血小板激活因子与炎症

血小板激活因子(platelet-activating factor,PAF)最初是在抗原致过敏的兔嗜碱性粒细胞释放物中发现的,与过敏反应和炎症过程有关,有很强的促血小板聚集作用。现已证实大多数炎症细胞能释放PAF,PAF又能作用于多种炎症细胞,与前列腺素、白三烯、氧自由基、细胞因子等炎症介质相互作用,可降低血压,增高血管壁通透性,引起心肺功能障碍,     

血小板激活因子对内皮细胞形态参数影响的计算机量分析

利用具有大容量、高运算速度和高分辨率的计算机图像分析系统建立量分析内皮细胞面积、形状因子、细胞间距及细胞间空隙面积占细胞单层面积百分比的软件，并分析血小板激活因子对ＥＣ形态参数的影响。结果表明，对照组ＥＣ相互连接紧密，细胞间隙较窄。ＰＡＦ作用６０ｍｉｎ，细胞明显回缩，膜表面有很多粗细不等的突起，细胞间隙增大。计算机定量分析表明，ＰＡＦ（１０＾８ｍｏｌ／Ｌ）作用１０ｍｉｎ，就可使细胞间距和细胞间空隙     

血小板激活因子对内皮细胞形态参数影响的计算机定量分析

利用具有大容量、高运算速度和高分辨率的计算机图像分析系统建立定量分析内皮细胞(endothelial cell,EC)面积、形状因子、细胞间距及细胞间空隙面积占细胞单层面积百分比的软件,并分析血小板激活因子(platelet activating factor,PAF)对EC形态参数的影响。结果表明,对照组EC相互连接紧密,细胞间隙较窄。PAF作用60min,细胞明显回缩,膜表面有很多粗细不等的突起,细胞间隙增大。计算机定量分析表明,PAF(10~-?mol/L)作用10min,就可使细胞间距和细胞间空隙面积占细胞单层面积百分比增大,30min细胞面积减小,形状因子增大,证明细胞发生了回缩,这可能是PAF增加血管壁通透性的重要机制。计算机图像分析有助于迅速、准确地定量测定EC形态变化,为研究EC在血管屏障中的作用提供了新方法。     

血小板激活因子介导白细胞粘附的单细胞定量研究

血小板激活因子介导白细胞粘附的单细胞定量研究第三军医大学大坪医院内科教研室（重庆６３００４２）周向东杨肇享洪新血小板激活因子（ｐｌａｔｅｌｅｔａｃｔｉｖａｔｉｎｇｆａｃｔｏｒ，ＰＡＦ）在炎症早期对中性粒细胞（ｐｏｌｙｍｏｒｐｈｏｎｕｃｌｅａｒｎｅ...     

血小板激活因子在小肠缺血再灌注损伤中的意义及山莨菪碱的保护作用

在大鼠小肠原位灌注模型上,发现小肠缺血—再灌注(I-R)损伤时,肠道产生的PAF显著增加;山莨菪碱灌流明显抑制其PAF的产生,并有与PAF受体拮抗剂Kadsurenone相似的抗I-R损伤效应。但山莨菪碱对外源PAF灌流引起的小肠组织损伤无显著防治效果。提示PAF在小肠I-R损伤中具有发病学意义,山莨菪碱可能是通过抑制肠道PAF的产生,而主要不是通过拮抗PAF,以改善小肠的I-R损伤。     

过敏性哮喘豚鼠肺泡灌洗液一氧化氮的变化

采用镉还原柱层析和比色法测定了过敏性哮喘豚鼠模型血浆及支气管肺泡灌洗液中亚硝酸／硝酸根离子（NO2-／NO3－）水平,以及CGMP和循环内皮细胞（CEC）水平。以探讨一氧化氮（NO）在过敏性哮喘发病机理中的作用。结果：（1）过敏性哮喘豚鼠血浆NO2－／NO3－水平无明显变化,而支气管肺泡灌洗液中水平显著升高（P＜0．01）;（2）哮喘组血浆及支气管肺泡灌洗液中cGMP均明显升高（P分别＜0．05、＜0．01）,循环血中CEC水平亦升高显著（P＜0．05）;（3）糖皮质激素可降低cGMP及CEC水平,减轻哮喘发作.提示：支气管肺泡灌洗液水平与过敏性哮喘密切相关,NO参与了哮喘的病理生理变化,糖皮质激素具有明显的治疗作用．     

