MK—447对家兔凝血酶诱导的血小板聚集,ATP释放及细胞内游离钙动…

研究ＭＫ－４４７对家兔凝血酶诱导的血小板聚集释放反应及单细胞内钙水平的影响，方法利用浊度法及测定ＰＲＰ中ＡＴＰ的含量评价聚集和释放反应，以荧光图像法分析细胞内钙浓度。结果：ＭＫ－４４７仅使兔多血小板血浆透光度降低，即血小板变形，单血小板轻度增加     

5—HT增强家兔ADP介导的血小板聚集反应

AIM: To study the enhanced effects of 5-hydroxytryptamine (5-HT) on ADP-induced aggregation. METHODS: Platelet aggregation was quantified by the light transmission, the cytosolic-free calcium ([Ca2+]i) was measured by digital fluorescent microscopy, and inositol 1,4,5-triphosphate (IP3) was determined by receptor binding assay. RESULTS: In rabbit platelet-rich plasma (PRP), 5-HT 0.03-3 mumol.L-1 induced a decrease in light transmission (DLT) in a concentration-dependent manner with centralization of granules, as revealed by electron microscopy. The DLT was accompanied with neither platelet aggregation nor a release reaction. In single washed platelets loaded with Fura-2, 5-HT caused a concentration-dependent elevation of [Ca2+]i, and IP3 level was also transiently increased in washed platelets at 15 s after stimulation by 5-HT. Adenosine diphosphate (ADP) also caused DLT transiently in PRP before its own aggregation without a release reaction. Pretreatment of PRP or washed platelets with 5-HT, the DLT by ADP was reduced concentration-dependently and ADP-induced aggregation and [Ca2+]i mobilization were enhanced. CONCLUSION: The enhancement of ADP-induced aggregation was attributed to the superimposition of the calcium release from the storage sites and calcium influx induced by ADP over the calcium release from the storage sites by 5-HT.     

家兔血小板密度与其聚集和ATP释放反应及细胞内游离钙动员的关系(英文)

目的:研究血小板密度与其功能及单细胞内游离钙动员的关系.方法:以Percoll间断梯度离心法及萤光图像法评价和测量血小板密度及细胞内钙浓度.结果:家兔血小板可分为高(HD),中(ID)和低(LD)三个密度亚群,各亚群之间大小明显差异,且与密度相关(r=0.988,P<0.01).0.5U凝血酶的聚集和ATP释放反应HD均较LD强.150U凝血酶剌激后,单血小板内游离钙水平HD明显高于其它亚群(P<0.01).尽管血清素3μmolL~(-1)无聚集和释放反应,但对细胞内游离钙影响的结果与凝血酶相似.结论:家兔血小板的功能及单细胞内游离钙水平随血小板的密度增加而增强.     

槲皮素单硫酸酯钠盐对凝血酶诱导的猪血小板聚集的抑制作用

研究槲皮素单硫酸酯钠盐对凝血酶诱导的猪血小板聚集的抑制作用。方法：用比浊法测定血小板聚集,Ｆｕｒａ ２－ＡＭ荧光法检测胞浆游离钙浓度（「Ｃａ＾２＋）ｉ」。用组蛋白ⅢＳ,「γ＾３２Ｐ」ＡＴＰ与蛋白激酶Ｃ酶液一起温育的方法测定ＰＫＣ的活性。用ＳＤＳ－ＰＡＧＥ分离骨架蛋白。     

MK-447对家兔凝血酶诱导的血小板聚集,ATP释放及细胞内游离钙动员的影响(英文)

目的:研究MK-447对家兔凝血酶诱导的血小板聚集释放反应及单细胞内钙水平的影响.方法:利用浊度法及测定PRP中ATP的含量评价聚集和释放反应,以荧光图像法分析细胞内钙浓度.结果:MK-447仅使兔多血小板血浆(PRP)透光度降低(DLT),即血小板变形,单血小板[Ca~(2 )]_i轻度增加(160 nmol·L~(-1)),并不被依他酸3 mmol·L~(-1)抑制.MK-447消除凝血酶诱导的DLT,聚集和ATP释放增强,呈剂量依赖性,且凝血酶介导的[Ca2 ]_i由369 ±45 nmol·L~(-1)增加到621±121 nmol·L~(-1).结论:MK-447的血小板变形与其[Ca~(2 )]_i释放有关.MK-447增强凝血酶的血小板聚集和ATP释放.MK-447的这一作用可能于[Ca2 ]_i的协同作用有关.     

5HT对STA2介导的血小板聚集和解释反应的双重影响

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介血小板变形，聚集反应和［Ｃａ＾］ｉ水平。结果：（１）５－ＨＴ预处理可消除ＳＴＡ２的血小板变形，ＳＴＡ２ ０．３μｍｏｌ·Ｌ＾－１的聚集增强，１－２ｍｏｌ·Ｌ＾－１的聚集不变，释放反应抑制。（２）５－ＴＨ预处理增加ＳＴＡ２ ０．３μｍｏｌ·Ｌ＾－１的［Ｃａ＾２＋］ｉ降低３μｍｏｌ·     

Effects of 5-HT released from platelets on thrombin-induced aggregation and ATP release in rabbit pla

Ｅｆｅｃｔｓｏｆ５ＨＴｒｅｌｅａｓｅｄｆｒｏｍｐｌａｔｅｌｅｔｓｏｎｔｈｒｏｍｂｉｎｉｎｄｕｃｅｄａｇｇｒｅｇａｔｉｏｎａｎｄＡＴＰｒｅｌｅａｓｅｉｎｒａｂｂｉｔｐｌａｔｅｌｅｔｓｉｎｖｉｔｒｏＬＩＢａｉＹａｎ１，ＬＩＷｅｎＨａｎ（Ｄｅｐａｒ...     

