摘要：
Objective To evaluate the effect of therapeutic hypercapnia preconditioning on lung ischemia-reperfusion (I/R) injury in rats.Methods Forty healthy adult Sprague-Dawley rats of either sex,aged 2 months,weighing 250-300 g,were divided into 5 groups (n=8 each) using a random number table:sham operation group (group S),grouP I/R and preconditioning with therapeutic hypercapnia of different level groups (group THP1-3).Lung I/R injury was induced by clamping the left hilum of lung for 45 min followed by 120 min of reperfusion.In THP1-3 groups,the respiratory parameters were adjusted at 5 min of stability after isolating the left hilum of lung to make PETCO2 reach 55-65,65-75 and 75-85 mmHg respetively and maintained at this level for 5 min,normal ventilation was then used to make PETCO2 restore the normal level,continuously repeating for 3 circles,and then the left hilum of lung was blocked for 45 min followed by 120 min of reperfusion.The bronchoalveolar lavage fluid (BALF) was collected at the end of reperfusion for determination of the total protein (TP) concentration using Coomassie brilliant blue staining.Lung tissues were obtained at the end of reperfusion for examination of pathological changes after haematoxylin and eosin staining (under a light microscope) and for determination of wet/dry weight ratio (W/D ratio),malondialdehyde (MDA) content,superoxide dismutase (SOD) activity,interleukin-8 (IL-8) and IL-10 contents (by enzyme-linked immunosorbent assay),tumor necrosis factor-alpha (TNF-α) expression (by immunohistochemistry) and expression of TNF-α mRNA (by real-time polymerase chain reaction).Results Compared with group S,the TP concentration in BALF,W/D ratio and contents of MDA,IL-8 and IL-10 in lung tissues were significantly increased,the SOD activity was decreased,the expression of TNF-α mRNA was up-regulated (P＜0.05),strong positive expression of TNF-α was found,and the pathological changes of lung tissues were aggravated in group I/R.Compared with group I/R,the TP concentration in BALF,W/D ratio and contents of MDA and IL-8 in lung tissues were significantly decreased,the SOD activity was increased,the expression of TNF-α mRNA was down-regulated (P＜0.05),no significant change was found in IL-10 content (P＞0.05),the staining range and intensity of TNF-α were decreased,and the pathological changes of lung tissues were significantly attenuated in THP1-3 groups.Conclusion Therapeutic hypercapnia preconditioning can reduce lung I/R injury in rats,and the mechanism is related to inhibiting inflammatory responses and oxidative stress responses.%目的 评价治疗性高碳酸血症预处理对大鼠肺缺血再灌注损伤的影响.方法 健康成年SD大鼠40只,2月龄,雌雄不限,体重250～ 300 g,采用随机数字表法分为5组(n=8):假手术组(S组)、缺血再灌注组(I/R组)和不同水平治疗性高碳酸血症预处理组(THP1-3组).采用夹闭左肺门45 min再灌注120 min的方法制备肺缺血再灌注损伤模型.THP1-3组游离左肺门后稳定5 min时,调节呼吸参数,使PETCO2分别达到55～ 65、65 ～ 75、75～85 mmHg并维持5 min,然后正常通气使PETCO2恢复正常,连续重复3个循环,随后阻断左肺门45 min再灌注120 min.于再灌注120 min时,收集左支气管肺泡灌洗液,采用考马斯亮蓝染色法测总蛋白(TP)浓度;取肺组织,计算湿/干重比值(W/D比值);HE染色后光镜下观察病理学改变;分别采用硫代巴比妥酸法和羟胺法测定MDA含量和SOD活性;采用ELISA法测定IL-8和IL-10含量;采用免疫组化法测定TNF-α的表达;采用RT-PCR法测定TNF-α mRNA的表达.结果 与S组比较,I/R组支气管肺泡灌洗液TP浓度、肺组织W/D比值、MDA、IL-8和IL-10含量升高,SOD活性降低,TNF-α mRNA表达上调(P＜0.05),TNF-α表达强阳性,肺组织病理学损伤加重;与I/R组比较,THP1-3组支气管肺泡灌洗液TP浓度、肺组织W/D比值、MDA和IL-8含量降低,肺组织SOD活性升高,TNF-α mRNA表达下调(P＜0.05),IL-10含量差异无统计学意义(P＞0.05),TNF-α染色范围、染色强度均减小,肺组织病理学损伤减轻.结论 治疗性高碳酸血症预处理可减轻大鼠肺缺血再灌注损伤,机制与抑制炎症反应和氧化应激反应有关.