血小板激活因子及其拮抗剂在生殖医学中的作用

血小板激活因子（ＰＡＦ）是一种活性很强的磷脂介质，在人类生殖的各个环节，如排卵、受精、着床、分娩以及一些妊娠合并症中均发挥作用。ＰＭ通过与细胞表面特异受体结合传递跨膜信息。本文就ＰＡＦ在生殖中的作用，ＰＡＦ受体的理化特性、分子结构、信息传递机制，以及几类ＰＡＦ受体拮抗剂的作用等方面进行综述。     

血小板源生长因子—B及其受体在哮喘豚鼠气道中的表达

为探讨血小板源生长因子－Ｂ多肽（ＰＤＧＦ－Ｂ）在哮喘发病中的作用，应用免疫组织化学方法，检测了豚鼠哮喘模型气道及肺组织中ＰＤＧＦ－Ｂ多肽及其受体（ＰＤＧＦＲ－β）的表达。结果表明：实验组气道壁及周围组织有大量ＰＤＧＦ－Ｂ多肽阳性细胞，主要为气道上皮细胞及浸润的炎症细胞。ＰＤＧＦＲ－β阳性细胞主要分布在气道基底膜及周围结缔组织，偶见于平滑肌和肺间质。提示ＰＤＧＦ－Ｂ多肽及ＰＤＧＦＲ－β的表达与哮喘发     

树鼩血栓性脑缺血中心区及半暗区神经元PAF受体结合特性的研究

目的：观察血栓性局部脑缺血过程中缺血中心区及半暗区血小板活化因子（PAF）受体的消长变化,探讨PAF在脑缺血中心区及半暗区神经元继发性脑损伤中的分子机制。方法：建立光化学诱导树鼩血栓性局部脑缺血模型并提取树鼩脑细胞膜蛋白,用[³H]-PAF放射配体结合试验检测中枢神经细胞膜不同特性的PAF结合位点（受体）。结果：树鼩脑细胞膜上存在两种亲和性不同的PAF受体,即高亲和性和低亲和性受体,其亲和力（kD）分别为(3.61±0.72) nmol/L（kD₁）和17.04±2.41) nmol/L（kD₂）相应的最大结合容量（B_max）分别为(1 457.94±168.01) pmol/g蛋白和(5 017.40±742.16) pmol/g蛋白。脑缺血4、24及72 h中心区、半暗区及对侧区高、低亲和性受体的kD值、B_max值均显著低于假手术组（P<0.01）,中心区及半暗区尤为明显,其中以缺血后24 h的变化最为显著。结论：PAF受体在介导缺血性脑损伤过程中起着重要作用,缺血中心区及半暗区机能代谢的不同与PAF受体亲和特性及最大结合容量改变不同有关,亦是PAF介导继发性脑损伤的重要分子基础。     

哮喘豚鼠内皮素、心钠素含量的变化及心钠素对内皮素含量的影响

目的:探讨内皮素-1(ET-1)在哮喘发病中的可能作用及心钠素(ANF)对ET-1水平的影响。方法:采用放免法测定各组豚鼠支气管肺泡灌洗液(BALF)和血浆ET-1、ANF、cGMP含量。结果:哮喘组豚鼠血浆及BALF中ET-1、ANF、cGMP均显著高于对照组;哮喘组豚鼠血浆中ANF与ET-1含量呈显著负相关(r=-0.638,P<0.05);BALF中ET-1与ANF含量呈高度负相关(r=-0.921,P<0.01)。哮喘组豚鼠血浆中ANF与cGMP含量呈显著正相关(r=0.848,P<0.01),BALF中ANF与cGMP含量呈显著正相关(r=0.831,P<0.01)。哮喘+重组大鼠ANF(rANF)组豚鼠停止输注rANF后30min,血浆及BALF中ET-1水平均明显低于哮喘组。cGMP水平显著高于哮喘组。结论:ET-1在哮喘的发病中可能有重要作用,ANF抑制ET-1合成及分泌。     

