不同液体复苏对未控制失血性休克大鼠肺损伤及肺水通道蛋白表达的影响

目的 观察不同液体复苏对未控制失血性休克大鼠肺损伤和肺水通道蛋白l(AQP1)和AQP5表达的影响.方法 SD大鼠被随机分为假手术组(C组)、无液体复苏组(NF组)、乳酸林格液组(LRS组)、高渗盐水组(HS组)和羟乙基淀粉组(HES)5组,每组12只.建立未控制失血性休克大鼠模型,模拟临床分为4期;动态观察各期的平均动脉压(MAP)变化.①失血性休克期(时间为60 min):在15 min内将MAP降至40 mm Hg(1mm Hg=0.133 kPa)并维持60 min;然后向气管内注射内毒素2 mg/kg,并用断尾法造成大鼠未控制失血性休克.②液体复苏期(时间为30 min):LRS、HS、HES组分别用3倍放血量的LRs、4 ml/kg的7.5%NaCl和1倍放血量的6%HES 130/0.4进行复苏,C组和NF组不处理.③综合复苏期(时间为1 h):在1 h内回输全部失血及1:1失血量的生理盐水.④复苏后观察期:输血、输液结束后继续观察3.5 h. 实验结束后测定肺组织湿/干重(W/D)比值;用免疫组化测定肺组织AQPl和AQP5表达,用苏木素一伊红(HE)染色,光镜下观察肺损伤程度.结果 在C组和HES组,肺血管内皮细胞AQP1和肺泡上皮AQP5均呈阳性表达;HS组仅AQP1呈阳性表达,AQP5则呈微弱表达;NF组和LRS组AQP1、AQP5均呈微弱表达.各组MAP、肺W/D比值和肺组织损伤程度比较显示,HS组和HES组显著优于NF组和LRS组(P<0.05或P<0.01).结论 遭受"二次打击"失血性休克大鼠并发肺损伤时,肺AQP1和AQP5表达下调;采用6%HES 130/0.4进行休克复苏可有效抑制AQP1和AQP5下调,并使肺损伤明显减轻;采用7.5%NaCI复苏仅能抑制AQPl表达下调和在一定程度上减轻肺水肿;而采用LRS复苏既不能保持AQP1、AQP5的表达,也不能有效防止肺损伤的发生.

Effects of different fluid resuscitation regimes on lung injury and expression of pulmonary aquaporin 1 and aquaporin 5 in uncontrolled hemorrhagic shock in rats

Objective To investigate the effects of different fluid resuscitation regimes on lung injury and expression of pulmonary aquaporin 1(AQP1)and AQP5 in rats with uncontrolled hemorrhagic shock. Methods Sixty Sprague-Dawley(SD)rats were randomly assigned to the following five groups:control group(C group),no fluid resuscitation group(NF group),lactated Ringer's solution group(LRS group), 7.5%NaCl group(HS group)and hydroxylethyl starch group(hydroxylethyl starch 130/0.4,HES group). A four-phased uncontrolled hemorrhagic shock model was reproduced.Uncontrolled hemorrhagic shock phase began with blood withdrawal extended over 1 5 minutes,in which animals were subjected to massive hemorrhagemean arterial pressure(MAP)=40 mm Hg(1 mm Hg=0.133 kPa)]for 60 minuts and foilowed by intratracheal lipopolysaccharide 2 mg/kg and continuous bleeding with amputation of the tail. Then,animals were partially resuscitated with LRS of 3 times the volume of shed blood(LRS group), followed by a bolus dose of 4 ml/kg body weight of 7.5%NaCl(Hs),or hydroxylethyl starch(a volume equal to that of the shed blood),respectively,during different fluid resuscitation regimes. After that, comprehensive resuscitation phase of 60 minutes began with hemostasis,and transfusion of all the shed blood Dius same amount of normal saline.Observation phase was continued for 3.5 hours.At the end the experiment,the lung tissue was sampled to measure wet-to-dry lung weight ratio(W/D),and the expression of AQP1 and AQP5 were determined with immunohistochemistry.The paraffin-embedded lungs were stained with hematoxylin and eosin for pathological analysis.Results When compared with NF and LRS groups, the lung W/D ratio was significantly decreased,and the shock induced decreased expression of AQP1 and AQP5 in lung tissue were attenuated in HES group,but these beneficial effects were blunted in the HS group.Conclusion Uncontrolled hemorrhagic shock may induce lung injury and pulmonary edema as well as down regulation of the expression of AQP1 and AQP5 in rats.Resuscitation with hypertonic fluids, especially with HES,can reduce lung damage and pulmonary edema in this kind of shock.The cause may be due in part to maintenance of the expression of AQP1 and/or AQP5 in the lung.Pulmonary AQP1 and AQP5 play an important role in fluid transportation.