内毒素血症幼鼠小肠黏膜组织学及血浆、肠组织二胺氧化酶、血浆D-乳酸的变化

目的 观察内毒素血症幼鼠小肠黏膜组织学及血浆、肠组织二胺氧化酶(DAO)、血浆D-乳酸的变化.方法 18日龄wistar大鼠48只,随机分为内毒素血症组(n=40),正常对照组(n=8),内毒素血症组根据注射脂多糖(LPS)后取标本时间分为1.5 h、6 h、24 h、72 h、7 d共5个亚组,各组于各时间点分别取血浆及小肠匀浆,测定血浆DAO活性及D-乳酸、小肠匀浆DAO值.结果 (1)内毒素血症组呈小肠黏膜损伤的组织学改变;(2)内毒素血症1.5 h、6 h、24 h、72 h亚组血浆DAO较正常对照组增高(P<0.05);而7 d亚组较正常对照组偏低;(3)内毒素血症各亚组小肠组织DAO低于正常对照组DAO;(4)内毒素血症组血浆D-乳酸较正常组增高(P<0.05);(5)血浆DAO与小肠组织DAO含量呈负相关(r=-0.392,P=0.006).结论 腹腔注射LPS可以引起小肠上皮细胞受损,紧密连接破坏,肠通透性增加,提示临床上可以通过测定血浆DAO及D-乳酸来及时了解肠道屏障功能.     

血小板活化因子受体拮抗剂对内毒素血症幼年大鼠肠黏膜上皮细胞间连接蛋白的影响

目的观察血小板活化因子（PAF）对内毒素血症大鼠肠黏膜上皮细胞间连接蛋白β-连环蛋白（β-catenin）的影响，探讨PAF受体拮抗剂对肠上皮屏障完整性的保护作用机制。方法采用腹腔注射脂多糖（LPS）制备内毒素血症大鼠模型。于注射LPS前和注射后30min腹腔注射PAF受体拮抗剂BN52021 5mg／kg作为预防组和治疗组；腹腔注射等量生理盐水作为对照组。分别于注射LPS后1．5、3、6、24、48和72h取各组大鼠回肠，用免疫组化及逆转录-聚合酶链反应（RT—PCR）方法检测肠上皮细胞β-catenin蛋白及mRNA表达。结果对照组β-catenin均匀分布于上皮细胞间细胞膜的表面；内毒素组细胞膜表面β-catenin蛋白明显减少，分布不均。免疫组化和RT—PCR检测均可见内毒素组β-catenin蛋白及mRNA水平明显低于对照组，3～24h内降低非常明显（P均〈0．01）；预防组及治疗组变化趋势同内毒素组，各时间点β-catenin蛋白及mRNA水平均较内毒素组高，但差异无显著性。结论PAF在内毒素血症肠黏膜的机械屏障功能损伤中发挥一定作用，预防和治疗性应用PAF受体拮抗剂BN52021可减轻肠损伤。     

血小板活化因子在急性肝肾衰竭动物模型中对肾功能的影响

目的:了解血小板活化因子(PAF)在急性肝、肾衰竭动物模型中对肾功能的影响及可能的作用机制。方法:设4组大鼠,分别注射D-氨基半乳糖(D-GaLN)加内毒素(LPS),D-GaLN加PAF,D-GaLN加LPS加PAF受体拮抗剂及生理盐水,诱导急性肝、肾衰竭动物模型,测肝、肾功能指标并观察肝、肾组织病理改变。结果:注射D-GaLN大鼠的血清丙氨酸氨基转移酶、总胆红素比生理盐水组升高10倍以上,差异有显著性,病检有肝细胞坏死。注射PAF或LPS组与PAF受体拮抗剂组或生理盐水组比,肾功能指标差异有显著性。肾组织病检可见部分肾小管坏死。结论:PAF与急性肝、肾衰竭动物模型中的急性肾衰有关;PAF可能参与了内毒素相关的肝肾综合征(HRS)的形成;PAF受体拮抗剂对HRS可能有治疗作用。     

