Cardiodepressor action of platelet activating factor

Biophysics Research Laboratory, A. V. Vishnevskii Institute of Surgery, Academy of Medical Sciences of the USSR, Moscow. Laboratory of Lipid Biochemistry, Research Institute of Biomedical Technology, Moscow. (Presented by Academecian of the Academy of Medical Sciences of the USSR D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 1, pp. 27–30, January, 1989.     

Influence of prostaglandins and platelet activating factor on implantation

Several studies indicate that prostaglandins and platelet activating factor (PAF) affect implantation of the embryo. Most studies relate to animal data on prostaglandin synthesis at the site of implantation and on prostaglandin production by blastocysts. The few experimental data available on human implantation suggest that prostaglandins and PAF behave similarly in man. A review of the literature on this subject suggests possible mechanisms for prostaglandin and PAF participation in the process of human implantation.     

Andrology: Effects of platelet activating factor on human sperm function in vitro

The direct effects of platelet activating factor (PAF) and thespecific PAF receptor antagonist, CV-3988, on the fertilizingability of human spermatozoa were investigated. PAF (10^–7–10^–11M) increased the human sperm penetration rates in a sperm penetrationassay at all doses >10^–11 M. In contrast, treatmentof the spermatozoa with 10^–5 CV-3988 caused a significantdecrease in human sperm penetration of zona-free hamster oocytesand adversely affected sperm motility after 24 h of incubation.This suppression was reversed by the addition of PAF. The acrosomereaction was also enhanced by PAF treatment of spermatozoa butthis effect was not observed in calcium-free medium. While 10^–5M CV-3988 decreased the acrosome reaction, the inhibition wasalso reversed by the addition of PAF. These results suggestthat PAF may have a direct role in the fertilizing capacityof human spermatozoa. These findings also suggest that PAF mayhave a clinical application in an in-vitro fertilization programme.     

Enhanced production of platelet activating factor by peripheral granulocytes from children with asthma

Schauer U, Koch B, Michl U, Jäger R, Rieger CHL. Enhanced production of platelet activating factor by peripheral granulocytes from children with asthma.
Granulocytes from 23 asthmatic children aged 4–15 years and 32 age-matched healthy children were studied. Cells were purified by Dextran sedimentation and Percoll gradient centrifugation from heparinized blood. After in vitro stimulation by ionophore A23187 the amount of newly synthesized PAF and LTC₄ was assessed by radio receptor assay or radioimmunoassay respectively. Eight patients had symptoms of asthma within the last 3 weeks before examination. Granulocytes from the symptomatic patients showed a significantly higher PAF generation (median 125 ng/10⁶ cells, range 7–189 ng/10⁶ cells) when compared to asymptomatic patients ( p < 0.001. median 14 ng/10⁶cells, range 6–33 ng/10⁶ cells) or controls ( p < 0.001, median 11 ng/10⁶ cells, range 3–26 ng/10⁶ cells). In contrast, LTC₄ generation was increased in both patient groups. The results suggest a regulatory role of PAF in the exacerbation of asthma.     

Measurement of human embryo-derived platelet-activating factor (PAF) using a quantitative bioassay of platelet aggregation

A quantitative bioassay was used to measure the concentration of platelet activating factor (PAF) in medium in which human embryos produced by IVF had been cultured and in various other biological fluids. Following extraction and partial purification, 121 of 228 (53%) media samples in which single human embryos were cultured for 24 h had PAF levels greater than found in corresponding control media. This was assigned as embryo-derived PAF and the corresponding embryos termed 'PAF-positive'. Medium from those PAF-positive embryos transferred to patients who achieved an ongoing pregnancy had a mean PAF concentration of 295 +/- 107 nM (mean +/- SEM, n = 55), which was significantly greater (P less than 0.03) than media of PAF-positive embryos transferred to patients who failed to become pregnant (75 +/- 27 nM, n = 66, t-test). The embryos with the faster cleavage rates tended to secrete more PAF (P less than 0.01). Although a greater proportion of culture media derived from embryos transferred to patients who achieved a pregnancy were PAF-positive (66 out of 121, 54.5%) compared with those transferred to patients who failed to achieve a pregnancy (55 out of 121, 45.4%), this was not significant (P greater than 0.05). It was observed that 13% of women who achieved a pregnancy had embryos transferred which did not produce significant amounts of PAF in vitro. This occurred in 26% of women not achieving pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

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。     

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。     

Platelet activating factor and endotoxin-induced platelet activation

Central Research Institute of Epidemiology, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. I. Pokrovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 5, pp. 538–540, May, 1989.     