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.     

MN-9202对兔血小板聚集、5-HT释放、TXB_2合成及Ca~(2 )转运的影响(英文)

目的:研究新二氢吡啶类钙拮抗剂MN-9202对兔血小板激活的影响,并探讨其作用机制。方法:以Fu-ra-2 AM为荧光探针,采用时间扫描方式记录血小板内Ca~(2 )的变化;分别用HPLC/ECD和放射免疫测定法检测5-HT及TXB_2。结果:MN-9202剂量依赖地抑制ADP或凝血酶诱导的血小板聚集,抑制TXA_2的释放并且能有效阻滞激活血小板胞内Ca~(2 )水平的增加。MN-9202 1μmol·L~(-1)能抑制胶原15mg·L~(-1)诱导的5-HT释放反应,但对胶原45mg·L~(-1)诱导的反应无抑制作用。结论:MN-9202阻滞血小板Ca~(2 )内流并抑制血小板花生四烯酸代谢及激活反应。     

5-carboxamidotryptamine elicits 5-HT2 and 5-HT3 receptor-mediated cardiovascular responses in the conscious rabbit: evidence for 5-HT release from platelets

The selective "5-HT1-like" receptor agonist 5-carboxamidotryptamine (5-CT, 0.2-1.6 micrograms/kg bolus i.v.), serotonin (5-HT, 3-10 micrograms/kg), and phenylbiguanide (10-40 micrograms/kg) all elicited the "Bezold-Jarisch-like" bradycardia reflex in conscious rabbits. This reflex was antagonised by the 5-HT3 receptor antagonist, MDL 72222. After autonomic blockade (mecamylamine), 5-CT and 5-HT infusion (i.v.) caused renal artery spasm (Doppler flowmeter) that was antagonised by ketanserin, a 5-HT2-receptor antagonist. Both 5-CT and 5-HT caused 5-HT1-like receptor mediated increases in hindquarter conductance that were unaltered by ketanserin (0.5 mg/kg). The anomalous 5-HT3 and 5-HT2 receptor actions of 5-CT were completely prevented by 16 h pretreatment with reserpine (5 mg/kg) that lowered total serum serotonin to less than 3% of normal but did not reduce the cardiovascular actions of 5-HT. Fluoxetine (1 mg/kg i.v.), an inhibitor of 5-HT uptake into platelets, significantly attenuated the Bezold-Jarisch-like reflex evoked by 5-CT but not by 5-HT. These studies suggest that 5-CT is carried into platelets where it releases 5-HT. This illustrates how apparent receptor selectivity asserted in in vitro assays can be destroyed in vivo.     

Effects of various ginseng saponins on 5-hydroxytryptamine release and aggregation in human platelets

The effects of various ginseng saponins isolated from red ginseng roots, on aggregation and 5-hydroxytryptamine release (5-HT) human platelets have been investigated. Among the six saponins tested, only ginsenoside Rg1 inhibited adrenaline- and thrombin-induced platelet aggregation and 5-HT release dose-dependently, at concentrations of 5 to 500 micrograms ML-1. Ginsenoside Rg1 had no effect on adrenaline- and thrombin-induced arachidonic acid release and diacylglycerol production. But it did reduce the elevation of cytosolic free calcium concentration (Ca2+)i shown in the second phase induced by adrenaline and thrombin, at concentrations of 10 to 500 micrograms mL-1. Those data suggest that the inhibitory effects of ginsenoside Rg1 on 5-HT release from, and aggregation of, platelets might be due to the reduction of (Ca2+)i elevation at the second phase induced by adrenaline and thrombin. The results suggest that ginsenoside Rg1 in red ginseng roots may be active as a drug in the treatment of artheroscleorosis and thrombosis.     

In vitro inhibition by endothelins of thrombin-induced aggregation and Ca2+ mobilization in human platelets.

1. The in vitro effects of endothelins (ET-1 and ET-3) on human platelets were investigated by measurement of the aggregatory responses of washed platelets to thrombin and by the determination of cytosolic pH (pHi) and free Ca2+ concentration ([Ca2+]i) determined with the fluorescent indicators, BCECF and Fura-2. 2. ET-1 and ET-3 at concentrations ranging from 10(-10) to 5 x 10(-7) M, did not promote platelet aggregation but inhibited in a dose-dependent manner the aggregation induced by 0.05 u ml-1 thrombin (P less than 0.002 and less than 0.001, respectively) with maximal effects reached at 10(-8) M (17 +/- 3 and 15 +/- 2%, n = 11, P = 0.002 for each). 3. Even at 5 x 10(-7) M, ET-1 and ET-3 did not cause a measurable change in basal [Ca2+]i and pHi. When tested in combination with thrombin, 5 x 10(-7) M ET-1 and ET-3 decreased the transient peak of [Ca2+]i by 17 +/- 7 and 28 +/- 7% (n = 7 and 11, P = 0.03 and P = 0.002). No effect on pHi variations was detected. In the virtual absence of external Ca2+, 5 x 10(-7) M ET-3 inhibited the peak of [Ca2+]i by 18 +/- 6% (n = 6, P = 0.02). 4. The anti-aggregating agents, prostacyclin (PGI2, 10(-8)-10(-7) M) and nitroprusside (NP, 10 ng-50 micrograms l-1) also induced a dose-dependent inhibition of the thrombin-induced [Ca2+]i peak (P = 0.001 for each).(ABSTRACT TRUNCATED AT 250 WORDS)