抑制c-Jun蛋白氨基末端激酶信号通路对内毒素血症大鼠肠屏障功能的保护作用

目的 探讨阻断细胞质内应激信号通路c-Jun蛋白氨基末端激酶(JNK)对内毒素血症大鼠肠屏障损伤的保护作用.方法 24只雄性SD大鼠,按随机数字表法分为对照组、内毒素血症模型组、JNK抑制剂组3组,每组8只.对照组仅给予生理盐水2 ml/kg+JNK抑制剂SP600125的溶剂PPCES液2.5 ml/kg;内毒素血症模型组静脉注射脂多糖( LPS) 10 mg/kg+PPCES液2.5 ml/kg;JNK抑制剂组静脉注射LPS 10 mg/kg+JNK抑制剂SP600125 10 mg/kg.记录各组大鼠活动和生存情况;并于12h后取大鼠同肠,光镜下观察肠道黏膜病理改变;同时取血,采用酶联免疫吸附试验( ELISA)测定血浆D-乳酸含量.结果 对照组大鼠活动正常,无死亡;模型组大鼠精神萎靡、活动减少,12h内死亡1只;JNK抑制剂组大鼠活动较模型组活跃,无死亡.回肠黏膜病理检查显示:与对照组相比,模型组大鼠回肠组织黏膜水肿,绒毛缩短,炎性细胞浸润;INK抑制剂组回肠组织病变较模型组减轻.模型组大鼠血浆D-乳酸含量(μg/L)较对照组显著升高(943.8±439.6比227.9±130.0,P＜0.05);JNK抑制剂能显著降低内毒素血症大鼠血浆D-乳酸含量(637.4±114.4比943.8±439.6,P＜0.05).结论 抑制细胞质内应激信号通路JNK能减轻内毒素血症大鼠肠屏障损伤.     

胆碱酯酶抑制剂中毒大鼠肠屏障功能和形态结构变化及宾赛克嗪治疗作用的研究

目的 观察胆碱酯酶抑制剂类神经性毒剂中毒后大鼠肠屏障功能和组织形态结构的变化以及宾赛克嚷的治疗作用.方法 40只雄性Wistar大鼠按随机数字表法均分为对照组、维埃克斯染毒模型组及宾赛克嗪1、3、9 mg/kg治疗组.皮下注射维埃克斯13μg/kg染毒;宾赛克嗪组在染毒后5 min腹腔注射相应剂量药物.各组于染毒后3 h取血,检测血浆D-乳酸浓度及二胺氧化酶(DAO)活性;同时取小肠组织,观察肠黏膜形态和超微结构变化.结果 与对照组比较.模型组血浆D-乳酸浓度和DAO活性均明显升高[D-乳酸:(87.752±22.906)mg/L比(29.072±6.546)mg/L,DAO:(6.72±0.93)U/L比(2.99±0.43)U/L,均P<0.01];宾赛克嗪1、3、9 mg/kg组呈现剂量依赖性降低血浆D-乳酸浓度和DAO活性,其中宾赛克嗪9 mg/kg组可逆转染毒后血浆D-乳酸浓度[(45.290±11.141)mg/L]和DAO活性C(3.17±0.68)U/L]增高(均P<0.01).光镜下观察模型组大鼠空肠和回肠肠壁变薄,皱壁变短,结构紊乱,固有层毛细血管扩张充血,黏膜间质水肿等病理变化;电镜下观察模型组大鼠回肠上皮细胞发生坏死,细胞器损伤,紧密连接破坏等变化.宾赛克嗪1、3、9 mg/kg组呈现剂量依赖性抑制小肠的病理变化.结论 胆碱酯酶抑制剂中毒时出现肠黏膜上皮细胞损伤,肠黏膜屏障功能破坏,通透性增加;宾赛克嗪能抑制中毒肠黏膜屏障结构和功能的损伤.     

急性脑出血大鼠肠屏障功能的变化

目的:研究急性脑出血对肠粘膜屏障功能的影响。方法:成年雄性Wistar大鼠60只,随机分为脑出血组和对照组各30只。脑出血组采用立体定向技术将大鼠自体尾动脉不抗凝动脉血液50μL缓慢注入尾状核制备脑出血模型,对照组注射等量生理盐水。2组分别于造模前和造模后0.5、3、6、12、24 h检测血浆二胺氧化酶(DAO)活性和D-乳酸(D-Lac)浓度,于造模前和造模后12、24 h检测血浆内毒素(LPS)浓度;造模后24 h取空肠l cm,光镜下观察肠粘膜。结果:与对照组比较,脑出血组造模后12、24 h DAO活性和造模后6、12、24 h D-Lac浓度及造模后12、24 h LPS浓度明显增高,差异有统计学意义(P<0.05或P<0.01)。光镜下观察,脑出血组小肠存在病理性损伤,对照组小肠结构正常。结论:急性脑出血早期即发生肠屏障功能障碍。     

