血小板活化因子受体拮抗剂-BN 52021对内毒素引起大鼠急性肺动脉高压影响的观察

目的：探讨特异性血小板活化因子（PAF）受体拮抗剂－BN52021对内毒素引起的肺动脉高压的影响。方法：Wistar大鼠静脉注入内毒素引起急性肺动脉高压；应用BN52021预处理：观察BN52021对经内毒素处理大鼠的血液动力学、血浆肿瘤坏死因子α（TNF－α）、血栓素B2（TXB2）及动脉血气变化的影响。结果：BN52021可部分抑制内毒素引起的急性肺动脉高压；降低血浆TNF－α和TXB2的含量，提高动脉血氧分压。结论：BN52021能减轻内毒素引起的肺伤；降低内毒素引起的大鼠肺动脉高压。     

银杏苦内脂B对急性坏死性胰腺炎大鼠胰腺组织NF-kB p65、IkBαmRNA表达的影响

目的观察NF—kBp65、IkBαmRNA在急性坏死性胰腺炎（ANP）大鼠胰腺组织中的表达以及银杏苦内脂B（BN52021）对其表达的影响。方法180只Wistar大鼠随机分为对照组（NC组）、ANP模型组（ANP组）、BN52021治疗组（BN组），每组大鼠分别在术后1h、2h、3h、6h、12h和24h6个时间点处死，抽血测定血淀粉酶含量，取胰腺组织行病理学检查，RT—PCR法检测NF—kB p65、IkBαmRNA表达。结果血清淀粉酶和病理学改变符合ANP。BN52021能降低ANP大鼠的血清淀粉酶含量和改善胰腺的病理损害。ANP组和BN组NF—kB p65mRNA均呈双峰改变，第1峰在1h，第2峰分别在24h和12h，6h时降至最低。ANP组NF—kB p65mRNA表达在2h、3h、12h和24h较NC组显著增加（P〈0．05或0．001），仅在1h时较BN组有显著差异（P〈0．041），其他时间点无显著差异；但较NC组各时点显著升高（P〈0．05或0．001）。ANP组IkBαmRNA表达仅在24h点较NC组明显增加（P=0．000），BN组在1h、6h和12h较ANP组显著增加（P〈0．01），在1h、12h和24h也较NC组显著增加（P〈0．01）。结论NF—kBp65mRNA在ANP大鼠胰腺组织表达上调，IkBαmRNA仅在造模后24h时表达上调。BN52021可能通过上调IkBαmRNA的表达，破坏NF-kBp65mRNA和IkBαmRNA的平衡，从而发挥其治疗作用。     

基质金属蛋白酶在类似人类2型糖尿病大鼠肾病中的研究

目的 动态研究基质金属蛋白酶－2（MMP－2）和其体内特异的抑制物－金属蛋白酶组织抑制剂－2（TIMP－2）在类似人类2型糖尿病大鼠肾组织的改变。方法 利用免疫组织化学观察Ⅳ型胶原在肾小球的表达,酶谱法测定肾皮质MMP－2的活性,蛋白印迹法检测肾皮质TIMP－2的含量,Northern Blot观察肾皮质MMP－2和TIMP－2的基因表达。结果 类似人类2型糖尿病大鼠肾小球Ⅳ型胶原成分表达增强,肾皮质MMP－2基因表达减弱（P＜0．01）;其活性进行性减少（P＜0．0001）,而TIMP－2基因表达（P＜0．01）及其含量逐渐增加（P＜0．01）。结论 类似人类2型糖尿病大鼠肾组织MMP－2活性进行性降低、TIMP－2含量增加,两者比例失衡为肾小球ECM成份沉积的重要原因之一,基质降解减弱也参与了2型糖尿病大鼠肾脏病变的发生和发展。     

