灯盏花、丹参液在体外对血小板活化抑制作用的研究

目的通过对灯盏花素、丹参在体外对血小板活化抑制作用观察,分析血小板相关活化指标的变化情况,为中医优选活血化瘀药物提供客观理论依据。方法用三色流式细胞术法分析灯盏花素、丹参在体外对血小板活化指标血小板膜表面纤维蛋白原受体（PAC-1）和P-选择素（CD62P）抑制的变化。结果灯盏花素、丹参对ADP活化的血小板膜表面纤维蛋白原受体（PAC-1）和血小板内P-选择素（CD62P）表达都有抑制作用,并且随着药物浓度的增加,抑制作用增强;丹参能显著抑制PAC-1和CD62P两者的表达;灯盏花素抑制PAC-1表达的作用显著,但对CD62P表达的抑制较小。结论与灯盏花素相比,丹参是一种较强的抗血小板活化药物,既可抑制PAC-1的表达而降低血小板的聚集性,又可抑制血小板的释放而降低其促凝血活性,在血栓性疾病的防治中有重要作用。     

心肌缺血预处理抗血小板活化和抗血栓形成作用的实验研究

目的 探讨心肌缺血预处理(myocardial ischemic preconditioning,MIP)对缺血-再灌注(Ischmia/Reperfusion,I/R)期血小板活化、血管内血栓形成的影响.方法 40只成年新西兰大白兔随机分为缺血-再灌注对照组和缺血预处理(ischemic preconditioning,IPC)组(n=20),分别在基础状态、缺血前、缺血40 min、再灌注60 min和再灌注120min测定血浆可溶性P-选择素(sPselectin)、血栓烷B2(TXB2)的浓度(n=12).另一方案则通过颈总动脉-颈外静脉旁路法观测基础状态和再灌注60 min时的血栓湿重(n=8).结果 再灌注期,两组实验动物sP-selectin、TXB2浓度和血栓湿重与基础状态时相比均升高(P＜0.05);组间比较,IPC组上述参数均低于对照组,再灌注60 min和120 min时差异均有显著性.结论 心肌缺血预处理可以有效抑止再灌注期血小板活化、限制血管内血栓形成.     

西洛他唑对小鼠慢性缺血性脑损伤的保护作用及机制

目的：观察西洛他唑对小鼠慢性缺血性脑损伤的保护作用,探讨其与促血管生成的关系。方法：以大脑中动脉栓塞方法诱导小鼠局灶性脑缺血,缺血后1、4、7h和术后1～14d腹腔注射西洛他唑（10mg／kg）,每天一次,观察缺血后35d西洛他唑对神经症状评分、斜板角度、脑梗死体积、神经元密度和缺血侧血管内皮生长因子（VEGF）、血管内皮生长因子受体2（Flk-1）表达的作用。结果：西洛他唑能降低缺血后神经症状评分,提高斜板角度,减少脑梗死体积,增加存活神经元密度和VEGF、Flk-1表达的数目。结论：西洛他唑对小鼠慢性局灶性脑缺血具有保护作用,其作用机制可能与诱导缺血侧VEGF、Flk-1表达,促进血管生成有关。     

Possible mechanism of action of diazepam as an adenosine potentiator

Diazepam (10(-5)-3 X 10(-4) M) selectively enhanced the negative inotropic responses of guinea-pig atria and the relaxation of guinea-pig taenia coli caused by adenosine and ATP. In the atria, the effect of 2-chloroadenosine, a stable analog of adenosine, was not affected by diazepam. Segments of guinea-pig atria or taenia coli took up 3H-activity during incubation with [3H]adenosine but did not take up 32P-activity from [32P]ATP. Diazepam at concentrations sufficient to enhance the in vitro responses reduced by half the uptake of 3H-activity into the preparations. Adenosine (10(-6) M) and ATP (10(-6) M) were degraded to inactive inosine during incubation with atrial segments and their degradation was inhibited by diazepam. In contrast, in rat atria, diazepam did not enhance the negative inotropic effects of adenosine and ATP, and did not prevent the uptake of adenosine. These results suggest that in guinea-pig atria and taenia coli, diazepam like dipyridamole, acts as an adenosine potentiator by preventing the uptake and degradation of adenosine.     

