硫化氢对肢体缺血再灌注所致大鼠急性肺损伤的作用及机制

Role of hydrogen sulfide in acute lung injury induced by ischemia-reperfusion of hind limbs in rats

目的:探讨内、外源性硫化氢(H2S)在肢体缺血再灌注(IR)所致大鼠急性肺损伤(ALI)中的作用并初探其机制。方法:应用双大腿根部止血带复制大鼠双后肢缺血及再灌注后肺损伤模型。将120只SD大鼠随机分为对照组(control)、IR组、NaHS+IR组和抑制H2S生成的炔丙基甘氨酸(PPG)+IR组。肢体缺血再灌注后4 h处死动物,测定肺系数;光镜下观察肺组织形态学改变;化学法检测血浆H2S、NO、CO含量,肺组织丙二醛(MDA)含量、胱硫醚-γ-裂解酶(CSE)、诱导型一氧化氮合酶(iNOS)和血红素加氧酶(HO)活性以及支气管肺泡灌洗液(BALF)中中性粒细胞(PMN)数目和蛋白含量变化,并对血浆H2S含量与上述指标进行相关性分析。结果:大鼠肢体IR可引起肺组织明显的形态学改变、肺系数和肺组织MDA含量增加、BALF中PMN数目和蛋白含量增加、血浆H2S含量和肺组织CSE活性下降、肺组织iNOS活性和HO活性及血浆中NO含量和CO含量增加。预先给予NaHS可显著减轻IR所致上述指标的改变;而预先给予PPG可加重IR所致肺损伤,使BALF中PMN数目和蛋白含量、血浆NO含量和肺组织iNOS活性进一步增加,但对血浆CO含量和肺组织HO活性无明显影响。H2S含量与CSE活性、血浆CO含量、肺组织HO活性呈正相关(均P<0.01);与其它指标呈负相关(均P<0.01)。结论:H2S/CSE体系的下调参与介导了大鼠肢体IR所致大鼠ALI的发生,内、外源性H2S具有抗肢体IR所致ALI的作用,该作用可能与其抗氧化效应、减轻PMN所致肺部过度炎症反应以及下调NO/iNOS体系、上调CO/HO体系有一定关系。

AIM：To explore the role of endogenous and exogenous hydrogen sulfide（H2S） in acute lung injury（ALI） induced by ischmia-reperfusion（IR） of hind limbs in rats.METHODS：A Sprague-Dawley rat model of acute lung injury was induced by ischemia of the hind limbs for 4 h and reperfusion for another 4 h.The rats（n=120） were randomly divided into 4 groups：control,IR,NaHS（H2S donor）＋IR,and propargylglycine [PPG,inhibitor of cystathionine γ-lyase（CSE）]＋IR.The animals were sacrificed after reperfusion.Lung weight/body weight ratio（LW/BW） was measured and calculated.Morphological changes of the lung tissues were observed.The concentrations of H2S,nitric oxide（NO） and carbon monoxide（CO） in plasma were tested.The content of malondialdehyde（MDA）,the activity of CSE,inducible nitric oxide synthase（iNOS） and hemeoxygenase（HO） in the lungs were determined.The polymorpho-nuclear neutrophils（PMN） and protein content in bronchoalveolar lavage fluid（BALF） were also measured.The correlation of H2S content with the above indices was analyzed.RESULTS：Compared with control group,severe injuries of the lung tissues,raised LW/BW,MDA concentration,PMN and protein contents in BALF were observed in IR group.Limb IR also made a drop in the concentration of plasma H2S and the activity of lung CSE,while the activity of iNOS and HO in the lung tissues and the levels of plasma NO and CO increased.Administration of NaHS before IR attenuated the changes induced by IR,while pre-administration of PPG exacerbated the IR injuries and increased the plasma NO level and lung iNOS activity.The H2S content was positively correlated with CSE activity,CO content and HO-1 activity（P0.01）,and negatively correlated with the other indices（P0.01）.CONCLUSION：Down-regulation of H2S/CSE is involved in the pathogenesis of acute lung injury induced by IR.Endogenous and exogenous H2S protects against lung injuries.The anti-injury effects of H2S are related with its anti-oxidative activity to attenuate the inflammatory over-reactions in the lung induced by PMN.Down-regulation of NO/iNOS system and up-regulation of CO/HO-1 system by H2S are also involved in the process of anti-injury to ALI.