川芎嗪对急性坏死性胰腺炎大鼠胰腺及肾损伤的保护作用

目的 探讨川芎嗪对急性坏死性胰腺炎（ANP）胰腺及肾损伤的保护作用。方法 192只SD大鼠,随机分为对照（C）组、胰腺炎（P）组、川芎嗪治疗（T）组,并制作模型。三组模型制作后0．5、2、6及12h分别测定肾血流量,对胰腺、肾组织病理进行评分、分级,观察肾功能及血栓素A2（TXA2）／前列环素（PGI2）。结果 与C组相比,P组各时间点肾血流量均明显降低（P〈0．01）,胰腺及肾病理改变明显加重,血浆尿素氮（BUN）、肌酐（Cr）明显升高（P均〈20．05）,TXA2／PGI2在2、6、12h明显增加（P〈0．01）。与P组相比,T组各时间点肾血流量均明显增加（P〈0．01）,胰脓及肾的病理损害有所减轻．血浆BUN、Cr较C组明显降低（P均〈0．05）,TXA2／PGI2在6、12h明显降低（P均〈0．05）。结论 川芎嗪可以减轻ANP大鼠的胰腺及肾损伤。     

系统性红斑狼疮患者血浆11—去氢—血栓烷B2测定及其临床意义

目的 观察系统性红斑狼疮（SLE）患者体内血小板活化状态。方法 采用酶联免疫吸附法（ELISA）检测32例SLE患者血浆11－去氢－血栓烷B2（DH－TXB2）,同时测定TXB2,并与对照组比较。结果 与对照组比较,SLE患者血浆DH－TXB2、TXB2均显著增高（P＜0．01及P＜0．05）,且DH－TXB2增高程度明显高于TXB2,对对照组无重叠,肾受累者显著高于无肾脏受累者（P＜0．05）,经治疗者显著低于初发未治疗者（P＜0．01）,但仍高于对照组（P＜0．05）。血浆TXB2与DH－TXB2浓度与疾病活动指数均呈正相关（r1＝0．478,P＜0．05及r2＝0．530,P＜0．01）。结论 血浆DH－TXB2水平测定是准确反映血小板活化的指标,SLE患者体内血小板高度活化。     

灵芝多糖对糖尿病大鼠肾组织MMP-2和TIMP-2表达的影响

目的观察基质金属蛋白酶-2（MMP-2）、基质金属蛋白酶抑制因子-2（TIMP-2）在糖尿病大鼠肾组织中的表达及灵芝多糖干预后的影响。方法腹腔注射链脲佐菌素（STZ）诱导制备糖尿病大鼠模型，分组给予不同剂量灵芝多糖（GLP，100、200、400mg／kg）进行治疗性灌胃。8w后，免疫组化和RT-PCR方法雄测各组大鼠肾皮质MMP-2、TIMP-2的表达。结果糖尿病组大鼠肾小球MMP-2的表达较正常对照组明显减少，TIMP-2明显升高（P〈0．01）；灵芝多糖各组较糖尿病组MMP-2表达升高（P〈0．01），TIMP-2表达减少（P〈0．01）。结论灵芝多糖通过调节MMP-2／TIMP-2的平衡，减少细胞外基质积聚，对糖尿病大鼠肾脏起保护作用。     

脑缺血再灌注胃肠损伤老年大鼠前列腺素和肿瘤坏死因子的变化及其意义

目的：从血栓素（TXA2）与前列环素（PGI2）和肿瘤坏死因子（TNF）的变化方面研究老年大鼠脑缺血再灌注胃肠损伤的机制。方法：青年（5月龄）和老年（20月龄以上）大鼠均分为模型组和正常对照组，观察大鼠全脑缺血30min再灌注60min后胃肠组织变化和TXA2，PGI2，TNF含量。结论：青年和老年模型组胃肠组织出现明显的病理损伤，老年模型组较青年模型组严重。青年模型组胃组织中TXB2／6－Keto-PGF1α比值高于青年对照组和老年模型组，青年对照组小肠组织中TXB2／6－Keto-PGF1α低于青年模型组和老年对照组。老年模型组小肠中TNF含量高于青年模型组和老年对照组，结论：脑缺血再灌注胃肠损伤机制与以TXA2占优势的TXA2与PGI2的平衡失调和TNF增高有关，但由于老年大鼠胃肠组织前列腺素和TNF的增龄变化，使戎脑缺血再灌注胃肠组织TXA2与PGI2的平衡失调不明显，而TNF的改变较显著。     