Interplay between milrinone and adenosine in the inhibition of human platelet response

• 1.1. In this study, we investigated the influence of the isotropic agent and coronary vasodilator milrinone on platelet aggregation and intracellular levels of 3′,5′ cyclic adenosine monophosphate (cAMP) in human platelet-rich plasma (PRP) and whole blood (WB). Furthermore, we evaluated the influence of milrinone on the effects of adenosine, which reduces the platelet aggregation through an elevation of intraplatelet cAMP levels.
• 2.2. Milrinone decreased the platelet aggregation in response to agonists in both PRP and WB. A dose-dependent increase of intraplatelet cAMP levels was demonstrated: this result is in accordance with an effect on platelet phosphodiesterases.
• 3.3. Milrinone at low concentration and adenosine exerted additive effects on platelet aggregation and intraplatelet cAMP levels.
• 4.4. An interplay between milrinone and adenosine was shown in WB. Furthermore, dipyridamole, which prevents the uptake of endogenous adenosine, markedly enhanced the milrinone antiaggregating effect, whereas the adenosine receptor blocker, theophylline, decreased it.
• 5.5. The present data provide evidence that milrinone modulates the platelet function through an influence on intraplatelet levels of cAMP and it is able to interplay with substances stimulating adenylyl cyclase.
• 6.6. The interplay between milrinone and adenosine in the inhibition of the human platelet function could be effective during milrinone administration in the treatment of heart failure, when blood adenosine levels are significantly increased. These milrinone effects could be advantageous from a therapeutic point of view, since patients with heart failure are at risk of thrombosis and ischemic heart disease.

     

海兰地嗪对血小板聚集的影响及机理探讨

海兰地嗪(Her)体外对胶原,ADP,A23187和AA诱导的大鼠血小板聚集有明显抑制作用,其IC_(50)分别为14.5,41.6,44.1和48.3μg/ml。Her对AA诱导的大鼠血小板MDA生成不能抑制,但能升高兔血小板cAMP水平和抑制凝血酶诱导的人血小板胞浆内游离钙离子浓度升高。Her的抗血小板聚集作用机理可能与升高血小板内cAMP水平和抑制细胞内游离钙离子浓度升高有关。     

Inhibition of platelet aggregation by papaverine-like drugs: evidence for a novel mechanism of action.

Trimethoquinol [6,7-dihydroxy-1-(3′,4′,5′-trimethoxybenzyl)-1,2,3,4-tetrahydroisoquinoline] (TMQ) was chosen as a model compound for studying inhibition of platelet aggregation in vitro, because of its β-adrenoceptor agonist properties and structural resemblance to the anti-aggregatory agent, papaverine. TMQ inhibited collagen-induced aggregation of human platelet-rich plasma (I₅₀, 2 μM), the second wave of aggregation induced by 2.5 μM ADP (I₅₀, 0.9 μM), and the second wave of aggregation induced by 45 μM epinephrine (I₅₀, 2.5 μM). Collagen-induced aggregation of human washed platelets was inhibited by TMQ (I₅₀, 1 μM). TMQ was a better inhibitor than aspirin and papaverine and had an inhibitory activity similar to indomethacin in all of the systems studied. TMQ retained inhibitory activity in the presence of both β-adrenoceptor antagonist: propranolol (50 μM), and α-adrenoceptor antagonist: phentolamine (2.5 μM). Platelet adenylate cyclase was not activated and neither cAMP nor cGMP-phosphodiesterase activities were inhibited by TMQ, PGF_2α, biosynthesis by aggregating platelets during the coagulation of blood obtained from rats pretreated with aspirin (10 mg/kg, p.o.) or indomethacin (1 mg/kg, p.o.) was inhibited. However, similar pretreatment with TMQ (100 mg.kg, p.o.) and papaverine hydrochloride (100 mg/kg, p.o.) had no effect. TMQ acted synergistically with the aggregation inhibitors: papaverine, aspirin, and PGE₁. The in vitro inhibitory action of papaverine, aspirin, and TMQ was enhanced by increasing calcium concentration. These data indicate that the platelet anti-aggregation activity of TMQ, in contrast to its myocardial stimulating and bronchodilating mechanism, is independent of adrenergic activation. Cyclic AMP accumulation or prostaglandin biosynthesis also seem not to be involved in TMQ action. Therefore, it appears that TMQ may have a novel anti-aggregatory mechanism of action.     

