过氧亚硝基阴离子在哮喘豚鼠气道高反应性中的作用

Role of peroxynitrite on airway hyperresponsiveness in asthmatic guinea pigs

目的 探讨哮喘豚鼠肺内过氧亚硝基阴离子 (ONOO-)的生成及其在哮喘气道高反应性形成中的作用。方法 18只哮喘豚鼠模型随机分为 3组 :(1)哮喘组 (6只 ) :用 10 %卵蛋白 1ml腹腔注射致敏 ,2周后用 1%卵蛋白超声雾化吸入复制豚鼠哮喘模型。 (2 )哮喘加氨基胍 (AG)组 (6只 ) :诱喘同哮喘组 ,在每次诱喘前 1h腹腔注射AG 10mg/kg。 (3)正常对照组 (6只 ) :用生理盐水代替诱喘剂。每组哮喘豚鼠均用免疫组织化学技术检测肺内ONOO-的生成及定位 ;用健康豚鼠 15只制备气管条 ,观察外源性ONOO-对离体豚鼠气管条反应性的影响 ,电镜观察ONOO-对气道上皮细胞的损伤情况。结果 哮喘豚鼠支气管肺组织中有ONOO-特异性标志物 硝基酪氨酸 (NT)的过量生成 ,主要分布于气道上皮细胞和小气道周围炎性细胞内 ;加用AG组 ,NT阳性细胞减少 ;正常对照组仅有较少的NT阳性细胞 ;ONOO-0 5mmol/L组气管条对各浓度组胺 (10 8mol/L除外 )的反应性与溶剂对照组比较 ,差异有显著性 (P分别 <0 0 5、<0 0 1及 <0 0 0 1) ;ONOO-0 5mmol/L组气管条对组胺反应的敏感性与溶剂对照组比较 ,差异有显著性 (P <0 0 0 1) ;电镜观察ONOO-可致气管粘膜上皮细胞损伤、脱落。结论 哮喘豚鼠气道上皮细胞内有过量ONOO-生成 。

Objective To study the formation and localization of peroxynitrite(ONOO -) in the lung tissues of asthmatic guinea pig and investigate the effects of ONOO - on airway hyperresponsiveness in asthma Methods 18 guinea pigs were randomly divided into three groups of 6 each: (1) asthmatic group: guinea pigs were injected intraperitoneally with 1 ml of 10% ovalbumin After 14 days, the animals were exposed to aerosol of 1% OVA; (2) aminoguonidine (AG) group: Animal immunization was the same as above, but 1 h before the animals were exposed to OVA aerosol, 10 mg/kg AG were injected intraperitoneally (3) control group The formation and localization of ONOO - in the lung tissues of the guinea pig asthma model were observed by immunohistochemical detection The effect of exogenous ONOO - on contractions of isolated tracheal strips of the guinea pigs to various concentrations of histamine was examined The damage of airway epithelial cells induced by ONOO - was observed by electron microscopy Results There was strong immunoreactivity for nitrotyrosine (NT), a specific marker of ONOO - formation in vivo , in the airway epithelisl cells and inflammatory cells surrounding small airways of the guinea pigs with asthma The AG group showed significantly decreased number of NT positive cells in the lung tissues There were only a few NT positive cells in the control group The responsiveness of isolated tracheal strips to various concentration of histamine(except 10 8 mol/L) in the ONOO - 0 5 mmol/L group were significantly increased compared with the vehicle group ( P <0 05, P <0 01 or P <0 001) The sensitivity of isolated tracheal strips to histamine in the ONOO - 0 5 mmol/L group were also increased compared with the vehicle group( P <0 001). Electron microscopical observation of the airways revealed airway epithelial injury and shedding Conclusion There was ONOO - overproduction in airway epithelial cells of asthmatic guinea pigs,which may contribute to airway epithelial damage and hyperresponsiveness in asthma