Effects Of Short-term Hyperoxia On Pulmonary Surfactant Protein And Oxidoreductase In Rats

Objective Long-term hyperoxia can induce lung injury.General anesthesia is associated with a very high incidence of hyperoxaemia,despite it usually lasts for a relatively short period of time.It remains unclear whether short-term hyperoxia has an adverse impact on the lungs.The present study aimed to assess whether short-term mechanical ventilation with hyperoxia may cause lung injury in rats,and to detect changes in lung surfactant protein C and D,xanthine oxidase and glutathione reductase during mechanical ventilation.To explore the mechanism of lung tissue injury caused by hyperoxic mechanical ventilation.Methods 16 healthy adult male Sprague-Dawley rats were randomly divided into two groups:air mechanical ventilation group?group M,FiO₂=21%?and hyperoxia mechanical ventilation group?group H,FiO₂=90%?,8 rats in each group.Mechanical ventilation under different oxygen concentrations was given for 4 hours,and ECG was monitored.Carotid artery cannulation was carried out to monitor the blood gas parameters under mechanical ventilation for 2 hours and 4 hours,respectively,and the PaO₂/FiO₂ ratio was calculated.After 4 hours ventilation,the anterior lobe of right lung was taken to observe the pathological change and the injury level was scored.The middle lobe of right lung was prepared for making tissue homogenate,and the posterior lobe of right lung was used to measure the wet/dry weight?W/D?ratio.The bronchoalveolar lavage fluid?BALF?was prepared in left lung.The content of pulmonary surfactant protein C?SP-C?,pulmonary surfactant protein D?SP-D?,xanthine oxidase?XOD?and glutathion reductase?GR?were detected in lung tissue homogenate and BALF by ELISA.Results 1.Changes in lung tissues pathological:Under the microscope,the alveolar structure of group M was clear and basically intact,inflammatory cells in the lung interstitial and alveolar cavity were rare,the alveolar space was not wide,and the pulmonary vessels were not significantly dilated;part of the alveolar wall in group H was broken,and a small amount of alveolar fusion was mainly manifested It is the widening of the alveolar space,the congestion and expansion of the pulmonary blood vessels,and the exudation of inflammatory cells and fluids in the interstitial space and the alveolar cavity;2.Comparing with group M,the PaO₂,lung histopathology score,lung W/D and the content of XOD in group H were significantly increased?P<0.05?;3.Comparing with group M,the PaO₂/FiO₂ ratio,the content of SP-C,SP-D and GR in lung tissue homogenate and BALF were significantly decreased?P<0.05?.Conclusion 4 hours of hyperoxia ventilation in rats can cause lung injury histologically,and reduce the levels of SP-C,SP-D in lung tissue homogenate and BALF.The mechanism may be related to the increase of XOD level and the decrease of GR level.