细胞相互作用对PAF、系膜细胞paf-R基因表达的影响及阿托伐他汀的干预作用

目的:探讨高糖高脂条件下内皮细胞与系膜细胞相互作用对PAF产生、系膜细胞paf-R基因表达的影响及阿托伐他汀的干预作用。方法:内皮细胞与系膜细胞共培养和系膜细胞单独培养后随机,分为对照组、甘露醇组、高糖高脂组、阿托伐他汀组,培养24h后,ELISA法检测各组细胞上清液PAF含量,实时荧光定量检测系膜细胞paf-RmRNA表达。结果:(1)高糖高脂促进共培养组和单培养组PAF升高(P0.05),共培养组PAF均较单培养组升高(P0.05);(2)高糖高脂可上调系膜细胞paf-R mRNA表达(P0.05);(3)共培养和单培养条件下,阿托伐他汀可抑制高糖高脂引起的PAF升高(P0.05),并可抑制高糖高脂引起的系膜细胞paf-RmRNA表达上调(P0.05)。结论:(1)高糖高脂环境下,系膜细胞和内皮细胞存在异常的相互作用,这种作用促进PAF产生;(2)高糖高脂促进系膜细胞paf-R基因表达,使PAF的生物效应进一步放大;(3)阿托伐他汀可影响高糖高脂条件下内皮细胞与系膜细胞之间的相互作用。     

血小板活化因子受体拮抗剂对实验性肾病综合征的疗效观察及机制探讨

目的:探讨血小板活化因子受体拮抗剂对实验性肾病综合征的疗效及机制。方法: 实验大鼠均复制成阿霉素(ADR)肾病模型,分为2组:ADR肾病组和ADR肾病+血小板活化因子(PAF)受体拮抗剂(BN52021)组。结果: ADR肾病+BN52021组大鼠各期尿蛋白量、血清总蛋白下降幅度、血清胆固醇上升幅度均显著低于ADR肾病组(P＜0.05),第21 d时血清肌酐含量显著低于ADR肾病组(P＜0.05);电镜下肾组织病理改变显著轻于ADR肾病组。ADR肾病组中,肾皮质PAF最大产量在14 d(先于最大蛋白尿量),而肿瘤坏死因子(TNFα)最大含量在21 d,而且, ADR肾病+BN52021组肾皮质内PAF、TNFα含量显著低于ADR肾病组。结论: PAF可能直接或间接通过刺激肾小球固有细胞(肾小球系膜细胞、上皮细胞等)产生TNF导致肾小球损伤,PAF拮抗剂可能通过抑制肾皮质内PAF、TNFα合成,而减轻肾小球损伤。     

血小板活化因子拮抗剂对抗原引起气道嗜酸性粒细胞浸润的影响

为探讨血小板活化因子（ＰＡＦ）拮抗剂消除哮喘气道炎症的价值，应用鸡卵清蛋白致敏和刺激小鼠复制过敏性气道炎症模型，研究ＰＡＦ拮抗剂对于抗原引起气道嗜酸性粒细胞（ＥＯＳ）浸润的影响。体内实验结果表明，正常小鼠支气管肺泡灌洗液（ＢＡＬＦ）中未见到ＥＯＳ；致敏小鼠给予抗原多次反复吸入刺激后，ＢＡＬＦ中ＥＯＳ急剧增多。在ＰＡＦ一种选择性拮抗剂ＹＭ－２６４治疗各组中，ＹＭ－２６４的不同剂量０．１ｍｇ／ｋｇ、１．０ｍｇ／ｋｇ及１０ｍｇ／ｋｇ分别导致ＥＯＳ数下降２７．０％，４８．２％及６７．９％。还发现ＹＭ－２６４抑制ＥＯＳ对气道的浸润还伴随着脾脏细胞培养上清液中白细胞介素５（ＩＬ－５）水平的明显降低。体外实验结果表明，ＰＡＦ另一种选择性拮抗剂ＯＮＯ－６２４０于体外培养时能抑制淋巴细胞产生ＩＬ－５并呈明显的剂量相关性，而这种抑制作用至少可以维持７２小时。这些结果提示ＰＡＦ拮抗剂通过抑制ＩＬ－５的产生从而抑制了ＥＯＳ在气道的聚集。认为ＰＡＦ拮抗剂用于临床治疗支气管哮喘患者理应取得较好的疗效。     