Recent developments in the discovery of novel adenosine kinase inhibitors: mechanism of action and therapeutic potential

Adenosine (ADO) is an endogenous inhibitory neuromodulator that limits cellular excitability in response to tissue trauma and inflammation. Adenosine kinase (AK; EC 2.7.1.20) is the primary metabolic enzyme regulating intra- and extracellular concentrations of ADO. AK inhibitors have been shown to significantly increase ADO concentrations at sites of tissue injury and to provide effective antinociceptive, antiinflammatory, and anticonvulsant activity in animal models. Structurally novel nucleoside and non-nucleoside AK inhibitors that demonstrate high specificity for the AK enzyme compared with other ADO metabolic enzymes, transporters, and receptors have recently been synthesized. These compounds have also demonstrated improved cellular and tissue penetration compared with earlier tubercidin analogs. These compounds have been shown to exert beneficial effects in animal models of pain, inflammation and epilepsy with reduced cardiovascular side effects compared with direct acting ADO receptor (P1) agonists, thus supporting the hypothesis that AK inhibitors can enhance the actions of ADO in a site- and event-specific fashion.     

西洛他唑对糖尿病微血管病变患者血小板指标的影响

目的：为了评价西洛他唑对糖尿病微血管病变的防治作用。方法：对120例糖尿病患者测定平均血小板体积（MPV）、血小板压积（PCT）、血小板分布宽度（PDW）、血小板计数（PLT）四项指标，并对60例伴有微血管病变者进行西洛他唑治疗1个月，观察其治疗前后的变化。结果：1．糖尿病患者MPV、PCT、PDW明显高于正常对照组；有微血管病变患者MPV、PCT、PDW增高更明显。2．西洛他唑治疗后微血管病变患者MPV、PDW明显下降。结论：西洛他唑改善血小板参数，预防微血管病变的进展，对防治糖尿病微血管病变起重要作用。     

Evidence for a difference in mechanism of action between fenfluramine- and amphetamine-induced anorexia

The influence of drugs, active on 5-hydroxytryptamine (5-HT) mechanisms, has been examined on the anorexigenic activity of fenfluramine and (+)-amphetamine in rats trained to consume their daily food ration during 6 h. Chlorimipramine, which inhibits the re-uptake mechanisms in central 5-HT neurons, and the 5-HT blocking drugs methergoline and methysergide were used. Fenfluramine, 7.5 mg kg^?1, and amphetamine, 2.5 mg kg^?1, given 1/2 h before feeding reduced the food intake during the following 2 h to approximately 40% compared with control days. Pretreatment with methergoline in the optimal dose (1 mg kg^?1) produced only a weak but significant antagonism to amphetamine anorexia, whereas the fenfluramine anorexia was strongly antagonized by methergoline in all doses tested (0.3, 1 and 3 mg kg^?1). Methysergide (0.1, 0.3, 1 and 3 mg kg^?1) showed no significant antagonism against amphetamine or fenfluramine anorexia. Chlorimipramine produced a strong antagonistic effect to the fenfluramine anorexia, but showed no antagonism against amphetamine. In contrast the highest dose of chlorimipramine (20 mg kg^?1) potentiated amphetamine anorexia. The present results together with other evidence discussed support the conclusion that 5-HT mechanisms are involved in fenfluramine anorexia, whereas amphetamine anorexia seems mainly correlated with catecholamine dependent mechanisms.     

