and radioimmunoassay (RIA) respectively. Cytoplasmic free Ca2+ concentration ([Ca2+]i) in platelets was measured by Fura 2-AM fluorescence technique. RESULTS: In washed platelets, thrombin (200 U/L) or arachidonic acid (AA) (30 mumol/L)-induced aggregation was inhibited by MLB 50-800 mg/L in a concentration-dependent manner. In addition, MLB had more inhibitory effects on platelet aggregation in the absence of extracellular calcium with IC50 of 102 mg/L than in the presence of CaCl2 1 mmol/L with IC50 of 194 mg/L. MLB concentration-dependently decreased the thrombin-activated release of 5-HT, whereas it did not affect the formation of TXA2 in platelets. Furthermore, MLB not only inhibited the rise of [Ca2+]i in thrombin stimulated platelets, but decreased the [Ca2+]i in resting platelets. CONCLUSION: MLB inhibited the aggregation and 5-HT release in rabbit platelets and it is probably by attenuating intracellular calcium concentration.     

Effect of tolmetin on responsiveness of isolated guinea pig tracheal smooth muscles

Tolmetin directly relaxed the isolated guinea pig tracheal smooth muscles, increased the muscle responsiveness to histamine or carbachol and enhanced the tracheal Schultz-Dale reaction. Prostaglandin E2 synthesized by cyclooxygenase was transformed into prostaglandin B2 (PGB2) with alkali, PGB2 and the lipoxygenase metabolite leukotriene B4 (LTB4) were measured by high-performance liquid chromatography, whereas slow-reacting substance of allergy (SRS-A) was determined by bioassay. Tolmetin showed inhibitory effects on prostaglandin E2 synthesis, with the IC50 being 30 mumol/L, but no effect on LTB4 synthesis (up to 100 mumol/L). SRS-A release was potentiated by tolmetin at 10 and 50 mumol/L. The effects of tolmetin on arachidonic acid metabolism may be responsible for its effects on tracheal smooth muscles. It is suggested that asthma attacks may be induced or enhanced by tolmetin in patients with asthma.