Decrease of ciliary beat frequency by platelet activating factor: Protective effect of ketotifen

The ciliary beat frequency (CBF) of the tracheal epithelial cells controls in part the respiratory tract mucociliary transport efficiency. We investigated the effects on CBF of PAF-acether (PAF) and its metabolite/precursor lyso-PAF. Guinea-pig tracheal rings were incubated for 3 to 6 h with 1 M PAF (C16, C18, C16/C18: 80/20%), lyso-PAF C16 or lyso-phosphatidylcholine (LPC). CBF changes were assessed by microphotooscillography (mean number of measures per ring=14). We also examined the effect on PAF-induced CBF changes of the PAF receptor-antagonist WEB 2086, the anti-asthmatic/anti-anaphylactic drug ketotifen and the anti-histamine H1 pyribenzamine. CBF of control rings exposed to vehicle only from 0 to 6 h showed no significant statistical variations (hertz, mean±SEM): 10.8±0.1 (n of measures=890). By contrast, 1 M C16, C18, and C16/C18 PAF significantly inhibited CBF after 3 to 6h incubation. C16 and C16/C18 PAF were more potent than C18 PAF (8.8±0.2, n=112, 8.7±0.2, n=64, and 9.6±0.1, n=537 respectively; ANOVA analysis, p<0.001 from control). At the same concentration, lyso-PAF also inhibited CBF, 9.5±0.1 (n=197, p<0.001) but not LPC, 10.5±0.2 (n=127). WEB 2086 inhibited lyso-PAF and C16/18 PAF-induced CBF decrease. Preincubation (20 min) with ketotifen but not with pyribenzamine (1 M) also suppressed the CBF inhibitory effect of PAF and lyso-PAF. Incubation of [³H]PAF with tracheal rings from 10 min to 6 h resulted in its partial metabolism (25%) into [³H]lyso-PAF and a compound with a short retention time (10 min). [³H]lyso-PAF incubated for 3 h with tracheal rings was partially metabolized (10%) into [³H]PAF and a compound with a short retention time. The PAF-induced decrease of CBF is congruent with its influence on pulmonary clearance, possibly via a specific receptor, since WEB 2086 abolished the effect of PAF. The inhibition of the PAF-induced CBF decrease by ketotifen may contribute to the therapeutic properties of this antiallergic drug.accepted by M. J Parnham     

Morphological characteristics of bovine platelets activated with platelet activating factor or thrombin

The morphological alterations induced by the activation of bovine platelet rich plasma suspensions with the inflammatory mediator, platelet activating factor (PAF), and following the activation of washed bovine platelet suspensions with thrombin are described. The unstimulated bovine platelet exhibits a smooth oval or discoid shape and granules are randomly dispersed throughout the cytoplasm. The initial activation response to PAF is the development of irregularly shaped cells, the migration of granules to the periphery of the cell and the appearance of large pseudopodia devoid of membrane organelles. As activation continues and large platelet aggregates form, two zones of irregularly shaped, discrete platelets are evident within each large aggregate: an outer zone in which the cells are devoid of granules and an inner zone in which many of the platelets exhibit the typical ultrastructural features of a non-activated cell. In washed platelet preparations activated with thrombin, virtually all platelets undergo shape change and yet many cells retain their alpha granules. In addition, discrete irregularly shaped agranular platelets are also found. The distinctive morphological alterations observed in activated bovine platelets are likely associated with the absence of an open canalicular system, characteristic of many other types of mammalian platelets, and with the ability of the cytoplasmic microtubule coil to reorganise into a linear array following thrombin activation. It is postulated that the bovine platelet has evolved as a cell that can respond to various stimuli, for example inflammatory mediators, by releasing active metabolites from its granular stores without forming platelet-platelet bridges that can serve as a foci for thrombus formation. In this manner the bovine platelet can effectively function as an inflammatory cell without acting as a potent thrombogenic agent.     