The relationship between inflammation, platelet activation and antiplatelet resistance

Even though there is a strong evidence suggestive of benefits and safety of dual (aspirin plus clopidogrel) antiplatelet therapy, decreased responsiveness or "resistance" to mono- and/or dual antiplatelet therapy has been described in association with an increased thrombotic risk. Various mechanisms contribute to antiplatelet resistance, with abundant production of inflammatory markers being of particular importance. The current review overviews implications of inflammation in antiplatelet resistance.     

他巴唑体外抑制酪氨酸碘化的机制

目的　探讨抗甲状腺药物的作用机制。方法　①在甲状腺过氧化物酶（ＴＰＯ）中加入他巴唑、碘化钾、过氧化氢,然后进行透析,用３,３,５,５, 四甲基联苯胺（ＴＭＢ）测ＴＰＯ的活性;②在ＴＰＯ催化酪氨酸碘化的反应体系中,加入他巴唑,并逐渐增加过氧化脲的浓度,观察过氧化脲浓度对他巴唑干扰酪氨酸碘化的影响。结果　ＴＰＯ中加入他巴唑,与加入磷酸盐缓冲液（ＰＢ）对照,经透析后,两者酶活性没有明显的区别。在ＴＰＯ催化的酪氨酸碘化的反应体系中,提高过氧化脲的浓度,能抵消他巴唑对酪氨酸碘化的抑制作用。结论　他巴唑对ＴＰＯ无直接抑制作用,其作用机制是夺去酪氨酸碘化所必需的活性氧（他巴唑本身被氧化）从而抑制甲状腺素的合成。     

Effects of diazepam on adenosine and acetylcholine release from rat cerebral cortex: further evidence for a purinergic mechanism in action of diazepam.

1 Diazepam administered intraperitoneally (0.25 mg/kg) enhanced the rate of efflux of [3H]-adenosine and its metabolites from rat cerebral cortex. At a lower dose (0.05 mg/kg), this effect could be detected in only one of four rats. 2 Diazepam (0.05 and 0.25 mg/kg i.p.) depressed acetylcholine release from the rat cerebral cortex. Its effect was reversed by theophylline. 3 Theophylline (15 and 30 mg/kg) enhanced acetylcholine release from the rat cerebral cortex. Diazepam (0.25 mg/kg) administered after theophylline failed to cause a reduction in the rate of release, rather there appeared to be a further enhancement of release. 4 Pentobarbitone sodium (5, 10 and 15 mg/kg i.p.) did not elicit any increase in adenosine release. 5 These results support the proposal that benzodiazepines may exert their pharmacological actions by preventing adenosine uptake, thus enhancing the levels of extracellular adenosine.     

Neutrophil-mediated platelet activation: A key role for serine proteinases

• 1.1. Neutrophils and platelets interact in vitro through multiple biochemical pathways in both directions, resulting in an inhibition or a potentiation of their reactivity, depending on the experimental conditions.
• 2.2. Under some conditions, a full stimulation of platelets (aggregation and degranulation) can be induced by neutrophils. The present review is focused on this aspect for which serine proteinases released from the azurophilic granules of neutrophils activate surrounding platelets.
• 3.3. The different facets of this process at the cellular and molecular levels, are presently depicted and their relevance to the in vivo situation suggested.

     

In vitro inhibition of adenosine deaminase by flavonoids and related compounds. New insight into the mechanism of action of plant phenolics.

The effects of 20 flavonoids, anthocyanes and other phenolic compounds of plant origin have been tested in vitro for their inhibitory effect on the enzyme adenosine deaminase (ADA). Significant effects were obtained with most compounds at concentrations between 0.0001 and 0.1 mg/mI. Thus, plant phenolics can be considered as natural ADA enzyme inhibitors. It is assumed that they also increase the actual adenosine (Ado) concentration in vivo. This may explain many of the pharmacological activities of these compounds on a molecular basis.