右美托咪定对脓毒症大鼠心肌组织水通道蛋白-1及炎症细胞因子水平的干预作用

Dexmedetomidine intervention effects on aquaporin -1 and inflammatory cytokines in myocardial tissue of septic rat

目的：研究脓毒症大鼠心肌组织水通道蛋白-1（AQP-1）水平的变化规律，并比较AQP-1与心肌细胞炎症因子肿瘤坏死因子-α（TNF-α）、白细胞介素-6（IL-6）及心肌组织含水量的相关性，探讨右美托咪定对脓毒症大鼠心肌的保护作用及可能机制。方法将90只雄性SD 大鼠按随机数字表法分为假手术组、脓毒症模型组和右美托咪定组，每组30只。采用盲肠结扎穿孔术（CLP）复制大鼠脓毒症模型；假手术组仅开腹、关腹，不行CLP。右美托咪定组于术前0.5 h静脉注射右美托咪定1μg/kg，浓度为2μg/mL，模型组和假手术组大鼠术后皮下注射生理盐水5 mL/kg。于术后2、12、24、48、72 h处死6只大鼠取出心脏，采用酶联免疫吸附试验（ELISA）测定各时间点心肌组织匀浆中AQP-1含量及炎症细胞因子TNF-α、IL-6水平，利用干湿重法检测心肌组织含水量，并比较AQP-1与TNF-α、IL-6及心肌组织含水量的相关性。结果模型组术后2 h起心肌组织AQP-1、TNF-α及IL-6水平均较假手术组明显升高；随时间延长，AQP-1水平及心肌组织含水量有所降低，但TNF-α及IL-6水平却持续增高。右美托咪定组除术后72 h心肌组织含水量外，从术后2 h起上述各指标即均较模型组明显降低〔AQP-1（ng/g）：9.29±0.15比9.73±0.26，TNF-α（pg/g）：109.47±8.41比128.13±7.36，IL-6（pg/g）：232.95±20.56比279.71±22.24，心肌组织含水量：（74.82±6.37）%比（75.62±6.39）%，均P＜0.05〕，但仍高于假手术组。相关性分析显示，脓毒症大鼠AQP-1与早期心肌组织含水量（r＝0.418，P＝0.001）和晚期心肌组织含水量（r＝0.235，P＝0.022）的变化呈正相关，与早期（术后2 h）细胞因子TNF-α（r＝0.235，P＝0.021）及IL-6（r＝0.345，P＝0.003）浓度变化呈正相关，与晚期（术后72 h）细胞因子TNF-α（r＝-0.408，P＝0.037）及IL-6（r＝-0.276，P＝0.002）浓度变化呈负相关。结论脓毒症大鼠早期即出现明显心肌损伤，导致AQP-1的过度表达，从而引起心肌细胞水肿；右美托咪定可通过减少心肌组织AQP-1的表达及心肌炎症细胞因子水平进而减轻心肌细胞水肿，而发挥心肌保护作用。

Objective To study the regulation of aquaporin-1（AQP-1）changes in the heart of septic rats, compare the correlations of the AQP-1 with myocardial cytokines tumor necrosis factor-α（TNF-α）,interleukin-6 （IL-6）,and myocardial tissue water content,and to investigate the dexmedetomidine protective effect on myocardia in septic rats and its possible mechanism. Methods According to the random number table methods,90 male Sprague-Dawley（SD）rats were divided into sham operation group,sepsis model group and dexmedetomidine group, 30 rats in each group. The rat sepsis model was established by cecal ligation and puncture（CLP）. In the sham operation group,the animal abdomen was only opened and closed without CLP. Half hour before operation in dexmedetomidine group,dexmedetomidine 1μg/kg（2μg/mL）was injected into the vein,while in the model and sham groups,saline 5 mL/kg was subcutaneously injected into the rat after the operation. At 2,12,24,48,72 hours after operation,6 rats were sacrificed and their hearts removed at one time point in a group. Enzyme linked immunosorbent assay（ELISA）was used to detect the content of AQP-1 and the levels of the TNF-α,IL-6 in the myocardial tissue homogenate at all time points,the myocardial tissue water content was detected by dry wet weight,and the correlations between AQP-1 and TNF-α,IL-6 and between AQP-1 and myocardial tissue water content were compared. Results From 2 hours after operation,the levels of the AQP-1,TNF-αand IL-6 in model group were significantly higher than those in the sham operation group;with prolongation of time,the level of AQP-1 and myocardial tissue water content were decreased, but the levels of TNF-α and IL-6 were persistently increased. From 2 hours after operation in dexmedetomidine group,all the above indexes except myocardial tissue water content at 72 hours after operation were significantly lower than those in the model group〔AQP-1（ng/g）：9.29±0.15 vs. 9.73±0.26,TNF-α（pg/g）：109.47±8.41 vs. 128.13±7.36,IL-6（pg/g）：232.95±20.56 vs. 279.71±22.24,myocardial tissue water content：（74.82±6.37）%vs.（75.62±6.39）%,all P〈0.05〕,but still higher than those of the sham operation group. The correlation analyses＆amp;nbsp;for the septic group showed that the change of AQP-1 was positively correlated to the myocardial water content in early stage（r=0.418,P=0.001）and later stage（r=0.235,P=0.022）,and the changes of the AQP-1 in early stage （at post-operative 2 hours）were positively correlated to the concentration changes of the cytokines TNF-α（r=0.235,P=0.021）and IL-6（r=0.345,P=0.003）,but in the later stage（at post-operative 72 hours）were negatively correlated with the changes of TNF-α（r=-0.408,P=0.037）and IL-6（r=-0.276,P=0.002）. Conclusions In the early stage of septic rats,there is obvious myocardial injury,resulting in the over expression of AQP-1 and the occurrence of myocardial edema,dexmedetomidine can play a role in myocardial protection in such rats and its mechanism is possibly related to the reduction of the expression of AQP-1 and the levels of inflammatory cytokines, and in turn the alleviation of myocardial cell edema.