Cutaneous and pulmonary histopathological responses to platelet activating factor (Paf-acether) in the guinea-pig

The effect of synthetic Paf-acether has been studied in guinea-pig skin, following intradermal injection, and in guinea-pig lung, following intravenous administration. Histopathological responses to Paf-acether were assessed by both light microscopy and electron microscopy. In addition, plasma protein extravasation and platelet accumulation were quantitatively assessed using radiolabelling techniques. Intradermal injection of Paf-acether, but not lyso-Paf, elicited acute increased vascular permeability, accompanied by intravascular accumulation of platelets and neutrophils. There was evidence, 2-8 h after intradermal injection of Paf-acether, of perivascular infiltration with neutrophils. At 24 h there was a mixed cellular infiltrate comprising mononuclear cells in addition to neutrophils. Following systemic administration of Paf-acether, aggregates of platelets in close association with neutrophils were evident within the pulmonary vasculature. Intravenous injection of Paf-acether, but not lyso-Paf, caused intrathoracic accumulation of radiolabelled platelets. These results suggest that Paf-acether has properties consistent with those of a mediator of inflammation.     

血小板活化因子对豚鼠心室肌细胞钾电流及动作电位的影响

 目的：研究血小板活化因子(PAF)对豚鼠心室肌细胞钾电流及动作电位的影响。 方法:应用全细胞膜片钳技术，记录豚鼠心室肌细胞动作电位及钾电流(I_K 与I_K1)。 结果:当电极内液ATP浓度为5 mmol/L，1 μmol/L PAF使APD₉₀由对照的(225.8±23.3)ms延长至(352.8±29.8)ms(n=5, P<0.05)；使I_K尾电流在指令电压 +30 mV 时由对照的(173.5±16.7)pA降为(152.1±11.5)pA(P<0.05, n=4)；使I_K1在指令电压 -120 mV 时从(-6.1±1.3)nA降为(-5.6±1.1)nA(P<0.05, n=5)；当电极内液ATP 为0 mmol/L，APD₉₀明显缩短，1 μmol/L PAF使APD₉₀由对照的(153.0±24.6)ms缩短为(88.2±19.4)ms (n=5, P<0.01)，而用1 μmol/L格列本脲 ( I_KATP特异性阻滞剂)预处理后，恢复了PAF可显著延长动作电位时程的作用。 结论: PAF使缺血区K_ATP开放，动作电位时程缩短，却可抑制正常区I_K 与I_K1，使动作电位延长，从而放大了缺血区与正常区的不均一性，这可能与缺血时心律失常的发生有关。     

血小板活化因子在颈髓损伤后线粒体功能损伤中的作用

目的和方法;采用Ａｌｌｅｎ打击法造成Ｃ６．７损伤,鞘内注射血小板活化因子及静脉注射ＰＡＦ受体拮抗剂ＮＢ５２０２１,观察其对颈颈髓损伤后脊髓组织ＰＡＦ含量,颈髓线粒体ＡＴＰ酶活性,线粒体呼吸功能的影响,结果;颈髓损伤后颈髓组织ＰＡＦ含量明显增加,蛛网膜下腔注射ＰＡＦ可使伤后ＰＡＦ含量增加更为显著;ＰＡＦ能够抑制Ｃａ＾２＋－ＮＭｇ＾２＋－ＡＴＰ酶,Ｎａ＾＋－Ｋ＾＋－ＡＴ「Ｐ酶活性,明显降低线粒体耗年头