Expression Of Aquaporin 5 In Lung Tissue In Rat Model Of Ventilator Induced Lung Injury

Objective To build the model of ventilator-induced lung injury (VILI) in rats.Methods Sixty specific-pathogen free (SPF) Sprague-Dawley rats were randomly assigned into 3 groups(n=20), then mechanically ventilated in the following manners after anesthesia and tracheotomy:group A, with spontaneous breath for 4h; group B, ventilated with tidal volume at 7ml/kg for 4h; group C, ventilated with tidal volume at 40ml/kg for 4h. Respiratory rate(RR) was set up to 40 bpm for the rats in groups of B and C. After ventilation, the rats were sacrificed and the left lungs were excised for determination of wet/dry (W/D) lung weight ratio. The right lungs were fixed by 4% formaldehyde solution and stained with hematoxylin and eosin for histopathology evaluation.Results (1) No substantial changes in morphology were observed between group A and group B. But the alveolar congestion, hemorrhage, infiltration of neutrophils in airspace and vessel wall and the thickness of alveolar wall were observed in group C, as well as the interstitial pulmonary edema and pneumorrhagia; (2) The W/D ratio was significantly higher in group C than in the groups A and B, while no difference was found between groups A and B in rats lung tissues.Conclusions With the data, we find that large tidal volume mechanical ventilation might cause the lung injury. And ventilation in this way can build the model of ventilator induced lung injury in rats. Objective To investigate the expression of aquaporin 5 in lung tissue in a rat model of ventilator induced lung injury.Methods Sixty specific-pathogen free (SPF) Sprague-Dawley rats were randomly assigned into 3 groups(n=20), then mechanically ventilated in the following manners after anesthesia and tracheotomy:group A, with spontaneous breath for 4h; group B, ventilated with tidal volume at 7ml/kg for 4h; group C, ventilated with tidal volume at 40ml/kg for 4h. The respiratory rate(RR) was set up to 40 bpm for the rats in groups of B and C. After ventilation, the rats were killed and lungs were removed to detect, Expression of mRNAs and the protein of aquaporin 5 were tested by immunohistochemistry, RT-PCR and Western blot.Results (1) The expressions of AQP5 in group C were significantly decreased than that in group A and group B. (2)The levels of AQP5 were in coincidence with the changes of lung injury.Conclusions The down regulation of AQP5 expressins in the rat's lung tissues in VILI. And these changes may be one of the mechanisms of VILI induced lung edema.