人组织激肽释放酶对糖尿病肾病大鼠的影响

目的：探讨基因重组人组织激肽释放酶（KLK）对大鼠糖尿病肾病的影响。方法：大鼠经链脲佐菌素诱导制成糖尿病（DM）模型于第8、12、16周留取尿标本。比色法检测大鼠血浆KLK变化，放射免疫技术、酶联免疫吸附试验（ELISA）、免疫组化技术测定肾组织一氧化氮（NO）、环磷腺苷（cAMP）、血内皮素1（ET-1）变化及光镜电镜观察肾组织形态改变。结果：（1）DM组与正常对照组（C）组大鼠比较，体重（BW）、血浆KLK活性、肾组织中NO、cAMP含量下降（P〈0．01或P〈0．05）。而DM组的血糖（BG）、血肌酐、血尿素氮（BUN）、肾重（KW）体重比值、ET-1、尿白蛋白（Ualb）排泄率、24h尿蛋白定量均高于（NC）组（P〈0．01或P〈0．05）。（2）糖尿病KLK治疗组（DK）组与NC组大鼠比较，BW、血浆KLK活性、肾组织中NO、cAMP含量下降（P〈0．01或P〈0．05）；而BG、KW／BW、Ualb排泄率、24h尿蛋定量均高于c组（P〈0．01或P〈0．05）。DM组、DK组间BG、BUN、BW、KW／BW无显著性差异，血浆KLK活性、肾组织中NO、cAMP含量，DK组明显高于DM组（P〈0．01或P〈0．05）。而血肌酐、Ualb排泄率、24h尿蛋白定量则显著低于DM组（P〈0．01或P〈0．05）。（3）①16周时，DM组血浆KLK活性明显低于8周时的水平（P〈0．01），明显较NC组降低（P〈0．01）；而DK组血浆KLK活性明显高于8周时的水平（P〈0．05），该组病变较DM组轻。②DK组12周、16周尿白蛋白排泄率均低于8周时的水平（P〈0．05），16周时，DK和DM比较尿白蛋排泄率差异显著（P〈0．05）。③16周时，DM组肾组织中NO、cAMP含量则明显低于C组（P〈0．01），而与DM组相比，DK组肾组织中NO、cAMP含量较高（P〈0．01或P〈0．05）。结论：给予外源性人组织KLK可抑制糖尿病大鼠肾小球系膜细胞增殖、基质增多，可使尿蛋白排泄减少，延缓糖尿病肾病的发展。     

伊贝沙坦对大鼠糖尿病模型肾脏肥大和肾小球毛细血管基底膜厚度的影响

目的 观察伊贝沙坦对大鼠糖尿病模型肾脏肥大和肾小球毛细血管基底膜厚度的影响。方法 将SD大鼠分为糖尿病肾病组(A组)、伊贝沙坦治疗组(B组)、健康对照组(C组),A和B组大鼠制成糖尿病模型,B组予以50mg／kg伊贝沙坦灌胃。观察第4、8、12周大鼠的血糖、体重、尿白蛋白、24h尿蛋白的改变及第12周时的肌酐清除率(Ccr)、肾重、肾脏肥大指数、肾组织总蛋白含量、肾小球面积和体积、肾小球毛细血管基底膜(GBM)厚度的改变。通过免疫组化观察肾结缔组织生长因子(CTGF)和转化生长因子(TGF)-βl的表达。结果 A组和B组大鼠血糖较C组明显升高且维持在一个较高水平(P＜0．01)。A组大鼠的体重较C组明显下降,B组有所增加(P＜0．05)。随时间的推移(第4、8、12周),A组大鼠尿蛋白、尿白蛋白逐渐增加,B组明显减少(P＜0．01)。A组大鼠Ccr较C组显著升高(P＜0．01),B组Ccr明显下降(P＜0．05)。至第12周时,A组大鼠肾脏重量、肾脏肥大指数、肾组织总蛋白含量、肾小球面积和体积均较C组明显增加(P＜0．01),B组均较A组降低(P＜0．01,P＜0．05)。免疫组化半定量分析显示,A组大鼠CTGF与TGF-βl的表达均高于C组(P＜0．01),B组明显低于A组(P＜0．01,P＜0．05)。A组大鼠GBM较C组明显增厚(P＜0．01),B组较A组明显变薄(P＜0．01）。肾小球CTGF、TGF—βl的表达与肾脏体积呈正相关(r＝0．83,r＝0．83;P＜0．05)。结论 早期应用伊贝沙坦可抑制糖尿病大鼠早期肾脏肥大和CTGF表达等。     