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。     

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。     

The potentiation of arterial contraction with platelet activating factor

The incubation of porcine carotid arteries with platelet activating factor induces a potentiation of contraction when the artery is subsequently challenged with 100mM KCl compared with control preparations. This potentiation of arterial contraction is not observed when extracellular Ca²⁺ influx or prostaglandin metabolism is inhibited.     

Eosinophil migration in response to three molecular species of platelet activating factor

Multiple molecular species of the eosinophil chemoattractant platelet activating factor (PAF) are produced as a result of inflammatory processes. We therefore compared the ability of three naturally occurring PAF species (C160, C180, and C181), which only varied at carbon 1, to induce eosinophil chemotaxis through naked 3-m pore polycarbonate filters. Timecourse experiments indicated that all species of PAF tested induced significant and equivalent eosinophil migration at 1 h which peaked at 2 h. Overall, the rank order of chemotactic potency for the PAF species was relatively equivalent. The specific PAF antagonist WEB 2086 inhibited eosinophil migration induced by all three PAF species equally. We conclude that the degree of PAF-induced eosinophil migration is not dependent upon the molecular species of PAF.accepted by G. W. CarterThis work was supported in part by a Veterans Administration Merit Review Award.     

Platelet activating factor in culture media as an indicator of human embryonic development after in-vitro fertilization.

Although human chorionic gonadotrophin can detect trophoblast after implantation of the conceptus, there is a need to detect the conceptus before implantation. We have investigated whether human embryo-derived platelet activating factor is formed during embryonic development after in-vitro fertilization. A total of 99 ova from 12 patients were cultured and the 54 media were analysed. Platelet activating factor was also measured by radioimmunoassay after extraction. Fertilization increased the amount of platelet activating factor 4-fold over non-fertilized ova to a level of 4 ng/ml. This increase was also dependent on the degree of embryonic development with a maximum level of platelet activating factor of 7 ng/ml at the 2-cell stage. The follicular inducing agent used to treat the patient also had an effect on platelet activating factor; buserelin treatment gave embryos with a higher level than did clomiphene citrate treatment. These results indicate that platelet activating factor may have a role in embryonic development before implantation and may serve as a useful marker for fertilization and the developmental stage of the embryo.     

Modulating action of adenosine on human platelet activation

Research Center for Molecular Diagnosis and Treatment, Ministry of Health of Russia, Moscow. (Presented by Academician of the Russian Academy of Medical Sciences R. V. Petrov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 6, pp. 606–608, June, 1992.     

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     

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     

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。     

Platelet activating factor enhances the acrosome reaction, fertilization in vitro by subzonal sperm injection and resulting embryonic development in the rabbit

This study was conducted to investigate the effect of plateletactivating factor (PAF) on the acrosome reaction and fertilizingcapacity of spermatozoa, and development of the resulting embryosin the rabbit. Rabbit spermatozoa were exposed to PAF, Iyso-PAF,or high ionic strength medium (HIS) prior to subzonal sperminjection (SUZI) into 326 mature oocytes, or morphological assessmentof the acrosome reaction. The rates of fertilization and blastocystformation were compared among the three treatment groups. Acrosomereaction was assessed by fluorescein isothiocyanate-conjugatedPisum sativum agglutinin (FITC–PSA) staining and electronmicroscopy. PAF-treated spermatozoa fertilized the oocytes ata significantly higher rate (56.1%) than did lyso-PAF-(36.8%,P< 0.01) or HIS- (38.2%, P < 0.05) treated spermatozoa.The embryos produced by PAF-treated spermatozoa showed significantlyhigher blastocyst formation rates (34.0%) than lyso-PAF- (8.6%,P < 0.050) or HIS-(8.8%, P< 0.05) treated spermatozoa.FITC-PSA staining demonstrated a significantly higher incidenceof acrosome reaction in PAF-treated spermatozoa (45.8%) thanin Iyso-PAF- (28.0%, P < 0.01) or HIS- (34.9%, P < 0.01)treated spermatozoa. Acrosome reaction of PAF-treated spermatozoawas also confirmed by electron microscopy. PAF treatment ofspermatozoa enhances fertilizing capacity for SUZI possiblyby augmenting the acrosome reaction. Enhanced embryonic developmentwas also found in the oocytes fertilized by SUZI of PAF-treatedspermatozoa.