内毒素预处理对内毒素血症大鼠肝损伤的保护作用

目的 探讨内毒素预处理对内毒素血症大鼠肝损伤的保护作用.方法 采用直接注射内毒素的方法建市大鼠急性内毒素血症模型.雄性Wistar人鼠72只,随机分成三组:生理盐水对照组(N组,n=24只)、内素脂多糖(IPS)(L组,n=24只)和LPS预处理组(P组,n=24只),每组义按时间分为2 h组、4 h组、6 h组、12 h组4个亚组,每个亚组6只.P组:首次经腹腔注射LPS 0.25mg/kg;24 h后再经腹腔注射IPSO.5 mg/kg,其余两组给予等容量生理盐水.第二次腹腔注射72 h后,L组和P组经尾静脉一次注射LPS 10 mg/kg,N组给予等量生理盐水,L组和P组在注射LPS后2,4,6,12 h,N组在注射最后一次NS后2,4,6,12 h,各取6只取肝组织制成匀浆检测Toll样受体4(Toll likereceptor-4,TLR-4)、核因子-кB(nuclear factor kappa B,NF-кB)、肿瘤坏死因子-α(tulnor necrosis factor-a,TNF-α)和丙二醛(malondiahtehyde,MDA),抽血检测谷丙转氨酶(ALT),谷草转氨酶(ASF),取肝脏(肝左上叶)用10%的中性甲醛固定.采用SPSS 13.0统汁软件进行单因素方差分析.结果 内毒素血症时符时间点肝脏组织TLR-4,NF-кB和TNF-α浓度较对照组显著升高,而内毒素预处理后则有明显下降,其中内毒素血症时4 h组肝脏组织TLR-4,NF-кB和TNF-α分别为(38.76±0.67),(170.82±31.40),(293.16±49.49)和(6.263±0.351),显著高于对照组(P＜0.05),而内毒素预处理后上述指标降至(22.32±1.35),(135.55±26.44)和(234.23±44.96),差异有统计学意义(P＜0.05).结论 内毒素预处理可减轻内毒素血症时的肝损伤,其机理可能与肝组织TLR-4,NF-кB和TNF-α的表达减少有关.     

腹腔复苏对失血性休克大鼠小肠黏膜的保护作用

目的 探讨腹腔复苏对失血性休克大鼠小肠黏膜的保护作用.方法 健康雄性SD大鼠50只随机(随机数字法)分成5组:假手术组(Ⅰ组)、失血性休克组(Ⅱ组)、静脉复苏组(Ⅲ组)、静脉复苏加生理盐水腹腔复苏组(Ⅳ组)、静脉复苏加PD-2液腹腔复苏组(Ⅴ组).Ⅰ组依次行右颈总动脉、右股静脉、左股动脉插管及全身肝索化;Ⅱ组在Ⅰ组基础上经左股动脉放血制备失血性休克大鼠模型;Ⅲ组在造模后经右股静脉补入放出的血量及2倍量林格氏液进行复苏;Ⅳ组和Ⅴ组分别在Ⅲ组基础上经腹腔内注入生理盐水、2.5%PD-2液各30 mL.各组分别于造模及复苏后60～120 min取材.测定血浆二胺氧化酶(DAO)活性、D-乳酸(D-LA)含量及内毒素(LPS)含量,光镜和电镜下观察大鼠小肠黏膜组织学和超微结构变化.采用单因素方差分析对数据进行统计学处理.结果 Ⅱ组血浆DAO活性、D-LA及LPS含量均较Ⅰ组明显升高,差异具有统计学意义(P<0.01);Ⅴ组分别与Ⅱ、Ⅲ及Ⅳ组比较,血浆DAO活性、D-LA及LPS含量差异有统计学意义(P<0.05 or P<0.01).各组小肠黏膜组织病理学及黏膜超微结构比较,Ⅱ组较Ⅰ组有明显损伤,Ⅴ组较Ⅱ、Ⅲ及Ⅳ组损伤明显减轻.结论 PD-2液腹腔复苏可减轻失血性休克大鼠小肠黏膜组织病理学损害,保护肠黏膜完整性,降低肠壁通透性,防止内毒素血症发生.     