单侧输尿管梗阻肾间质纤维化大鼠肾组织PHB1和 PHB2的表达及意义

目的：观察单侧输尿管梗阻（ UUO）肾间质纤维化（ RIF）大鼠肾组织PHB1和PHB2的表达,并探讨其意义。方法80只雄性6周龄Wistar大鼠随机分为模型组和假手术组各40只。模型组大鼠分离左侧输尿管后行双重结扎,假手术组只探查到肾包膜。于造模后第2周末和第4周末,每组各处死20只大鼠,取左侧肾组织进行肾脏病理学检查,并计算RIF指数;应用实时荧光定量PCR检测大鼠肾组织PHB1、PHB2、TGF-β1 mRNA;Western blot检测肾组织PHB1、PHB2、TGF-β1、Ⅳ型胶原（ Col-Ⅳ）和纤维连接蛋白（ FN）。结果与假手术组比较,模型组大鼠各时间点RIF指数增高,梗阻时间越长RIF指数越高,P均＜0．01;肾组织PHB1、PHB2 mRNA及蛋白表达均降低,梗阻时间越长表达水平越低,P均＜0．01;TGF-β1 mRNA及蛋白、Col-Ⅳ和FN蛋白表达均增高,P均＜0．01。肾组织PHB1蛋白表达与RIF指数、TGF-β1、Col-Ⅳ、FN呈负相关（ r分别为－0．86、－0．87、－0．70、－0．73,P均＜0．05）;PHB2蛋白表达与RIF指数、TGF-β1、Col-Ⅳ、FN呈负相关（r分别为－0．73、－0．81、－0．91、－0．84, P均＜0．05）;PHB1蛋白表达与PHB2蛋白表达呈正相关（ r＝0．78,P＜0．05）。结论在UUO所致RIF大鼠肾组织中,PHB1和PHB2表达显著降低,参与RIF的发生发展。     

血小板活化因子刺激肾小球系膜细胞的自分泌作用

提出了纯金属电阻率的两个简化模型：一个统计模型，一个电子－声子耦合模型。由统计模型可得出；纯金属电阻率与声子深度及声子平均动量的平方成正比。由电子－声子耦合模型得出：电子的散射几率不仅正比于声子数，而且正比于电子－声子的耦合强度。由这两个模型皆能得出纯金属电阻率在高湿时与温度Ｔ成正比，低温时与Ｔ＾５成正比的结果。由电阻率－温度曲线的比较表明，两模型相当吻合。     

血小板活化因子在急性胰腺炎大鼠并发肾损伤中病理生理作用

目的:本文旨在观察血小板活化因子在急性出血坏死性胰腺炎(AHNP)大鼠肾损伤发生中作用。方法:159只SD大鼠随机分三组:假手术组、AHNP非治疗组和AHNP BN(52021)治疗祖。采用胰管内注入5％牛磺胆酸钠溶液诱导大鼠AHNP,应用~(86)Rb组织摄取法测定肾脏相对血流量及组织灌注量,并测定血小板聚集率(PAgR)。结果:与非治疗组相比较,BN(52021)治疗组肾脏相对血流量、组织灌注量显著提高;PAgR下降;肾脏病理损害减轻。结论:血小板活化因子参与了急性出血坏死性胰腺炎大鼠肾损害的发生。     

急性出血坏死性胰腺炎大鼠肠粘膜病变的实验研究

以胆胰管内注入牛磺胆酸钠诱发大鼠急性出血坏死性胰腺炎（ＡＨＮＰ）模型。术后１、６、１２小时应用８６ＲｂＣｌ标记法动态测定空回肠血流量；取回肠标本小块作光镜、扫描和透视电镜观察；同时观察ＮＢ５２０２１、Ｄａｚｍｅｇｒｅｌ对上述指标的影响。结果表明ＡＨＮＰ模型制备后，肠粘膜病理损伤呈时间依赖性，术后１２小时呈显著的粘膜下水肿、绒毛脱落裸露、上皮细胞间桥粒断裂；肠血流量进行性下降；ＢＮ５２０２１、Ｄａｚｍｅｇｒｅｌ显著增加肠血流量，减轻肠粘膜病理损伤。提示ＡＨＮＰ大鼠存在肠粘膜损伤，可能与血小板活化因子及血栓素Ａ２介导的肠血流减少有关。     

A PAF receptor antagonist, BN 52021, attenuates thromboxane release and improves survival in lethal canine endotoxemia.

