L-精氨酸对肺缺血/再灌注损伤时bcl-2、bax基因表达的影响

目的： 探讨L-精氨酸对肺缺血-再灌注损伤（PIRI）时bcl-2、bax基因表达的影响。方法： 采用在体兔单肺原位缺血-再灌注模型。实验兔36只，随机分为假手术对照组（sham，12只）、肺缺血-再灌注组（I/R，12只）和肺缺血-再灌注加L-精氨酸组（L-Arg，12只）。分别于再灌注5 h取左肺组织，观察bcl-2、bax mRNA定位表达、凋亡指数（AI）、肺组织湿干重比（W/D）、肺损伤组织学定量评价指标（IQA）及光镜、电镜下的组织形态学改变。结果： 在肺小动脉内（外）膜、肺小静脉内膜、肺泡上皮及细支气管上皮，L-Arg组bcl-2 mRNA的表达及bcl-2/bax mRNA的比值显著高于I/R组（均P<0.01），bax mRNA的表达明显低于I/R组（P<0.01）；AI、W/D和IQA值显著低于I/R组（P<0.01和P<0.05）；肺组织形态学异常改变不同程度减轻。结论： L-精氨酸可上调肺组织bcl-2 mRNA的表达、下调肺组织bax mRNA的表达、调控bcl-2/bax mRNA 之间的平衡而减轻细胞凋亡，对PIRI发挥积极的防治作用。

Effect of L-arginine on expression of bcl-2 and bax mRNA in pulmonary injury induced by ischemia-reperfusion in rabbits

AIM:To investigate the effect of L-arginine(L-Arg) on expression of bcl-2,bax mRNA during pulmonary ischemia and reperfusion injury(PIRI) in rabbits.METHODS: Single lung ischemia and reperfusion animal model was used in vivo.The rabbits were randomly divided into three groups: sham operated group(sham,n=12),ischemia-reperfusion group(I/R,n=12) and I/R L-arginine group(L-Arg,n=12).Changes of several parameters,which included apoptotic index(AI),wet to dry ratio of lung tissue weight(W/D) and index of quantitative assessment of histologic lung injury(IQA),were measured at 300 min after reperfusion in lung tissue.Meanwhile the location and expression of bcl-2,bax mRNA as well as the ratio of bcl-2 mRNA/bax mRNA were observed.The lung tissue was prepared for light microscopic and electron microscopic observation at 60,180 and 300 min after reperfusion.RESULTS: As compared with I/R group,in intima and extima of small pulmonary artery,alveoli,and bronchiole epithelia,the expression of bcl-2 mRNA and the ratio of bcl-2 mRNA/bax mRNA were increased,and the expression of bax mRNA was decreased in L-Arg treatment group.The values of AI,W/D and IQA showed significantly lower than that in I/R group at 180 minutes after reperfusion in lung tissue(P<0.01 and P<0.05).Meanwhile,abnormal changes of the lung tissue in morphologically were markedly lessened in L-Arg treatment group.CONCLUSION: L-arginine produces a notable protective effect on PIRI in rabbits by up-regulating bcl-2 mRNA expression,down-regulating bax mRNA expression in lung tissue and regulating the balance of bcl-2 mRNA and bax mRNA to decrease apoptosis.