外源性一氧化氮抗内毒素致肺微血管高通透性的作用机制初探

目的和方法:应用气管内滴注脂多糖(LPS)致SD大鼠急性肺损伤(ALI)模型和体外培养人血中性粒细胞(PMN),观察一氧化氮(NO)供体硝普钠(SNP)对LPS所致肺内PMN聚集、微血管通透性增高及PMN凋亡的影响。结果:①整体实验中LPS组(气管滴注LPS100μg/只)的支气管肺泡灌洗液(BALF)中蛋白含量、PMN数量、肺组织中伊文思蓝(EB)含量和染料单星蓝(MB)颗粒标记的肺微血管数目均明显高于假手术组,而LPS+SNP组(气管同时滴注LPS和SNP5μg/只)上述指标均明显低于LPS组;②体外培养人血PMN,SNP(5×10^-3mol/L)组的PMN凋亡百分率明显高于对照组,SNP+LPS组明显高于LPS(10μg/L)组。结论:气管内滴注SNP能够减少PMN在肺内的聚集,在一定程度上起到抗LPS所致的以肺微血管高通透性为特征的ALI的作用。促进PMN凋亡可能是SNP减轻PMN在肺内聚集的机制之一。

Mechanism of exogenous nitric oxide in attenuating endotoxin-induced increase of rat pulmonary microvascular permeability

AIM and METHODS:The animal model of acute lung injury (ALI) caused by intratracheal instillation of lipopolysaccharides(LPS) in vivo and human peripheral blood polymorphonuclear neutrophil (PMN) in vitro were used to study the effects of sodium nitroprusside (SNP), nitric oxide (NO) donor, on LPS-induced PMN accumulation, microvascular permeability and PMN apoptosis. RESULTS:①In vivo, PMN accumulation in lung, the protein content in bronchoalveolar lavage fluid (BALF) and the Evans blue dye and monastral blue dye extravasation in lung tissue of LPS group were markedly higher than those of both sham operation group and LPS+SNP group. ②In vitro, the apoptotic percentage of SNP group was much higher than that of control group, while compared with LPS group, SNP+LPS group has significantly higher apoptotic percentage. CONCLUSIONS:SNP intratracheal instillation attenuated LPS-induced microvascular permeability and alleviated ALI. PMN apoptosis induced by SNP may be one of the potential mechanisms underlying the decrease of PMN accumulation in lung tissue.