Platelet-activating (PAF) is a putative mediator in endotoxemia and sepsis. Administration of a PAF receptor antagonist prior to endotoxin improves survival in rats and attenuates the hypotension of endotoxemia. Both PAF and endotoxin stimulate eicosanoid production. We hypothesized that a PAF receptor antagonist, BN 52021, would alter the hemodynamic events, improve the survival and attenuate the eicosanoid release associated with endotoxemia in a resuscitated, but lethal, canine model. Male dogs were randomzied to two groups (n = 10 each). Group I received only E. coli endotoxin, 1 mg/kg IV, at time 0, while group II received BN 52021, 5 mg/kg IV, 30 min before and again 240 min after endotoxin treatment. During the 4-h study period, hemodynamics were measured and blood samples were taken at 0, 2, 60, 120, and 240 min. Survival was determined at 24, 48, and 72 h. All group I animals died before 24 h; all group II lived longer than 72 h (P less than 0.05). In group I, plasma TXB2 values increased from a baseline value of 0.26 +/- .04 ng/ml to 4.38 +/- 1.56 ng/ml at 120 min and then decreased to 2.64 +/- .96 ng/ml by 240 min. For group II, respective plasma TXB2 values were 0.35 +/- 0.13 ng/ml at baseline, 0.58 +/- 0.14 ng/ml at 120 min, and 0.39 +/- .09 ng/ml at 240 min. At the 120-min and 240-min time points, the groups differed at P less than 0.05. Heart rate tended to be less in group II, but MAP was unaffected. In group I, pH values were more acidotic than those observed in group II.     

Effects of PAF antagonist, BN52021, on the PAF-, methacholine-, and allergen-induced bronchoconstriction in asthmatic children

Platelet-activating factor (PAF) is an inflammatory mediator capable of inducing protracted inflammation of the airways and bronchial hyperreactivity. Twenty-one asthmatic children were evenly divided into three groups and each group performed a double-blind, placebo-controlled and crossover study on the effect of aerosolized BN52021, a PAF antagonist, on the bronchoconstriction induced by PAF, methacholine, or specific allergen, respectively. One group of healthy children was included for comparison. Total WBC, neutrophils, and eosinophils were counted before and after PAF challenge. The results showed the following: (1) six of seven asthmatics and one of seven normal subjects gave a positive bronchial provocation with PAF; (2) in asthmatics, prior inhalation of BN52021 could inhibit the bronchoconstriction induced by PAF (6/6) and allergen (3/7), but not by methacholine; and (3) 5 min after inhalation of PAF, there was a marked decrease of peripheral blood eosinophils and neutrophils that could be inhibited by prior inhalation of BN52021 in normal subjects but not in asthmatics. These findings support the idea that PAF may be involved in the pathogenesis of bronchial asthma and PAF antagonist may have a role in the prevention and treatment of this disease.     

海风藤新木脂素类成分对缺血脑区血小板活化因子及花生四烯酸代谢的影响

目的　研究海风藤新木脂素类成分等天然血小板活化因子 (PAF)受体拮抗剂对脑缺血后PAF及花生四烯酸(AA)代谢的作用影响 ,探讨内在关系及机制。方法　应用放免法测定大脑中动脉线栓闭塞再通不同时相大脑中动脉供血区顶叶皮质PAF、血栓素B2 浓度。结果　单纯缺血 90min时 ,PAF含量已显著高于对照组 ,再灌注 3h稍有回降 ,随即持续升高至 12h ;对应血栓素B2 值再灌注 3h增加 ,在 18h达高峰 ,两者分别于再灌注 2 4h和 36h降至对照组水平。海风藤新木脂素复合物、海风藤酮及银杏叶类制剂银杏内酯B均能明显抑制PAF和血栓素B2 的升高。结论　局灶性脑缺血再灌注后 ,PAF与AA协同参与了神经细胞损伤的发生及发展过程。两类天然PAF受体拮抗剂均可抑制脑缺血后PAF的过量生成、纠正AA代谢紊乱     

Effects of a thromboxane synthetase inhibitor (OKY-046) on vascular reactivity to angiotensin II after stricture of the abdominal aorta in pregnant rabbits.

