右美托咪定对机械通气相关性肺损伤大鼠肺组织ERK/Na+-K+-ATPase信号通路的影响

Effect of dexmedetomidine on ERK/Na+-K+-ATPase signaling pathway in lung tissues of rats with mechanical ventilation-induced lung injury

目的:评价右美托咪定对机械通气相关性肺损伤(VILI)大鼠细胞外信号调节激酶(ERK)/钠钾ATP酶(Na^+-K^+-ATPase)信号通路的影响。方法:清洁级健康雄性SD大鼠48只,体重270~320 g,4~5月龄,采用随机数字表法分为4组(n=12):对照组(C组)、VILI组(V组)、右美托咪定组(D组)和右美托咪定^+育亨宾(α2肾上腺素能受体阻断剂)组(DY组)。C组不行机械通气,自主呼吸空气4 h;V组机械通气(通气频率40次/min,V T 40 ml/kg,I∶E 1∶1,PEEP 0,FiO 221%)4 h;D组机械通气前20 min静脉输注右美托咪定5.0μg/kg,机械通气期间以5.0μg·kg-1·h-1的速率静脉输注,DY组给予右美托咪定前10 min时静脉注射育亨宾0.1 mg/kg,其余处理同D组。机械通气4 h时,取血标本和肺组织,测定肺湿/干重(W/D)比值与肺通透指数(LPI),观察肺组织病理学结果,测定肺泡内液体清除率(AFC)。采用Western blot法检测肺组织ERK、磷酸化ERK(p-ERK)、Na^+-K^+-ATPase的表达水平。结果:与C组比较,V组与DY组肺组织LPI和W/D比值升高,AFC降低,p-ERK表达上调,Na^+-K^+-ATPase表达下调(P<0.05),D组上述指标差异无统计学意义(P>0.05);与V组比较,D组肺组织LPI和W/D比值降低,AFC升高,p-ERK表达下调,Na^+-K^+-ATPase表达上调(P<0.05),肺组织病理学损伤减轻,DY组上述指标差异无统计学意义(P>0.05);与D组比较,DY组肺组织LPI和W/D比值升高,AFC降低,p-ERK表达上调,Na^+-K^+-ATPase表达下调(P<0.05),肺组织病理学损伤加重。结论:右美托咪定减轻大鼠VILI的机制可能与激动α2肾上腺素能受体,抑制ERK/Na^+-K^+-ATPase信号通路有关。

Objective To evaluate the effect of dexmedetomidine on the extracellular signal-regulated kinase(ERK)/sodium-potassium ATPase(Na^+-K^+-ATPase)signaing pathway in lung tissues of rats with mechanical ventilation-induced lung injury(VILI).Methods Forty-eighty clean-grade male Sprague-Dawley rats,weighing 270-320 g,aged 4-5 months,were divided into 4 groups(n=12 each)using a random number table method:control group(group C),VILI(alpha2-adrenergic receptor antagonist)group(group V),dexmedetomidine group(group D),and dexmedetomidine plus yohimbine group(group DY).Group C underwent no mechanical ventilation and breathed air spontaneously for 4 h.Mechanical ventilation(respiratory rate 40 breaths/min,tidal volume 40 ml/kg,inspiratory/expiratory ratio 1∶1,PEEP 0,fraction of inspired oxygen 21%)lasted 4 h in group V.Dexmedetomidine was infused intravenously in a dose of 5.0μg/kg at 20 min before ventilation followed by an infusion of 5.0μg·kg^-1·h^-1 throughout ventilation in group D.In group DY,yohimbine 0.1 mg/kg was injected intravenously at 10 min before dexmedetomidine,and the other treatments were similar to these previously described in group D.Blood samples and lung tissues were taken at 4 h of mechanical ventilation to determine the wet/dry weight ratio(W/D ratio),lung permeability index(LPI),alveolar fluid clearance rate(AFC),and expression of extracellular signal-regulated kinase(ERK),phosphorylated extracellular signal-regulated kinase(p-ERK),and Na^+-K^+-ATPase in lung tissues(by Western blot)and to observe pathological changes of lung tissues.Results Compared with group C,LPI and W/D ratio were significantly increased,AFC was decreased,p-ERK expression was up-regulated,and Na^+-K^+-ATPase expression was down-regulated in group V and group DY(P<0.05),and no significant change was found in the incidence of the parameters mentioned above in group D(P>0.05).Compared with group V,LPI and W/D ratio were significantly decreased,AFC was increased,p-ERK expression was down-regulated,Na^+-K^+-ATPase expression was up-regulated(P<0.05),and the pathological changes of lung tissues were significantly attenuated in group D,and no significant change was found in the incidence of the parameters mentioned above in group DY(P>0.05).Compared with group D,LPI and W/D ratio were significantly increased,AFC was decreased,p-ERK expression was up-regulated,Na^+-K^+-ATPase expression was down-regulated(P<0.05),and the pathological changes of lung tissues were accentuated in group DY.Conclusion The mechanism by which dexmedetomidine alleviates VILI may be related to activating alpha2-adrenergic receptors and inhibiting ERK/Na^+-K^+-ATPase signaling pathway in rats.