RESUMO
Objective To evaluate the effects of mechanical ventilation preconditioning on the expression of Rho-associated kinase 1 (ROCK1) in the lung tissue in a rat model of ventilator-induced lung injury.Methods Forty-eight male Sprague-Dawley, aged 8-12 weeks, weighing 250-300 g, were randomly assigned into 6 groups (n =8 each) using a random number table: control group (group C);normal mechanical ventilation group (group N);mechanical ventilation with large tidal volume (VT) group (group L);preconditioning with mechanical ventilation with different VT groups (P1, P2 and P3 groups).The animals were anesthetized with intraperitoneal pentobarbital sodium, and tracheostomized.In group C, the animals kept spontaneous breathing after intubation.In group N, the animals were mechanically ventilated for 3 h with the VT of 8-10 ml/kg.In group L, the animals were mechanically ventilated for 3 h with the VT of 40 ml/kg.In P1, P2 and P3 groups, the animals were mechanically ventilated for 30 min with the VT of 6-7, 20 and 30 ml/kg, respectively, and then were mechanically ventilated for 3 h with the VT of 40 ml/kg.The respiratory rate was 40 breaths/min, and inspiratory/expiratory ratio was 1 : 1.The animals were sacrificed at the end of ventilation.Broncho-alveolar lavage fluid was collected, and pulmonary permeability index (PPI) was calculated.Lungs were removed for examination of pathological changes which were scored,and for detection of the wet to dry lung weight ratio (W/D ratio), apoptosis in alveolar epithelial cells, and expression of ROCK1 (by immunohistochemistry and Western blot).Apoptosis index (AI) was calculated.Results Compared with group C, the pathological scores, W/D ratio, PPI and AI were significantly increased, and the expression of ROCK1 was up-regulated in L, P1, P2 and P3 groups (P＜0.05) , and no significant change was found in the parameters mentioned above in group N (P＞0.05).Compared with group L, the pathological scores, W/D ratio, PPI and AI were significantly decreased, and the expression of ROCK1 was down-regulated in group P1 (P＜0.05) , and no significant change was found in the parameters mentioned above in P2 and P3 groups (P＞0.05).Conclusion The mechanism by which mechanical ventilation preconditioning decreases ventilator-induced lung injury may be related to inhibition of the expression of ROCK1 in lung tissues of rats.
RESUMO
Objective To evaluate the effects of mechanical ventilation preconditioning on ventilatorinduced lung injury in rats.Methods Forty-eight healthy male Sprague-Dawley rats,weighing 250-300 g,were randomly assigned into 6 groups (n =8 each) using a random number table:control group (group C),normal ventilation group (group N),mechanical ventilation with large tidal volume (VT) group (group L) and mechanical ventilation preconditioning group (group P).The animals were anesthetized with intraperitoneal 2 ％ pentobarbital sodium 0.2 ml/100 g.Tracheal intubation was performed.In group C,the animals kept spontaneous breathing after intubation.In group N,the animals were mechanically ventilated for 3 h with the VT of 8-10 ml/kg.The animals were mechanically ventilated for 3 h with the VT of 40 ml/kg in group L.In group P,the animals were mechanically ventilated for 30 min with the VT of 6 ml/kg,and then were mechanically ventilated for 3 h with the VT of 40 ml/kg (RR 40 bpm,I:E =l:l,PET CO2 35-45 mmHg).The animals were sacrificed at the end of ventilation,and the lungs were removed for measurement of wet to dry lung weight ratio (W/D ratio) and cell apoptosis and for microscopic examination of the pathological changes of the lung and the lung injury was scored.The apoptosis.index was calculated.Results Compared with group C,the lung injury score,W/D ratio,and apoptosis index were significantly increased in L and P groups,and no significant change was found in the parameters mentioned above in group N.Compared with group L,the lung injury score,W/D ratio,and apoptosis index were significantly decreased in group P.Conclusion Mechanical ventilation preconditioning can reduce ventilator-induced lung injury in rats.