The abdominal aorta of 20 pregnant rabbits was surgically constricted below the renal arteries on the 21st day of pregnancy, producing a stricture that decreased the blood flow by 60%. Four pregnant rabbits underwent sham operation and served as control. The pressor response to angiotensin II (A-II) was assessed by measuring the systolic blood pressure in the ear of rabbits. We intravenously administered 20 mg/kg of OKY-046, a thromboxane A2 (TXA2) synthetase inhibitor (OKY group: n = 13) or saline (n = 7) daily from the 23rd day of pregnancy until the day of delivery. After stricture of the abdominal aorta, the "effective pressor dose" (EPD:nanograms of A-II/kg/min necessary to cause a 20 mmHg rise in systolic pressure) was significantly lower in the saline group than in the control group. On the 27th and 29th day of pregnancy, the EPD in the OKY group was significantly higher than that in the control group. The plasma thromboxane B2 (TXB2) level in the OKY group was significantly lower than that in the saline group on the 27th day. The fetal birth weight in the saline group was significantly lower than that in the control group. These finding suggest that OKY-046 restores the vascular refractoriness induced by A II and suppresses TXA2 synthesis in pregnant rabbits with aortic constriction.     

Platelet Activating Factor (PAF) Antagonism with Ginkgolide B Protects the Liver Against Acute Injury. Importance of Controlling the Receptor of PAF

Platelet activating factor (PAF) is an ubiquitous phospholipid that acts as a mediator of numerous pathophysiological conditions, including hepatotoxicity. The present study has been conducted to evaluate the eventual role of the platelet activating factor in post-acetaminophen intoxication of liver, using ginkgolide B, BN52021, a selective PAF receptor antagonist. One group of rats was treated with a toxic dose of acetaminophen (APAP) (3.5 g/kg b.w.) (control group) and a second one with the same dose of APAP followed by a dose of ginkgolide B, BN52021 (10 mg/kg b.w.) (BN52021-treated group). The animals were killed at 8, 16, 24, 32 and 40 h after treatment. APAP was found to cause an acute hepatic injury, evident by alterations of biochemical (serum enzymes: ALT, AST and ALP) and liver histopathological (degree of inflammation and apoptosis) indices, which was followed by liver regeneration evident by three independent indices ([3H] thymidine incorporation into hepatic DNA, liver thymidine kinase activity and hepatocyte mitotic index). Hepatic levels of malondialdehyde and serum cholesterol/HDL cholesterol fraction were also measured as parameters of oxidant–antioxidant balance. The protected effects of ginkgolide B were qualified during post treatment time by: (1) reduction of oxidative stress, (2) high decrease of hepatic injury, and (3) decrease of regenerating activity. These results indicate that PAF may play an important role in APAP-induced liver injury and regeneration, and that the use of ginkgolide B attenuates liver damage providing important means of improving liver function following acetaminophen intoxication.     

Contribution of platelets and platelet-activating factor (PAF) to the arrhythmogenic, haemodynamic and necrotic effects of acute myocardial ischaemia

The effects of alterations in platelet activity on arrhythmias, haemodynamics and extent of necrosis during coronary ligation for 30 min were assessed in rabbits. Reduction of platelet counts to less than 1% of control by intravenous injection of platelet antiserum (1 ml kg-1 i.v.) reduced the volume of necrosed tissue from 23 +/- 2% to 15 +/- 1%, P less than 0.01 (expressed as % of total LV) and attenuated the hypotensive effect of ischaemia. Pretreatment with the platelet activating factor (PAF) antagonist BN 52021 also attenuated the hypotension and necrosis caused by coronary ligation 23 +/- 2% vs 14 +/- 1%, P less than 0.01. Pretreatment with the thromboxane antagonist CGS 13080 attenuated the hypotensive response to ischaemia but had only a very small effect on the area of necrosis. Administration of PAF at 10 min following coronary ligation markedly increased the volume of necrosed tissue 36 +/- 2%, P less than 0.01 and caused VF and haemodynamic collapse in 10 out of 12 animals. Pretreatment with platelet antiserum or the PAF antagonist BN 52021 reversed this effect of PAF. Pretreatment with CGS 13080 attenuated the marked hypotensive effect of PAF but failed to reverse its necrotic or arrhythmogenic effects. These findings indicate that platelet activation contributes to the necrosis and hypotension following coronary ligation and that platelet-activating factor may contribute to this. The ameliorating effects of platelet antiserum or BN 52021 support the concept that inhibition of platelet activity may have a useful role in the treatment of acute myocardial infarction.