整肠生对肝纤维化大鼠肠黏膜屏障及肥大细胞的影响

目的明确整肠生对肝纤维化大鼠肠黏膜屏障是否具有保护作用及对肠黏膜肥大细胞有何影响。方法雄性SD大鼠32只随机分为4组,每组8只:正常对照组、模型组、整肠生低剂量组、整肠生高剂量组。采用经典的硫代乙酰胺(TAA)皮下注射制备肝纤维化模型,整肠生干预组在此基础上给予整肠生活菌制剂灌胃。取血检测血浆内毒素水平、血清天门冬氨酸氨基转移酶(AST)水平和反映肠黏膜屏障功能的二胺氧化酶(DAO)水平,取肝组织行HE染色,回肠组织行HE染色及甲苯胺蓝染色。结果 9周后模型组、整肠生低和高剂量组大鼠体重增长与正常对照组体重增长相比差异有统计学意义(P<0.01),模型组大鼠体重增长与整肠生低和高剂量组体重增长相比差异无统计学意义(P>0.05);与正常对照组血浆内毒素水平[(0.07±0.03)EU/ml]、血清AST水平[(15.26±1.40)IU/L]、血清DAO水平[(10.65±4.09)U/L]相比,模型组血浆内毒素水平[(0.35±0.19)EU/ml]、血清AST水平[(18.03±1.13)IU/L]和DAO水平[(22.26±6.18)U/L]均升高(P均<0.01);与模型组相比,整肠生低剂量组血浆内毒素水平[(0.11±0.04)EU/ml]、血清AST水平[(15.68±1.52)IU/L]、血清DAO水平[(11.39±5.96)U/L]和整肠生高剂量组血浆内毒素水平[(0.14±0.05)EU/ml]、血清AST水平[(15.28±1.50)IU/L]、血清DAO水平[(12.03±7.37)U/L]均降低(P均<0.01);与正常对照组血浆内毒素水平相比,整肠生高剂量组血浆内毒素水平升高(P<0.01);与模型组相比,肝组织及回肠组织病理改变均减轻,回肠组织肥大细胞数量均减少,脱颗粒现象亦减少。结论整肠生对肝纤维化大鼠肠黏膜屏障具有保护作用,并能减少其肠黏膜肥大细胞的数量及脱颗粒现象,进而减轻肝损伤。     

宾赛克嗪对有机磷农药中毒时肠黏膜屏障功能破坏的保护作用

目的 研究有机磷农药敌敌畏中毒后小鼠肠黏膜屏障功能的变化及新型抗毒剂宾赛克嗪的保护作用.方法昆明小鼠65只,雌雄各半,随机分为正常对照组、敌敌畏染毒模型组、宾赛克嗪2,6,18mg/ks预防治疗组;各预防治疗组腹腔注射预防给予相应约物,10min后灌胃给予敌敌畏55mg/ks,于染毒后3 h取血,使用紫外分光光度计检测血浆二胺氧化酶(DAO)活性及D-乳酸质量浓度,采用单因素方差分析定量数据.结果 与正常对照组比较,模型组血浆DAO活性明显升高(P<0.01);与模型组比较,各预防治疗组血浆DAO活性明显下降(P<0.01),其中6 mg/kg预防治疗组效果最好;与正常对照组比较,模型组血浆D-乳酸质量浓度明显升高(P<0.01);与模型组比较,各预防治疗组血浆D-酸质量浓度叫显降低(P<0.01),并且能呈剂量依赖性降低D-酸质量浓度.结论 敌敌畏染毒小鼠血浆DAO活性及D-酸质量浓度显著增高,肠黏膜屏障功能遭到破坏,宾赛克嗪能减轻肠黏膜屏障功能的损伤,具有保护作用.     

泛素-蛋白酶体途径对烫伤脓毒症大鼠肠道炎症反应与屏障功能的作用研究

目的研究泛素-蛋白酶体途径对烫伤脓毒症大鼠肠组织核转录因子-κB（NF-κB）活化、肿瘤坏死因子-α（TNF-α）表达以及血浆二胺氧化酶（DAO）活性的作用。方法采用30％总体表面积（TBSA）Ⅲ度烫伤合并内毒素攻击大鼠为模型模拟临床烫伤哝毒症。60只Wistar大鼠随机分为正常对照组、烫伤哝毒症模型组、泛素-蛋白酶体抑制剂N-乙酰亮氨酰亮氨酰正亮氨酸（ALLN）组、NF-κB抑制剂吡咯烷二硫基甲酸酯（PDTC）组。采用凝胶电泳迁移率改变分析法（EMSA）分析肠组织NF—κB活性；采用酶联免疫吸附法（ELISA）检测肠组织TNF-α含量；采用分光光度法检测血浆DAO活性。结果各组肠组织NF—κB活性于伤后1h均明显增强，并达到高峰（P均〈0．01）．之后呈现下降趋势；两种抑制剂均可显著降低伤后1h和2hNF-κB的活性。ALLN可明显降低伤后1h肠组织中TNF—α含量（P〈0.01）。两种抑制剂对伤后1h和2h血浆I）AO活性均无明显影响。结论早期使用泛素-蛋白酶体抑制剂可降低烫伤脓毒症大鼠肠组织NF—κB活性．降低肠组织中炎症反应．但对肠组织屏障功能无保护作用。     

严重烧伤休克期切痂对肠粘膜损伤的影响

目的：探讨严重烧伤休克期切痂对肠粘膜损伤的影响。方法：采用４０％总体表面积（ＴＢＳＡ）Ⅲ度烫伤犬模型,随机分为切痂组（Ｅ组）和非切痂组（Ｃ组）,伤后１小时按Ｐａｒｋｌａｎｄ公式补给平衡盐溶液,Ｅ组动物伤后３小时切痂。分别于伤前、伤后３０分钟及３、６、１２、２４和４８小时测定血浆二胺氧化酶（ＤＡＯ）、乳酸、内毒素（ＬＰＳ）含量,伤后４８小时检测肠组织丙二醛（ＭＤＡ）、超氧化物歧化酶（ＳＯＤ）含量。结果：２组动物伤后血浆ＤＡＯ、乳酸、ＬＰＳ含量明显增加。切痂后能明显降低血浆中ＤＡＯ、ＬＰＳ和乳酸含量,肠组织中ＭＤＡ含量也明显减少。结论：严重烧伤休克期切痂有利于保护肠粘膜屏障功能。     

烧伤复合内毒素血症早期肺损害及其机制的实验研究

目的：探讨烧伤复合内毒素血症早期肺损害的病变特点及发生机制。方法：采用20％Ⅲ度体表烧伤复合一次性腹腔内注射低剂量内毒素（1mg/kg)为实验动物模型并分别以单纯烧伤（单烧组）、单纯内毒素注射（单注组）、生理盐水为对照组,血小板激活因子（PAF）受体拮抗剂BN50739为治疗组。动态观察烧伤后0．5、1、1．5、3、6、12、24和48小时肺的形态和功能变化,血浆肿瘤坏死因子（TNF）、PAF、肺泡灌洗液（BALF）中蛋白含量以及肺组织内TNF分布。结果：烧注组出现肺病变较单烧组、单注组出现早,程度重,持续时间长;病变发展过程可大致分为间质性肺水肿、间质性肺炎和肺泡内渗出3个阶段。烧注组血PAF和TNF分别于伤后0．5和1小时显著高于对照组,于1．5小时呈大峰值并持续至伤后48小时;BALF蛋白含量也于伤后0．5小时明显升高;治疗组血PAF、TNF和BALF蛋白含量均显著下降,TNF阳性细胞也明显减少,肺水肿以及损伤程度明显减轻。结论：PAF和TNF是烧伤内毒素血症急性肺损伤时的重要炎症介质,能增加肺血管对蛋白质的通透性,能相互促进合成,发挥协同损伤效应。而PAF拮抗剂BN50739能阻断这些效应,减轻肺损伤。     

血必净对严重烧伤患者肠道功能及炎症反应的影响

目的 探讨血必净注射液对严重烧伤患者肠道功能及炎症反应的影响.方法 将同期严重程度相当的32例严重烧伤患者随机(随机数字法)分为血必净治疗组(n=16)和对照组(n=16).对照组按烧伤常规治疗;治疗组在常规治疗基础上给予血必净注射液,每次100 mL,静脉滴注,2次/d,连续使用7 d.检测两组患者治疗前与治疗后3 d和7 d血浆二胺氧化酶(DAO)、内毒素(LPS)、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)水平变化.采用SPSS 12.0统计软件进行统计分析.结果 两组烧伤患者治疗后,血浆DAO,LPS,TNF-α及IL-6水平均较治疗前下降(P＜0.05);血必净治疗组在治疗后3 d和7 d,血浆DAO,LPS,TNF-α及IL-6水平明显低于对照组(P＜0.05).结论 血必净注射液可保护烧伤患者肠道功能,减少内毒素人血,对改善严重烧伤患者的炎症反应有积极作用.     

Protective effect of BN 50739, a new platelet-activating factor antagonist, in endotoxin-treated rabbits

Platelet-activating factor (PAF) has been demonstrated in the circulation and organs of animals exposed to gram negative endotoxins, whereas PAF antagonists have been shown to exhibit some efficacy in modifying the course of endotoxemia. In this study we evaluated BN 50739, a novel specific PAF antagonist, for its capacity to block PAF or lipopolysaccharide endotoxin (LPS)-mediated effects in rabbits. Pretreatment with BN 50739 (3 and 10 mg/kg i.p.) inhibited PAF (500 pmol/kg i.v.)-induced thrombocytopenia, leukopenia and plasma thromboxane B2 elevation in a dose-dependent manner. The inhibitory effect lasted 3.5 to 4.5 hr. BN 50739 (10 mg/kg) prevented the early phase of LPS (50 micrograms/kg i.v.)-induced thrombocytopenia and thromboxane B2 elevation, and reduced the 24-hr mortality rate from 75 to 22% (P less than .05). Post-treatment with BN 50739 increased the 10-hr survival rate from 33 to 87% (P less than .05); however, it had no effect on the 24-hr mortality. BN 50739 did not affect LPS-induced leukopenia or the elevation in plasma tumor necrosis factor. Our data support possible therapeutic efficacy of PAF antagonists in septic shock despite their inability to prevent the generation of tumor necrosis factor.     

Tetrahydrobiopterin prevents platelet-activating factor-induced intestinal hypoperfusion and necrosis: Role of neuronal nitric oxide synthase

OBJECTIVE: We reported previously that neuronal nitric oxide synthase (nNOS) is the predominant NOS in rat small intestine and is down-regulated by platelet-activating factor (PAF). The severity of the bowel injury induced by PAF is inversely related to its suppressing effect on nNOS. Here, we investigated whether intestinal perfusion is regulated by nNOS and whether tetrahydrobiopterin, a co-factor and stabilizer of nNOS, reverses PAF-induced intestinal hypoperfusion and injury. SETTING: Animal laboratory. DESIGN: We first examined nNOS regulation of splanchnic blood flow by measuring the perfusion of the heart, lung, ileum, and kidney in rats after a nNOS inhibitor. We then examined the protective effect of tetrahydrobiopterin on PAF-induced bowel injury, mesenteric hypoperfusion, and systemic inflammation. SUBJECTS: Adult male Sprague-Dawley rats. INTERVENTION: In part 1 of the experiment, rats were given 7-nitroindazole (a specific nNOS inhibitor, 50 mg.kg.day). In part 2 of the experiment, rats were treated with tetrahydrobiopterin (20 mg/kg) 5 mins before and 30 mins after PAF challenge (2.2 microg/kg, intravenously) MEASUREMENTS: Perfusion of the heart, lung, ileum, and kidney was measured at 1 and 4 days after 7-nitroindazole, using fluorescent microspheres. Intestinal injury and inflammation (myeloperoxidase content), blood perfusion, calcium dependent-NOS activity, and systemic inflammation (hypotension and hematocrit increase) were assessed 1 hr after PAF with and without tetrahydrobiopterin treatment. RESULTS: In part 1 of the experiment, 7-nitroindazole induced a long-lasting reduction of blood perfusion and inducible NOS expression selectively in the ileum but not in nonsplanchnic organs such as heart, lungs, and kidneys. In part 2, tetrahydrobiopterin protected against PAF-induced intestinal necrosis, hypoperfusion, neutrophil influx, and NOS suppression. It also reversed hypotension and hemoconcentration. Sepiapterin (2 mg/kg, stable tetrahydrobiopterin precursor) also attenuated PAF-induced intestinal injury. CONCLUSIONS: We conclude that nNOS selectively regulates intestinal perfusion. Tetrahydrobiopterin prevents PAF-induced intestinal injury, probably by stabilizing nNOS and maintaining intestinal perfusion.     

Cardiac functional and structural alterations induced by endotoxin in rats: importance of platelet-activating factor

OBJECTIVE: In this study, we evaluated the time course of the alterations in left ventricular (LV) dimensions, LV wall thickness, and LV systolic function in rats with endotoxemia by using echocardiography as well as myocardial histopathologic assessments. Our second goal was to examine whether pretreatment with a platelet-activating factor (PAF) antagonist would ameliorate the lipopolysaccharide (LPS)-induced cardiovascular collapse during the early phase. DESIGN: A prospective, controlled, in vivo animal laboratory study. SETTING: Research laboratory at a university. SUBJECTS: Male, Wistar rats (8-9 wks old; n = 83). INTERVENTIONS: In pentobarbital-anesthetized rats, the right carotid artery was cannulated to measure the arterial blood pressure and to sample blood. The right jugular vein also was catheterized for the administration of drugs. LPS (2 mg/kg) derived from Klebsiella pneumoniae or physiologic saline was administered in the presence or absence of pretreatment with TCV-309, a specific potent PAF antagonist. Echocardiographic studies were performed with an 8- to 13-MHz transducer. MEASUREMENTS AND MAIN RESULTS: LPS administration immediately induced progressive hypotension. The maximal hypotensive response was observed at 10 mins after LPS infusion with mean arterial pressure decreasing from 119 +/- 2 to 56 +/- 3 mm Hg (p < .001). LV end-diastolic internal dimensions decreased from 6.4 +/- 0.1 to 3.1 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced compared with control rats. LV end-systolic dimensions also decreased dramatically from 3.5 +/- 0.2 to 0.5 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced throughout the experiment. LV fractional shortening increased from 45 +/- 1% to 84 +/- 2% (p < .001) at 30 mins after LPS and remained elevated compared with control rats. LV wall thickness increased strikingly from 15 mins until 2 hrs after LPS infusion. Pathologic studies demonstrated marked congestion of capillaries and mild edema in the LV myocardium. The hematocrit increased after the administration of LPS. LPS markedly increased sympathetic tone as demonstrated by the elevation of plasma concentrations of epinephrine and norepinephrine. There was no elevation of concentrations of nitrite and nitrate. Pretreatment with TCV-309, a specific potent PAF antagonist, reduced LPS-induced hypotension and attenuated LV functional and structural changes. TCV-309 administration reduced the LPS-induced adrenergic activation and hemoconcentration. CONCLUSIONS: The hypotension that occurred during the initial phase of LPS-induced shock was accompanied by LV functional and structural alterations. The marked increase in LV wall thickness can be ascribed to the congestion of capillaries and edema in the LV myocardium. Pretreatment with a PAF antagonist reduced LPS-induced alterations. PAF may play a pivotal role during the initial phase of LPS-induced cardiovascular responses.     

Lysophosphatidic acid reduces the organ injury caused by endotoxemia-a role for G-protein-coupled receptors and peroxisome proliferator-activated receptor-gamma

Exogenous lysophosphatidic acid (LPA) has been shown to beneficial in renal ischemia/reperfusion injury, wound healing and colitis. LPA acts via specific G-protein-coupled receptors and also peroxisome proliferator-activated receptor-gamma (PPAR-gamma). However, activation of PPAR-gamma is dependent on the presence of an unsaturated acyl chain. Here we investigate the effects of saturated LPA (18:0) and unsaturated LPA (18:1) on the organ injury associated with endotoxemia and the receptors mediating LPA activity. Male Wistar rats received either lipopolysaccharide (LPS, 6 mg/kg i.v.) or vehicle. The PPAR-gamma antagonist GW9662 (1 mg/kg i.v.), the LPA receptor antagonist Ki16425 (0.5 mg/kg i.v.) or vehicle was administered 30 min after LPS. LPA 18:0 or LPA 18:1 (1 mg/kg i.v.) or vehicle was administered 1 h after injection of LPS. Endotoxemia for 6 h resulted in an increase in serum levels of aspartate aminotransferase, alanine aminotransferase and creatine kinase. Therapeutic administration of LPA 18:0 or 18:1 reduced the organ injury caused by LPS. LPA 18:0 also attenuated the increase in plasma IL-1beta caused by LPS. Ki16425, but not GW9662, attenuated the beneficial effects of LPA 18:0, however, Ki16425 and GW9662 attenuated the beneficial effects of 18:1. In conclusion, LPA reduces the organ injury caused by endotoxemia in the rat. Thus, LPA may be useful in the treatment of shock of various aetiologies. The mechanism of action is related to acyl chain saturation, with LPA 18:0 acting via G-protein-coupled receptors and LPA 18:1 acting via G-protein-coupled receptors and PPAR-gamma.